Arq (ARQ) 10-Q7 Nov 242024 Q3 Quarterly reportFinancial data

Company Profile

Cover Page

Cover Page - shares	9 Months Ended
Cover Page - shares	Sep. 30, 2024	Nov. 05, 2024
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2024
Document Transition Report	false
Entity File Number	001-37822
Entity Registrant Name	ARQ, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	27-5472457
Entity Address, Address Line One	8051 E. Maplewood Ave.
Entity Address, Address Line Two	Ste. 210
Entity Address, City or Town	Greenwood Village
Entity Address, State or Province	CO
Entity Address, Postal Zip Code	80111
City Area Code	720
Local Phone Number	598-3500
Title of 12(b) Security	Common stock, par value $0.001 per share
Trading Symbol	ARQ
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		42,032,086
Entity Central Index Key	0001515156
Current Fiscal Year End Date	--12-31
Amendment Flag	false
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q3

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Current assets:
Cash	$ 48,662	$ 45,361
Receivables, net	16,590	16,192
Inventories, net	18,487	19,693
Prepaid expenses and other current assets	3,530	5,215
Total current assets	87,269	86,461
Restricted cash, long-term	8,718	8,792
Property, plant and equipment, net of accumulated depreciation of $25,146 and $19,293, respectively	139,137	94,649
Other long-term assets, net	44,841	45,600
Total Assets	279,965	235,502
Current liabilities:
Accounts payable and accrued expenses	20,191	14,603
Current portion of debt obligations	2,324	2,653
Other current liabilities	7,671	5,792
Total current liabilities	30,186	23,048
Long-term debt obligations, net of current portion	17,634	18,274
Other long-term liabilities	14,029	15,780
Total Liabilities	61,849	57,102
Commitments and contingencies (Note 7)
Stockholders’ equity:
Preferred stock: par value of $0.001 per share, 50,000,000 shares authorized, none issued or outstanding	0	0
Common stock: par value of $0.001 per share, 100,000,000 shares authorized, 46,652,061 and 37,791,084 shares issued, and 42,033,915 and 33,172,938 shares outstanding at September 30, 2024 and December 31, 2023, respectively	47	38
Treasury stock, at cost: 4,618,146 and 4,618,146 shares as of September 30, 2024 and December 31, 2023, respectively	(47,692)	(47,692)
Additional paid-in capital	197,988	154,511
Retained earnings	67,773	71,543
Total Stockholders’ Equity	218,116	178,400
Total Liabilities and Stockholders’ Equity	$ 279,965	$ 235,502

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Statement of Financial Position [Abstract]
Accumulated depreciation	$ 25,146	$ 19,293
Preferred stock par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	50,000,000	50,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	100,000,000	100,000,000
Common stock, shares issued (in shares)	46,652,061	37,791,084
Common stock, shares outstanding (in shares)	42,033,915	33,172,938
Treasury stock (in shares)	4,618,146	4,618,146

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Revenues:
Revenue	$ 34,774	$ 29,829	$ 81,919	$ 71,079
Cost of revenue, exclusive of depreciation and amortization	21,339	20,707	52,279	53,218
Operating expenses:
Selling, general and administrative	8,058	8,297	22,735	27,574
Research and development	787	639	3,341	2,145
Depreciation, amortization, depletion and accretion	2,716	2,711	6,090	7,276
Gain on sale of assets	(154)	0	(154)	(2,695)
Total operating expenses	11,407	11,647	32,012	34,300
Operating income (loss)	2,028	(2,525)	(2,372)	(16,439)
Other (expense) income:
Earnings from equity method investments	127	412	127	1,512
Interest expense	(806)	(787)	(2,426)	(2,155)
Other	268	725	931	1,510
Total other (expense) income	(411)	350	(1,368)	867
Income (loss) before income taxes	1,617	(2,175)	(3,740)	(15,572)
Income tax (expense) benefit	0	0	(30)	33
Net income (loss)	$ 1,617	$ (2,175)	$ (3,770)	$ (15,539)
Income (loss) per common share (Note 1):
Basic (in dollars per share)	$ 0.04	$ (0.07)	$ (0.11)	$ (0.56)
Diluted (in dollars per share)	$ 0.04	$ (0.07)	$ (0.11)	$ (0.56)
Weighted-average number of common shares outstanding:
Basic (in shares)	36,124	31,807	34,085	27,894
Diluted (in shares)	37,442	31,807	34,085	27,894

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Treasury Stock	Additional Paid-in Capital	Retained Earnings
Beginning balance (in shares) at Dec. 31, 2022		23,788,319
Beginning balance at Dec. 31, 2022	$ 139,979	$ 24	$ (47,692)	$ 103,698	$ 83,949
Beginning balance (in shares) at Dec. 31, 2022			(4,618,146)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation (in shares)		483,242
Stock-based compensation	563			563
Issuance of common stock pursuant to Arq Acquisition, net of offering costs (in shares)		3,814,864
Issuance of common stock pursuant to Arq Acquisition, net of offering costs	12,437	$ 4		12,433
Issuance of common stock related to private placement transaction, net of offering costs (in shares)		3,842,315
Issuance of common stock related to private placement transaction, net of offering costs	15,220	$ 4		15,216
Issuance of warrant	826			826
Repurchase of common shares to satisfy minimum tax withholdings (in shares)		(74,104)
Repurchase of common shares to satisfy minimum tax withholdings	(146)			(146)
Preferred stock dividends declared on redeemable preferred stock	(157)				(157)
Net income (loss)	(7,508)				(7,508)
Ending balance (in shares) at Mar. 31, 2023		31,854,636
Ending balance at Mar. 31, 2023	161,214	$ 32	$ (47,692)	132,590	76,284
Ending balance (in shares) at Mar. 31, 2023			(4,618,146)
Beginning balance (in shares) at Dec. 31, 2022		23,788,319
Beginning balance at Dec. 31, 2022	139,979	$ 24	$ (47,692)	103,698	83,949
Beginning balance (in shares) at Dec. 31, 2022			(4,618,146)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(15,539)
Ending balance (in shares) at Sep. 30, 2023		37,799,053
Ending balance at Sep. 30, 2023	174,294	$ 38	$ (47,692)	153,695	68,253
Ending balance (in shares) at Sep. 30, 2023			(4,618,146)
Beginning balance (in shares) at Mar. 31, 2023		31,854,636
Beginning balance at Mar. 31, 2023	161,214	$ 32	$ (47,692)	132,590	76,284
Beginning balance (in shares) at Mar. 31, 2023			(4,618,146)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation (in shares)		(16,430)
Stock-based compensation	545			545
Issuance of common stock upon conversion of preferred stock (in shares)		5,362,926
Issuance of common stock upon conversion of preferred stock	18,926	$ 5		18,921
Repurchase of common shares to satisfy minimum tax withholdings (in shares)		(6,973)
Repurchase of common shares to satisfy minimum tax withholdings	(14)			(14)
Net income (loss)	(5,856)				(5,856)
Ending balance (in shares) at Jun. 30, 2023		37,194,159
Ending balance at Jun. 30, 2023	174,815	$ 37	$ (47,692)	152,042	70,428
Ending balance (in shares) at Jun. 30, 2023			(4,618,146)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation (in shares)		105,244
Stock-based compensation	702			702
Issuance of common stock to related party (in shares)		527,779
Issuance of common stock to related party		$ 1		999	1,000
Repurchase of common shares to satisfy minimum tax withholdings (in shares)		(28,129)
Repurchase of common shares to satisfy minimum tax withholdings	(48)			(48)
Net income (loss)	(2,175)
Ending balance (in shares) at Sep. 30, 2023		37,799,053
Ending balance at Sep. 30, 2023	174,294	$ 38	$ (47,692)	153,695	68,253
Ending balance (in shares) at Sep. 30, 2023			(4,618,146)
Beginning balance (in shares) at Dec. 31, 2023		37,791,084
Beginning balance at Dec. 31, 2023	$ 178,400	$ 38	$ (47,692)	154,511	71,543
Beginning balance (in shares) at Dec. 31, 2023	(4,618,146)		(4,618,146)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation (in shares)		81,253
Stock-based compensation	$ 782			782
Repurchase of common shares to satisfy minimum tax withholdings (in shares)		(104,163)
Repurchase of common shares to satisfy minimum tax withholdings	(599)			(599)
Exercise of warrant, net (in shares)		324,955
Net income (loss)	(3,419)				(3,419)
Ending balance (in shares) at Mar. 31, 2024		38,093,129
Ending balance at Mar. 31, 2024	175,164	$ 38	$ (47,692)	154,694	68,124
Ending balance (in shares) at Mar. 31, 2024			(4,618,146)
Beginning balance (in shares) at Dec. 31, 2023		37,791,084
Beginning balance at Dec. 31, 2023	$ 178,400	$ 38	$ (47,692)	154,511	71,543
Beginning balance (in shares) at Dec. 31, 2023	(4,618,146)		(4,618,146)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	$ (3,770)
Ending balance (in shares) at Sep. 30, 2024		46,652,061
Ending balance at Sep. 30, 2024	$ 218,116	$ 47	$ (47,692)	197,988	67,773
Ending balance (in shares) at Sep. 30, 2024	(4,618,146)		(4,618,146)
Beginning balance (in shares) at Mar. 31, 2024		38,093,129
Beginning balance at Mar. 31, 2024	$ 175,164	$ 38	$ (47,692)	154,694	68,124
Beginning balance (in shares) at Mar. 31, 2024			(4,618,146)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation (in shares)		(43,566)
Stock-based compensation	653			653
Issuance of common stock pursuant to Arq Acquisition, net of offering costs (in shares)		2,142,858
Issuance of common stock pursuant to Arq Acquisition, net of offering costs	14,951	$ 2		14,949
Issuance of common stock to related party (in shares)		422,221
Issuance of common stock to related party	800	$ 1		799
Net income (loss)	(1,968)				(1,968)
Ending balance (in shares) at Jun. 30, 2024		40,614,642
Ending balance at Jun. 30, 2024	189,600	$ 41	$ (47,692)	171,095	66,156
Ending balance (in shares) at Jun. 30, 2024			(4,618,146)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation (in shares)		580,826
Stock-based compensation	750	$ 1		749
Issuance of common stock in public offering, net of offering costs (in shares)		5,485,500
Issuance of common stock in public offering, net of offering costs	26,659	$ 5		26,654
Repurchase of common shares to satisfy minimum tax withholdings (in shares)		(28,907)
Repurchase of common shares to satisfy minimum tax withholdings	(510)			(510)
Net income (loss)	1,617				1,617
Ending balance (in shares) at Sep. 30, 2024		46,652,061
Ending balance at Sep. 30, 2024	$ 218,116	$ 47	$ (47,692)	$ 197,988	$ 67,773
Ending balance (in shares) at Sep. 30, 2024	(4,618,146)		(4,618,146)

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Cash flows from operating activities
Net loss	$ (3,770)	$ (15,539)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation, amortization, depletion and accretion	6,090	7,276
Stock-based compensation expense	2,185	1,810
Operating lease expense	1,518	2,061
Amortization of debt discount and debt issuance costs	450	395
Gain on sale of assets	(154)	(2,695)
Earnings from equity method investments	(127)	(1,512)
Other non-cash items, net	(113)	0
Changes in operating assets and liabilities:
Receivables and related party receivables	(399)	(359)
Prepaid expenses and other assets	1,812	3,595
Inventories, net	2,486	(811)
Other long-term assets, net	(1,366)	(3,646)
Accounts payable and accrued expenses	(2,611)	(12,033)
Other current liabilities	1,467	148
Operating lease liabilities	(1,255)	(140)
Other long-term liabilities	(945)	305
Net cash provided by (used in) operating activities	5,268	(21,145)
Cash flows from investing activities
Acquisition of property, plant, equipment, and intangible assets, net	(42,210)	(17,008)
Acquisition of mine development costs	(167)	(1,856)
Proceeds from sale of property and equipment	150	0
Distributions from equity method investees in excess of cumulative earnings	127	1,512
Cash and restricted cash acquired in business acquisition	0	2,225
Payment for disposal of Marshall Mine, LLC	0	(2,177)
Net cash used in investing activities	(42,100)	(17,304)
Cash flows from financing activities
Net proceeds from common stock issued in private placement transactions	14,951	15,220
Repurchase of common stock to satisfy tax withholdings	(1,109)	(208)
Principal payments on finance lease obligations	(838)	(855)
Principal payments on notes payable	(404)	(341)
Net proceeds from CFG Loan, related party, net of discount and issuance costs	0	8,522
Net cash provided by financing activities	40,059	23,338
Increase (decrease) in Cash and Restricted Cash	3,227	(15,111)
Cash and Restricted Cash, beginning of period	54,153	76,432
Cash and Restricted Cash, end of period	57,380	61,321
Supplemental disclosure of non-cash investing and financing activities:
Change in accrued purchases for property and equipment	8,199	255
Purchase of property and equipment through note payable	258	0
Equity issued as consideration for acquisition of business	0	31,206
Paid-in-kind dividend on Series A Preferred Stock	0	157
Public Offerings
Cash flows from financing activities
Net proceeds from common stock issued	26,659	0
Related Party
Cash flows from financing activities
Net proceeds from common stock issued	$ 800	$ 1,000

