Ten Eco-Friendly Companies

Granted, we're still a long way from a hydrogen-powered car in every driveway, but Hydrogenics is working on other applications to build a market for the technology. (Hydrogenics produces fuel cells that fit together like LEGOs and extract electricity from the chemical reaction of hydrogen and water.) Last December, it installed a hydrogen re-fueler inside a General Motors car-assembly plant in Canada to power two forklifts. And this summer, Hydrogenics technology started fueling a Purolator truck in Toronto and a transit bus in Winnipeg. GM, which holds a 20 percent stake in Hydrogenics, deems its trial a success.

Hydrogen fuel cells aren't just clean--they're also silent, and they produce water as a byproduct. That's also creating defense applications that can capitalize on a stealth approach. Another upside: in desert settings like Iraq, the technology produces drinking water for soldiers. The U.S. Army recently started a yearlong trial using Hydrogenics to power a few of its Stryker light armored utility vehicles.

When this technology will move into mass markets is unclear. GM says it may happen in the auto industry over the next decade. (Hydrogenics helped develop a "neighborhood car" prototype that looks like a street-legal golf cart.) Hydrogenics' sales fell by 37 percent last year, but it has a big backlog of orders. David Smith, an analyst at Smith Barney, remains bullish on the company, and ABI Research estimates the fuel-cell market could reach $2 billion by 2012. For now, Rivard is content to focus on smaller projects. "It is important for us to go after these low-hanging fruits," he says.

--Jessica Silver-Greenberg

4 Cow Manure. Really.

Panda Development: Burning bovine 'biomass' to fuel plants that convert corn to ethanol