Fuel Tech (FTEK) 10-Q 9 Nov 21 2021 Q3 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	9 Months Ended
	Sep. 30, 2021	Oct. 31, 2021
Document Information [Line Items]
Entity Central Index Key	0000846913
Entity Registrant Name	FUEL TECH, INC.
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Document Fiscal Period Focus	Q3
Document Fiscal Year Focus	2021
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2021
Document Transition Report	false
Entity File Number	001-33059
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	20-5657551
Entity Address, Address Line One	27601 Bella Vista Parkway
Entity Address, City or Town	Warrenville
Entity Address, State or Province	IL
Entity Address, Postal Zip Code	60555-1617
City Area Code	630
Local Phone Number	845-4500
Title of 12(b) Security	Common Stock
Trading Symbol	FTEK
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		30,263,791

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Current Period Unaudited) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 35,161	$ 10,640
Restricted cash	891	1,595
Accounts receivable, net	5,062	6,548
Inventories, net	128	97
Prepaid expenses and other current assets	1,064	2,193
Total current assets	42,306	21,073
Property and equipment, net of accumulated depreciation of $18,582 and $26,889, respectively	5,293	5,220
Goodwill	2,116	2,116
Other intangible assets, net of accumulated amortization of $871 and $757, respectively	475	553
Restricted cash	270	371
Right-of-use operating lease assets	283	394
Other assets	296	361
Total assets	51,039	30,088
Current liabilities:
Accounts payable	1,354	2,353
Accrued liabilities:
Operating lease liabilities - current	128	149
Employee compensation	701	930
Other accrued liabilities	1,829	2,099
Total current liabilities	4,012	5,531
Operating lease liabilities - non-current	147	237
Long-term borrowings	0	1,556
Deferred income taxes, net	134	134
Other liabilities	302	309
Total liabilities	4,595	7,767
Stockholders’ equity:
Common stock, $.01 par value, 40,000,000 shares authorized, 31,227,300 and 25,639,702 shares issued, and 30,263,791 and 25,228,951 shares outstanding, respectively	312	262
Additional paid-in capital	164,178	140,138
Accumulated deficit	(114,305)	(114,603)
Accumulated other comprehensive loss	(1,583)	(1,370)
Nil coupon perpetual loan notes	76	76
Treasury stock, at cost	(2,234)	(2,182)
Total stockholders’ equity	46,444	22,321
Total liabilities and stockholders’ equity	$ 51,039	$ 30,088

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Accumulated depreciation	$ 18,582	$ 26,889
Accumulated amortization, intangible assets	$ 871	$ 757
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	40,000,000	40,000,000
Common stock, shares issued (in shares)	31,227,300	25,639,702
Common stock, shares outstanding (in shares)	30,263,791	25,228,951

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Revenues	$ 7,559	$ 8,155	$ 17,810	$ 16,334
Costs and expenses:
Cost of sales	3,840	2,249	9,150	8,299
Selling, general and administrative	2,801	3,184	8,858	9,825
Research and development	340	285	1,070	880
Costs and Expenses, Total	6,981	5,718	19,078	19,004
Operating income (loss) from operations	578	2,437	(1,268)	(2,670)
Interest expense	(5)	(9)	(14)	(15)
Interest income	1	3	4	16
Other income (expense),net	104	(55)	1,586	83
Income (loss) before income taxes	678	2,376	308	(2,586)
Income tax expense	0	0	(10)	(149)
Net income (loss)	$ 678	$ 2,376	$ 298	$ (2,735)
Net income (loss) per common share:
Basic net income (loss) per common share (in dollars per share)	$ 0.02	$ 0.10	$ 0.01	$ (0.11)
Diluted net income (loss) per common share (in dollars per share)	$ 0.02	$ 0.09	$ 0.01	$ (0.11)
Weighted-average number of common shares outstanding:
Basic (in shares)	30,264,000	24,701,000	29,356,000	24,656,000
Diluted (in shares)	30,335,000	25,120,000	29,482,000	24,656,000

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Net income (loss)	$ 678	$ 2,376	$ 298	$ (2,735)
Other comprehensive income (loss):
Foreign currency translation adjustments	(153)	268	(213)	189
Comprehensive income (loss)	$ 525	$ 2,644	$ 85	$ (2,546)

Condensed Statements of Stockho

Condensed Statements of Stockholders' Equity (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Common Stock Outstanding [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Nil Coupon Perpetual Loan Notes [Member]	Treasury Stock [Member]	Total
Beginning balance (in shares) at Dec. 31, 2019	24,592
Beginning balance at Dec. 31, 2019	$ 254	$ 139,560	$ (110,325)	$ (1,778)	$ 76	$ (1,612)	$ 26,175
Net loss	0	0	(2,567)	0	0	0	(2,567)
Foreign currency translation adjustments	0	0	0	(231)	0	0	(231)
Stock compensation expense	$ 0	81	0	0	0	0	81
Common shares issued upon vesting of restricted stock units (in shares)	55
Common shares issued upon vesting of restricted stock units	$ 0	0	0	0	0	0	0
Treasury shares withheld (in shares)	(11)
Treasury shares withheld	$ 0	0	0	0	0	(5)	(5)
Net income (loss)	0	0	(2,567)	0	0	0	(2,567)
Foreign currency translation adjustments	$ 0	0	0	(231)	0	0	(231)
Ending balance (in shares) at Mar. 31, 2020	24,636
Ending balance at Mar. 31, 2020	$ 254	139,641	(112,892)	(2,009)	76	(1,617)	23,453
Beginning balance (in shares) at Dec. 31, 2019	24,592
Beginning balance at Dec. 31, 2019	$ 254	139,560	(110,325)	(1,778)	76	(1,612)	26,175
Net loss							(2,735)
Foreign currency translation adjustments							189
Net income (loss)							(2,735)
Foreign currency translation adjustments							189
Ending balance (in shares) at Sep. 30, 2020	24,701
Ending balance at Sep. 30, 2020	$ 255	139,767	(113,060)	(1,589)	76	(1,618)	23,831
Beginning balance (in shares) at Mar. 31, 2020	24,636
Beginning balance at Mar. 31, 2020	$ 254	139,641	(112,892)	(2,009)	76	(1,617)	23,453
Net loss	0	0	(2,544)	0	0	0	(2,544)
Foreign currency translation adjustments	0	0	0	152	0	0	152
Stock compensation expense	$ 0	69	0	0	0	0	69
Common shares issued upon vesting of restricted stock units (in shares)	66
Common shares issued upon vesting of restricted stock units	$ 1	0	0	0	0	(1)	0
Treasury shares withheld (in shares)	(1)
Treasury shares withheld	$ 0	0	0	0	0	0	0
Net income (loss)	0	0	(2,544)	0	0	0	(2,544)
Foreign currency translation adjustments	$ 0	0	0	152	0	0	152
Ending balance (in shares) at Jun. 30, 2020	24,701
Ending balance at Jun. 30, 2020	$ 255	139,710	(115,436)	(1,857)	76	(1,618)	21,130
Net loss	0	0	2,376	0	0	0	2,376
Foreign currency translation adjustments	0	0	0	268	0	0	268
Stock compensation expense	0	57	0	0	0	0	57
Net income (loss)	0	0	2,376	0	0	0	2,376
Foreign currency translation adjustments	$ 0	0	0	268	0	0	268
Ending balance (in shares) at Sep. 30, 2020	24,701
Ending balance at Sep. 30, 2020	$ 255	139,767	(113,060)	(1,589)	76	(1,618)	23,831
Beginning balance (in shares) at Dec. 31, 2020	25,229
Beginning balance at Dec. 31, 2020	$ 262	140,138	(114,603)	(1,370)	76	(2,182)	22,321
Net loss	0	0	398	0	0	0	398
Foreign currency translation adjustments	0	0	0	(193)	0	0	(193)
Stock compensation expense	$ 0	20	0	0	0	0	20
Common shares issued upon vesting of restricted stock units (in shares)	50
Common shares issued upon vesting of restricted stock units	$ 0	0	0	0	0	0	0
Treasury shares withheld (in shares)	(15)
Treasury shares withheld	$ 0	0	0	0	0	(52)	(52)
Net income (loss)	0	0	398	0	0	0	398
Foreign currency translation adjustments	$ 0	0	0	(193)	0	0	(193)
Common stock issued in connection with private placement, net (in shares)	5,000
Common stock issued in connection with private placement, net	$ 50	23,979	0	0	0	0	24,029
Ending balance (in shares) at Mar. 31, 2021	30,264
Ending balance at Mar. 31, 2021	$ 312	164,137	(114,205)	(1,563)	76	(2,234)	46,523
Beginning balance (in shares) at Dec. 31, 2020	25,229
Beginning balance at Dec. 31, 2020	$ 262	140,138	(114,603)	(1,370)	76	(2,182)	22,321
Net loss							298
Foreign currency translation adjustments							(213)
Net income (loss)							298
Foreign currency translation adjustments							(213)
Ending balance (in shares) at Sep. 30, 2021	30,264
Ending balance at Sep. 30, 2021	$ 312	164,178	(114,305)	(1,583)	76	(2,234)	46,444
Beginning balance (in shares) at Mar. 31, 2021	30,264
Beginning balance at Mar. 31, 2021	$ 312	164,137	(114,205)	(1,563)	76	(2,234)	46,523
Net loss	0	0	(778)	0	0	0	(778)
Foreign currency translation adjustments	0	0	0	133	0	0	133
Stock compensation expense	0	20	0	0	0	0	20
Net income (loss)	0	0	(778)	0	0	0	(778)
Foreign currency translation adjustments	$ 0	0	0	133	0	0	133
Ending balance (in shares) at Jun. 30, 2021	30,264
Ending balance at Jun. 30, 2021	$ 312	164,157	(114,983)	(1,430)	76	(2,234)	45,898
Net loss	0	0	678	0	0	0	678
Foreign currency translation adjustments	0	0	0	(153)	0	0	(153)
Stock compensation expense	0	21	0	0	0	0	21
Net income (loss)	0	0	678	0	0	0	678
Foreign currency translation adjustments	$ 0	0	0	(153)	0	0	(153)
Ending balance (in shares) at Sep. 30, 2021	30,264
Ending balance at Sep. 30, 2021	$ 312	$ 164,178	$ (114,305)	$ (1,583)	$ 76	$ (2,234)	$ 46,444