Organization and Basis of Prese

Organization and Basis of Presentation	9 Months Ended
Organization and Basis of Presentation	Sep. 30, 2024
Accounting Policies [Abstract]
Organization and Basis of Presentation	Organization and Basis of Presentation Arq, Inc. ("Arq" or the "Company"), is an environmental technology company that is principally engaged in the sale of consumable air, water, and soil treatment solutions including activated carbon ("AC") and chemical technologies. The Company's proprietary AC products enable customers to reduce air, water, and soil contaminants, including mercury, per and polyfluoroalkyl substances ("PFAS") and other pollutants, to help our customers meet the challenges of existing and pending air quality and water regulations. The Company manufactures and sells AC and other chemicals used to capture and remove contaminants for coal-fired power generation, industrial, municipal water and air, water, and soil treatment and remediation markets (collectively, the advanced purification technologies or "APT" market). The Company’s primary products are comprised of AC, which is produced from a variety of carbonaceous raw materials. The Company’s AC products include both powdered activated carbon ("PAC") and granular activated carbon ("GAC"). Additionally, the Company owns the Five Forks Mine, a lignite mine that currently supplies the primary raw material for the manufacturing of the Company’s products. The Company, formerly known as Advanced Emissions Solutions, Inc., is a Delaware corporation with its principal office located in Greenwood Village, Colorado, manufacturing, mining and logistics operations located in Louisiana and coal waste recovery and manufacturing operations located in Kentucky. In February 2023, the Company acquired 100% of the equity of the subsidiaries of Arq Limited (the "Arq Acquisition," and hereafter the Arq Limited subsidiaries are referred to as "Legacy Arq") to secure access to a feedstock, a manufacturing facility and certain patented processes as a means to manufacture additional GAC products for sale into the APT and other markets. With the Arq Acquisition, the Company now controls bituminous coal waste reserves and owns a manufacturing facility, both located in Corbin, Kentucky (the "Corbin Facility"), and a process to recover and purify the bituminous coal waste for sale or further conversion to GAC products. Using the Corbin Facility's manufacturing process, the Company is converting bituminous coal waste into a purified, microfine carbon powder known as Arq powder TM ("Arq Powder"). See further discussion of the Arq Acquisition in Note 2. Basis of Presentation The accompanying Condensed Consolidated Financial Statements of Arq are unaudited and have been prepared in conformity with accounting principles generally accepted in the United States ("U.S. GAAP") and with Article 10 of Regulation S-X of the Securities and Exchange Commission. In compliance with those instructions, certain information and footnote disclosures normally included in annual consolidated financial statements prepared in accordance with U.S. GAAP have been condensed or omitted. The unaudited Condensed Consolidated Financial Statements of Arq in this quarterly report ("Quarterly Report") are presented on a consolidated basis and include Arq and its wholly-owned subsidiaries (collectively, the "Company"). Also included within the unaudited Condensed Consolidated Financial Statements are the Company's unconsolidated equity investments, Tinuum Group and Tinuum Services, which are accounted for under the equity method of accounting, and Highview Enterprises Limited (the "Highview Investment"), which is accounted for in accordance with U.S. GAAP applicable to equity investments that do not qualify for the equity method of accounting. Results of operations and cash flows for the interim periods are not necessarily indicative of the results that may be expected for the entire year. All significant intercompany transactions and accounts were eliminated in consolidation for all periods presented in this Quarterly Report. In the opinion of management, these Condensed Consolidated Financial Statements include all normal and recurring adjustments considered necessary for a fair presentation of the results of operations, financial position, stockholders' equity and cash flows for the interim periods presented. These Condensed Consolidated Financial Statements should be read in conjunction with the Company’s Annual Report on Form 10-K for the year ended December 31, 2023 (the "2023 Form 10-K"). Significant accounting policies disclosed therein have not changed. Earnings (Loss) Per Share Basic earnings (loss) per share is computed using the weighted-average number of shares of the Company's common stock outstanding during the reporting period. Diluted earnings (loss) per share is computed in a manner consistent with that of basic earnings per share, while considering other potentially dilutive securities. For the three and nine months ended September 30, 2024 and September 30, 2023, potentially dilutive securities consist of unvested restricted stock awards ("RSAs"), stock options and contingent performance stock units ("PSUs"). The following table sets forth the calculations of basic and diluted loss per share: Three Months Ended September 30, Nine Months Ended September 30, (in thousands, except per share amounts) 2024 2023 2024 2023 Net income (loss) $ 1,617 $ (2,175) $ (3,770) $ (15,539) Less: Dividends declared on redeemable preferred stock — — — 157 Income (loss) attributable to common stockholders $ 1,617 $ (2,175) $ (3,770) $ (15,696) Basic weighted-average common shares outstanding 36,124 31,807 34,085 27,894 Add: dilutive effect of equity instruments 1,318 — — — Diluted weighted-average shares outstanding 37,442 31,807 34,085 27,894 Earnings (loss) per share - basic $ 0.04 $ (0.07) $ (0.11) $ (0.56) Earnings (loss) per share - diluted $ 0.04 $ (0.07) $ (0.11) $ (0.56) For the three and nine months ended September 30, 2024 and 2023, potentially dilutive securities of 0.3 million and 2.3 million and 2.5 million and 1.4 million shares of common stock, respectively, are outstanding but are not included in the calculation of diluted net loss per share because the effect would be anti-dilutive. Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. There have been no changes in the Company's critical accounting estimates from those that were disclosed in the 2023 Form 10-K. Actual results could differ from these estimates. Fair value measurements The carrying amounts of our cash, restricted cash, accounts receivable, accounts payable and other current liabilities approximate fair value as recorded due to the short-term nature of these instruments. Seasonality The timing of the sale of consumable products is dependent upon several factors. Power generation is weather dependent, with electricity and steam production varying in response to heating and cooling demands. As a result, the Company's revenue is generally higher in our first and third fiscal quarters during the warmer and colder months of the year, respectively. Abnormally high and low temperatures during the summer and winter months, respectively, may significantly increase coal consumption for electricity generation and cause increased impurities within various municipalities' water sources, and thus increase the demand for the Company's products. Additionally, power generating units routinely schedule maintenance outages in the spring and/or fall depending on the operation of their boilers. During the period in which an outage may occur, which may range from one week to over a month, the Company's product sales may decrease. Also, the Company's revenue and sales volumes are highly dependent upon the level of coal consumption at coal-fired power plants, which in turn is significantly affected by the prices of competing power generation sources, such as natural gas and renewables. During periods of low natural gas prices, natural gas provides a competitive alternative to coal-fired power generation and therefore, coal consumption for power generation may be reduced, which in turn reduces the demand for the Company's products. In contrast, during periods of higher prices for competing power generation sources, coal consumption generally increases, which generally increases demand for the Company's products. In the sale of water purification products, demand is driven largely from municipal water treatment facilities. Depending on weather conditions and other environmental factors, the summer months historically have the highest demand for the Company's products used in water treatment. One of the major uses for PAC is for the treatment of taste and odor episodes caused by increased degradation of organic contaminants and natural materials in water that occurs during the summer months. Additionally, the rainy season generally results in more demand from water municipalities due to rain run-offs and contaminant dilution. Reclassifications Certain balances have been reclassified from the prior year to conform to the current year presentation. Such reclassifications had no effect on the Company’s results of operations or financial position in any of the periods presented. New Accounting Standards In November 2023, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures ("ASU 2023-07"). ASU 2023-07 is intended to improve reportable segment disclosures and to enhance disclosures of reportable segment expenses. This ASU is effective for annual reporting periods beginning after December 15, 2023, and interim periods within fiscal years beginning after December 15, 2024. Early adoption is permitted. ASU 2023-07 is required to be applied retrospectively to all prior periods presented in the financial statements. Because the amendments do not change the methodology for the identification of operating segments, the aggregation of those operating segments or the application of the quantitative thresholds to determine reportable segments, we do not expect the guidance to have a material effect on our financial position or results of operations. In December 2023, the FASB issued Accounting Standards Update 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures . ("ASU 2023-09"). ASU 2023-09 requires entities to disclose: (1) consistent categories and greater disaggregation of information in the rate reconciliation and (2) the disaggregation of income taxes paid by jurisdiction. This update also makes several other changes to the income tax disclosure requirements. For public entities, the amendments in ASU 2023-09 are effective for fiscal years beginning after December 15, 2024, with early adoption permitted, and is required to be applied prospectively, but retrospective application is permitted. The Company is currently evaluating the impact of ASU 2023-09 on its income tax disclosures.

Arq Acquisition

Arq Acquisition	9 Months Ended
Arq Acquisition	Sep. 30, 2024
Business Combination, Asset Acquisition, and Joint Venture Formation [Abstract]
Arq Acquisition	Arq Acquisition On February 1, 2023 (the "Acquisition Date"), the Company entered into a securities purchase agreement (the "Purchase Agreement") with Arq Limited ("Arq Ltd.") to acquire 100% of the equity of Legacy Arq in exchange for consideration (the "Purchase Consideration") totaling $31.2 million, and consisting of (i) 3,814,864 shares of the Company's common stock and (ii) 5,294,462 shares of the Company's Series A Convertible Preferred Stock, par value $0.001 per share (the "Series A Preferred Stock" or the "Preferred Shares"). The Company accounted for the Arq Acquisition as an acquisition of a business, and the total Purchase Consideration of $31.2 million was allocated to the acquired assets and assumed liabilities of Legacy Arq based on their estimated fair values as of the Acquisition Date. The Purchase Consideration was comprised of the fair values as of the Acquisition Date of 3,814,864 shares of the Company's common stock, valued at $12.4 million, and 5,294,462 Preferred Shares, valued at $18.8 million. The Company also incurred $8.7 million in acquisition-related costs, which were expensed as incurred during fiscal years 2022 and 2023 and included in the "Selling, general and administrative" line item in the Statements of Operations for those years. Legacy Arq's principal location is in Corbin, Kentucky where it operates the Corbin Facility, which processes bituminous coal waste into Arq Powder. Arq Powder can be used in high value applications, such as for a raw material to produce GAC products or as an additive in other applications. With the completion of the Arq Acquisition, the Company intends to use Arq Powder as a feedstock to produce high-quality AC for use in water and air purification markets. The Company expects to begin using Arq Powder to produce GAC products during the first quarter of 2025. The following table provides the final purchase price allocation to the assets acquired and liabilities assumed as of the Acquisition Date: (in thousands) Purchase Price Allocation Fair value of assets acquired: Cash $ 1,411 Prepaid expenses and other current assets 2,229 Restricted cash, long-term 814 Property, plant and equipment, net 39,159 Other long-term assets, net 11,717 Amount attributable to assets acquired 55,330 Fair Value of liabilities assumed: Accounts payable and accrued expenses 9,806 Current portion of long-term debt 494 Other current liabilities 103 Long-term debt, net of current portion 9,199 Other long-term liabilities 4,523 Amount attributable to liabilities assumed 24,125 Net assets acquired $ 31,205 The following represents the intangible asset identified as part of the Arq Acquisition and which is included in "Other long-term-assets, net" in the table above: (in thousands) Amount Weighted Average Useful Life (years) Developed technology $ 7,700 20 Series A Preferred Stock In connection with the issuance of the Series A Preferred Stock pursuant to the Purchase Agreement, the Company filed the Certificate of Designations of Preferred Stock for the Series A Preferred Stock (the "Certificate of Designations") with the Secretary of State of the State of Delaware. Under the Certificate of Designations, 8.9 million preferred shares were designated as Series A Preferred Stock. Of the total Preferred Shares issued in the Arq Acquisition, 833,914 were held in escrow (the "Escrow Shares") based on a contingent redemption feature. The fair value of the Preferred Shares issued was determined to be $3.46 per Preferred Share on the Acquisition Date plus the value of the contingent redemption feature related to the Escrow Shares. The Escrow Shares were converted into shares of the Company's common stock (the "Escrow Common Shares") on the Conversion Date, as defined below. Pursuant to the terms of the Series A Preferred Stock, on March 31, 2023, the Company declared a dividend of 68,464 Series A paid-in kind shares (the "PIK Dividend") with respect to the accrued dividends on the Preferred Shares for the first quarter of 2023. The PIK Dividend was recorded at the estimated fair value of $0.2 million as of March 31, 2023 and was paid on April 21, 2023. On June 13, 2023 (the "Conversion Date"), the Company's stockholders approved the conversion of all of the outstanding shares of Series A Preferred Stock, including the Escrow Shares, and the corresponding issuance of shares of the Company's common stock. Upon such approval, each outstanding share of Series A Preferred Stock was automatically converted into the number of shares of the Company's common stock described below. Each share of Series A Preferred Stock was deemed to have an original issue price of $4.00 per share (the "Original Issue Amount"). The number of shares of the Company's common stock issued upon conversion of each share of Series A Preferred Stock was equal to the product of (i) the sum of (A) the Original Issue Amount plus (B) an amount equal to the cumulative amount of the accrued and unpaid dividends on such share at such time divided by (ii) the Original Issue Amount, subject to adjustment. The Escrow Common Shares were withheld pending a determination by the United States Internal Revenue Service (the "IRS") that no tax withholding was required by Arq Ltd. on the Purchase Consideration issued to Arq Ltd. (the "Arq Ltd. Tax Liability"). The Company estimated the fair value of the potential Arq Ltd. Tax Liability at $3.3 million. In the event that the IRS determined that no withholding was required by Arq Ltd., all of the Escrow Common Shares would be released and delivered to Arq Ltd. In the event that the IRS determined that any amount of withholding was required by Arq Ltd., the Company agreed to redeem a sufficient number of Escrow Common Shares to fund the required payment to the IRS, and that number of Escrow Common Shares would be returned to the Company. In April 2024, the Company received notice from Arq Ltd. that the IRS had approved its filing for no tax withholding on the Purchase Consideration. Accordingly, in April 2024, the Company instructed its stock transfer agent to release the Escrow Common Shares to the Arq Ltd. stockholders. Equity Financing On February 1, 2023, and pursuant to the Arq Acquisition, the Company entered into Subscription Agreements (the "Subscription Agreements") with certain persons (the "Subscribers"), which included existing shareholders of Arq Ltd., three of which were appointed to the Company's Board of Directors (the "Board"), pursuant to which the Subscribers subscribed for and purchased shares of the Company's common stock for an aggregate purchase price of $15.4 million and at a price per share of $4.00 (such transaction, the "PIPE Investment"). Unaudited Pro Forma Financial Information The following represents the pro forma effects for the nine months ended September 30, 2023 of the Arq Acquisition as if it had occurred on January 1, 2023. The pro forma net loss for the period presented has been calculated after applying the Company’s accounting policies in effect for that period. In addition, pro forma net loss includes: (1) a decrease in depreciation and amortization of $0.2 million resulting from fair value adjustments to Property, plant, equipment; (2) an increase in amortization of $0.1 million resulting from fair value adjustments to intangible assets; and (3) increases to interest expense of $0.2 million for: (a) the issuance of the CFG Loan (as defined below) including stated interest and the amortization of the CFG Loan's discount and issuance costs and (b) amortization of debt discount related to a fair value adjustment to the CTB Loan (as defined below), which was assumed by the Company on the Acquisition Date; together with the income tax effects on (1) through (3). Since Legacy Arq had no revenues for the nine months ended September 30, 2023, pro forma revenues are the same as the Company's reported revenues for that period. (in thousands) Nine Months Ended September 30, 2023 Revenues $ 71,079 Net loss $ (12,100)

