Photos: The future of energy

When air-conditioners kick into overdrive on a hot afternoon, the price of electricity rises dramatically. Heavy air-conditioning usage can also prompt brownouts and blackouts. To get around it, companies such as Comverge, of East Hanover, N.J., and EnerNoc, based in Boston, have created systems that effectively redistribute electricity between buildings and appliances on a grid. If a brownout is looming, swimming pool heaters might be turned down so that air-conditioners can go full throttle. The systems save money too by cutting back on power usage in the afternoon, when rates peak. Utilities in Utah, Florida and other states have begun to install these systems.

Forget all of the ads about turning corn into ethanol. An acre of corn produces only about 480 gallons of ethanol, according to Patrick McCroskey, chief financial officer at Ceres, the California Environmental Resources Evaluation System, a government agency that facilitates access to environmental data. Instead, researchers are looking at switchgrass and other leafy plants for making cellulosic ethanol. These plants potentially could produce twice as much or more energy per acre as corn, and the ethanol could be processed with microbes, pictured here. These plants would also fertilize themselves, ideally, and consume less water. Some companies, like Greenfuel Technologies, based in Cambridge, Mass., are looking at ways of harvesting algae for ethanol.

In Wales, Shell Solar has set up the CIGS-based panels shown in the photo to the left. In the second photo, CIGS cells are printed at Nanosolar, a solar-power company based in Palo Alto, Calif.

The notion of converting wave power into electrical power draws strong reactions. "Wave energy is hopeless," said venture capitalist and Nobel Prize winner Arno Penzias in an interview in 2005. At the other end of the spectrum, Ocean Power Delivery, based in Edinburgh, Scotland, says its Pelamis system can harvest electricity from waves safely and efficiently. It's in the midst of installing a system off the coast of Portugal.

Will hydrogen work as an alternative-energy source? Maybe, but making the stuff isn't cheap. Some Japanese companies have experimented with hydrogen-powered home systems like the one shown here, while Toyota Motor, Volkswagen and Ford Motor have crafted prototype hydrogen-powered cars.