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Operating Activities
Net income (loss)	$ 298	$ (2,735)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Depreciation	457	495
Amortization	114	139
Loss (gain) on sale of equipment	13	(3)
Provision for doubtful accounts, net of recoveries	(2)	(1,144)
Stock-based compensation, net of forfeitures	61	208
Changes in operating assets and liabilities:
Accounts receivable	1,405	(863)
Inventories	(32)	(71)
Prepaid expenses, other current assets and other non-current assets	1,176	239
Accounts payable	(980)	820
Accrued liabilities and other non-current liabilities	(382)	(376)
Net cash provided by (used in) operating activities	572	(3,291)
Investing Activities
Purchases of equipment and patents	(584)	(206)
Net cash used in investing activities	(584)	(206)
Financing Activities
Proceeds from sale of common stock issued in connection with private placement	25,812	0
Costs related to sale of common stock issued in connection with private placement	(1,783)	0
Taxes paid on behalf of equity award participants	(52)	(6)
Net cash provided by financing activities	23,977	1,550
Effect of exchange rate fluctuations on cash	(249)	256
Net increase (decrease) in cash, cash equivalents and restricted cash	23,716	(1,691)
Cash, cash equivalents, and restricted cash at beginning of period (Note 2)	12,606	13,501
Cash, cash equivalents and restricted cash at end of period (Note 2)	36,322	11,810
Paycheck Protection Program CARES Act [Member]
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Gain of forgiveness on Paycheck Protection Plan Loan	(1,556)	0
Financing Activities
Proceeds from borrowings	$ 0	$ 1,556

Note 1 - General

Note 1 - General	9 Months Ended
	Sep. 30, 2021
Notes to Financial Statements
Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block]	1. Organization Fuel Tech, Inc. and subsidiaries ("Fuel Tech", the "Company", "we", "us" or "our") develops and provides proprietary technologies for air pollution control, process optimization, water treatment, and advanced engineering services. These technologies enable customers to operate in a cost-effective and environmentally sustainable manner. The Company’s NOx reduction technologies reduce nitrogen oxide emissions from boilers, furnaces and other stationary combustion sources. To reduce NOx emissions, our technologies utilize advanced combustion modification techniques and post-combustion NOx control approaches including non-catalytic, catalytic and combined systems. The Company also provides solutions for the mitigation of particulate matter, including particulate control with electrostatic precipitator products and services, and using flue gas conditioning systems which modify the ash properties of particulate for improved collection efficiency. The Company’s FUEL CHEM® technology improves the efficiency, reliability, fuel flexibility, boiler heat rate, and environmental status of combustion units by controlling slagging, fouling, corrosion, and opacity. Water treatment technologies include DGI™ Dissolved Gas Infusion Systems which utilize a patented nozzle to deliver supersaturated oxygen solutions and other gas-water combinations to target process applications or environmental issues. This infusion process has a variety of applications in the water and wastewater industries, including remediation, aeration, biological treatment, and wastewater odor management. Many of Fuel Tech’s products and services rely heavily on the Company’s Computational Fluid Dynamics modeling capabilities, which are enhanced by internally developed, high-end visualization software. Basis of Presentation The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America ("U.S. GAAP") for interim financial information and with the instructions to Form 10 10 X not three nine September 30, 2021 not December 31, 2021. 10 December 31, 2020 COVID- 19 The effects of the coronavirus (COVID- 19 not may third Management cannot predict the full impact of the COVID- 19 19 Private Placement Offering On February 11, 2021, five one five one

Note 2 - Summary of Significant

Note 2 - Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2021
Notes to Financial Statements
Significant Accounting Policies [Text Block]	2. Restricted cash Restricted cash as of September 30, 2021 no September 30, 2022 February 1, 2023) 10 The following table provides a reconciliation of cash, cash equivalents, and restricted cash reported within the Condensed Consolidated Balance Sheets that sum to the total of the same such amounts shown in the Condensed Consolidated Statements of Cash Flows: September 30, September 30, 2021 2020 Cash and cash equivalents $ 35,161 $ 9,418 Restricted cash included in current assets 891 2,025 Restricted cash included in long-term assets 270 367 Total cash, cash equivalents, and restricted cash shown in the Consolidated Statements of Cash Flows $ 36,322 $ 11,810 Leases The Company applies the provisions of Accounting Standards Codification ("ASC") 842, Operating lease ROU assets and operating lease liabilities are recognized based on the present value of the future minimum lease payments over the lease term at commencement date. As most of our leases do not may We have lease agreements with lease and non-lease components, and we elected the practical expedient to not 12

