During the first quarter, venture capitalists invested $513 million into companies that have a clean-technology aspect to them, a six-year high, according to the Cleantech Venture Network quarterly report, to be released tomorrow.

That's a 2.3% increase over the previous quarter, and a significant 52.9 percent jump over the same quarter a year ago. Moreover, a record $357 million was invested into clean-tech energy companies.

The average deal size rose to $8.28 million, up twenty percent from the fourth quarter average of $6.88 million and 16.7 percent from first quarter of 2005.

The record quarter for clean-tech investments was $797 million, made during the bubbly first quarter of 2000.