Revenues

Revenues	9 Months Ended
Revenues	Sep. 30, 2024
Revenue from Contract with Customer [Abstract]
Revenues	Revenue For the three and nine months ended September 30, 2024 and 2023, all material performance obligations related to revenue recognized were satisfied at a point in time. For the three and nine months ended September 30, 2024, approximately 5% and 7%, respectively, of total revenue was generated in Canada, and all other revenues were generated in the U.S. For the three and nine months ended September 30, 2023, 7% and 8%, respectively, of total revenue was generated in Canada, and all other revenues were generated in the U.S. Trade receivables Trade receivables represent an unconditional right to consideration in exchange for goods or services transferred to a customer. The Company invoices its customers in accordance with the terms of the contract. Credit terms are generally net 30 - 45 days from the date of invoice. The timing between the satisfaction of performance obligations and when payment is due from the customer is generally not significant. Contract assets Contract assets are comprised of unbilled receivables from customers and are included in Receivables, net in the Consolidated Balance Sheets. Unbilled receivables represent a conditional right to consideration in exchange for goods or services transferred to a customer. The following table shows the components of the Company's Receivables, net: As of (in thousands) September 30, 2024 December 31, 2023 Trade and other receivables, net $ 16,465 $ 11,330 Unbilled receivables 125 4,862 Receivables, net $ 16,590 $ 16,192 Contract liabilities Contract liabilities are comprised of deferred revenue, which represents an obligation to transfer goods or services to a customer for which the Company has received consideration from the customer and, if deliverable within one year or less, are included in "Other current liabilities" in the Condensed Consolidated Balance Sheets and, if deliverable outside of one year, are included in "Other long-term liabilities" in the Condensed Consolidated Balance Sheets.

Inventories, net

Inventories, net	9 Months Ended
Inventories, net	Sep. 30, 2024
Inventory Disclosure [Abstract]
Inventories, net	Inventories, net The following table summarizes the Company's inventories as of September 30, 2024 and December 31, 2023: As of (in thousands) September 30, 2024 December 31, 2023 Product inventory, net $ 11,498 $ 9,524 Raw material inventory 6,989 10,169 Total inventories, net $ 18,487 $ 19,693

Debt Obligations

Debt Obligations	9 Months Ended
Debt Obligations	Sep. 30, 2024
Debt Disclosure [Abstract]
Debt Obligations	Debt Obligations As of (in thousands) September 30, 2024 December 31, 2023 CFG Loan due February 2027, related party $ 10,000 $ 10,000 CTB Loan due January 2036 9,123 9,527 Finance lease obligations 2,192 3,465 Other 258 — 21,573 22,992 Unamortized debt discounts (623) (815) Unamortized debt issuance costs (992) (1,250) 19,958 20,927 Less: Current maturities (2,324) (2,653) Total long-term debt obligations $ 17,634 $ 18,274 CFG Loan As required under the Purchase Agreement, and on February 1, 2023 (the "Closing Date"), the Company, as borrower, certain of its subsidiaries, as guarantors, and CF Global ("CFG"), a related party, as administrative agent and lender, entered into a term loan (the "CFG Loan") in the amount of $10.0 million, less original issue discount ("OID") of $0.2 million, upon execution of a Term Loan and Security Agreement (the "CFG Loan Agreement"). The Company received net cash proceeds of $8.5 million after deducting the OID and debt issuance costs of $1.3 million. One of the Company's directors is a principal with CFG. The CFG Loan Agreement also required the issuance of a warrant (the "Warrant") to CFG to purchase 325,457 shares of the Company's common stock at an exercise price of $0.01 per share. The Warrant had a term of 7 years and contained a cashless exercise provision. On March 29, 2024, CFG exercised the warrant in full and the Company issued CFG 324,955 shares of its common stock, net of shares representing the exercise price of the warrant. The CFG Loan matures on February 1, 2027 and bears interest at a rate equal to either (a) Adjusted Term SOFR (subject to a 1.00% floor and a cap of 2.00%) plus a margin of 9.00% paid in cash and 5.00% paid in kind or (b) Base Rate (as defined in the CFG Loan Agreement) plus a margin of 8.00% paid in cash and 5.00% paid in kind, which interest on the CFG Loan in each case shall be payable (or capitalized, in the case of in kind interest) quarterly in arrears. The Company may prepay the CFG Loan at any time subject to the following prepayment premium: (i) prior to the twelve month anniversary of the Closing Date, the Make-Whole Amount (as defined below), (ii) thereafter but prior to the thirty-six month anniversary of the Closing Date, 2.00% of the outstanding principal amount of the CFG Loan being repaid or prepaid or (iii) thereafter until the maturity date, 1.00% of the outstanding principal amount of the CFG Loan being repaid or prepaid. The "Make-Whole Amount," with respect to any repayment or prepayment, is (i) an amount equal to all required interest payable (except for currently accrued and unpaid interest) on the aggregate principal amount of the CFG Loan subject to such prepayment or repayment from the date of such prepayment or repayment through but excluding the date that is the first anniversary of the Closing Date calculated using an interest rate equal to (x) Adjusted Term SOFR for an interest period of one month in effect on the third U.S. Government Securities Business Day prior to such prepayment or repayment plus (y) 14.00% per annum and assuming all interest was paid in cash, plus (ii) a prepayment premium of 2.00% on the aggregate principal amount of the CFG Loan subject to such prepayment or repayment. The CFG Loan is secured by substantially all of the assets of the Company and its subsidiaries (including those acquired in the Acquisition, but excluding those pledged as collateral (the "CTB Loan Assets") under the CTB Loan, as defined and described below), subject to customary exceptions. The CFG Loan Agreement includes, among others, the following covenants: (1) a minimum unrestricted balance of $5.0 million as of the end of each fiscal quarter; (2) (x) as of December 31, 2024, for the fiscal year then ended, the Company must have a minimum annual revenue, on a consolidated basis, of $85.0 million and (y) for any fiscal year thereafter, the Company must have a minimum annual revenue, on a consolidated basis, of $100.0 million; (3) (x) as of December 31, 2024, for the fiscal year then ended, the Company must have a minimum Consolidated EBITDA of $3.0 million and (y) for any fiscal year thereafter, the Company must have a minimum Consolidated EBITDA of $16.0 million; and (4) during a period including a LTV Trigger Event (as defined in the CFG Loan Agreement), the Company must not exceed a loan to value ratio of 0.40:1.00 (based on the consolidated total assets of the Company and its subsidiaries, but excluding the CTB Loan Assets). The Company allocated the cash proceeds of the CFG Loan to both the CFG Loan and the Warrant based on their relative fair values. The amount allocated to the Warrant was recorded as a debt discount and is amortized to interest expense over the term of the CFG Loan. The standalone fair value of the CFG Loan was based on a comparison of borrowings and associated credit ratings consistent with those of the Company. As the Warrant was exercisable for $0.01 per share, the fair value was deemed to be equal to the fair value of the underlying shares, and accordingly, the fair value of the Warrant was determined as the number of shares issuable from the exercise of the Warrant (based on 1.0% of post-transaction fully diluted share capital, as defined in the Purchase Agreement) multiplied by the closing share price of the Company's common stock on the Acquisition Date. CTB Loan Upon completion of the Arq Acquisition, the Company assumed a term loan (the "CTB Loan") held by certain Arq subsidiaries as set out in the CTB Loan (the "Arq Subsidiaries") with a financial institution ("CTB") in the principal amount of $10.0 million. The Company recorded the CTB Loan on the Acquisition Date at its estimated fair value of $9.7 million, with the difference of $0.3 million between the estimated fair value and the principal amount recorded as a debt discount and recognized as interest expense over the term of the CTB Loan. The CTB Loan was originally entered into on January 27, 2021 and is comprised of two promissory notes (the "Notes"): (1) "Note A" in the principal amount of $8.0 million, which is guaranteed by the U.S. Department of Agriculture; and (2) "Note B" in the principal amount of $2.0 million. The Notes mature on January 27, 2036 and bear interest at 6.0% per annum through January 2026 and at the prime rate plus 2.75% thereafter. The Company is required to make combined interest and principal payments monthly in the fixed amount of $0.1 million. Interest is computed and payable on the outstanding principal as of the end of the prior month and the balance of the fixed monthly payment amount is applied to the outstanding principal. The Notes carry a prepayment penalty of 3.0% of the outstanding principal if paid prior to January 27, 2024, 2.0% of the outstanding principal if paid prior to January 27, 2025 and 1.0% of the outstanding principal if paid prior to January 27, 2026. Thereafter, the Notes may be prepaid without penalty. On June 2, 2023 (the "Amendment Date"), certain of the Arq Subsidiaries, which included Corbin Project LLC, Arq Projects Holding Company LLC, Arq St. Rose LLC, Arq Corbin LLC and Arq Corbin Land LLC (collectively, the "Borrowers") and CTB entered into a loan modification agreement (the "CTB Loan Modification Agreement") to the CTB Loan, as amended by that certain letter agreement by and among CTB and Borrowers dated January 21, 2022, and as otherwise amended, modified and/or extended by the parties from time to time (collectively, the "CTB Loan Agreement"). As consideration for CTB entering into the CTB Loan Modification Agreement, the Borrowers agreed to pay a fee of $50,000 plus additional fees incurred by CTB and were required to deposit an additional $0.7 million into a deposit account (the "Interest Reserve Account" as defined in the CTB Loan Agreement), where the Interest Reserve Account is held as collateral by CTB. The Borrowers may withdraw funds from the Interest Reserve Account beginning one year from the Amendment Date, subject to restrictions as stated in the CTB Loan Modification Agreement. The CTB Loan Modification Agreement clarified and modified certain terms under the CTB Loan Agreement. The principal clarifications and modifications in effect are as follows: • The Borrowers are not entitled to any further disbursements of proceeds under those promissory notes described in the CTB Loan Modification Agreement; • CTB agreed to waive certain required financial covenants required as of December 31, 2023; and • CTB is authorized to amend and/or amend and restate its then-current security instruments to include additional collateral represented by the Borrowers' acquisition of any equipment or other fixed and/or operating assets in which CTB does not then hold a lien or security interest. The CTB Loan is secured by substantially all assets of the Borrowers and includes among others, the following covenants with respect to the Borrowers, which are tested annually (Capitalized terms are defined in the CTB Loan Agreement): (a) Total Indebtedness to Net Worth greater than 4 to 1; (b) Balance Sheet Equity greater than or equal to 20% of the book value of all assets of the Borrowers; (c) (i) net income plus interest, taxes, depreciation and amortization divided by (ii) interest expense plus current maturities on long-term debt greater than or equal to 1.25 to 1. The carrying values of both the CFG Loan and the CTB Loan approximate their fair values as both instruments bear interest at rates indexed to market rates for similar instruments.