Note 3 - Revenue

Note 3 - Revenue	9 Months Ended
	Sep. 30, 2021
Notes to Financial Statements
Revenue from Contract with Customer [Text Block]	3. The Company recognizes revenue when control of the promised goods or services is transferred to our customers, in an amount that reflects the consideration we expect to be entitled to in exchange for those goods or services. Fuel Tech’s sales of products to customers generally represent single performance obligations. The majority of our contracts have a single performance obligation as the promise to transfer the individual goods or services is not not We generally expense sales commissions on a ratable basis when incurred because the amortization period would have been one Air Pollution Control Technology Fuel Tech’s Air Pollution Control (“APC”) contracts are typically six eighteen three four As part of most of its contractual APC project agreements, Fuel Tech will agree to customer-specific acceptance criteria that relate to the operational performance of the system that is being sold. These criteria are determined based on modeling that is performed by Fuel Tech personnel, which is based on operational inputs that are provided by the customer. The customer will warrant that these operational inputs are accurate as they are specified in the binding contractual agreement. Further, the customer is solely responsible for the accuracy of the operating condition information; typically all performance guarantees and equipment warranties granted by us are voidable if the operating condition information is inaccurate or is not Since control transfers over time, revenue is recognized based on the extent of progress towards completion of the single performance obligation. Fuel Tech uses the cost-to-cost input measure of progress for our contracts since it best depicts the transfer of assets to the customer which occurs as we incur costs on our contracts. Under the cost-to-cost input measure of progress, the extent of progress towards completion is measured based on the ratio of costs incurred to date to the total estimated costs at completion of the performance obligation. Revenues are recorded proportionally as costs are incurred. Costs to fulfill include all internal and external engineering costs, equipment charges, inbound and outbound freight expenses, internal and site transfer costs, installation charges, purchasing and receiving costs, inspection costs, warehousing costs, project personnel travel expenses and other direct and indirect expenses specifically identified as project- or product-line related, as appropriate (e.g. test equipment depreciation and certain insurance expenses). Fuel Tech’s APC product line also includes ancillary revenue for post contractual goods and services. Revenue associated with these activities are recognized at point in time when delivery of goods or completion of the service obligation is performed. Fuel Tech has installed over 1,200 units with APC technology and normally provides performance guarantees to our customers based on the operating conditions for the project. As part of the project implementation process, we perform system start-up and optimization services that effectively serve as a test of actual project performance. We believe that this test, combined with the accuracy of the modeling that is performed, enables revenue to be recognized prior to the receipt of formal customer acceptance. FUEL CHEM Revenues from the sale of chemical products are recognized when control transfers to customer upon shipment or delivery of the product based on the applicable shipping terms. We generally recognize revenue for these arrangements at a point in time based on our evaluation of when the customer obtains control of the promised goods or services. On occasion, Fuel Tech will engineer and sell its chemical pumping equipment. These projects are similar in nature to the APC projects described above and for those project where control transfers over time, revenue is recognized based on the extent of progress towards completion of the single performance obligation. For projects containing multiple performance obligations, the Company allocates the transaction price based on the estimated standalone selling price. The Company must develop assumptions that require judgment to determine the stand-alone selling price for each performance obligation identified in the contract. The Company utilizes key assumptions to determine the stand-alone selling price, which may one The consideration allocated to each performance obligation is recognized as revenue when control is transferred for the related goods or services. For performance obligations which consist of licenses and other promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. The Company receives payments from its customers based on billing schedules established in each contract. Up-front payments and fees are recorded as deferred revenue upon receipt or when due until the Company performs its obligations under these arrangements. Amounts are recorded as accounts receivable when the Company’s right to consideration is unconditional. Disaggregated Revenue by Product Technology The following table presents our revenues disaggregated by product technology: Three Months Ended Nine Months Ended September 30, September 30, 2021 2020 2021 2020 Air Pollution Control Technology solutions $ 1,172 $ 2,326 $ 1,768 $ 4,524 Spare parts 407 254 823 667 Ancillary revenue 365 306 1,246 828 Total Air Pollution Control Technology revenues 1,944 2,886 3,837 6,019 FUEL CHEM FUEL CHEM technology solutions 5,615 5,269 13,973 10,315 Total Revenues $ 7,559 $ 8,155 $ 17,810 $ 16,334 Disaggregated Revenue by Geography The following table presents our revenues disaggregated by geography, based on the billing addresses of our customers: Three Months Ended Nine Months Ended September 30, September 30, 2021 2020 2021 2020 United States $ 6,049 $ 6,473 $ 15,100 $ 12,880 Foreign Revenues Latin America 121 195 338 400 Europe 663 904 1,339 1,494 Asia 726 583 1,033 1,560 Total Foreign Revenues 1,510 1,682 2,710 3,454 Total Revenues $ 7,559 $ 8,155 $ 17,810 $ 16,334 Timing of Revenue Recognition The following table presents the timing of our revenue recognition: Three Months Ended Nine Months Ended September 30, September 30, 2021 2020 2021 2020 Products transferred at a point in time $ 6,387 $ 5,108 $ 16,042 $ 11,089 Products and services transferred over time 1,172 3,047 1,768 5,245 Total Revenues $ 7,559 $ 8,155 $ 17,810 $ 16,334 Contract Balances The timing of revenue recognition, billings and cash collections results in billed accounts receivable, unbilled receivables (contract assets), and customer advances and deposits (contract liabilities) on the consolidated balance sheets. In our Air Pollution Control Technology segment, amounts are billed as work progresses in accordance with agreed-upon contractual terms. Generally, billing occurs subsequent to revenue recognition, resulting in contract assets. For the FUEL CHEM technology segment, deliveries made in the current period but billed in subsequent periods are also considered unbilled receivables (contract assets). These assets are reported on the consolidated balance sheet on a contract-by-contract basis at the end of each reporting period. At September 30, 2021 December 31, 2020 However, the Company will periodically bill in advance of costs incurred before revenue is recognized, resulting in contract liabilities. These liabilities are reported on the consolidated balance sheet on a contract-by-contract basis at the end of each reporting period. Contract liabilities were $1,246 and $850, at September 30, 2021 December 31, 2020 Changes in the contract asset and liability balances during the nine September 30, 2021 not three nine September 30, 2021 three nine September 30, 2020 As of September 30, 2021 December 31, 2020 14 Remaining Performance Obligations Remaining performance obligations represents the transaction price of Air Pollution Control technology booked orders for which work has not September 30, 2021 Accounts Receivable The components of accounts receivable are as follows: As of September 30, 2021 December 31, 2020 Trade receivables $ 5,423 $ 5,015 Unbilled receivables 375 2,348 Other short-term receivables 102 20 Allowance for doubtful accounts (838 ) (835 ) Total accounts receivable $ 5,062 $ 6,548

Note 4 - Restructuring Activiti

Note 4 - Restructuring Activities	9 Months Ended
	Sep. 30, 2021
Notes to Financial Statements
Restructuring and Related Activities Disclosure [Text Block]	4. On January 18, 2019, September 30, 2021 The following table presents our revenues and net income (loss) which includes the Restructuring charge line item within the Condensed Statements of Operations for 2021 2020 Three Months Ended Nine Months Ended September 30, September 30, 2021 2020 2021 2020 Total revenues $ 2 $ 6 $ 17 $ 11 Net loss (47 ) (73 ) (85 ) (31 ) Total assets primarily consist of cash, accounts receivable, contract assets, prepaid expenses and other current assets. Total liabilities consist of accounts payable and certain accrued liabilities. The following table presents net assets in China as follows: As of September 30, 2021 December 31, 2020 Total assets $ 1,444 $ 2,463 Total liabilities 290 396 Total net assets $ 1,154 $ 2,067

Note 5 - Accumulated Other Comp

Note 5 - Accumulated Other Comprehensive Loss	9 Months Ended
	Sep. 30, 2021
Notes to Financial Statements
Comprehensive Income (Loss) Note [Text Block]	5. The changes in accumulated other comprehensive loss by component were as follows: Three Months Ended Nine Months Ended September 30, September 30, 2021 2020 2021 2020 Foreign currency translation Balance at beginning of period $ (1,430 ) $ (1,857 ) $ (1,370 ) $ (1,778 ) Other comprehensive income (loss): Foreign currency translation adjustments (1) (153 ) 268 (213 ) 189 Total accumulated other comprehensive loss $ (1,583 ) $ (1,589 ) $ (1,583 ) $ (1,589 ) ( 1 In all periods presented, there were no no

Note 6 - Treasury Stock

Note 6 - Treasury Stock	9 Months Ended
	Sep. 30, 2021
Notes to Financial Statements
Treasury Stock [Text Block]	6. Common stock held in treasury totaled 963,509 and 948,347 with a cost of $2,234 and $2,182 at September 30, 2021 December 31, 2020

Note 7 - Earnings Per Share

Note 7 - Earnings Per Share	9 Months Ended
	Sep. 30, 2021
Notes to Financial Statements
Earnings Per Share [Text Block]	7. Basic earnings per share excludes the dilutive effects of stock options, restricted stock units (RSUs), warrants, and the nil nil nine September 30, 2020, The following table sets forth the weighted-average shares used in calculating the earnings per share for the three nine September 30, 2021 2020 Three Months Ended Nine Months Ended September 30, September 30, 2021 2020 2021 2020 Basic weighted-average shares 30,264,000 24,701,000 29,356,000 24,656,000 Conversion of unsecured loan notes — — — — Unexercised options and unvested RSUs 71,000 419,000 126,000 — Diluted weighted-average shares 30,335,000 25,120,000 29,482,000 24,656,000 For the nine September 30, 2020,

Note 8 - Stock-based Compensati

Note 8 - Stock-based Compensation	9 Months Ended
	Sep. 30, 2021
Notes to Financial Statements
Share-based Payment Arrangement [Text Block]	8. Under our stock-based employee compensation plan, referred to as the Fuel Tech, Inc. 2014 may may may September 30, 2021 2014 We did not three nine September 30, 2021 no three nine September 30, 2021 no Stock-based compensation is included in selling, general, and administrative costs in our Condensed Consolidated Statements of Operations. The components of stock-based compensation for the three nine September 30, 2021 2020 Three Months Ended Nine Months Ended September 30, September 30, 2021 2020 2021 2020 Stock options and restricted stock units, net of forfeited $ 21 $ 57 $ 61 $ 207 After-tax effect of stock-based compensation $ 21 $ 57 $ 61 $ 207 Stock Options Stock options granted to employees under the Incentive Plans have a 10-year life and they vest as follows: 50% after the second third fourth four Fuel Tech uses the Black-Scholes option pricing model to estimate the grant date fair value of employee stock options. The principal variable assumptions utilized in valuing options and the methodology for estimating such model inputs include: ( 1 2 3 Stock option activity for Fuel Tech’s Incentive Plans for the nine September 30, 2021 Weighted- Average Number Weighted- Remaining Aggregate of Average Contractual Intrinsic Options Exercise Price Term Value Outstanding on January 1, 2021 484,500 $ 3.57 Granted — — Exercised — — Expired or forfeited (50,000 ) 8.16 Outstanding on September 30, 2021 434,500 $ 3.05 3.34 $ 73 Exercisable on September 30, 2021 434,500 $ 3.05 3.34 $ 73 As of September 30, 2021 Restricted Stock Units Restricted stock units (RSUs) granted to employees vest over time based on continued service (typically vesting over a period between two four In addition to the time vested RSUs, the Company entered into a 2021 “2021 2021 2021 no 2021. i.e., 1/3, 1/3 1/3 three one no not At September 30, 2021 A summary of restricted stock unit activity for the nine September 30, 2021 Weighted Average Grant Date Shares Fair Value Unvested restricted stock units at January 1, 2021 100,005 $ 4.08 Granted — — Forfeited (5,000 ) 0.97 Vested (50,002 ) 1.50 Unvested restricted stock units at September 30, 2021 45,003 $ 7.29 The fair value of restricted stock that vested during the nine September 30, 2021 Deferred Directors Fees In addition to the Incentive Plans, Fuel Tech has a Deferred Compensation Plan for Directors (Deferred Plan). Under the terms of the Deferred Plan, Directors can elect to defer Directors’ fees for shares of Fuel Tech Common Stock that are issuable at a future date as defined in the agreement. In accordance with ASC 718, nine September 30, 2021 2020

