From the February 2006 issue of Entrepreneur

Walk through the maze of metal kegs, six-packs of boutique beer, and cartons of pop, juice and fruity syrup on Tim Curtiss' production floor, and you'll think for a minute that you're in a beverage warehouse. However, these are just raw materials for Liquid Resources of Ohio LLC in Medina, Ohio. Beverage companies pay Curtiss, 45, to take out-of-date or flawed products off their hands. Curtiss' company then smashes the containers and, through fermentation and distillation, converts the liquid contents into fuel-grade ethanol.

Launched in 2003, Liquid Resources has the capacity to produce about 3 million gallons of ethanol a year. As both gas prices and fears of global warming rise, ethanol looks better and better-it burns far cleaner than gasoline and reduces our reliance on oil imports. Most cars already use fuel that contains up to 10 percent ethanol-usually produced from corn -- but Curtiss says some experts think cars could run on a mix of up to 40 percent ethanol. Many city buses run on fuel that's 85 percent ethanol.

And not only does Curtiss' company produce clean fuel, but it also helps fight the burgeoning piles of waste that threaten to overwhelm our landfills. The company uses every bit of its raw materials: Metal, plastic and cardboard containers are crushed and shipped to recyclers; glass is sold to abrasives and road-building companies. The company's only waste product is water.

A self-styled "serial entrepreneur," Curtiss didn't set out to tackle America's energy crisis, but in waste processing, he found a business model he couldn't resist. He took the plunge even though he had no background in energy. He now projects $1 million in sales for 2006.

Renewable, clean energy is a booming field these days-even in the U.S., which has lagged behind other countries. "The best evidence of this was at the second annual conference of the Renewable Energy Finance Forum in New York City," says Michael Rosenfeld, vice consul of UK Trade & Investment, an international economic development agency for the United Kingdom's government that works on trade export and investment opportunities, including renewable energy projects with U.S. companies. "You used to just see VCs and smaller players investing in renewable energy, but now you see the big institutional investors putting in billions. But because it's still a relatively young market, the opportunities for entrepreneurs are fairly wide open."

According to John Anderson of the Rocky Mountain Institute, a Snowmass, Colorado, energy think tank, Curtiss is typical of a lot of the entrepreneurs headed into the renewable energy field: Many are experts in something else.

"Energy has been dominated by the regulated-monopoly utilities structure," says Anderson, RMI's team leader for energy and resources. "Energy has not had an entrepreneurial culture. A lot of the most successful energy entrepreneurs I'm seeing right now are immigrants from other tech areas."

Anderson says that the regulated-monopoly paradigm has made it tough in the past for entrepreneurs. However, as energy deregulation proceeds, he expects to see a huge wave of energy innovation and opportunities. "The flood will be so big and widespread that it's tough to know where the cool things are going to be," he says.

Curtiss' business is certainly one cool thing to develop as the energy picture changes in this country, but there are many others, even outside the now almost-mainstream areas of wind and solar power. Near a Butterball turkey processing facility in Carthage, Missouri, Renewable Environmental Solutions is converting 270 tons of turkey offal into 300 barrels of crude oil every day. Formed in 2000 as a joint venture between Con-Agra and Changing World Technologies, a West Hempstead, New York, company that developed a thermal conversion process, RES uses water, heat and pressure to convert the turkey parts into energy. In addition to creating oil, the process reduces solid wastes and destroys prions, the mutated proteins that are suspected to cause mad cow disease.

"People are amazed that we're using animal parts to create energy, but years ago [people] took parts of whales and made lamp oil," says Changing World CEO Brian Appel, 47. "That's not so different from what we're doing here."

Changing World's technology works for a wide variety of other wastes, from municipal sludge to worn-out tires. "In fact, our initial focus was to find a sensible solution to waste," Appel says. "Energy production was second, but now that's become primary."

Another energy solution puts a new spin on power derived from water. Arlington, Virginia-based Verdant Power has spent years examining new designs for turbines that create energy from the free flow of water in rivers, canals or tidal areas without using dams. The 5-year-old company is now testing one of its designs and anticipates its first commercial revenue in 2007 with the installation of a few hundred turbines in New York's East River. The installation will produce about 10 megawatts of electricity per day for New York City--a tiny percentage of the city's daily 1,500 to 2,000 megawatt gulp.

Verdant Power has faced a difficult uphill climb toward its first commercial project. Since its technology is being deployed in a highly prized and regulated natural resource, getting the necessary permits has been tough. Beyond that, the company faces a seeming lack of urgency for dealing with the energy crisis in the U.S. Fortunately for Verdant Power and others, the global market for renewable energy is brisk. Says Verdant Power CEO Ron Smith, 57, "We're talking to people all over the world."

Kristin Ohlson is a Cleveland writer and author of the award-winning memoir Stalking the Divine.