Note 2 - Revenue Recognition

12 Months Ended

Dec. 31, 2023

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,
	2023		2022
Air Pollution Control
Technology solutions	$	9,497	$	7,935
Spare parts		2,239		911
Ancillary revenue		1,747		1,751
Total Air Pollution Control technology		13,483		10,597
FUEL CHEM
FUEL CHEM technology solutions		13,598		16,344
Total Revenues	$	27,081	$	26,941

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,
	2023		2022
United States	$	21,062	$	20,311
Foreign Revenues
Americas		577		213
Europe		3,064		2,888
Asia		2,378		3,529
Total Foreign Revenues		6,019		6,630
Total Revenues	$	27,081	$	26,941

Timing of Revenue Recognition

The following table presents the timing of our revenue recognition:

	Twelve Months Ended December 31,
	2023		2022
Products transferred at a point in time	$	17,584	$	18,849
Products and services transferred over time		9,497		8,092
Total Revenues	$	27,081	$	26,941

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. For the FUEL CHEM technology segment, deliveries made in the current period but billed in subsequent periods are also considered 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, 2023, 2022, and 2021 contract assets for APC technology projects were approximately $2,285, $3,082, and $1,277, respectively, and are included in accounts receivable on the consolidated balance sheets. There were no contract assets for the FUEL CHEM technology segment as of  December 31, 2023, 2022, and 2021.

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 $1,279, $372, and $390 at December 31, 2023, 2022, and 2021, 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, 2023, 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 $368 and $384 for the years ended December 31, 2023 and 2022, respectively, which represented primarily revenue from progress toward completion of our APC technology contracts. 

As of December 31, 2023 and 2022 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, 2023, the aggregate amount of the transaction price allocated to remaining performance obligations was $7,458. The Company expects to recognize revenue on approximately $7,389 of the remaining performance obligations over the next 12 months.

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, 2023			December 31, 2022
Trade receivables	$	4,300		$	4,605
Unbilled receivables		2,285			3,082
Other short-term receivables		255			152
Allowance for credit losses		(111	)		(110	)
Total accounts receivable	$	6,729		$	7,729