Note 9 - Warrants

Note 9 - Warrants	9 Months Ended
	Sep. 30, 2021
Notes to Financial Statements
Warrants Disclosure [Text Block]	9. On February 11, 2021, five one five one Fuel Tech uses the Black-Scholes option pricing model to estimate the grant date fair value of the warrants. The principal variable assumptions utilized in valuing warrants and the methodology for estimating such model inputs are: ( 1 2 3 five one The calculated fair value allocated to the warrants is $7,337. This amount has been recorded as Additional paid in capital - warrants and is shown net in the Additional paid in capital line of the condensed consolidated balance sheets. The issuance of warrants to purchase shares of the Company's common stock are summarized as follows: Shares Outstanding on December 31, 2020 — Granted 2,850,000 Exercised — Outstanding as of September 30, 2021 2,850,000 The following table summarizes information about warrants outstanding and exercisable at September 30, 2021 Range of Exercise Price Number Outstanding/Exercisable Weighted Average Remaining Life in Years Weighted Average Exercise Price $5.10 2,500,000 4.87 $ 5.10 $6.45 350,000 4.87 $ 6.45 2,850,000

Note 10 - Debt Financing

Note 10 - Debt Financing	9 Months Ended
	Sep. 30, 2021
Notes to Financial Statements
Debt Disclosure [Text Block]	10. On April 17, 2020, April 15, 2020 ( On January 8, 2021, 470, 835 30.

Note 11 - Business Segment and

Note 11 - Business Segment and Geographic Financial Data	9 Months Ended
	Sep. 30, 2021
Notes to Financial Statements
Segment Reporting Disclosure [Text Block]	11. Business Segment Financial Data We segregate our financial results into two reportable segments representing two • The Air Pollution Control technology segment includes technologies to reduce NOx emissions in flue gas from boilers, incinerators, furnaces and other stationary combustion sources. These include Low and Ultra Low NOx Burners (LNB and ULNB), Over-Fire Air (OFA) systems, NOxOUT ® ™ ® ® • The FUEL CHEM ® ® The “Other” classification includes those profit and loss items not no We evaluate performance and allocate resources based on reviewing gross margin by reportable segment. The accounting policies of the reportable segments are the same as those described in the summary of significant accounting policies (Note 1 10 not Information about reporting segment net sales and gross margin from operations are provided below: Air Pollution FUEL CHEM Three months ended September 30, 2021 Control Segment Segment Other Total Revenues from external customers $ 1,944 $ 5,615 $ — $ 7,559 Cost of sales (1,134 ) (2,706 ) — (3,840 ) Gross margin 810 2,909 — 3,719 Selling, general and administrative — — (2,801 ) (2,801 ) Research and development — — (340 ) (340 ) Operating income (loss) from operations $ 810 $ 2,909 $ (3,141 ) $ 578 Air Pollution FUEL CHEM Three months ended September 30, 2020 Control Segment Segment Other Total Revenues from external customers $ 2,886 $ 5,269 $ — $ 8,155 Cost of sales 304 (2,553 ) — (2,249 ) Gross margin 3,190 2,716 — 5,906 Selling, general and administrative — — (3,184 ) (3,184 ) Research and development — — (285 ) (285 ) Operating income (loss) from operations $ 3,190 $ 2,716 $ (3,469 ) $ 2,437 Air Pollution FUEL CHEM Nine months ended September 30, 2021 Control Segment Segment Other Total Revenues from external customers $ 3,837 $ 13,973 $ — $ 17,810 Cost of sales (2,172 ) (6,978 ) — (9,150 ) Gross margin 1,665 6,995 — 8,660 Selling, general and administrative — — (8,858 ) (8,858 ) Research and development — — (1,070 ) (1,070 ) Operating income (loss) from operations $ 1,665 $ 6,995 $ (9,928 ) $ (1,268 ) Air Pollution FUEL CHEM Nine months ended September 30, 2020 Control Segment Segment Other Total Revenues from external customers $ 6,019 $ 10,315 $ — $ 16,334 Cost of sales (2,782 ) (5,517 ) — (8,299 ) Gross margin 3,237 4,798 — 8,035 Selling, general and administrative — — (9,825 ) (9,825 ) Research and development — — (880 ) (880 ) Operating income (loss) from operations $ 3,237 $ 4,798 $ (10,705 ) $ (2,670 ) Geographic Segment Financial Data Information concerning our operations by geographic area is provided below. Revenues are attributed to countries based on the location of the customer. Assets are those directly associated with operations of the geographic area. Three Months Ended Nine Months Ended September 30, September 30, 2021 2020 2021 2020 Revenues: United States $ 6,049 $ 6,473 $ 15,100 $ 12,880 Foreign 1,510 1,682 2,710 3,454 $ 7,559 $ 8,155 $ 17,810 $ 16,334 September 30, December 31, 2021 2020 Assets: United States $ 46,713 $ 24,524 Foreign 4,326 5,564 $ 51,039 $ 30,088

Note 12 - Leases

Note 12 - Leases	9 Months Ended
	Sep. 30, 2021
Notes to Financial Statements
Lessee, Operating Leases [Text Block]	12. Leases We have seven not no 842. Total operating lease expense for the three nine September 30, 2021 2020 Three Months Ended Nine Months Ended September 30, September 30, 2021 2020 2021 2020 Operating lease cost $ 44 $ 47 $ 133 $ 157 Short-term lease cost 4 5 15 12 Total lease cost $ 48 $ 52 $ 148 $ 169 The weighted average remaining lease term was 2.45 years as of September 30, 2021 September 30, 2021 Remaining maturities of our existing lease liabilities as of September 30, 2021 Year Ending December 31, Operating Leases 2021 (excluding the nine months ended September 30, 2021) 44 2022 132 2023 115 2024 29 2025 7 Total lease payments $ 327 Less imputed interest (52 ) Total $ 275 The following is the balance sheet classification of our existing lease liabilities as of September 30, 2021 As of September 30, 2021 December 31, 2020 Operating lease liabilities - current $ 128 $ 149 Operating lease liabilities - non-current 147 237 Total operating lease liabilities $ 275 $ 386 Supplemental cash flow information related to leases, was as follows: Three Months Ended Nine Months Ended September 30, September 30, 2021 2020 2021 2020 Cash paid for amounts included in the measurement of lease liabilities $ 50 $ 45 $ 148 $ 148 Leased assets obtained in exchange for operating lease liabilities 39 41 119 137

Note 13 - Accrued Liabilities

Note 13 - Accrued Liabilities	9 Months Ended
	Sep. 30, 2021
Notes to Financial Statements
Accounts Payable, Accrued Liabilities, and Other Liabilities Disclosure, Current [Text Block]	13. The components of other accrued liabilities are as follows: As of September 30, 2021 December 31, 2020 Contract liabilities (Note 3) $ 1,246 $ 850 Accrued remediation contingency (Note 14) — 176 Other accrued liabilities 583 1,073 Total other accrued liabilities $ 1,829 $ 2,099

Note 14 - Commitments and Conti

Note 14 - Commitments and Contingencies	9 Months Ended
	Sep. 30, 2021
Notes to Financial Statements
Commitments and Contingencies Disclosure [Text Block]	14. Fuel Tech is subject to various claims and contingencies related to, among other things, workers compensation, general liability (including product liability), and lawsuits. The Company records liabilities where a contingent loss is probable and can be reasonably estimated. If the reasonable estimate of a probable loss is a range, the Company records the most probable estimate of the loss or the minimum amount when no not not may From time to time we are involved in litigation with respect to matters arising from the ordinary conduct of our business. In the opinion of management, based upon presently available information, either adequate provision for anticipated costs have been accrued or the ultimate anticipated costs will not not During the third 2020, third 2021. September 30, 2021 December 31, 2020 Fuel Tech issues a standard product warranty with the sale of its products to customers. Our recognition of warranty liability is based primarily on analyses of warranty claims experienced in the preceding years as the nature of our historical product sales for which we offer a warranty are substantially unchanged. This approach provides an aggregate warranty accrual that is historically aligned with actual warranty claims experienced. There was no change in the warranty liability balance included in the other accrued liabilities line of the Condensed Consolidated Balance Sheets during the nine September 30, 2021 2020 September 30, 2021 December 31, 2020

Note 15 - Income Taxes

Note 15 - Income Taxes	9 Months Ended
	Sep. 30, 2021
Notes to Financial Statements
Income Tax Disclosure [Text Block]	15. The Company’s effective tax rate is approximately 3.2% and (5.8%) for the nine September 30, 2021 2020 nine September 30, 2021 no nine September 30, 2021 2020 nine September 30, 2021 Fuel Tech had no unrecognized tax benefits as of September 30, 2021 December 31, 2020

