How Raindrops Could Power Your TV

Solar, wind, and, until recently, nuclear: a few alternative energies seem to get all the good press. That’s understandable; they’re the old guard of well-established technologies. But there’s a new crowd of high-tech up-and-comers. From power-generating workouts to jet fuel algae, these alternatives might one day make the world cleaner, more livable—and maybe even more fun.

The Tech: ReRev
The Fuel: Human Power
How It Works: Retrofitted elliptical machines convert heat energy produced during a workout to electricity, then route it back into the building’s power grid. In other words, your sweating helps keeps the lights on.
Current Status: ReRev has 28 facilities nationwide, primarily at universities. The company estimates a typical 30-minute workout produces 50 watt hours of electricity—enough to power a laptop for an hour. If not likely to directly pay for itself, the technology appeals to customers who like knowing their workouts are a little greener.
What the Future Holds: Eco-friendlier gyms are a growing trend: fitness companies and colleges like the University of North Texas (which recently installed 30 of the machines) recognize that prominently displayed green technology is little pain for plenty of customer gain. Read this Men’s Health story to find out what it’s like to be a human generator.
The Tech: Solar Roadways
The Fuel Source: The sun (OK, this is solar, but it’s a whole new way to capture that energy)
How It Works: Take all the pavement and concrete surfaces we drive on every day and cover them with high-strength solar panels. Presto: all those highways and driveways become solar collectors.
Current Status: Still in development, though the project recently won GE’s Ecoimagination Challenge, earning $50,000 to move forward. It’ll require about $50 million to complete research and begin production.
What the Future Holds: “We can fix the power grid, build an intelligent highway and a smart grid all in one swoop and move into the 21st century,” the inventor told Wired magazine.
The Tech: KiOR bio-crude
The Fuel Source: Wood Chips (but not for burning)
How It Works: Uses proprietary technology based partly on fluid catalytic cracking, a technique long used in turning oil into gasoline and diesel. KiOr has adapted the approach to turn wood chips and other biomass into crude oil—accelerating that process that would normally take millions of years.
Current Status: The company has a working demonstration plant and just filed for an IPO to raise $100 million for full-scale production plants, including five in Mississippi.
What the Future Holds: Bio-crude works with existing infrastructure—there’s no need to re-engineer cars or build new gas stations. And unlike corn-based ethanol, it doesn’t affect food supplies. KiOR believes in can produce bio-crude for an unsubsidized $1.80 a gallon, which would undercut competing technologies, not to mention conventional gasoline.
The Tech: Solazyme algae oil
The Fuel Source: Algae
How It Works: Bio-engineered algae grown in special fermentation tanks produce oils that can replace those derived from petroleum, animals, and other plants. Algal oils could already replace palm oil and soy milk, for example.
Current Status: Solazyme, one among several algae-oil companies, has already produced over 20,000 gallons of algal jet fuel for testing and certification by the Navy. It hopes to have petroleum substitutes ready within two years, at a cost of $60 to $80 per barrel—compared to $100 a barrel for petrol.
What the Future Holds: Algal energy is undergoing a renaissance after languishing through the 1980’s and ’90’s, an era of cheap(er) oil. Rising oil prices have re-ignited algae’s profit potential, which has also drawn the attention of energy giants like Exxon and Chevron.
The Tech: Hygroelectricity
The Fuel Source: Raindrops
How It Works: During thunderstorms, raindrops take on an electrical charge. Scientists are currently experimenting with ways to collect that charge.
Current Status: Hygroelectricity is still in the earliest stages of development, though obviously it’s a compelling vision: energy from thin air.
What the Future Holds: In tropical, humid environments, roof-mounted hygroelectric harvesters could provide an inexpensive source of household energy. Said one researcher. “Just as solar energy could free some households from paying electric bills, this promising newenergy source could have a similar effect.”
Want to make a more immediate impact this Earth Day? Try one of these Eight Simple Ways to Protect the Environment.
—Jesse Hicks