Note 2 - Revenue Recognition

12 Months Ended

Dec. 31, 2024

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,
	2024		2023
Air Pollution Control
Technology solutions	$	7,897	$	9,497
Spare parts		1,616		2,239
Ancillary revenue		1,729		1,747
Total Air Pollution Control technology		11,242		13,483
FUEL CHEM
FUEL CHEM technology solutions		13,891		13,598
Total Revenues	$	25,133	$	27,081

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,
	2024		2023
United States	$	17,802	$	21,397
Foreign Revenues
Americas		924		577
Europe		2,146		2,558
South Africa		2,570		163
Pacific Rim and other		1,691		2,386
Total Foreign Revenues		7,331		5,684
Total Revenues	$	25,133	$	27,081

Timing of Revenue Recognition

The following table presents the timing of our revenue recognition:

	Twelve Months Ended December 31,
	2024		2023
Products transferred at a point in time	$	17,236	$	17,584
Products and services transferred over time		7,897		9,497
Total Revenues	$	25,133	$	27,081

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, 2024, 2023, and 2022 contract assets for APC technology projects were approximately $2,075, $2,285, and $3,082, 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 $721, $1,279, and $372 at December 31, 2024, 2023, and 2022, 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, 2024, 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 $1,276 and $368 for the years ended December 31, 2024 and 2023, respectively, which represented primarily revenue from progress toward completion of our APC technology contracts. 

As of December 31, 2024 and 2023 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, 2024, the aggregate amount of the transaction price allocated to remaining performance obligations was $6,175. The Company expects to recognize revenue on approximately $4,515 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, 2024			December 31, 2023
Trade receivables	$	5,375		$	4,300
Unbilled receivables		2,075			2,285
Receivable for employee retention credit		1,677			—
Other short-term receivables		347			255
Allowance for credit losses		(106	)		(111	)
Total accounts receivable	$	9,368		$	6,729