Note 16 - Goodwill and Other In

Note 16 - Goodwill and Other Intangibles	9 Months Ended
	Sep. 30, 2021
Notes to Financial Statements
Goodwill and Intangible Assets Disclosure [Text Block]	16. Goodwill is allocated among and evaluated for impairment at the reporting unit level, which is defined as an operating segment or one ® September 30, 2021 December 31, 2020 ® Goodwill is allocated to each of our reporting units after considering the nature of the net assets giving rise to the goodwill and how each reporting unit would enjoy the benefits and synergies of the net assets acquired. There were no indications of goodwill impairment in the nine September 30, 2021 2020 Fuel Tech reviews other intangible assets, which include patent assets, for impairment on a recurring basis or when events or changes in circumstances indicate the carrying amount of an asset may not may There were no indications of intangible asset impairments for the nine September 30, 2021 2020

Note 17 - Subsequent Events

Note 17 - Subsequent Events	9 Months Ended
	Sep. 30, 2021
Notes to Financial Statements
Subsequent Events [Text Block]	17. The Company has evaluated subsequent events through the filing of this Quarterly Report on Form 10 no

Note 18 - Liquidity

Note 18 - Liquidity	9 Months Ended
	Sep. 30, 2021
Notes to Financial Statements
Substantial Doubt about Going Concern [Text Block]	18 We continue to monitor our liquidity needs and in response to our continued losses have taken measures to reduce expenses and restructure operations which we feel are necessary to ensure we maintain sufficient working capital and liquidity to operate the business and invest in our future. We have experienced continued declines in revenues and recurring losses historically. As a result, we have evaluated our ongoing business needs, and considered the cash requirements of our base business of Air Pollution Control (APC) and Fuel Chem businesses. This evaluation included consideration of the following: a) customer and revenue trends in our APC and Fuel Chem business segments, b) current operating structure and expenditure levels, c) current availability of working capital, and d) support for our research and development initiatives. We continue to monitor our liquidity needs and have taken measures to reduce expenses and restructure operations which we feel are necessary to ensure we maintain sufficient working capital and liquidity to operate the business and invest in our future. We believe our current cash position and net cash flows expected to be generated from operations are adequate to fund planned operations of the Company for the next 12

Significant Accounting Policies

Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2021
Accounting Policies [Abstract]
Cash and Cash Equivalents, Restricted Cash and Cash Equivalents, Policy [Policy Text Block]	Restricted cash Restricted cash as of September 30, 2021 no September 30, 2022 February 1, 2023) 10 The following table provides a reconciliation of cash, cash equivalents, and restricted cash reported within the Condensed Consolidated Balance Sheets that sum to the total of the same such amounts shown in the Condensed Consolidated Statements of Cash Flows: September 30, September 30, 2021 2020 Cash and cash equivalents $ 35,161 $ 9,418 Restricted cash included in current assets 891 2,025 Restricted cash included in long-term assets 270 367 Total cash, cash equivalents, and restricted cash shown in the Consolidated Statements of Cash Flows $ 36,322 $ 11,810
Lessee, Leases [Policy Text Block]	Leases The Company applies the provisions of Accounting Standards Codification ("ASC") 842, Operating lease ROU assets and operating lease liabilities are recognized based on the present value of the future minimum lease payments over the lease term at commencement date. As most of our leases do not may We have lease agreements with lease and non-lease components, and we elected the practical expedient to not 12

Note 2 - Summary of Significa_2

Note 2 - Summary of Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2021
Notes Tables
Schedule of Cash and Cash Equivalents [Table Text Block]	September 30, September 30, 2021 2020 Cash and cash equivalents $ 35,161 $ 9,418 Restricted cash included in current assets 891 2,025 Restricted cash included in long-term assets 270 367 Total cash, cash equivalents, and restricted cash shown in the Consolidated Statements of Cash Flows $ 36,322 $ 11,810

Note 3 - Revenue (Tables)

Note 3 - Revenue (Tables)	9 Months Ended
	Sep. 30, 2021
Notes Tables
Disaggregation of Revenue [Table Text Block]	Three Months Ended Nine Months Ended September 30, September 30, 2021 2020 2021 2020 Air Pollution Control Technology solutions $ 1,172 $ 2,326 $ 1,768 $ 4,524 Spare parts 407 254 823 667 Ancillary revenue 365 306 1,246 828 Total Air Pollution Control Technology revenues 1,944 2,886 3,837 6,019 FUEL CHEM FUEL CHEM technology solutions 5,615 5,269 13,973 10,315 Total Revenues $ 7,559 $ 8,155 $ 17,810 $ 16,334
Revenue from External Customers by Geographic Areas [Table Text Block]	Three Months Ended Nine Months Ended September 30, September 30, 2021 2020 2021 2020 United States $ 6,049 $ 6,473 $ 15,100 $ 12,880 Foreign Revenues Latin America 121 195 338 400 Europe 663 904 1,339 1,494 Asia 726 583 1,033 1,560 Total Foreign Revenues 1,510 1,682 2,710 3,454 Total Revenues $ 7,559 $ 8,155 $ 17,810 $ 16,334
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table Text Block]	Three Months Ended Nine Months Ended September 30, September 30, 2021 2020 2021 2020 Products transferred at a point in time $ 6,387 $ 5,108 $ 16,042 $ 11,089 Products and services transferred over time 1,172 3,047 1,768 5,245 Total Revenues $ 7,559 $ 8,155 $ 17,810 $ 16,334
Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block]	As of September 30, 2021 December 31, 2020 Trade receivables $ 5,423 $ 5,015 Unbilled receivables 375 2,348 Other short-term receivables 102 20 Allowance for doubtful accounts (838 ) (835 ) Total accounts receivable $ 5,062 $ 6,548

Note 4 - Restructuring Activi_2

Note 4 - Restructuring Activities (Tables)	9 Months Ended
	Sep. 30, 2021
Notes Tables
Restructuring and Related Costs [Table Text Block]	Three Months Ended Nine Months Ended September 30, September 30, 2021 2020 2021 2020 Total revenues $ 2 $ 6 $ 17 $ 11 Net loss (47 ) (73 ) (85 ) (31 ) As of September 30, 2021 December 31, 2020 Total assets $ 1,444 $ 2,463 Total liabilities 290 396 Total net assets $ 1,154 $ 2,067

Note 5 - Accumulated Other Co_2

Note 5 - Accumulated Other Comprehensive Loss (Tables)	9 Months Ended
	Sep. 30, 2021
Notes Tables
Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]	Three Months Ended Nine Months Ended September 30, September 30, 2021 2020 2021 2020 Foreign currency translation Balance at beginning of period $ (1,430 ) $ (1,857 ) $ (1,370 ) $ (1,778 ) Other comprehensive income (loss): Foreign currency translation adjustments (1) (153 ) 268 (213 ) 189 Total accumulated other comprehensive loss $ (1,583 ) $ (1,589 ) $ (1,583 ) $ (1,589 )

Note 7 - Earnings Per Share (Ta

Note 7 - Earnings Per Share (Tables)	9 Months Ended
	Sep. 30, 2021
Notes Tables
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]	Three Months Ended Nine Months Ended September 30, September 30, 2021 2020 2021 2020 Basic weighted-average shares 30,264,000 24,701,000 29,356,000 24,656,000 Conversion of unsecured loan notes — — — — Unexercised options and unvested RSUs 71,000 419,000 126,000 — Diluted weighted-average shares 30,335,000 25,120,000 29,482,000 24,656,000

Note 8 - Stock-based Compensa_2

Note 8 - Stock-based Compensation (Tables)	9 Months Ended
	Sep. 30, 2021
Notes Tables
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Table Text Block]	Three Months Ended Nine Months Ended September 30, September 30, 2021 2020 2021 2020 Stock options and restricted stock units, net of forfeited $ 21 $ 57 $ 61 $ 207 After-tax effect of stock-based compensation $ 21 $ 57 $ 61 $ 207
Share-based Payment Arrangement, Option, Activity [Table Text Block]	Weighted- Average Number Weighted- Remaining Aggregate of Average Contractual Intrinsic Options Exercise Price Term Value Outstanding on January 1, 2021 484,500 $ 3.57 Granted — — Exercised — — Expired or forfeited (50,000 ) 8.16 Outstanding on September 30, 2021 434,500 $ 3.05 3.34 $ 73 Exercisable on September 30, 2021 434,500 $ 3.05 3.34 $ 73
Schedule of Nonvested Restricted Stock Units Activity [Table Text Block]	Weighted Average Grant Date Shares Fair Value Unvested restricted stock units at January 1, 2021 100,005 $ 4.08 Granted — — Forfeited (5,000 ) 0.97 Vested (50,002 ) 1.50 Unvested restricted stock units at September 30, 2021 45,003 $ 7.29

Note 9 - Warrants (Tables)

