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Description of business and summary of significant accounting policies - Revenue by Product Line and Services (Details) (USD $)
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3 Months Ended | |
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Mar. 31, 2013
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Mar. 31, 2012
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| Revenue by Producks and Services [Line Items] | ||
| Products | $ 2,052,665 | $ 1,489,707 |
| Services | 1,993,653 | 1,762,821 |
| Total revenues | 4,046,318 | 3,252,528 |
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Cogeneration
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| Revenue by Producks and Services [Line Items] | ||
| Products | 1,278,156 | 582,250 |
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Chiller
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| Revenue by Producks and Services [Line Items] | ||
| Products | $ 774,509 | $ 907,457 |
| X | ||||||||||
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- Details
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| X | ||||||||||
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- Definition
Aggregate revenue during the period from the sale of goods in the normal course of business, after deducting returns, allowances and discounts. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
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- Definition
Total revenue from sale of goods and services rendered during the reporting period, in the normal course of business, reduced by sales returns and allowances, and sales discounts. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
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- Definition
Aggregate revenue during the period from services rendered in the normal course of business, after deducting allowances and discounts. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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