Note 2 - Revenue Recognition

12 Months Ended

Dec. 31, 2025

Notes to Financial Statements

Revenue from Contract with Customer [Text Block]

2.     REVENUE RECOGNITION

Disaggregated Revenue by Product Technology

The following table presents our revenues disaggregated by product technology:

	Twelve Months Ended December 31,
	2025		2024
Air Pollution Control
Technology solutions	$	5,420	$	7,897
Spare parts		1,739		1,616
Ancillary revenue		1,749		1,729
Total Air Pollution Control technology		8,908		11,242
FUEL CHEM
FUEL CHEM technology solutions		17,769		13,891
Total Revenues	$	26,677	$	25,133

Disaggregated Revenue by Geography

The following table presents our revenues disaggregated by geography, based on the location of the end-user:

	Twelve Months Ended December 31,
	2025		2024
United States	$	21,022	$	17,802
Foreign Revenues
Americas		707		924
Europe		2,239		2,146
South Africa		318		2,570
Pacific Rim and other		2,391		1,691
Total Foreign Revenues		5,655		7,331
Total Revenues	$	26,677	$	25,133

Timing of Revenue Recognition

The following table presents the timing of our revenue recognition:

	Twelve Months Ended December 31,
	2025		2024
Products transferred at a point in time	$	21,257	$	17,236
Products and services transferred over time		5,420		7,897
Total Revenues	$	26,677	$	25,133

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 APC 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. These assets are reported on the Consolidated Balance Sheet on a contract-by-contract basis at the end of each reporting period. At December 31, 2025, 2024, and 2023 contract assets for APC technology projects were approximately $887, $2,075, and $2,285, respectively, and are included in accounts receivable on the consolidated balance sheets. 

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 $1,026, $721, and $1,279 at December 31, 2025, 2024, and 2023, respectively, and are included in other accrued liabilities on the consolidated balance sheets.

Changes in the contract asset and liability balances during the year ended  December 31, 2025, were not materially impacted by any other items other than amounts billed and revenue recognized as described previously. Revenue recognized that was included in the contract liability balance at the beginning of the period was $557 and $1,276 for the years ended December 31, 2025 and 2024, respectively, which represented primarily revenue from progress toward completion of our APC technology contracts. 

As of December 31, 2025 and 2024 we had no construction contracts in progress that were identified as a loss contract. 

Remaining Performance Obligations

Remaining performance obligations, represents the transaction price of APC technology booked orders for which work has not been performed. As of December 31, 2025, the aggregate amount of the transaction price allocated to remaining performance obligations was $7,047. The Company expects to recognize revenue on approximately $6,032 of the remaining performance obligations over the next 12 months with the remaining recognized thereafter.

Practical Expedients and Exemptions

We generally expense sales commissions on a ratable basis when incurred because the amortization period would have been one year or less. These costs are recorded within selling, general and administrative expenses within the Consolidated Statements of Operations. A practical expedient was elected to not recognize shipping and handling costs as a separate performance obligation under ASC 606.

Accounts Receivable

The components of accounts receivable are as follows:

	As of
	December 31, 2025			December 31, 2024
Trade receivables	$	4,494		$	5,375
Unbilled receivables		887			2,075
Receivable for employee retention credit		—			1,677
Other short-term receivables		82			347
Allowance for credit losses		(108	)		(106	)
Total accounts receivable	$	5,355		$	9,368