Note 9 - Warrants (Tables)	9 Months Ended
	Sep. 30, 2021
Notes Tables
Schedule of Warrant Activity [Table Text Block]	Shares Outstanding on December 31, 2020 — Granted 2,850,000 Exercised — Outstanding as of September 30, 2021 2,850,000
Schedule of Stockholders' Equity Note, Warrants or Rights [Table Text Block]	Range of Exercise Price Number Outstanding/Exercisable Weighted Average Remaining Life in Years Weighted Average Exercise Price $5.10 2,500,000 4.87 $ 5.10 $6.45 350,000 4.87 $ 6.45 2,850,000

Note 11 - Business Segment an_2

Note 11 - Business Segment and Geographic Financial Data (Tables)	9 Months Ended
	Sep. 30, 2021
Notes Tables
Schedule of Segment Reporting Information, by Segment [Table Text Block]	Air Pollution FUEL CHEM Three months ended September 30, 2021 Control Segment Segment Other Total Revenues from external customers $ 1,944 $ 5,615 $ — $ 7,559 Cost of sales (1,134 ) (2,706 ) — (3,840 ) Gross margin 810 2,909 — 3,719 Selling, general and administrative — — (2,801 ) (2,801 ) Research and development — — (340 ) (340 ) Operating income (loss) from operations $ 810 $ 2,909 $ (3,141 ) $ 578 Air Pollution FUEL CHEM Three months ended September 30, 2020 Control Segment Segment Other Total Revenues from external customers $ 2,886 $ 5,269 $ — $ 8,155 Cost of sales 304 (2,553 ) — (2,249 ) Gross margin 3,190 2,716 — 5,906 Selling, general and administrative — — (3,184 ) (3,184 ) Research and development — — (285 ) (285 ) Operating income (loss) from operations $ 3,190 $ 2,716 $ (3,469 ) $ 2,437 Air Pollution FUEL CHEM Nine months ended September 30, 2021 Control Segment Segment Other Total Revenues from external customers $ 3,837 $ 13,973 $ — $ 17,810 Cost of sales (2,172 ) (6,978 ) — (9,150 ) Gross margin 1,665 6,995 — 8,660 Selling, general and administrative — — (8,858 ) (8,858 ) Research and development — — (1,070 ) (1,070 ) Operating income (loss) from operations $ 1,665 $ 6,995 $ (9,928 ) $ (1,268 ) Air Pollution FUEL CHEM Nine months ended September 30, 2020 Control Segment Segment Other Total Revenues from external customers $ 6,019 $ 10,315 $ — $ 16,334 Cost of sales (2,782 ) (5,517 ) — (8,299 ) Gross margin 3,237 4,798 — 8,035 Selling, general and administrative — — (9,825 ) (9,825 ) Research and development — — (880 ) (880 ) Operating income (loss) from operations $ 3,237 $ 4,798 $ (10,705 ) $ (2,670 )
Schedule of Revenue from External Customers and Long-Lived Assets, by Geographical Areas [Table Text Block]	Three Months Ended Nine Months Ended September 30, September 30, 2021 2020 2021 2020 Revenues: United States $ 6,049 $ 6,473 $ 15,100 $ 12,880 Foreign 1,510 1,682 2,710 3,454 $ 7,559 $ 8,155 $ 17,810 $ 16,334 September 30, December 31, 2021 2020 Assets: United States $ 46,713 $ 24,524 Foreign 4,326 5,564 $ 51,039 $ 30,088

Note 12 - Leases (Tables)

Note 12 - Leases (Tables)	9 Months Ended
	Sep. 30, 2021
Notes Tables
Lease, Cost [Table Text Block]	Three Months Ended Nine Months Ended September 30, September 30, 2021 2020 2021 2020 Operating lease cost $ 44 $ 47 $ 133 $ 157 Short-term lease cost 4 5 15 12 Total lease cost $ 48 $ 52 $ 148 $ 169
Lessee, Operating Lease, Liability, Maturity [Table Text Block]	Year Ending December 31, Operating Leases 2021 (excluding the nine months ended September 30, 2021) 44 2022 132 2023 115 2024 29 2025 7 Total lease payments $ 327 Less imputed interest (52 ) Total $ 275
Operating Lease Liabilities [Table Text Block]	As of September 30, 2021 December 31, 2020 Operating lease liabilities - current $ 128 $ 149 Operating lease liabilities - non-current 147 237 Total operating lease liabilities $ 275 $ 386
Lessee, Operating Leases, Supplemental Cash Flow Information [Table Text Block]	Three Months Ended Nine Months Ended September 30, September 30, 2021 2020 2021 2020 Cash paid for amounts included in the measurement of lease liabilities $ 50 $ 45 $ 148 $ 148 Leased assets obtained in exchange for operating lease liabilities 39 41 119 137

Note 13 - Accrued Liabilities (

Note 13 - Accrued Liabilities (Tables)	9 Months Ended
	Sep. 30, 2021
Notes Tables
Other Current Liabilities [Table Text Block]	As of September 30, 2021 December 31, 2020 Contract liabilities (Note 3) $ 1,246 $ 850 Accrued remediation contingency (Note 14) — 176 Other accrued liabilities 583 1,073 Total other accrued liabilities $ 1,829 $ 2,099

Note 1 - General (Details Textu

Note 1 - General (Details Textual) - USD ($) $ / shares in Units, $ in Thousands	Feb. 11, 2021	Sep. 30, 2021	Sep. 30, 2020
Class of Warrant or Right, Number of Warrants Issued (in shares)		2,850,000
Proceeds from Issuance of Private Placement		$ 25,812	$ 0
Payments of Stock Issuance Costs		$ 1,783	$ 0
Warrants Issued in Connection with Private Placement [Member]
Class of Warrant or Right, Number of Warrants Issued (in shares)	2,500,000
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)	2,500,000
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)	$ 5.10	$ 5.10
Warrants and Rights Outstanding, Term (Year)	5 years 6 months
The Placement Agent Warrants [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)	350,000
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)	$ 6.45	$ 6.45
Warrants and Rights Outstanding, Term (Year)	5 years 6 months
Private Placement [Member]
Stock Issued During Period, Shares, New Issues (in shares)	5,000,000
Shares Issued, Price Per Share (in dollars per share)	$ 5.1625
Proceeds from Issuance of Private Placement	$ 25,812
Payments of Stock Issuance Costs	$ 1,783

Note 2 - Summary of Significa_3

Note 2 - Summary of Significant Accounting Policies (Details Textual) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020
Restricted Cash and Cash Equivalents, Total	$ 1,161
Restricted Cash and Cash Equivalents, Current, Total	891	$ 1,595	$ 2,025
Restricted Cash and Cash Equivalents, Noncurrent, Total	$ 270	$ 371	$ 367

Note 2 - Summary of Significa_4

Note 2 - Summary of Significant Accounting Policies - Reconciliation of Cash, Cash Equivalents, and Restricted Cash (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020
Cash and cash equivalents	$ 35,161	$ 10,640	$ 9,418
Restricted cash included in current assets	891	1,595	2,025
Restricted cash included in long-term assets	270	$ 371	367
Total cash, cash equivalents, and restricted cash shown in the Consolidated Statements of Cash Flows	$ 36,322		$ 11,810

Note 3 - Revenue 1 (Details Tex

Note 3 - Revenue 1 (Details Textual) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021USD ($)	Sep. 30, 2020USD ($)	Sep. 30, 2021USD ($)	Sep. 30, 2020USD ($)	Dec. 31, 2020USD ($)
Number Of Units Installed	1,200		1,200
Contract with Customer, Liability, Current	$ 1,246		$ 1,246		$ 850
Contract with Customer, Liability, Revenue Recognized	$ 173	$ 97	$ 331	$ 555
Contract with Customer, Contracts in Progress, Number of Contracts Identified as Loss Contracts	0		0		1
Provision for Loss on Contracts					$ 176
Revenue, Remaining Performance Obligation, Amount	$ 8,173		$ 8,173
Air Pollution Control [Member]
Contract with Customer, Asset, after Allowance for Credit Loss, Total	375		375		2,080
FUEL CHEM [Member]
Contract with Customer, Asset, after Allowance for Credit Loss, Total	$ 0		$ 0		$ 269
Minimum [Member]
Contract Term (Month)			6 months
Maximum [Member]
Contract Term (Month)			18 months

Note 3 - Revenue 2 (Details Tex

Note 3 - Revenue 2 (Details Textual) $ in Thousands	Sep. 30, 2021USD ($)
Revenue, Remaining Performance Obligation, Amount	$ 8,173
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-10-01
Revenue, Remaining Performance Obligation, Amount	$ 5,517
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period (Month)	12 months

Note 3 - Revenue - Revenues Dis

Note 3 - Revenue - Revenues Disaggregated by Product Technology (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Revenues	$ 7,559	$ 8,155	$ 17,810	$ 16,334
Air Pollution Control [Member]
Revenues	1,944	2,886	3,837	6,019
Air Pollution Control [Member] | Technology Solutions [Member]
Revenues	1,172	2,326	1,768	4,524
Air Pollution Control [Member] | Spare Parts [Member]
Revenues	407	254	823	667
Air Pollution Control [Member] | Ancillary Revenue [Member]
Revenues	365	306	1,246	828
FUEL CHEM [Member]
Revenues	5,615	5,269	13,973	10,315
FUEL CHEM [Member] | Technology Solutions [Member]
Revenues	$ 5,615	$ 5,269	$ 13,973	$ 10,315

