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Note that this is a dollar-for-dollar tax credit, rather than a deduction from taxable income.
In addition to credits for renewable energy, you may also be eligible for additional tax credits for the following energy efficiency improvements:
Automobile Tax Credits
Consumers who buy or lease a new hybrid gas-electric car or truck are eligible for, and can receive, an income tax credit of $250-$3,400.
Home Energy Efficiency Improvement Tax Credits
Consumers who purchase and install specific products, such as energy-efficient windows, insulation, doors, roofs, and heating and cooling equipment in the home can receive a tax credit of up to $500 beginning in January 2006.
Business Credits
Businesses are eligible for tax credits for buying hybrid vehicles, for building energy- efficient buildings, and for improving the energy efficiency of commercial buildings (as outlined in the Energy Policy Act of 2005).
http://www.energy.gov/taxbreaks.htm