Note 11 - Business Segment and Geographic Financial Data - Reporting Segment Net Sales and Gross Margin (Details) - USD ($) $ in Thousands |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2026 |
Jun. 30, 2025 |
Jun. 30, 2026 |
Jun. 30, 2025 |
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| Revenues from external customers | $ 6,485 | $ 5,558 | $ 12,565 | $ 11,940 |
| Cost of sales | (3,810) | (3,029) | (7,246) | (6,452) |
| Gross margin | 2,675 | 2,529 | 5,319 | 5,488 |
| Selling, general and administrative | (3,594) | (3,347) | (7,310) | (6,688) |
| Research and development | (646) | (490) | (1,170) | (1,060) |
| Income (loss) from operations | (1,565) | (1,308) | (3,161) | (2,260) |
| Air Pollution Control [Member] | ||||
| Revenues from external customers | 2,785 | 2,505 | 4,389 | 3,808 |
| Cost of sales | (1,775) | (1,406) | (2,764) | (2,284) |
| Gross margin | 1,010 | 1,099 | 1,625 | 1,524 |
| Selling, general and administrative | 0 | 0 | 0 | 0 |
| Research and development | 0 | 0 | 0 | 0 |
| Income (loss) from operations | 1,010 | 1,099 | 1,625 | 1,524 |
| FUEL CHEM [Member] | ||||
| Revenues from external customers | 3,700 | 3,053 | 8,176 | 8,132 |
| Cost of sales | (2,035) | (1,623) | (4,482) | (4,168) |
| Gross margin | 1,665 | 1,430 | 3,694 | 3,964 |
| Selling, general and administrative | 0 | 0 | 0 | 0 |
| Research and development | 0 | 0 | 0 | 0 |
| Income (loss) from operations | 1,665 | 1,430 | 3,694 | 3,964 |
| Other Operating Segment [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 | (3,594) | (3,347) | (7,310) | (6,688) |
| Research and development | (646) | (490) | (1,170) | (1,060) |
| Income (loss) from operations | $ (4,240) | $ (3,837) | $ (8,480) | $ (7,748) |
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- Definition The aggregate cost of goods produced and sold and services rendered during the reporting period. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Aggregate revenue less cost of goods and services sold or operating expenses directly attributable to the revenue generation activity. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition The net result for the period of deducting operating expenses from operating revenues. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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- Definition Amount of expense for research and development. Includes, but is not limited to, cost for computer software product to be sold, leased, or otherwise marketed and writeoff of research and development assets acquired in transaction other than business combination or joint venture formation or both. Excludes write-down of intangible asset acquired in business combination or from joint venture formation or both, used in research and development activity. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition The aggregate total costs related to selling a firm's product and services, as well as all other general and administrative expenses. Direct selling expenses (for example, credit, warranty, and advertising) are expenses that can be directly linked to the sale of specific products. Indirect selling expenses are expenses that cannot be directly linked to the sale of specific products, for example telephone expenses, Internet, and postal charges. General and administrative expenses include salaries of non-sales personnel, rent, utilities, communication, etc. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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