Note 3 - Revenue - Revenues D_2

Note 3 - Revenue - Revenues Disaggregated by Geography (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Revenues	$ 7,559	$ 8,155	$ 17,810	$ 16,334
UNITED STATES
Revenues	6,049	6,473	15,100	12,880
Latin America [Member]
Revenues	121	195	338	400
Europe [Member]
Revenues	663	904	1,339	1,494
Asia [Member]
Revenues	726	583	1,033	1,560
Non-US [Member]
Revenues	$ 1,510	$ 1,682	$ 2,710	$ 3,454

Note 3 - Revenue - Timing of Re

Note 3 - Revenue - Timing of Revenue Recognition (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Revenues	$ 7,559	$ 8,155	$ 17,810	$ 16,334
Transferred at Point in Time [Member]
Revenues	6,387	5,108	16,042	11,089
Transferred over Time [Member]
Revenues	$ 1,172	$ 3,047	$ 1,768	$ 5,245

Note 3 - Revenue - Components o

Note 3 - Revenue - Components of Accounts Receivable (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Trade receivables	$ 5,423	$ 5,015
Unbilled receivables	375	2,348
Other short-term receivables	102	20
Allowance for doubtful accounts	(838)	(835)
Total accounts receivable	$ 5,062	$ 6,548

Note 4 - Restructuring Activi_3

Note 4 - Restructuring Activities (Details Textual) $ in Thousands	Sep. 30, 2021USD ($)
CHINA
Discontinued Operations, Revenue, Remaining Performance Obligation, Amount	$ 10

Note 4 - Restructuring Activi_4

Note 4 - Restructuring Activities - Charges and Net Assets (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Revenues	$ 7,559			$ 8,155			$ 17,810	$ 16,334
Net loss	678	$ (778)	$ 398	2,376	$ (2,544)	$ (2,567)	298	(2,735)
Total assets	51,039						51,039		$ 30,088
Total liabilities	4,595						4,595		7,767
CHINA
Revenues	2			6			17	11
Net loss	(47)			$ (73)			(85)	$ (31)
Total assets	1,444						1,444		2,463
Total liabilities	290						290		396
Total net assets	$ 1,154						$ 1,154		$ 2,067

Note 5 - Accumulated Other Co_3

Note 5 - Accumulated Other Comprehensive Loss - Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Beginning balance		$ 45,898	$ 21,130	$ 22,321	$ 26,175
Ending balance		46,444	23,831	46,444	23,831
AOCI Attributable to Parent [Member]
Beginning balance		(1,430)	(1,857)	(1,370)	(1,778)
Foreign currency translation adjustments (1)	[1]	(153)	268	(213)	189
Ending balance		$ (1,583)	$ (1,589)	$ (1,583)	$ (1,589)
[1]	In all periods presented, there were no tax impacts related to rate changes and no amounts were reclassified to earnings.

Note 6 - Treasury Stock (Detail

Note 6 - Treasury Stock (Details Textual) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Treasury Stock, Shares, Ending Balance (in shares)	963,509	948,347
Treasury Stock, Value, Ending Balance	$ 2,234	$ 2,182

Note 7 - Earnings Per Share (De

Note 7 - Earnings Per Share (Details Textual)	3 Months Ended
	Sep. 30, 2020shares
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount (in shares)	520,000

Note 7 - Earnings Per Share - E

Note 7 - Earnings Per Share - Earnings Per Share (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Basic weighted-average shares (in shares)	30,264,000	24,701,000	29,356,000	24,656,000
Conversion of unsecured loan notes (in shares)	0	0	0	0
Unexercised options and unvested RSUs (in shares)	71,000	419,000	126,000	0
Diluted weighted-average shares (in shares)	30,335,000	25,120,000	29,482,000	24,656,000

Note 8 - Stock-based Compensa_3

Note 8 - Stock-based Compensation (Details Textual) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2021	Sep. 30, 2020
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total	$ 39	$ 39
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year)		5 months 19 days
Deferred Compensation Plan for Directors [Member]
Deferred Compensation Arrangement with Individual, Compensation Expense		$ 0	$ 0
The 2014 Long-term Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized (in shares)	5,600,676	5,600,676
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant (in shares)	2,603,801	2,603,801
Share-based Payment Arrangement, Expense, Tax Benefit	$ 0	$ 0
The 2014 Long-term Incentive Plan [Member] | Share-based Payment Arrangement, Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period (Year)		10 years
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total	$ 0	$ 0
The 2014 Long-term Incentive Plan [Member] | Share-based Payment Arrangement, Option [Member] | Share-based Payment Arrangement, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage		50.00%
The 2014 Long-term Incentive Plan [Member] | Share-based Payment Arrangement, Option [Member] | Share-based Payment Arrangement, Tranche Two [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage		25.00%
The 2014 Long-term Incentive Plan [Member] | Share-based Payment Arrangement, Option [Member] | Share-based Payment Arrangement, Tranche Three [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage		25.00%
The 2014 Long-term Incentive Plan [Member] | Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year)		3 years
Share-Based Compensation Arrangement By Share-based Payment Award, Performance Threshold, Operating Income		$ 1,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value		$ 75
The 2014 Long-term Incentive Plan [Member] | Restricted Stock Units (RSUs) [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year)		2 years
The 2014 Long-term Incentive Plan [Member] | Restricted Stock Units (RSUs) [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year)		4 years
The 2014 Long-term Incentive Plan [Member] | Restricted Stock Units (RSUs) [Member] | Share-based Payment Arrangement, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage		33.33%
The 2014 Long-term Incentive Plan [Member] | Restricted Stock Units (RSUs) [Member] | Share-based Payment Arrangement, Tranche Two [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage		33.33%
The 2014 Long-term Incentive Plan [Member] | Restricted Stock Units (RSUs) [Member] | Share-based Payment Arrangement, Tranche Three [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage		33.33%

Note 8 - Stock-based Compensa_4

Note 8 - Stock-based Compensation - Stock-based Compensation (Details) - Selling, General and Administrative Expenses [Member] - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Stock options and restricted stock units, net of forfeited	$ 21	$ 57	$ 61	$ 207
After-tax effect of stock-based compensation	$ 21	$ 57	$ 61	$ 207

Note 8 - Stock-based Compensa_5

Note 8 - Stock-based Compensation - Stock Option Activity (Details) $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2021USD ($)$ / sharesshares
Beginning balance, number of options outstanding (in shares) | shares	484,500
Beginning balance, option, weighted average exercise price (in dollars per share) | $ / shares	$ 3.57
Granted, options (in shares) | shares	0
Granted, option, weighted average exercise price (in dollars per share) | $ / shares	$ 0
Exercised, options (in shares) | shares	0
Exercised, option, weighted average exercise price (in dollars per share) | $ / shares	$ 0
Expired or forfeited, options (in shares) | shares	(50,000)
Expired or forfeited, option, weighted average exercise price (in dollars per share) | $ / shares	$ 8.16
Ending balance, number of options outstanding (in shares) | shares	434,500
Ending balance, option, weighted average exercise price (in dollars per share) | $ / shares	$ 3.05
Outstanding, weighted average remaining contractual term (Year)	3 years 4 months 2 days
Outstanding, aggregate intrinsic value | $	$ 73
Exercisable, options (in shares) | shares	434,500
Exercisable, option, weighted average exercise price (in dollars per share) | $ / shares	$ 3.05
Exercisable, weighted average remaining contractual term (Year)	3 years 4 months 2 days
Exercisable, aggregate intrinsic value | $	$ 73

Note 8 - Stock-based Compensa_6

Note 8 - Stock-based Compensation - Restricted Stock Activity (Details) - Restricted Stock Units (RSUs) [Member]	9 Months Ended
	Sep. 30, 2021$ / sharesshares
Beginning balance, unvested restricted stock units, shares (in shares) | shares	100,005
Beginning balance, unvested restricted stock units, weighted average grant date fair value (in dollars per share) | $ / shares	$ 4.08
Granted, restricted stock units, shares (in shares) | shares	0
Granted, restricted stock units, weighted average grant date fair value (in dollars per share) | $ / shares	$ 0
Forfeited, restricted stock units, shares (in shares) | shares	(5,000)
Forfeited, restricted stock units, weighted average grant date fair value (in dollars per share) | $ / shares	$ 0.97
Vested, restricted stock units, shares (in shares) | shares	(50,002)
Vested, restricted stock units, weighted average grant date fair value (in dollars per share) | $ / shares	$ 1.50
Ending balance, unvested restricted stock units, shares (in shares) | shares	45,003
Ending balance, unvested restricted stock units, weighted average grant date fair value (in dollars per share) | $ / shares	$ 7.29

