The Cleantech Venture Network LLC reports that “cleantech” became the third largest venture investment category in the second quarter with US$843 million invested.

Cleantech venture capital investing in North America saw its eighth consecutive quarter of growth, it reported. And, cleantech investment represented a 64% increase over the US$514 million invested in the first quarter and a 129% increase over Q2 2005.

Cleantech investment represented 13.4% of all venture capital invested in all categories for the quarter. Year-to-date cleantech investments totalled US$1.4 billion, nearly doubling the US$704 million invested in the first half of 2005. For all of 2005, cleantech investing totaled US$1.6 billion.

In the first half 2006, energy investment tripled to US$946 million, from same time last year. The energy segment was also the biggest sub-category in Q2, with US$594 million of investment, a 69% increase over the US$352 million invested in the first quarter.

“In addition to seeing a surge of venture investment in clean energy-related companies, we are seeing significant growth in other cleantech segments such as agriculture, environmental IT, transportation and water,” said Nicholas Parker, chairman and co-founder of the Cleantech Venture Network. “Growth in venture flows is being matched by more cleantech mergers, acquisitions and public market activity, along with a lengthening list of major corporations placing cleantech at the heart of their competitive strategies.”

In Q2, cleantech surged ahead of the two previously popular venture investment categories, telecommunications and medical. It now ranks third behind only biotech and software, indicating its shift into the mainstream, observed Keith Raab, CEO and co-founder of the Cleantech Venture Network. “The interest in cleantech has moved beyond investors to corporations, global media, national and state governments, academia, and the general consumer, reflecting its broad acceptance.”