Leases

Leases	9 Months Ended
Leases	Sep. 30, 2024
Leases [Abstract]
Leases	Leases The Company's operating and finance lease right-of-use ("ROU") assets and liabilities as of September 30, 2024 and December 31, 2023 consisted of the following items (in thousands): As of Leases September 30, 2024 December 31, 2023 Operating Leases Operating lease right-of-use assets, net of accumulated amortization (1) $ 9,331 $ 10,592 Operating lease obligations, current $ 1,991 $ 1,944 Long-term operating lease obligations 7,569 8,870 Total operating lease obligation $ 9,560 $ 10,814 Finance Leases Finance lease right-of-use assets, net of accumulated amortization (2) $ 975 $ 1,694 Finance lease obligations, current $ 1,699 $ 2,131 Long-term finance lease obligations 493 1,334 Total finance lease obligations $ 2,192 $ 3,465 (1) Operating lease ROU assets are reported net of accumulated amortization of $4.0 million and $5.1 million as of September 30, 2024 and December 31, 2023, respectively. (2) Finance lease ROU assets are reported net of accumulated amortization of $3.0 million and $2.7 million as of September 30, 2024 and December 31, 2023, respectively. Operating leases ROU assets under operating leases and operating lease liabilities are included in the " Other long-term assets Other current liabilities Other long-term liabilities Lease expense for operating leases for the three and nine months ended September 30, 2024 was $1.3 million and $4.0 million, respectively, of which $0.9 million and $2.9 million, respectively, is included in the "Cost of revenue, exclusive of depreciation and amortization" line item, and $0.4 million and $1.1 million, respectively, is included in the "Selling, general and administrative" line item in the Condensed Consolidated Statements of Operations for those periods. Lease expense for operating leases for the three and nine months ended September 30, 2023 was $1.6 million and $4.3 million, respectively, of which $1.2 million and $3.4 million, respectively, is included in the "Cost of revenue, exclusive of depreciation and amortization" line item, and $0.4 million and $0.9 million, respectively, is included in the "Selling, general and administrative" line item in the Condensed Consolidated Statements of Operations for those periods. Finance leases ROU assets under finance leases are included in the "Property, plant and equipment" line item in the Condensed Consolidated Balance Sheets as of September 30, 2024 and December 31, 2023. Interest expense related to finance lease obligations and amortization of ROU assets under finance leases are included in the "Interest expense" and "Depreciation, amortization, depletion and accretion" line items, respectively, in the Condensed Consolidated Statements of Operations for the three and nine months ended September 30, 2024 and 2023. Lease financial information as of and for the three and nine months ended September 30, 2024 and 2023 is provided in the following table: Three Months Ended September 30, Nine Months Ended September 30, (in thousands) 2024 2023 2024 2023 Finance lease cost: Amortization of right-of-use assets $ 46 $ 215 $ 466 $ 661 Interest on lease liabilities 50 59 149 190 Operating lease cost 773 1,000 2,448 3,017 Short-term lease cost 437 481 1,220 1,132 Variable lease cost (1) 104 81 313 145 Total lease cost $ 1,410 $ 1,836 $ 4,596 $ 5,145 Other Information: Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows for finance leases $ 149 $ 190 Operating cash flows for operating leases $ 1,512 $ 2,087 Financing cash flows for finance leases $ 838 $ 855 Right-of-use assets obtained in exchange for new finance lease liabilities $ — $ — Right-of-use assets obtained in exchange for new operating lease liabilities $ 257 $ 1,947 Weighted-average remaining lease term - finance leases 1.2 years 2.1 years Weighted-average remaining lease term - operating leases 7.4 years 7.8 years Weighted-average discount rate - finance leases 6.4 % 5.9 % Weighted-average discount rate - operating leases 12.4 % 12.7 % (1) Primarily includes common area maintenance, property taxes and insurance payable to lessors.
Leases	Leases The Company's operating and finance lease right-of-use ("ROU") assets and liabilities as of September 30, 2024 and December 31, 2023 consisted of the following items (in thousands): As of Leases September 30, 2024 December 31, 2023 Operating Leases Operating lease right-of-use assets, net of accumulated amortization (1) $ 9,331 $ 10,592 Operating lease obligations, current $ 1,991 $ 1,944 Long-term operating lease obligations 7,569 8,870 Total operating lease obligation $ 9,560 $ 10,814 Finance Leases Finance lease right-of-use assets, net of accumulated amortization (2) $ 975 $ 1,694 Finance lease obligations, current $ 1,699 $ 2,131 Long-term finance lease obligations 493 1,334 Total finance lease obligations $ 2,192 $ 3,465 (1) Operating lease ROU assets are reported net of accumulated amortization of $4.0 million and $5.1 million as of September 30, 2024 and December 31, 2023, respectively. (2) Finance lease ROU assets are reported net of accumulated amortization of $3.0 million and $2.7 million as of September 30, 2024 and December 31, 2023, respectively. Operating leases ROU assets under operating leases and operating lease liabilities are included in the " Other long-term assets Other current liabilities Other long-term liabilities Lease expense for operating leases for the three and nine months ended September 30, 2024 was $1.3 million and $4.0 million, respectively, of which $0.9 million and $2.9 million, respectively, is included in the "Cost of revenue, exclusive of depreciation and amortization" line item, and $0.4 million and $1.1 million, respectively, is included in the "Selling, general and administrative" line item in the Condensed Consolidated Statements of Operations for those periods. Lease expense for operating leases for the three and nine months ended September 30, 2023 was $1.6 million and $4.3 million, respectively, of which $1.2 million and $3.4 million, respectively, is included in the "Cost of revenue, exclusive of depreciation and amortization" line item, and $0.4 million and $0.9 million, respectively, is included in the "Selling, general and administrative" line item in the Condensed Consolidated Statements of Operations for those periods. Finance leases ROU assets under finance leases are included in the "Property, plant and equipment" line item in the Condensed Consolidated Balance Sheets as of September 30, 2024 and December 31, 2023. Interest expense related to finance lease obligations and amortization of ROU assets under finance leases are included in the "Interest expense" and "Depreciation, amortization, depletion and accretion" line items, respectively, in the Condensed Consolidated Statements of Operations for the three and nine months ended September 30, 2024 and 2023. Lease financial information as of and for the three and nine months ended September 30, 2024 and 2023 is provided in the following table: Three Months Ended September 30, Nine Months Ended September 30, (in thousands) 2024 2023 2024 2023 Finance lease cost: Amortization of right-of-use assets $ 46 $ 215 $ 466 $ 661 Interest on lease liabilities 50 59 149 190 Operating lease cost 773 1,000 2,448 3,017 Short-term lease cost 437 481 1,220 1,132 Variable lease cost (1) 104 81 313 145 Total lease cost $ 1,410 $ 1,836 $ 4,596 $ 5,145 Other Information: Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows for finance leases $ 149 $ 190 Operating cash flows for operating leases $ 1,512 $ 2,087 Financing cash flows for finance leases $ 838 $ 855 Right-of-use assets obtained in exchange for new finance lease liabilities $ — $ — Right-of-use assets obtained in exchange for new operating lease liabilities $ 257 $ 1,947 Weighted-average remaining lease term - finance leases 1.2 years 2.1 years Weighted-average remaining lease term - operating leases 7.4 years 7.8 years Weighted-average discount rate - finance leases 6.4 % 5.9 % Weighted-average discount rate - operating leases 12.4 % 12.7 % (1) Primarily includes common area maintenance, property taxes and insurance payable to lessors.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
Commitments and Contingencies	Sep. 30, 2024
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Surety Bonds and Restricted Cash As the owner of the Five Forks Mine, the Company is required to post a surety bond with a regulatory commission related to performance requirements associated with the Five Forks Mine. As of September 30, 2024 , the amount of this surety bond was $7.5 million . The Company leases land adjacent to the Corbin Facility and is required to post surety bonds with a regulatory commission for reclamation. As of September 30, 2024, the amount of these surety bonds was $3.0 million. The Company holds permits for an abandoned mine in West Virginia ("Mine 4") and is required to post a surety bond with a regulatory commission for reclamation. As of September 30, 2024, the amount of this surety bond was $0.7 million. As of September 30, 2024 and December 31, 2023, the Company posted cash collateral of $8.5 million and $8.5 million, respectively, as required by the Company's surety bond providers, which is reported as long-term restricted cash in the Condensed Consolidated Balance Sheets. As of September 30, 2024, the Company holds a deposit of $0.4 million with a third party for collateral as required under a bonding arrangement for Mine 4. This deposit is included in "Other long-term assets, net" in the Condensed Consolidated Balance Sheet as of September 30, 2024. The Company has a customer supply agreement that requires the Company to post a performance bond in an amount equal to the annual contract value of $3.7 million. As of September 30, 2024, the remaining commitment under this customer contract, which expires on December 31, 2024, was approximately $1.3 million. Red River Plant Construction Contract In January 2024, the Company executed a contract with a third-party contractor for the construction of a GAC facility at the Red River Plant, and immediately commenced construction operations. The Company terminated the contract in September 2024, and anticipates completing construction and commissioning with internal resources fulfilling the role of the third-party contractor. The Company expects to complete its first deliveries in the first quarter of 2025 and estimates that total construction costs will be in the range of $75.0 - $80.0 million. Tinuum Group The Company has certain limited obligations contingent upon future events in connection with the activities of Tinuum Group. The Company, NexGen Refined Coal, LLC ("NexGen") and two entities affiliated with NexGen have provided another Tinuum Group owner with limited guarantees (the "Tinuum Group Party Guarantees") related to certain losses it may suffer as a result of inaccuracies or breach of representations and covenants. The Company also is a party to a contribution agreement with NexGen under which any party called upon to pay on a Tinuum Group Party Guaranty is entitled to receive contribution from the other party equal to 50% of the amount paid. No liability or expense provision has been recorded by the Company related to this contingent obligation as the Company believes that it is not probable that a loss will occur with respect to Tinuum Group Party Guarantees. As of September 30, 2024 and December 31, 2023, the Company has a contractual obligation (the "Tinuum Group Obligation") of $1.7 million for its share of certain contingent liabilities of Tinuum Group as required under the Distribution and Repayment Agreement (the "Repayment Agreement") that was executed in December 2022 by the Company and certain owners of Tinuum Group. The Tinuum Group Obligation is included in the "Other current liabilities" line item in the Consolidated Balance Sheet. Legal Proceedings

Supplemental Financial Informat

Supplemental Financial Information	9 Months Ended
Supplemental Financial Information	Sep. 30, 2024
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Supplemental Financial Information	Supplemental Financial Information Supplemental Balance Sheet Information The following table summarizes the components of Prepaid expenses and other current assets, and Other long-term assets, net as presented in the Condensed Consolidated Balance Sheets: As of (in thousands) September 30, 2024 December 31, 2023 Prepaid expenses and other current assets: Prepaid expenses $ 1,317 $ 2,430 Prepaid income taxes and income tax refunds 192 349 Other 2,021 2,436 Total prepaid expenses and other current assets $ 3,530 $ 5,215 Other long-term assets, net: Spare parts, net $ 10,753 $ 9,147 Right of use assets, operating leases, net 9,331 10,592 Intangible assets, net 7,644 7,899 Mine development costs, net 7,125 7,377 Upfront Customer Consideration (1) 5,586 5,967 Mine reclamation asset, net 1,856 1,955 Other 2,546 2,663 Total other long-term assets, net $ 44,841 $ 45,600 (1) Represents remaining balance on consideration paid to a customer under a supply contract executed in 2020. This asset is being amortized as a reduction to revenue on a straight-line basis over the expected 15-year contractual period of the contract. Spare parts include critical spares required to support plant operations. Mine development costs include acquisition costs, the cost of other development work and mitigation costs related to the Five Forks Mine and are depleted over the estimated life of the related mine reserves. Mine reclamation asset, net represents an asset retirement obligation ("ARO") asset related to the Five Forks Mine and is depreciated over its estimated life. As of September 30, 2024 and December 31, 2023, Other includes the Highview Investment in the amount of $0.6 million that is carried at cost, less impairment, plus or minus observable changes in price for identical or similar investments of the same issuer. The following table details the components of Other current liabilities and Other long-term liabilities as presented in the Condensed Consolidated Balance Sheets: As of (in thousands) September 30, 2024 December 31, 2023 Other current liabilities: Current portion of operating lease obligations $ 1,991 $ 1,944 Sales, use and other taxes payable 1,719 948 Current portion of asset retirement obligations 1,259 182 Other (1) 2,702 2,718 Total other current liabilities $ 7,671 $ 5,792 Other long-term liabilities: Operating lease obligations, long-term $ 7,569 $ 8,870 Asset retirement obligations 5,335 5,981 Other 1,125 929 Total other long-term liabilities $ 14,029 $ 15,780 (1) Included in Other current liabilities as of September 30, 2024 and December 31, 2023 is $1.7 million for the Tinuum Group Obligation as discussed in Note 7 . As of September 30, 2024 and December 31, 2023, the ARO related to the Five Forks Mine is included in Other long-term liabilities. The Mine reclamation liabilities represent AROs. Changes in the AROs were as follows: As of (in thousands) September 30, 2024 December 31, 2023 Asset retirement obligations, beginning of period $ 6,163 $ 8,533 Asset retirement obligations assumed (1) — 1,500 Accretion 496 582 Liabilities settled (2) (65) (4,866) Changes due to scope and timing of reclamation — 414 Asset retirement obligations, end of period 6,594 6,163 Less current portion 1,259 182 Asset retirement obligations, long-term $ 5,335 $ 5,981 (1) Represents the Corbin ARO and Mine 4 ARO in the amounts of $0.5 million and $1.0 million, respectively, assumed during the period ended December 31, 2023. (2) Included in liabilities settled during the period ended December 31, 2023 is $4.7 million related to the removal of the ARO associated with Marshall Mine, LLC as a result of the sale of Marshall Mine, LLC in March 2023. Supplemental Income Statement Information Tinuum Group, LLC As of September 30, 2024 and December 31, 2023, the Company's ownership interest in Tinuum Group, an equity method investment, was 42.5%. For the three and nine months ended September 30, 2024, the Company recognized earnings from Tinuum Group of $0.1 million. For the three and nine months ended September 30, 2023, the Company recognized earnings from Tinuum Group of $0.2 million and $1.1 million, respectively. In 2024, Tinuum Group, LLC has continued to wind down its operations. For the three and nine months ended September 30, 2024, the Company recognized expense of $0.2 million and $0.7 million, respectively, in Cost of revenue, exclusive of depreciation and amortization, related to royalties owed to Tinuum Group under an agreement for certain of the Company's sales of M-Prove TM products. For the three and nine months ended September 30, 2023, the Company recognized expense of $0.2 million and $0.6 million, respectively, in Cost of revenue, exclusive of depreciation and amortization, related to royalties owed to Tinuum Group under an agreement for certain of the Company's sales of M-Prove TM products.