Note 9 - Warrants (Details Text

Note 9 - Warrants (Details Textual) $ / shares in Units, $ in Thousands	Feb. 11, 2021USD ($)$ / sharesshares	Sep. 30, 2021USD ($)$ / sharesshares	Sep. 30, 2020USD ($)
Class of Warrant or Right, Number of Warrants Issued (in shares) | shares		2,850,000
Proceeds from Issuance of Private Placement | $		$ 25,812	$ 0
Payments of Stock Issuance Costs | $		$ 1,783	$ 0
Warrants and Rights Outstanding | $	$ 7,337
Measurement Input, Risk Free Interest Rate [Member]
Warrants and Rights Outstanding, Measurement Input	0.0059
Measurement Input, Price Volatility [Member]
Warrants and Rights Outstanding, Measurement Input	0.9466
Measurement Input, Expected Term [Member]
Warrants and Rights Outstanding, Measurement Input	5.5
Warrants Issued in Connection with Private Placement [Member]
Class of Warrant or Right, Number of Warrants Issued (in shares) | shares	2,500,000
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares) | shares	2,500,000
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) | $ / shares	$ 5.10	$ 5.10
Warrants and Rights Outstanding, Term (Year)	5 years 6 months
The Placement Agent Warrants [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares) | shares	350,000
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) | $ / shares	$ 6.45	$ 6.45
Warrants and Rights Outstanding, Term (Year)	5 years 6 months
Private Placement [Member]
Stock Issued During Period, Shares, New Issues (in shares) | shares	5,000,000
Shares Issued, Price Per Share (in dollars per share) | $ / shares	$ 5.1625
Proceeds from Issuance of Private Placement | $	$ 25,812
Payments of Stock Issuance Costs | $	$ 1,783

Note 9 - Warrants - Warrant Act

Note 9 - Warrants - Warrant Activity (Details)	9 Months Ended
	Sep. 30, 2021shares
Beginning balance (in shares)	0
Granted (in shares)	2,850,000
Exercised (in shares)	0
Ending balance (in shares)	2,850,000

Note 9 - Warrants - Summary of

Note 9 - Warrants - Summary of Warrants Outstanding and Exerciseable (Details) - $ / shares	9 Months Ended
	Sep. 30, 2021	Feb. 11, 2021	Dec. 31, 2020
Number outstanding/ exercisable (in shares)	2,850,000		0
Warrants Issued in Connection with Private Placement [Member]
Number outstanding/ exercisable (in shares)	2,500,000
Weighted average remaining life (Year)	4 years 10 months 13 days
Weighted average exercise price (in dollars per share)	$ 5.10	$ 5.10
The Placement Agent Warrants [Member]
Number outstanding/ exercisable (in shares)	350,000
Weighted average remaining life (Year)	4 years 10 months 13 days
Weighted average exercise price (in dollars per share)	$ 6.45	$ 6.45

Note 10 - Debt Financing (Detai

Note 10 - Debt Financing (Details Textual) - Paycheck Protection Program CARES Act [Member] - USD ($) $ in Thousands	Jan. 08, 2021	Apr. 17, 2020	Sep. 30, 2021	Sep. 30, 2020
Proceeds from Issuance of Long-term Debt, Total		$ 1,556	$ 0	$ 1,556
Debt Instrument, Decrease, Forgiveness	$ 1,556

Note 11 - Business Segment an_3

Note 11 - Business Segment and Geographic Financial Data (Details Textual)	9 Months Ended
	Sep. 30, 2021
Number of Reportable Segments	2

Note 11 - Business Segment an_4

Note 11 - Business Segment and Geographic Financial Data - Reporting Segment Net Sales and Gross Margin (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Revenues from external customers	$ 7,559	$ 8,155	$ 17,810	$ 16,334
Cost of sales	(3,840)	(2,249)	(9,150)	(8,299)
Gross margin	3,719	5,906	8,660	8,035
Selling, general and administrative	(2,801)	(3,184)	(8,858)	(9,825)
Research and development	(340)	(285)	(1,070)	(880)
Operating income (loss) from operations	578	2,437	(1,268)	(2,670)
Air Pollution Control [Member]
Revenues from external customers	1,944	2,886	3,837	6,019
Cost of sales	(1,134)	304	(2,172)	(2,782)
Gross margin	810	3,190	1,665	3,237
Selling, general and administrative	0	0	0	0
Research and development	0	0	0	0
Operating income (loss) from operations	810	3,190	1,665	3,237
FUEL CHEM [Member]
Revenues from external customers	5,615	5,269	13,973	10,315
Cost of sales	(2,706)	(2,553)	(6,978)	(5,517)
Gross margin	2,909	2,716	6,995	4,798
Selling, general and administrative	0	0	0	0
Research and development	0	0	0	0
Operating income (loss) from operations	2,909	2,716	6,995	4,798
Other Segments [Member]
Revenues from external customers	0	0	0	0
Cost of sales	0	0	0	0
Gross margin	0	0	0	0
Selling, general and administrative	(2,801)	(3,184)	(8,858)	(9,825)
Research and development	(340)	(285)	(1,070)	(880)
Operating income (loss) from operations	$ (3,141)	$ (3,469)	$ (9,928)	$ (10,705)

Note 11 - Business Segment an_5

Note 11 - Business Segment and Geographic Financial Data - Geographic Segment Financial Data (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Revenues	$ 7,559	$ 8,155	$ 17,810	$ 16,334
Assets	51,039		51,039		$ 30,088
UNITED STATES
Revenues	6,049	6,473	15,100	12,880
Assets	46,713		46,713		24,524
Non-US [Member]
Revenues	1,510	$ 1,682	2,710	$ 3,454
Assets	$ 4,326		$ 4,326		$ 5,564

Note 12 - Leases (Details Textu

Note 12 - Leases (Details Textual) $ in Thousands	9 Months Ended
	Sep. 30, 2021USD ($)
Number of Operating Leases	7
Finance Lease, Liability, Total	$ 0
Operating Lease, Weighted Average Remaining Lease Term (Year)	2 years 5 months 12 days
Operating Lease, Weighted Average Discount Rate, Percent	4.55%
Minimum [Member]
Lessee, Operating Lease, Remaining Lease Term (Month)	2 months
Maximum [Member]
Lessee, Operating Lease, Remaining Lease Term (Month)	4 years

Note 12 - Leases - Operating Le

Note 12 - Leases - Operating Lease Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Operating lease cost	$ 44	$ 47	$ 133	$ 157
Short-term lease cost	4	5	15	12
Total lease cost	$ 48	$ 52	$ 148	$ 169

Note 12 - Leases - Remaining Ma

Note 12 - Leases - Remaining Maturities of Existing Lease Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
2021 (excluding the nine months ended September 30, 2021)	$ 44
2022	132
2023	115
2024	29
2025	7
Total lease payments	327
Less imputed interest	(52)
Total	$ 275	$ 386

Note 12 - Leases - Lease Liabil

Note 12 - Leases - Lease Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Operating lease liabilities - current	$ 128	$ 149
Operating lease liabilities - non-current	147	237
Total operating lease liabilities	$ 275	$ 386

Note 12 - Leases - Supplemental

Note 12 - Leases - Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Cash paid for amounts included in the measurement of lease liabilities	$ 50	$ 45	$ 148	$ 148
Leased assets obtained in exchange for operating lease liabilities	$ 39	$ 41	$ 119	$ 137

Note 13 - Accrued Liabilities -

Note 13 - Accrued Liabilities - Components of Other Accrued Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Contract liabilities (Note 3)	$ 1,246	$ 850
Accrued remediation contingency (Note 14)	0	176
Other accrued liabilities	583	1,073
Total other accrued liabilities	$ 1,829	$ 2,099

Note 14 - Commitments and Con_2

Note 14 - Commitments and Contingencies (Details Textual) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Standard Product Warranty Accrual, Period Increase (Decrease), Total	$ 0	$ 0
Standard Product Warranty Accrual, Ending Balance	159		$ 159
Failure of Equipment to Be Remedied Under Warranty Provision [Member]
Loss Contingency Accrual, Ending Balance	$ 0		$ 176

Note 15 - Income Taxes (Details

Note 15 - Income Taxes (Details Textual) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Effective Income Tax Rate Reconciliation, Percent, Total	3.20%	(5.80%)
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%
Unrecognized Tax Benefits, Ending Balance	$ 0		$ 0

Note 16 - Goodwill and Other _2

Note 16 - Goodwill and Other Intangibles (Details Textual) $ in Thousands	9 Months Ended
	Sep. 30, 2021USD ($)	Sep. 30, 2020USD ($)	Dec. 31, 2020USD ($)
Number of Reporting Units	2
Goodwill, Ending Balance	$ 2,116		$ 2,116
Goodwill, Impairment Loss	0	$ 0
Impairment of Intangible Assets, Finite-lived	0	$ 0
Air Pollution Control [Member]
Goodwill, Ending Balance	0
FUEL CHEM [Member]
Goodwill, Ending Balance	$ 2,116		$ 2,116