Being classified as "other" usually doesn't feel this good. But "other" is the category name where Dow Jones VentureOne and Ernst & Young place many greentech companies when adding up the number of venture-capital deals made.

Digging deeper into the "other" category, there are two subgroups -- "Energy" and "Advanced Specialty Materials & Chemicals" -- which the firms say made up the bulk of cleantech investments.

Energy investments jumped to $590 million, up 28 percent from the same quarter last year. And the nichier materials-and-chemicals category more than doubled to $277 million.

Greentech also was represented in two of the 10 largest U.S. venture-capital deals in the third quarter.

A $77-million round of funding for HelioVolt, an Austin, Texas-based company with a thinsolarthat uses no silicon -- an attractive characteristic in a worldwide shortage of solar-grade silicon -- ranked No. 4. (On Monday, the company said it added another $24 million to that Series-B round.)

An expected $70-million round of funding for Emeryville, Calif.-based Amyris Biotechnologies came in at No. 5 on the list. The company has raised an undisclosed amount toward that round so far (see Biofuels Get Financing Downpour).

Overall, U.S. venture capitalists invested more money in fewer deals last quarter. Total investment grew to $8.07 billion, up 8 percent from the year-ago quarter, while the number of deals dropped by 41, to 635.

But will the venture market continue to see growth? Ernst & Young thinks so.

"The overall level of investment and larger deal sizes are suggestive of a continued bullish view of these companies' prospects and liquidity options," said Joseph Muscat, a director for the Ernst & Young Venture Capital Advisory Group, in a statement.

Startup Gets Cash to Turn Traffic Lights Green

Most drivers can relate to the frustration of waiting futilely at an empty intersection as a traffic light refuses to turn green. These red lights aren't just bad for road rage; they also are bad for the environment, according to traffic-management startup Aldis.

The company is developing a so-called "Guardian Eye" that can identify different types of vehicles approaching an intersection and determine the distance and speed of those vehicles, and then can use the information to manage the lights to bring about the least possible delay.

The technology, which is being jointly developed with the Oak Ridge National Laboratory, could reduce the 296 million hours the lab estimates is wasted at traffic lights each year, said Glenn Kline, a general partner at Innovation Valley Partners.

Battelle Ventures and Innovation Valley Partners said Monday it had invested $1.9 million in Aldis, with another $1.9 million committed if the company reaches future milestones. Meritus Ventures also participated in the Series-A round.

While it works on the Guardian Eye, Aldis is entering the market by replacing electricity-guzzling incandescent lights with more energy-efficient light-emitting diodes at traffic lights. As it replaces those lights, Aldis is adding a proprietary signal that will allow it to connect its Eye to those lights when the technology is ready, Kline said.

"From a market perspective, in the traffic-management space, this is an extremely underserved market," he said. "It's a point of pain that a lot people have experienced, when you're just sitting there at a light. The Guardian Eye [could bring about] a dramatic reduction in carbon emissions."

Matt Horton, a principal at @Ventures, said his firm looked at the deal and "thought it was very interesting," but didn't pursue an investment -- although he hasn't ruled out the possibility of a future deal.

One challenge that traffic-management providers face is the length of time it takes to sell systems to municipalities and government agencies, he said.

These customers "can be slow to commit to a technology, and will often subject a company to 'death-by-trial,' where they will do small pilot programs over very long periods of time before making a final commitment" he said.

Still, Horton said traffic management could have an important place in the cleantech investment category.

"Limiting the amount of time that vehicles spend in traffic, on our roadways and searching for parking directly affects the amount of fuel burned and emissions levels," he said. "So, any new technologies that can help alleviate traffic should be very beneficial."