Stockholders' Equity

Stockholders' Equity	9 Months Ended
Stockholders' Equity	Sep. 30, 2024
Equity [Abstract]
Stockholders' Equity	Stockholders' Equity Common Stock Transactions In April 2024, the Company received $0.8 million in cash and issued 422,221 shares of its common stock pursuant to a subscription agreement between the Company and its CEO executed in July 2023. In May 2024, the Company entered into a securities purchase agreement (the "SPA") with certain accredited investors for the sale of an aggregate of 2,142,858 shares of the Company’s common stock, at a selling price of $7.00 per share (the "Private Placement"). After deducting offering costs, the Company raised net cash proceeds of $15.0 million from the Private Placement. In September 2024, the Company entered into an underwriting agreement (the "Underwriting Agreement") with certain underwriters, relating to the issuance and sale of 4,770,000 shares of the Company's common stock at a price to the public of $5.25 per share, as well as an overallotment option to purchase an additional 715,500 shares within 30 days following the date of the Underwriting Agreement (the "Public Offering"). The Company issued a total of 5,485,500 shares, inclusive of 715,500 shares issued pursuant to the underwriters' fully exercised overallotment option, and received net proceeds, after deducting offering costs, of approximately $26.7 million from the Public Offering. Stock Repurchase Program As of September 30, 2024, the Company had $7.0 million remaining under a stock repurchase program, which will remain in effect until all amounts are utilized or is otherwise modified by the Board. The Company did not repurchase any shares during the three and nine months ended September 30, 2024 or 2023. Tax Asset Protection Plan U.S. federal income tax rules, and Section 382 of the Internal Revenue Code in particular, could substantially limit the use of net operating losses and tax credits if the Company experiences an "ownership change" (as defined in the Internal Revenue Code). In general, an ownership change occurs if there is a cumulative change in the ownership of the Company by "5 percent stockholders" that exceeds 50 percentage points over a rolling three-year period. An entity that experiences an ownership change generally will be subject to an annual limitation on its pre-ownership change tax loss and credit carryforwards equal to the equity value of the entity immediately before the ownership change, multiplied by the long-term, tax-exempt rate posted monthly by the Internal Revenue Service (subject to certain adjustments). The annual limitation would be increased each year to the extent that there is an unused limitation in a prior year. On May 5, 2017, the Board approved the declaration of a dividend of rights to purchase Series B Junior Participating Preferred Stock for each outstanding share of common stock as part of a tax asset protection plan (the "TAPP"), which is designed to protect the Company’s ability to utilize its net operating losses and tax credits. The TAPP is intended to act as a deterrent to any person acquiring beneficial ownership of 4.99% or more of the Company’s outstanding common stock. On April 12, 2024, the Board approved the Seventh Amendment to the TAPP (the "Seventh Amendment"), which amends the TAPP, as previously amended by the First, Second, Third, Fourth, Fifth and Sixth Amendments that were approved by the Board on April 6, 2018, April 5, 2019, April 9, 2020, April 9, 2021, March 15, 2022, and April 13, 2023, respectively. The Seventh Amendment amends the definition of "Final Expiration Date" under the TAPP to extend the duration of the TAPP and makes associated changes in connection therewith. Pursuant to the Seventh Amendment, the Final Expiration Date shall be the close of business on the earlier of (i) December 31, 2025 or (ii) December 31, 2024 if stockholder approval of the Seventh Amendment has not been obtained prior to such date. At the Company's 2024 Annual Meeting of Stockholders held on June 10, 2024, the Company's stockholders approved the Seventh Amendment, thus the final expiration date will be the close of business on December 31, 2025.

Stock-Based Compensation

Stock-Based Compensation	9 Months Ended
Stock-Based Compensation	Sep. 30, 2024
Share-Based Payment Arrangement [Abstract]
Stock-Based Compensation	Stock-Based Compensation The Company grants equity-based awards to employees, non-employee directors and consultants that may include, but are not limited to, RSAs, PSUs, restricted stock units and stock options. Stock-based compensation expense related to manufacturing employees and administrative employees is included in the "Cost of revenue" and "Selling, general and administrative" line items, respectively, in the Condensed Consolidated Statements of Operations. Stock-based compensation expense related to non-employee directors and consultants is included in the "Selling, general and administrative" line item in the Condensed Consolidated Statements of Operations. Total stock-based compensation expense for the three and nine months ended September 30, 2024 and 2023 was as follows: Three Months Ended September 30, Nine Months Ended September 30, (in thousands) 2024 2023 2024 2023 RSA expense $ 483 $ 501 $ 1,268 $ 1,405 PSU expense 206 151 735 355 Stock option expense 61 50 182 50 Total stock-based compensation expense $ 750 $ 702 $ 2,185 $ 1,810 The amount of unrecognized compensation cost as of September 30, 2024, and the expected weighted-average period over which the cost will be recognized is as follows: As of September 30, 2024 (in thousands, expect years) Unrecognized Compensation Cost Expected Weighted- RSA expense $ 3,414 1.82 PSU expense 1,400 1.09 Stock option expense 435 1.79 Total unrecognized stock-based compensation expense $ 5,249 1.62 Restricted Stock Awards RSAs are typically granted with vesting terms of three years. The fair value of RSAs is determined based on the closing price of the Company's common stock on the authorization date of the grant multiplied by the number of shares subject to the stock award. Compensation expense for RSAs is generally recognized on a straight-line basis over the entire vesting period. A summary of RSA activity under the Company's various stock compensation plans for the nine months ended September 30, 2024 is presented below: Restricted Stock Weighted-Average Grant Date Fair Value Non-vested at January 1, 2024 790,005 $ 3.10 Granted 577,159 $ 5.79 Vested (541,166) $ 3.34 Forfeited (55,197) $ 2.82 Non-vested at September 30, 2024 770,801 $ 4.99 Performance Share Units Compensation expense for PSUs is recognized on a straight-line basis over the applicable service period, which is generally three years, based on the estimated fair value at the date of grant. The estimated fair value at the date of grant is determined using a Monte Carlo simulation model for those PSUs with market-based performance conditions. A summary of PSU activity for the nine months ended September 30, 2024 is presented below: Units Weighted-Average Aggregate Intrinsic Value (in thousands) Weighted-Average PSUs outstanding, January 1, 2024 968,918 $ 2.06 Granted 115,877 $ 10.94 Vested / Settled (1) (150,000) $ 2.28 Forfeited / Canceled (57,750) $ 5.90 PSUs outstanding, September 30, 2024 877,045 $ 2.94 $ 5,148 1.09 (1) The number of units shown in the table above are based on target performance. The final number of shares of common stock issued may vary depending on the achievement of market or performance conditions established within the awards, which could result in the actual number of shares issued ranging from zero to a maximum of two times the number of units shown in the above table. For the three and nine months ended September 30, 2024, 150,000 shares of common stock were issued upon vesting of PSUs. Stock Options Stock options vest over three years and have a contractual limit of ten years from the date of grant to exercise. The fair value of stock options granted is determined on the date of grant using the Black-Scholes option pricing model, and the related expense is recognized on a straight-line basis over the entire vesting period. The determination of the grant date fair value of stock options issued is affected by a number of variables, including the fair value of the Company’s common stock, the expected common stock price volatility over the expected term of the stock option, the expected term of the stock option, risk-free interest rates, and the expected dividend yield of the Company’s common stock. Risk-free interest rate - The risk-free interest rate for stock options granted was determined by using a zero-coupon U.S. Treasury rate for the periods that coincided with the expected term of the options. Dividend yield - An expected dividend yield of zero was included in the calculations, as the Company does not currently pay nor does it anticipate paying dividends on its common stock as of the grant date of the stock options. Expected volatility - To calculate expected volatility, the historical volatility of the Company's common stock was used. Expected term - The Company’s expected term of stock options was calculated using a simplified method whereby the midpoint between the vesting date and the end of the contractual term is utilized to compute the expected term, as the Company does not have sufficient historical data for options with similar vesting and contractual terms. The Company did not grant any stock options during the three and nine months ended September 30, 2024. The Company granted 1,000,000 stock options during the three and nine months ended September 30, 2023. A summary of stock option activity for the nine months ended September 30, 2024 is presented below: Number of Options Weighted-Average Aggregate Intrinsic Value (in thousands) Weighted-Average Options outstanding, January 1, 2024 1,000,000 $ 3.00 Options granted — — Options exercised — — Options expired / forfeited — — Options outstanding, September 30, 2024 1,000,000 $ 3.00 $ 2,870 8.79 Options vested and exercisable, September 30, 2024 333,333 $ 3.00 $ 957 8.79

Income Taxes

Income Taxes	9 Months Ended
Income Taxes	Sep. 30, 2024
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes For the three and nine months ended September 30, 2024 and 2023, the Company's income tax (expense) benefit and effective tax rates are presented below: Three Months Ended September 30, Nine Months Ended September 30, (in thousands, except for rate) 2024 2023 2024 2023 Income tax (expense) benefit $ — $ — $ (30) $ 33 Effective tax rate — % — % 1 % — % The Company incurred pretax loss for the nine months ended September 30, 2024 and expects to incur pretax loss for the year ending December 31, 2024. As a result, the effective rate for the three and nine months ended September 30, 2024 would be zero as the resultant tax benefit was offset by a valuation allowance recorded as of September 30, 2024, However, the Company recorded out of period state income tax expense for the nine months ended September 30, 2024 resulting in the effective tax rate of 1% for this period. The Company assesses a valuation allowance recorded against deferred tax assets at each reporting date. The determination of whether a valuation allowance for deferred tax assets is appropriate requires the evaluation of positive and negative evidence that can be objectively verified. Consideration must be given to all sources of taxable income available to realize deferred tax assets, including, as applicable, the future reversal of existing temporary differences, future taxable income forecasts exclusive of the reversal of temporary differences and carryforwards, taxable income in carryback years and tax planning strategies. In estimating income taxes, the Company assesses the relative merits and risks of the appropriate income tax treatment of transactions taking into account statutory, judicial and regulatory guidance.

Marshall Mine

Marshall Mine	9 Months Ended
Marshall Mine	Sep. 30, 2024
Business Combination, Asset Acquisition, and Joint Venture Formation [Abstract]
Marshall Mine	Marshall Mine On March 27, 2023, (the "MM Closing Date"), the Company completed the sale of all of its membership interests in Marshall Mine, LLC to a third party (the "Buyer") in exchange for a cash payment of $2.2 million (the "MM Purchase Price") made by the Company to the Buyer and the assumption by the Buyer of certain liabilities of Marshall Mine, LLC. As of the MM Closing Date, Marshall Mine, LLC had outstanding liabilities of approximately $4.9 million that were discharged upon payment of the MM Purchase Price by the Company, and the Company recognized a gain of approximately $2.7 million in the Statement of Operations for the nine months ended September 30, 2023.

Subsequent Events

Subsequent Events	9 Months Ended
Subsequent Events	Sep. 30, 2024
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events Unless disclosed elsewhere in the notes to the Condensed Consolidated Financial Statements, there were no significant matters that occurred subsequent to September 30, 2024.

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
Pay vs Performance Disclosure - USD ($) $ in Thousands	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2024	Sep. 30, 2023
Pay vs Performance Disclosure
Net loss	$ 1,617	$ (1,968)	$ (3,419)	$ (2,175)	$ (5,856)	$ (7,508)	$ (3,770)	$ (15,539)

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
Insider Trading Arrangements	Sep. 30, 2024
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Organization and Basis of Pre_2

Organization and Basis of Presentation (Policies)	9 Months Ended
Organization and Basis of Presentation (Policies)	Sep. 30, 2024
Accounting Policies [Abstract]
Basis of Presentation	The accompanying Condensed Consolidated Financial Statements of Arq are unaudited and have been prepared in conformity with accounting principles generally accepted in the United States ("U.S. GAAP") and with Article 10 of Regulation S-X of the Securities and Exchange Commission. In compliance with those instructions, certain information and footnote disclosures normally included in annual consolidated financial statements prepared in accordance with U.S. GAAP have been condensed or omitted. The unaudited Condensed Consolidated Financial Statements of Arq in this quarterly report ("Quarterly Report") are presented on a consolidated basis and include Arq and its wholly-owned subsidiaries (collectively, the "Company"). Also included within the unaudited Condensed Consolidated Financial Statements are the Company's unconsolidated equity investments, Tinuum Group and Tinuum Services, which are accounted for under the equity method of accounting, and Highview Enterprises Limited (the "Highview Investment"), which is accounted for in accordance with U.S. GAAP applicable to equity investments that do not qualify for the equity method of accounting. Results of operations and cash flows for the interim periods are not necessarily indicative of the results that may be expected for the entire year. All significant intercompany transactions and accounts were eliminated in consolidation for all periods presented in this Quarterly Report. In the opinion of management, these Condensed Consolidated Financial Statements include all normal and recurring adjustments considered necessary for a fair presentation of the results of operations, financial position, stockholders' equity and cash flows for the interim periods presented. These Condensed Consolidated Financial Statements should be read in conjunction with the Company’s Annual Report on Form 10-K for the year ended December 31, 2023 (the "2023 Form 10-K"). Significant accounting policies disclosed therein have not changed.
Earnings (Loss) Per Share	Basic earnings (loss) per share is computed using the weighted-average number of shares of the Company's common stock outstanding during the reporting period. Diluted earnings (loss) per share is computed in a manner consistent with that of basic earnings per share, while considering other potentially dilutive securities.
Use of Estimates	The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. There have been no changes in the Company's critical accounting estimates from those that were disclosed in the 2023 Form 10-K. Actual results could differ from these estimates.
Fair value measurement	The carrying amounts of our cash, restricted cash, accounts receivable, accounts payable and other current liabilities approximate fair value as recorded due to the short-term nature of these instruments.
Reclassifications	Certain balances have been reclassified from the prior year to conform to the current year presentation. Such reclassifications had no effect on the Company’s results of operations or financial position in any of the periods presented.
New Accounting Standards	New Accounting Standards In November 2023, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures ("ASU 2023-07"). ASU 2023-07 is intended to improve reportable segment disclosures and to enhance disclosures of reportable segment expenses. This ASU is effective for annual reporting periods beginning after December 15, 2023, and interim periods within fiscal years beginning after December 15, 2024. Early adoption is permitted. ASU 2023-07 is required to be applied retrospectively to all prior periods presented in the financial statements. Because the amendments do not change the methodology for the identification of operating segments, the aggregation of those operating segments or the application of the quantitative thresholds to determine reportable segments, we do not expect the guidance to have a material effect on our financial position or results of operations. In December 2023, the FASB issued Accounting Standards Update 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures . ("ASU 2023-09"). ASU 2023-09 requires entities to disclose: (1) consistent categories and greater disaggregation of information in the rate reconciliation and (2) the disaggregation of income taxes paid by jurisdiction. This update also makes several other changes to the income tax disclosure requirements. For public entities, the amendments in ASU 2023-09 are effective for fiscal years beginning after December 15, 2024, with early adoption permitted, and is required to be applied prospectively, but retrospective application is permitted. The Company is currently evaluating the impact of ASU 2023-09 on its income tax disclosures.

