"Ultracapacitors are lighter and more powerful than batteries, 10 times more powerful by size as well as 10 times lighter," notes Brendan Coffey.

The editor of Cabot Green Investor explains, "Within this market, Maxwell Technologies (MXWL) is a San Diego-based company whose patent-protected ultracapacitors are denser -- and therefore able to hold more energy -- than those of its competitors.

"In a simplified comparison of how powerful and quick Maxwell's ultracaps are, a lead acid battery takes 10 hours to fully charge. A lithium ion battery will charge in about an hour.

The venture capital (VC) industry demonstrated its commitment to the clean technology space in the second quarter of 2009, pumping $1.2 billion into the sector, according to a report by GTM Research. VC investments in cleantech are up 43.5% from the first quarter of the year, when $836 was put into play in the cleantech space.

The number of transactions increased, as well. In the first quarter, 59 deals were completed, and deal-flow surged 44% to 85 in the quarter just finished. Average deal size remained fairly consistent: $14.2 million for the first quarter and $14.1 for the second.