Not everything is new in greentech. A number of companies are based around technologies and concepts coined years and even centuries ago.

Achates Power... Testing a 4.2 liter, 4-cylinder engine "that rivals conventional engines nearly twice its size." Plans to license tech to big manufacturers and automakers

Achates Power, a company developing a new family of opposed-piston engines, has completed a $19.2M Series B round with the addition of a new investor, Triangle Peak Partners. Triangle Peak joins the company’s existing investors: Sequoia Capital Partners, Rockport Capital Partners, Madrone Capital Partners, and InterWest Partners.

These clean-energy startups are hitting the market with products and services that could radically alter how we think of, and consume, power

The same fuel efficiency that drew Europeans to embrace diesel engines is taking hold of the U.S., and startup Achates Power is ready to pounce.

Plug-in vehicles held the spotlight in the turnaround plans drafted by General Motors and Chrysler in recent months, and Congress has allocated billions of dollars for investment in plug-in car and battery research, production, and infrastructure. But there's another technology in the mix that could end up doing more to help automakers meet tightening fuel-economy standards over the near term, while also creating new opportunities for entrepreneurs: diesel.

From clean diesel engines to personal solar panels, investors had a wide range of new technologies to peruse.