Organization and Basis of Pre_3

Organization and Basis of Presentation (Tables)	9 Months Ended
Organization and Basis of Presentation (Tables)	Sep. 30, 2024
Accounting Policies [Abstract]
Schedule of Calculations of Basic and Diluted Loss Per Share	The following table sets forth the calculations of basic and diluted loss per share: Three Months Ended September 30, Nine Months Ended September 30, (in thousands, except per share amounts) 2024 2023 2024 2023 Net income (loss) $ 1,617 $ (2,175) $ (3,770) $ (15,539) Less: Dividends declared on redeemable preferred stock — — — 157 Income (loss) attributable to common stockholders $ 1,617 $ (2,175) $ (3,770) $ (15,696) Basic weighted-average common shares outstanding 36,124 31,807 34,085 27,894 Add: dilutive effect of equity instruments 1,318 — — — Diluted weighted-average shares outstanding 37,442 31,807 34,085 27,894 Earnings (loss) per share - basic $ 0.04 $ (0.07) $ (0.11) $ (0.56) Earnings (loss) per share - diluted $ 0.04 $ (0.07) $ (0.11) $ (0.56)

Arq Acquisition (Tables)

Arq Acquisition (Tables)	9 Months Ended
Arq Acquisition (Tables)	Sep. 30, 2024
Business Combination, Asset Acquisition, and Joint Venture Formation [Abstract]
Schedule of Final Purchase Price Allocation to the Assets Acquired and Liabilities Assumed	The following table provides the final purchase price allocation to the assets acquired and liabilities assumed as of the Acquisition Date: (in thousands) Purchase Price Allocation Fair value of assets acquired: Cash $ 1,411 Prepaid expenses and other current assets 2,229 Restricted cash, long-term 814 Property, plant and equipment, net 39,159 Other long-term assets, net 11,717 Amount attributable to assets acquired 55,330 Fair Value of liabilities assumed: Accounts payable and accrued expenses 9,806 Current portion of long-term debt 494 Other current liabilities 103 Long-term debt, net of current portion 9,199 Other long-term liabilities 4,523 Amount attributable to liabilities assumed 24,125 Net assets acquired $ 31,205 The following represents the intangible asset identified as part of the Arq Acquisition and which is included in "Other long-term-assets, net" in the table above: (in thousands) Amount Weighted Average Useful Life (years) Developed technology $ 7,700 20
Schedule of Pro Forma Revenues	Since Legacy Arq had no revenues for the nine months ended September 30, 2023, pro forma revenues are the same as the Company's reported revenues for that period. (in thousands) Nine Months Ended September 30, 2023 Revenues $ 71,079 Net loss $ (12,100)

Revenues (Tables)

Revenues (Tables)	9 Months Ended
Revenues (Tables)	Sep. 30, 2024
Revenue from Contract with Customer [Abstract]
Schedule of Accounts Receivables	The following table shows the components of the Company's Receivables, net: As of (in thousands) September 30, 2024 December 31, 2023 Trade and other receivables, net $ 16,465 $ 11,330 Unbilled receivables 125 4,862 Receivables, net $ 16,590 $ 16,192

Inventories, net (Tables)

Inventories, net (Tables)	9 Months Ended
Inventories, net (Tables)	Sep. 30, 2024
Inventory Disclosure [Abstract]
Schedule of Inventory	The following table summarizes the Company's inventories as of September 30, 2024 and December 31, 2023: As of (in thousands) September 30, 2024 December 31, 2023 Product inventory, net $ 11,498 $ 9,524 Raw material inventory 6,989 10,169 Total inventories, net $ 18,487 $ 19,693

Debt Obligations (Tables)

Debt Obligations (Tables)	9 Months Ended
Debt Obligations (Tables)	Sep. 30, 2024
Debt Disclosure [Abstract]
Schedule of Debt	As of (in thousands) September 30, 2024 December 31, 2023 CFG Loan due February 2027, related party $ 10,000 $ 10,000 CTB Loan due January 2036 9,123 9,527 Finance lease obligations 2,192 3,465 Other 258 — 21,573 22,992 Unamortized debt discounts (623) (815) Unamortized debt issuance costs (992) (1,250) 19,958 20,927 Less: Current maturities (2,324) (2,653) Total long-term debt obligations $ 17,634 $ 18,274

Leases (Tables)

Leases (Tables)	9 Months Ended
Leases (Tables)	Sep. 30, 2024
Leases [Abstract]
Schedule of Operating and Finance Lease Right-Of-Use ("ROU") Assets and Liabilities	The Company's operating and finance lease right-of-use ("ROU") assets and liabilities as of September 30, 2024 and December 31, 2023 consisted of the following items (in thousands): As of Leases September 30, 2024 December 31, 2023 Operating Leases Operating lease right-of-use assets, net of accumulated amortization (1) $ 9,331 $ 10,592 Operating lease obligations, current $ 1,991 $ 1,944 Long-term operating lease obligations 7,569 8,870 Total operating lease obligation $ 9,560 $ 10,814 Finance Leases Finance lease right-of-use assets, net of accumulated amortization (2) $ 975 $ 1,694 Finance lease obligations, current $ 1,699 $ 2,131 Long-term finance lease obligations 493 1,334 Total finance lease obligations $ 2,192 $ 3,465 (1) Operating lease ROU assets are reported net of accumulated amortization of $4.0 million and $5.1 million as of September 30, 2024 and December 31, 2023, respectively. (2) Finance lease ROU assets are reported net of accumulated amortization of $3.0 million and $2.7 million as of September 30, 2024 and December 31, 2023, respectively. Lease financial information as of and for the three and nine months ended September 30, 2024 and 2023 is provided in the following table: Three Months Ended September 30, Nine Months Ended September 30, (in thousands) 2024 2023 2024 2023 Finance lease cost: Amortization of right-of-use assets $ 46 $ 215 $ 466 $ 661 Interest on lease liabilities 50 59 149 190 Operating lease cost 773 1,000 2,448 3,017 Short-term lease cost 437 481 1,220 1,132 Variable lease cost (1) 104 81 313 145 Total lease cost $ 1,410 $ 1,836 $ 4,596 $ 5,145 Other Information: Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows for finance leases $ 149 $ 190 Operating cash flows for operating leases $ 1,512 $ 2,087 Financing cash flows for finance leases $ 838 $ 855 Right-of-use assets obtained in exchange for new finance lease liabilities $ — $ — Right-of-use assets obtained in exchange for new operating lease liabilities $ 257 $ 1,947 Weighted-average remaining lease term - finance leases 1.2 years 2.1 years Weighted-average remaining lease term - operating leases 7.4 years 7.8 years Weighted-average discount rate - finance leases 6.4 % 5.9 % Weighted-average discount rate - operating leases 12.4 % 12.7 % (1) Primarily includes common area maintenance, property taxes and insurance payable to lessors.

Supplemental Financial Inform_2

Supplemental Financial Information (Tables)	9 Months Ended
Supplemental Financial Information (Tables)	Sep. 30, 2024
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Schedule of Other Long Term Assets	The following table summarizes the components of Prepaid expenses and other current assets, and Other long-term assets, net as presented in the Condensed Consolidated Balance Sheets: As of (in thousands) September 30, 2024 December 31, 2023 Prepaid expenses and other current assets: Prepaid expenses $ 1,317 $ 2,430 Prepaid income taxes and income tax refunds 192 349 Other 2,021 2,436 Total prepaid expenses and other current assets $ 3,530 $ 5,215 Other long-term assets, net: Spare parts, net $ 10,753 $ 9,147 Right of use assets, operating leases, net 9,331 10,592 Intangible assets, net 7,644 7,899 Mine development costs, net 7,125 7,377 Upfront Customer Consideration (1) 5,586 5,967 Mine reclamation asset, net 1,856 1,955 Other 2,546 2,663 Total other long-term assets, net $ 44,841 $ 45,600 (1) Represents remaining balance on consideration paid to a customer under a supply contract executed in 2020. This asset is being amortized as a reduction to revenue on a straight-line basis over the expected 15-year contractual period of the contract.
Schedule of Other Liabilities	The following table details the components of Other current liabilities and Other long-term liabilities as presented in the Condensed Consolidated Balance Sheets: As of (in thousands) September 30, 2024 December 31, 2023 Other current liabilities: Current portion of operating lease obligations $ 1,991 $ 1,944 Sales, use and other taxes payable 1,719 948 Current portion of asset retirement obligations 1,259 182 Other (1) 2,702 2,718 Total other current liabilities $ 7,671 $ 5,792 Other long-term liabilities: Operating lease obligations, long-term $ 7,569 $ 8,870 Asset retirement obligations 5,335 5,981 Other 1,125 929 Total other long-term liabilities $ 14,029 $ 15,780 (1) Included in Other current liabilities as of September 30, 2024 and December 31, 2023 is $1.7 million for the Tinuum Group Obligation as discussed in Note 7 .
Schedule of Change in Asset Retirement Obligation	As of (in thousands) September 30, 2024 December 31, 2023 Asset retirement obligations, beginning of period $ 6,163 $ 8,533 Asset retirement obligations assumed (1) — 1,500 Accretion 496 582 Liabilities settled (2) (65) (4,866) Changes due to scope and timing of reclamation — 414 Asset retirement obligations, end of period 6,594 6,163 Less current portion 1,259 182 Asset retirement obligations, long-term $ 5,335 $ 5,981 (1) Represents the Corbin ARO and Mine 4 ARO in the amounts of $0.5 million and $1.0 million, respectively, assumed during the period ended December 31, 2023. (2) Included in liabilities settled during the period ended December 31, 2023 is $4.7 million related to the removal of the ARO associated with Marshall Mine, LLC as a result of the sale of Marshall Mine, LLC in March 2023.

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	9 Months Ended
Stock-Based Compensation (Tables)	Sep. 30, 2024
Share-Based Payment Arrangement [Abstract]
Schedule of Allocation of Compensation Expense	Total stock-based compensation expense for the three and nine months ended September 30, 2024 and 2023 was as follows: Three Months Ended September 30, Nine Months Ended September 30, (in thousands) 2024 2023 2024 2023 RSA expense $ 483 $ 501 $ 1,268 $ 1,405 PSU expense 206 151 735 355 Stock option expense 61 50 182 50 Total stock-based compensation expense $ 750 $ 702 $ 2,185 $ 1,810
Schedule of Unrecognized Compensation Cost	The amount of unrecognized compensation cost as of September 30, 2024, and the expected weighted-average period over which the cost will be recognized is as follows: As of September 30, 2024 (in thousands, expect years) Unrecognized Compensation Cost Expected Weighted- RSA expense $ 3,414 1.82 PSU expense 1,400 1.09 Stock option expense 435 1.79 Total unrecognized stock-based compensation expense $ 5,249 1.62
Schedule of Restricted Stock Activity	A summary of RSA activity under the Company's various stock compensation plans for the nine months ended September 30, 2024 is presented below: Restricted Stock Weighted-Average Grant Date Fair Value Non-vested at January 1, 2024 790,005 $ 3.10 Granted 577,159 $ 5.79 Vested (541,166) $ 3.34 Forfeited (55,197) $ 2.82 Non-vested at September 30, 2024 770,801 $ 4.99
Schedule of Performance Shares Units	A summary of PSU activity for the nine months ended September 30, 2024 is presented below: Units Weighted-Average Aggregate Intrinsic Value (in thousands) Weighted-Average PSUs outstanding, January 1, 2024 968,918 $ 2.06 Granted 115,877 $ 10.94 Vested / Settled (1) (150,000) $ 2.28 Forfeited / Canceled (57,750) $ 5.90 PSUs outstanding, September 30, 2024 877,045 $ 2.94 $ 5,148 1.09 (1) The number of units shown in the table above are based on target performance. The final number of shares of common stock issued may vary depending on the achievement of market or performance conditions established within the awards, which could result in the actual number of shares issued ranging from zero to a maximum of two times the number of units shown in the above table. For the three and nine months ended September 30, 2024, 150,000 shares of common stock were issued upon vesting of PSUs.
Summary of Option Activity	A summary of stock option activity for the nine months ended September 30, 2024 is presented below: Number of Options Weighted-Average Aggregate Intrinsic Value (in thousands) Weighted-Average Options outstanding, January 1, 2024 1,000,000 $ 3.00 Options granted — — Options exercised — — Options expired / forfeited — — Options outstanding, September 30, 2024 1,000,000 $ 3.00 $ 2,870 8.79 Options vested and exercisable, September 30, 2024 333,333 $ 3.00 $ 957 8.79

Income Taxes (Tables)

Income Taxes (Tables)	9 Months Ended
Income Taxes (Tables)	Sep. 30, 2024
Income Tax Disclosure [Abstract]
Schedule of Income Tax Expense and Effective Tax Rates	For the three and nine months ended September 30, 2024 and 2023, the Company's income tax (expense) benefit and effective tax rates are presented below: Three Months Ended September 30, Nine Months Ended September 30, (in thousands, except for rate) 2024 2023 2024 2023 Income tax (expense) benefit $ — $ — $ (30) $ 33 Effective tax rate — % — % 1 % — %

