Note 3 - Revenue

6 Months Ended

Jun. 30, 2022

Notes to Financial Statements

Revenue from Contract with Customer [Text Block]

3.     Revenue

Disaggregated Revenue by Product Technology

The following table presents our revenues disaggregated by product technology:

	Three Months Ended				Six Months Ended
	June 30,				June 30,
	2022		2021		2022		2021
Air Pollution Control
Technology solutions	$	1,966	$	223	$	3,807	$	596
Spare parts		262		236		358		416
Ancillary revenue		510		527		777		881
Total Air Pollution Control technology revenues		2,738		986		4,942		1,893
FUEL CHEM
FUEL CHEM technology solutions		3,630		4,232		6,961		8,358
Total Revenues	$	6,368	$	5,218	$	11,903	$	10,251

Disaggregated Revenue by Geography

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

	Three Months Ended				Six Months Ended
	June 30,				June 30,
	2022		2021		2022		2021
United States	$	4,279	$	4,588	$	7,967	$	9,051
Foreign Revenues
Latin America		60		142		129		217
Europe		922		301		1,326		676
Asia		1,107		187		2,481		307
Total Foreign Revenues		2,089		630		3,936		1,200
Total Revenues	$	6,368	$	5,218	$	11,903	$	10,251

Timing of Revenue Recognition

The following table presents the timing of our revenue recognition:

	Three Months Ended				Six Months Ended
	June 30,				June 30,
	2022		2021		2022		2021
Products transferred at a point in time	$	4,402	$	4,995	$	8,096	$	9,655
Products and services transferred over time		1,966		223		3,807		596
Total Revenues	$	6,368	$	5,218	$	11,903	$	10,251

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 Condensed Consolidated Balance Sheets. In our Air Pollution Control (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 unbilled receivables (contract assets). These assets are reported on the Condensed Consolidated Balance Sheets on a contract-by-contract basis at the end of each reporting period. At June 30, 2022,  December 31, 2021, and December 31, 2020, contract assets for APC technology projects were approximately $1,106, $1,277, and $2,079, respectively, and at December 31, 2020, contract assets for the FUEL CHEM technology segment were approximately $269, and are included in accounts receivable on the Condensed Consolidated Balance Sheets. There were no contract assets for the FUEL CHEM technology segment as of  June 30, 2022 or  December 31, 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 Condensed Consolidated Balance Sheets on a contract-by-contract basis at the end of each reporting period. Contract liabilities were $578, $390, and $850 at June 30, 2022,  December 31, 2021, and December 31, 2020, respectively, and are included in other accrued liabilities on the Condensed Consolidated Balance Sheets.

Changes in the contract asset and liability balances during the six month period ended June 30, 2022, 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 $20 and $250 for the three and six months ended June 30, 2022, respectively, and $49 and $157 for three and six months ended June 30, 2021, respectively, which represented primarily revenue from progress towards completion of our APC technology contracts.

As of June 30, 2022 and December 31, 2021, 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 June 30, 2022, the aggregate amount of the transaction price allocated to remaining performance obligations was $10,547. The Company expects to recognize revenue on approximately $8,414 of the remaining performance obligations over the next 12 months with the remaining recognized thereafter. 

Accounts Receivable

The components of accounts receivable are as follows:

	As of
	June 30, 2022			December 31, 2021
Trade receivables	$	5,500		$	2,122
Unbilled receivables		1,106			1,277
Other short-term receivables		78			83
Allowance for doubtful accounts		(260	)		(223	)
Total accounts receivable	$	6,424		$	3,259