Second-quarter 2008 venture capital investments in U.S. clean technology companies rose by 41% over the previous quarter, reaching a record $961.7 million, according to an Ernst & Young report based on data from Dow Jones VentureSource. Year-on-year cleantech investments were up 83% over the same quarter in the previous year. 

The record investment came even as overall venture capital investment was down by nearly 8% in the quarter.

Ernst & Young defines clean technology as products or services that optimize the use of natural resources or reduce negative environmental impact by their use, while also driving down costs and improving performances. Examples of cleantech include alternative fuels and products that improve energy efficiency.

Energy costs are fueling the investment in clean technology, as are corporate commitments to climate change, the tax advisory firm says. Energy and electricity generation attracted the most investment of any cleantech sector in the second quarter, garnering $494.9 million or 52% of the whole. Energy-efficiency companies garnered 20% of the total investment dollars.