Organization and Basis of Pre_4

Organization and Basis of Presentation - Schedule of Calculations of Basic and Diluted Loss Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2024	Sep. 30, 2023
Accounting Policies [Abstract]
Net income (loss)	$ 1,617	$ (1,968)	$ (3,419)	$ (2,175)	$ (5,856)	$ (7,508)	$ (3,770)	$ (15,539)
Less: Dividends declared on redeemable preferred stock	0			0			0	157
Income (loss) attributable to common stockholders, basic	1,617			(2,175)			(3,770)	(15,696)
Income (loss) attributable to common stockholders, diluted	$ 1,617			$ (2,175)			$ (3,770)	$ (15,696)
Basic weighted-average common shares outstanding (in shares)	36,124			31,807			34,085	27,894
Add: dilutive effect of equity instruments (in shares)	1,318			0			0	0
Diluted weighted-average shares outstanding (in shares)	37,442			31,807			34,085	27,894
Earnings (loss) per share - basic (in dollars per share)	$ 0.04			$ (0.07)			$ (0.11)	$ (0.56)
Earnings (loss) per share - diluted (in dollars per share)	$ 0.04			$ (0.07)			$ (0.11)	$ (0.56)
Total shares excluded from diluted shares outstanding (in shares)	300			2,300			2,500	1,400

Organization and Basis of Pre_5

Organization and Basis of Presentation - Narrative (Details)	Feb. 28, 2023
Arq Limited
Accounting Policies [Line Items]
Subsidiary, ownership percentage, parent	100%

Arq Acquisition - Narrative (De

Arq Acquisition - Narrative (Details) $ / shares in Units, $ in Thousands				1 Months Ended	3 Months Ended	9 Months Ended
	Apr. 21, 2023 USD ($)	Mar. 31, 2023 shares	Feb. 01, 2023 USD ($) $ / shares shares	Sep. 30, 2024 USD ($) $ / shares shares	Sep. 30, 2023 USD ($)	Sep. 30, 2024 USD ($) $ / shares shares	Sep. 30, 2023 USD ($)	Sep. 30, 2024 $ / shares shares	Dec. 31, 2023 $ / shares shares	Feb. 28, 2023
Business Acquisition [Line Items]
Purchase par value (in dollars per share) \| $ / shares				$ 0.001		$ 0.001			$ 0.001
Temporary equity, par value (in dollars per share) \| $ / shares			$ 0.001
Paid-in-kind dividend on Series A Preferred Stock	$ 200					$ 0	$ 157
Preferred stock, shares issued (in shares) \| shares				0		0		0	0
Preferred stock par value (in dollars per share) \| $ / shares				$ 0.001		$ 0.001			$ 0.001
Consideration received on transaction				$ 26,700
Price per share (in dollars per share) \| (per share)			$ 4					$ 5.25
Arq Limited
Business Acquisition [Line Items]
Subsidiary, ownership percentage, parent										100%
Series A Preferred Stock
Business Acquisition [Line Items]
Preferred stock dividends declared on redeemable preferred stock (in shares) \| shares		68,464
Common Stock
Business Acquisition [Line Items]
Consideration received on transaction			$ 15,400
Arq Limited
Business Acquisition [Line Items]
Consideration transferred			31,200
Acquisition related costs			$ 8,700
Preferred stock, shares issued (in shares) \| shares			833,914
Preferred stock par value (in dollars per share) \| $ / shares			$ 3.46
Contingent consideration, liability			$ 3,300
Decrease in depreciation and amortization					$ 200
Increase in intangible assets					100
Increase in interest expense					$ 200
Arq Limited \| Series A Preferred Stock
Business Acquisition [Line Items]
Preferred stock, shares designated (in shares) \| shares			8,900,000
Shares issued (in dollars per share) \| $ / shares			$ 4
Arq Limited \| Common Stock
Business Acquisition [Line Items]
Business acquisition, issued number of shares (in shares) \| shares			3,814,864
Business acquisition, issued number of shares issuable, value			$ 12,400
Arq Limited \| Preferred Stock
Business Acquisition [Line Items]
Business acquisition, issued number of shares (in shares) \| shares			5,294,462
Business acquisition, issued number of shares issuable, value			$ 18,800

Arq Acquisition - Schedule of F

Arq Acquisition - Schedule of Final Purchase Price Allocation to the Assets Acquired and Liabilities Assumed (Details) - Arq Limited $ in Thousands	Feb. 01, 2023 USD ($)
Business Acquisition [Line Items]
Cash	$ 1,411
Prepaid expenses and other current assets	2,229
Restricted cash, long-term	814
Property, plant and equipment, net	39,159
Other long-term assets, net	11,717
Amount attributable to assets acquired	55,330
Accounts payable and accrued expenses	9,806
Current portion of long-term debt	494
Other current liabilities	103
Long-term debt, net of current portion	9,199
Other long-term liabilities	4,523
Amount attributable to liabilities assumed	24,125
Net assets acquired	31,205
Developed technology
Business Acquisition [Line Items]
Amount	$ 7,700
Weighted Average Useful Life (years)	20 years

Arq Acquisition - Schedule of P

Arq Acquisition - Schedule of Pro Forma Revenues (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2023 USD ($)
Business Combination, Asset Acquisition, and Joint Venture Formation [Abstract]
Revenues	$ 71,079
Net loss	$ (12,100)

Revenues - Narrative (Details)

Revenues - Narrative (Details)	3 Months Ended		9 Months Ended
Revenues - Narrative (Details)	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Revenue from Contract with Customer [Abstract]
Collection terms			Credit terms are generally net 30 - 45 days from the date of invoice.
Disaggregation of Revenue [Line Items]
Collection terms			Credit terms are generally net 30 - 45 days from the date of invoice.
Revenue from Contract with Customer Benchmark \| Geographic Concentration Risk \| Canada
Disaggregation of Revenue [Line Items]
Percent of revenue generated	5%	7%	7%	8%

Revenues - Schedule of Accounts

Revenues - Schedule of Accounts Receivables (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Accounts, Notes, Loans and Financing Receivable [Line Items]
Receivables, net	$ 16,590	$ 16,192
Trade and other receivables, net
Accounts, Notes, Loans and Financing Receivable [Line Items]
Receivables, net	16,465	11,330
Unbilled receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Receivables, net	$ 125	$ 4,862

Inventories, net (Details)

Inventories, net (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Inventory Disclosure [Abstract]
Product inventory, net	$ 11,498	$ 9,524
Raw material inventory	6,989	10,169
Total inventories, net	$ 18,487	$ 19,693

Debt Obligations - Schedule of

Debt Obligations - Schedule of Debt (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Debt Instrument [Line Items]
Finance lease obligations	$ 2,192	$ 3,465
Other	258	0
Long-term debt	21,573	22,992
Unamortized debt discounts	(623)	(815)
Unamortized debt issuance costs	(992)	(1,250)
Long-term debt	19,958	20,927
Less: Current maturities	(2,324)	(2,653)
Total long-term debt obligations	17,634	18,274
CFG Loan due February 2027, related party
Debt Instrument [Line Items]
Loan due	10,000	10,000
CTB Loan due January 2036
Debt Instrument [Line Items]
Loan due	$ 9,123	$ 9,527

Debt Obligations - Narrative (D

Debt Obligations - Narrative (Details)				3 Months Ended	9 Months Ended
Debt Obligations - Narrative (Details)	Mar. 29, 2024 shares	Feb. 01, 2023 USD ($) $ / shares shares	Jan. 27, 2021 USD ($) debtInstrument	Mar. 31, 2024 shares	Sep. 30, 2024 USD ($)	Dec. 31, 2023 USD ($)	Jun. 02, 2023 USD ($)
Debt Instrument [Line Items]
Unamortized discount					$ 623,000	$ 815,000
Debt instrument, post-transaction from exercise of warrant		1%
Common Stock
Debt Instrument [Line Items]
Exercise of warrant, net (in shares) \| shares	324,955			324,955
CF Global Credit, LP
Debt Instrument [Line Items]
Issuance of warrant (in shares) \| shares		325,457
Exercise price of warrants (in dollars per share) \| $ / shares		$ 0.01
Term		7 years
Secured Debt
Debt Instrument [Line Items]
Proceeds from issuance of debt		$ 10,000,000
Unamortized discount		200,000
Net cash proceeds		8,500,000
Debt issuance costs		$ 1,300,000
Promissory Notes
Debt Instrument [Line Items]
Number of instruments (in instruments) \| debtInstrument			2
Secured Debt
Debt Instrument [Line Items]
Exercise price of warrants (in dollars per share) \| $ / shares		$ 0.01
Debt instrument, covenant loan to value ratio		0.40
Secured Debt \| Arq Limited
Debt Instrument [Line Items]
Unamortized discount		$ 300,000
Face amount		10,000,000
Estimated fair value		$ 9,700,000
Periodic payment, principal			$ 100,000
Debt instrument, fee amount							$ 50,000
Debt instrument, collateral amount							$ 700,000
Indebtedness to net worth ratio					4
Debt instrument, annual increase					20%
Equity percentage					1.25
Secured Debt \| Arq Limited \| Promissory Note A
Debt Instrument [Line Items]
Face amount			8,000,000
Secured Debt \| Arq Limited \| Promissory Note B
Debt Instrument [Line Items]
Face amount			$ 2,000,000
Secured Debt \| Between 1 And 36 Moths
Debt Instrument [Line Items]
Debt instrument, prepayment premium		2%
Secured Debt \| Between 37 Months And Maturity Date
Debt Instrument [Line Items]
Debt instrument, prepayment premium		1%
Secured Debt \| Adjusted Term SOFR for an Interest Period of One Month in Effect on the Third U.S. Government Securities Business Day
Debt Instrument [Line Items]
Debt instrument, prepayment premium		2%
Secured Debt \| Fiscal Year 2024
Debt Instrument [Line Items]
Debt covenant, minimum annual Revenue requirement		$ 85,000,000
Debt covenant, minimum consolidated EBITDA requirement		3,000,000
Secured Debt \| Fiscal Year 2025 and Thereafter
Debt Instrument [Line Items]
Debt covenant, minimum annual Revenue requirement		100,000,000
Debt covenant, minimum consolidated EBITDA requirement		16,000,000
Secured Debt \| Through January 2026 \| Arq Limited
Debt Instrument [Line Items]
Interest rate, stated percentage			6%
Secured Debt \| Penalty Year 2024 \| Arq Limited
Debt Instrument [Line Items]
Prepayment penalty, percentage					3%
Secured Debt \| Penalty Year 2025 \| Arq Limited
Debt Instrument [Line Items]
Prepayment penalty, percentage					2%
Secured Debt \| Penalty Year 2026 \| Arq Limited
Debt Instrument [Line Items]
Prepayment penalty, percentage					1%
Secured Debt \| Beginning March 31, 2023
Debt Instrument [Line Items]
Debt covenant, minimum cash balance requirement		$ 5,000,000
Secured Debt \| SOFR
Debt Instrument [Line Items]
Debt instrument, floor rate percentage		1%
Debt instrument, cap rate percentage		2%
Debt instrument, percent of paid in cash		9%
Debt instrument, percent of paid in kind		5%
Secured Debt \| SOFR \| Adjusted Term SOFR for an Interest Period of One Month in Effect on the Third U.S. Government Securities Business Day
Debt Instrument [Line Items]
Debt instrument, interest rate		14%
Secured Debt \| Base Rate
Debt Instrument [Line Items]
Debt instrument, percent of paid in cash		8%
Secured Debt \| Prime Rate \| After January 2026 \| Arq Limited
Debt Instrument [Line Items]
Interest rate, stated percentage			2.75%

Leases - Schedule of Operating

Leases - Schedule of Operating and Finance Lease Right-Of-Use ("ROU") Assets and Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Operating Leases
Operating lease right-of-use assets, net of accumulated amortization	$ 9,331	$ 10,592
Operating lease obligations, current	1,991	1,944
Long-term operating lease obligations	7,569	8,870
Total operating lease obligation	9,560	10,814
Finance Leases
Finance lease right-of-use assets, net of accumulated amortization	975	1,694
Finance lease obligations, current	1,699	2,131
Long-term finance lease obligations	493	1,334
Total finance lease obligations	2,192	3,465
Operating lease, accumulated amortization	4,000	5,100
Finance lease, accumulated amortization	$ 3,000	$ 2,700

Leases - Narrative (Details)

Leases - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
Leases - Narrative (Details) - USD ($) $ in Millions	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Lessee, Lease, Description [Line Items]
Operating lease, right-of-use asset, statement of financial position [Extensible Enumeration]	Other long-term assets, net		Other long-term assets, net		Other long-term assets, net
Operating lease, liability, current, statement of financial position [Extensible List]	Other current liabilities		Other current liabilities		Other current liabilities
Operating lease, liability, noncurrent, statement of financial position [Extensible List]	Other long-term liabilities		Other long-term liabilities		Other long-term liabilities
Operating lease, expense	$ 1.3	$ 1.6	$ 4	$ 4.3
General and Administrative Expense
Lessee, Lease, Description [Line Items]
Operating lease, expense	0.4		1.1
Selling, General and Administrative Expenses
Lessee, Lease, Description [Line Items]
Operating lease, expense		0.4		0.9
Revenue
Lessee, Lease, Description [Line Items]
Operating lease, expense	$ 0.9	$ 1.2	$ 2.9	$ 3.4

Leases - Schedule of Lease Liab

Leases - Schedule of Lease Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Finance lease cost:
Amortization of right-of-use assets	$ 46	$ 215	$ 466	$ 661
Interest on lease liabilities	50	59	149	190
Operating lease cost	773	1,000	2,448	3,017
Short-term lease cost	437	481	1,220	1,132
Variable lease cost	104	81	313	145
Total lease cost	$ 1,410	$ 1,836	4,596	5,145
Operating cash flows for finance leases			149	190
Operating cash flows for operating leases			1,512	2,087
Financing cash flows for finance leases			838	855
Right-of-use assets obtained in exchange for new finance lease liabilities			0	0
Right-of-use assets obtained in exchange for new operating lease liabilities			$ 257	$ 1,947
Weighted-average remaining lease term - finance leases	1 year 2 months 12 days	2 years 1 month 6 days	1 year 2 months 12 days	2 years 1 month 6 days
Weighted-average remaining lease term - operating leases	7 years 4 months 24 days	7 years 9 months 18 days	7 years 4 months 24 days	7 years 9 months 18 days
Weighted-average discount rate - finance leases	6.40%	5.90%	6.40%	5.90%
Weighted-average discount rate - operating leases	12.40%	12.70%	12.40%	12.70%

Commitments and Contingencies (

Commitments and Contingencies (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended	9 Months Ended
	Jan. 31, 2024	Mar. 31, 2024	Sep. 30, 2024	Dec. 31, 2023
Other Commitments [Line Items]
Restricted cash, long-term			$ 8.5	$ 8.5
Supply agreement performance bond			3.7
Contract with customer, liability			1.3
Tinuum Group, LLC
Other Commitments [Line Items]
Liabilities assumed		$ 1.7	$ 1.7
Tinuum Group, LLC
Other Commitments [Line Items]
Limited guarantees (as percent)			50%
Minimum \| Deliveries in First Quarter 2025
Other Commitments [Line Items]
Construction contract estimated costs	$ 75
Maximum \| Deliveries in First Quarter 2025
Other Commitments [Line Items]
Construction contract estimated costs	$ 80
Five Forks Mine
Other Commitments [Line Items]
Surety bond amount			$ 7.5
Corbin Facilities
Other Commitments [Line Items]
Surety bond amount			3
West Virginia ("Mine 4")
Other Commitments [Line Items]
Surety bond amount			0.7
Restricted cash, long-term			$ 0.4

Supplemental Financial Inform_3

Supplemental Financial Information - Schedule of Other Long Term Assets (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2024	Dec. 31, 2023
Prepaid expenses and other current assets:
Prepaid expenses	$ 1,317	$ 2,430
Prepaid income taxes and income tax refunds	192	349
Other	2,021	2,436
Prepaid expenses and other current assets	3,530	5,215
Other long-term assets, net:
Spare parts, net	10,753	9,147
Right of use assets, operating leases, net	9,331	10,592
Intangible assets, net	7,644	7,899
Mine development costs, net	7,125	7,377
Upfront Customer Consideration	5,586	5,967
Mine reclamation asset, net	1,856	1,955
Other	2,546	2,663
Total other long-term assets, net	$ 44,841	$ 45,600
Term of contract	15 years

Supplemental Financial Inform_4

Supplemental Financial Information - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Related Party Transaction [Line Items]
Earnings from equity method investments	$ 127	$ 412	$ 127	$ 1,512
Highview Enterprises Limited
Related Party Transaction [Line Items]
Equity method investments	$ 600		$ 600		$ 600
Tinuum Group, LLC
Related Party Transaction [Line Items]
Ownership interest, percent (as percent)	42.50%		42.50%		42.50%
Earnings from equity method investments	$ 100	200	$ 100	1,100
Tinuum Group, LLC \| Cost of Revenue
Related Party Transaction [Line Items]
Earnings from equity method investments	$ (200)	$ (200)	$ (700)	$ (600)

Supplemental Financial Inform_5

Supplemental Financial Information - Schedule of Other Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Mar. 31, 2024	Sep. 30, 2024	Dec. 31, 2023
Other current liabilities:
Operating lease, liability, current, statement of financial position [Extensible List]		Total other current liabilities	Total other current liabilities
Current portion of operating lease obligations		$ 1,991	$ 1,944
Sales, use and other taxes payable		1,719	948
Current portion of asset retirement obligations		1,259	182
Other		2,702	2,718
Total other current liabilities		$ 7,671	$ 5,792
Other long-term liabilities:
Operating lease, liability, noncurrent, statement of financial position [Extensible List]		Total other long-term liabilities	Total other long-term liabilities
Operating lease obligations, long-term		$ 7,569	$ 8,870
Asset retirement obligations		5,335	5,981
Other		1,125	929
Total other long-term liabilities		14,029	$ 15,780
Tinuum Group, LLC
Other long-term liabilities:
Liabilities assumed	$ 1,700	$ 1,700

Supplemental Financial Inform_6

Supplemental Financial Information - Schedule of Change in Asset Retirement Obligation (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
	Mar. 31, 2024	Sep. 30, 2024	Dec. 31, 2023
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset retirement obligations, beginning of period	$ 6,163	$ 6,163	$ 8,533
Asset retirement obligations assumed		0	1,500
Accretion		496	582
Liabilities settled		(65)	(4,866)
Changes due to scope and timing of reclamation		0	414
Asset retirement obligations, end of period		6,594	6,163
Less current portion		1,259	182
Asset retirement obligations, long-term		5,335	5,981
Business Acquisition [Line Items]
Asset retirement obligations assumed		0	1,500
Liabilities settled		$ 65	$ 4,866
Marshall Mine \| Disposed of by Sale
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Liabilities settled	(4,700)
Business Acquisition [Line Items]
Liabilities settled	4,700
Corbin ARO
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset retirement obligations assumed	500
Business Acquisition [Line Items]
Asset retirement obligations assumed	500
Mine 4 ARO
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset retirement obligations assumed	1,000
Business Acquisition [Line Items]
Asset retirement obligations assumed	$ 1,000

Stockholders' Equity (Details)

Stockholders' Equity (Details) $ / shares in Units, $ in Thousands		1 Months Ended			3 Months Ended		9 Months Ended
	Feb. 01, 2023 USD ($) $ / shares	Sep. 30, 2024 USD ($) shares	May 31, 2024 USD ($) $ / shares shares	Apr. 30, 2024 USD ($) shares	Sep. 30, 2024 USD ($) shares	Sep. 30, 2023 shares	Sep. 30, 2024 USD ($) shares	Sep. 30, 2023 shares	Sep. 30, 2024 $ / shares	Dec. 31, 2023 shares	May 05, 2017
Class of Stock [Line Items]
Issuance of common stock pursuant to Arq Acquisition, net of offering costs \| $					$ 26,659
Number of shares agreed to purchase (in shares)		5,485,500
Common stock, shares issued (in shares)		46,652,061			46,652,061		46,652,061			37,791,084
Deducting offering expenses \| $		$ 26,700
Stock repurchased (in shares)					0	0	0	0
Price per share (in dollars per share) \| (per share)	$ 4								$ 5.25
Over-Allotment Option
Class of Stock [Line Items]
Number of shares agreed to purchase (in shares)		715,500
Original Amount
Class of Stock [Line Items]
Number of shares agreed to purchase (in shares)		4,770,000
Additional Option
Class of Stock [Line Items]
Number of shares agreed to purchase (in shares)		715,500
Purchase period		30 days
Maximum
Class of Stock [Line Items]
Requirement to own shares outstanding (as percent)											4.99%
Common Stock
Class of Stock [Line Items]
Issuance of common stock pursuant to Arq Acquisition, net of offering costs \| $					$ 5
Issuance of common stock pursuant to Arq Acquisition, net of offering costs (in shares)					5,485,500
Deducting offering expenses \| $	$ 15,400
Remaining authorized amount \| $		$ 7,000			$ 7,000		$ 7,000
Securities Purchase Agreement
Class of Stock [Line Items]
Number of shares agreed to purchase (in shares)			2,142,858
Share price (amount per shares) \| $ / shares			$ 7
Net proceeds from common stock issued \| $			$ 15,000
Common Stock
Class of Stock [Line Items]
Issuance of common stock pursuant to Arq Acquisition, net of offering costs \| $				$ 800
Issuance of common stock pursuant to Arq Acquisition, net of offering costs (in shares)				422,221

Stock-Based Compensation - Sche

Stock-Based Compensation - Schedule of Allocation of Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Total stock-based compensation expense	$ 750	$ 702	$ 2,185	$ 1,810
RSA expense
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Total stock-based compensation expense	483	501	1,268	1,405
PSU expense
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Total stock-based compensation expense	206	151	735	355
Stock option expense
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Total stock-based compensation expense	$ 61	$ 50	$ 182	$ 50

Stock-Based Compensation - Sc_2

Stock-Based Compensation - Schedule of Unrecognized Compensation Cost (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2024 USD ($)
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Unrecognized Compensation Cost	$ 5,249
Expected Weighted- Average Period of Recognition (in years)	1 year 7 months 13 days
RSA expense
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Unrecognized Compensation Cost	$ 3,414
Expected Weighted- Average Period of Recognition (in years)	1 year 9 months 25 days
PSU expense
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Unrecognized Compensation Cost	$ 1,400
Expected Weighted- Average Period of Recognition (in years)	1 year 1 month 2 days
Stock option expense
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Unrecognized Compensation Cost	$ 435
Expected Weighted- Average Period of Recognition (in years)	1 year 9 months 14 days

Stock-Based Compensation - Narr

Stock-Based Compensation - Narrative (Details) - shares	3 Months Ended		9 Months Ended
Stock-Based Compensation - Narrative (Details) - shares	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Granted stock options (in shares)	0	1,000,000	0	1,000,000
Restricted Stock
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Vesting period (in years)			3 years
Performance Share Units
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Vesting period (in years)			3 years
Stock Option
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Vesting period (in years)			3 years
Options exercisable, weighted average remaining contractual term (in years)			8 years 9 months 14 days
Expected dividend rate			0%
Stock Option \| Maximum
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Options exercisable, weighted average remaining contractual term (in years)			10 years

Stock-Based Compensation - Sc_3

Stock-Based Compensation - Schedule of Restricted Stock Activity (Details) - RSA expense	9 Months Ended
	Sep. 30, 2024 $ / shares shares
Restricted Stock
Non-vested shares, beginning balance (in shares) \| shares	790,005
Granted (in shares) \| shares	577,159
Vested (in shares) \| shares	(541,166)
Forfeited (in shares) \| shares	(55,197)
Non-vested shares, ending balance (in shares) \| shares	770,801
Weighted-Average Grant Date Fair Value
Non-vested shares, beginning balance (in dollars per share) \| $ / shares	$ 3.10
Granted (in dollars per share) \| $ / shares	5.79
Vested (in dollars per share) \| $ / shares	3.34
Forfeited (in dollars per share) \| $ / shares	2.82
Non-vested shares, ending balance (in dollars per share) \| $ / shares	$ 4.99

Stock-Based Compensation - Sc_4

Stock-Based Compensation - Schedule of Performance Shares Units (Details) - Performance Share Units $ / shares in Units, $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2024 USD ($) $ / shares shares	Sep. 30, 2024 USD ($) $ / shares shares
Units
Non-vested shares, beginning balance (in shares)		968,918
Granted (in shares)		115,877
Vested / Settled (in shares)		(150,000)
Forfeited / Canceled (in shares)		(57,750)
Non-vested shares, ending balance (in shares)	877,045	877,045
Weighted-Average Grant Date Fair Value
Non-vested shares, beginning balance (in dollars per share) \| $ / shares		$ 2.06
Granted (in dollars per share) \| $ / shares		10.94
Vested / Settled (in dollars per share) \| $ / shares		2.28
Forfeited / Canceled (in dollars per share) \| $ / shares		5.90
Non-vested shares, ending balance (in dollars per share) \| $ / shares	$ 2.94	$ 2.94
Outstanding, aggregate intrinsic value \| $	$ 5,148	$ 5,148
Outstanding, weighted-average remaining contractual term (in years)		1 year 1 month 2 days
Issued Upon Vesting of PSUs
Units
Vested / Settled (in shares)	(150,000)	(150,000)

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Option Activity (Details) - Stock option expense $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2024 USD ($) $ / shares shares
Number of Options Outstanding and Exercisable
Options outstanding, start of year (in shares) \| shares	1,000,000
Options granted (in shares) \| shares	0
Options exercised (in shares) \| shares	0
Options expired / forfeited (in shares) \| shares	0
Options outstanding, end of year (in shares) \| shares	1,000,000
Weighted-Average Exercise Price
Options outstanding, start of year (in dollars per share) \| $ / shares	$ 3
Options granted (in dollars per share) \| $ / shares	0
Options exercised (in dollars per share) \| $ / shares	0
Options expired / forfeited (in dollars per share) \| $ / shares	0
Options outstanding, end of year (in dollars per share) \| $ / shares	$ 3
Options outstanding, intrinsic value \| $	$ 2,870
Options outstanding, weighted average remaining contractual term (in years)	8 years 9 months 14 days
Options vested (in shares) \| shares	333,333
Options exercisable (in shares) \| shares	333,333
Options exercisable, weighted average exercise price (in dollars per share) \| $ / shares	$ 3
Options vested, weighted average exercise price (in dollars per share) \| $ / shares	$ 3
Options exercisable, intrinsic value \| $	$ 957
Options vested, intrinsic value \| $	$ 957
Options vested, weighted average remaining contractual term (in years)	8 years 9 months 14 days
Options exercisable, weighted average remaining contractual term (in years)	8 years 9 months 14 days

Income Taxes - Schedule of Inco

Income Taxes - Schedule of Income Tax Expense and Effective Tax Rates (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Income Tax Disclosure [Abstract]
Income tax (expense) benefit	$ 0	$ 0	$ (30)	$ 33
Effective tax rate	0%	0%	1%	0%

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details)	3 Months Ended		9 Months Ended
Income Taxes - Narrative (Details)	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Triggering Event [Line Items]
Effective tax rate	0%	0%	1%	0%
Before Out Of Period State Income Tax Expense
Triggering Event [Line Items]
Effective tax rate	0%		0%

Marshall Mine (Details)

Marshall Mine (Details) - Marshall Mine - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2023	Mar. 27, 2023
Business Acquisition [Line Items]
Consideration		$ 2.2
Liabilities		$ 4.9
Gain on sale of Marshall Mine, LLC	$ 2.7