Thermoelectric materials, which generate electricity from heat otherwise lost through vehicle exhaust pipes, industrial equipment, and computer chips, could do a lot to help conserve energy and reduce greenhouse-gas emissions. So far, however, they have been too inefficient and expensive to be widely used. Some newer thermo­electric materials might more effectively convert waste heat into useful electricity, but they require expensive and impractical layer-by-layer assembly.

Mechanical engineer Ronggui Yang has created an easy-to-make alternative: nanocomposites made of semiconductors such as silicon-germanium alloys and bismuth telluride alloys. Because thermoelectrics generate a current when exposed to a heat differential, they must have the unusual property of conducting electricity well but heat poorly. Yang is improving the thermoelectric performance of the materials he uses by turning them into nano­particles and nanowires, which he then fuses to create composite materials. The nanoscale components help inhibit the flow of heat, which is conveyed by atomic vibrations. That increases the thermoelectric efficiency of the finished material. Yang’s theoretical work shows that the materials can match or improve on the efficiency of today’s best thermoelectrics.

The biggest advantage of Yang’s nanocomposites is that they could be mass-produced using a common industrial process. Yang has produced prototypes in conjunction with MIT, Boston College, and NASA’s Jet Propulsion Laboratory at Caltech. Eventually, low-cost nanocomposites could offer big payoffs–for instance, significantly boosting the fuel efficiency of cars.

PROBLEM: Every day, plants, algae, and bacteria generate more energy than all the world’s power plants, using sunlight to split water into hydrogen and oxygen and then storing the energy in sugar molecules. Artificial photosynthes­is–the process of using solar power to split water through the creation of chemical bonds, as plants do–holds promise as a clean, cheap source of hydrogen to power fuel cells. But to make the process practical, researchers must find catalysts to decrease the amount of energy needed.

SOLUTION: Most attempts at artificial photosynthesis try to split water with a single powerful chemical reaction. Theodore Betle­y, an assistant professor of chemistry and chemical biology, has come up with a method that mimics the multistep process plants use. He arranges small clusters of metals inside a molecular scaffold; the clusters work like a plant’s photosynthetic chloroplasts, splitting water molecules in a stepwise fashion that uses less energy than one big reaction. Betley has shown that he can split water using such complexes, but his team is still searching for more-efficient catalysts. If they succeed, they will have found a valuable route to hydrogen for fuel cells by mimicking three billion years of evolution.

In today’s power grid, a steady but essentially passive flow of electricity links power plants, distribution systems, and consumers. It is a “dumb, inefficient system,” says Peter L. Corsell, founder and CEO of GridPoint; in order to meet peak demand, power plants must be able to generate twice as much electricity as is typically needed. So Corsel­l has created energy management software that, combined with hardware from GridPoint and others, allows utilities to better balance power generation and elec­tricity demands, increasing both efficiency and reliability.

GridPoint’s software allows consumers to use a personalized Web portal to set limits on electricity consumption. Using a small computer attached to a home’s circuit box, utilities then measure energy consumption and control appliances such as water heaters and thermostats. “Consumers should be able to buy 74° and the utility company then sells them 74°,” says Corsell. In addition to helping people conserve energy and reduce their bills, the system makes it simpler to integrate renewable energy sources such as solar cells and wind turbines into the grid.

Corsell has raised $102 million, and utilities will begin deploying the technology within the next year. For instance, Xcel Energy, a Minneapolis-based utility, has selected GridPoint’s platform for its power grid project in Boulder, CO. Read why Corsell’s thinks we need to apply information technology to the grid.

In 2001, a professor of materials science and engineering at MIT, Yet-Ming ­Chiang, announced some promising results concerning new battery materials. But those materials might still be in the lab today were it not for Ric Fulop, then an enterprising 26-year-old from Vene­zuela. Today, the materials are being used to make high-performance batteries that General Motors is testing for use in its new electric car, the Volt.

Fulop founded his first company–which imported computer hardware and software and sold it to Venezuelan retailers–at the age of 16. He has since founded five more companies, including one, Into Networks, whose software is used in the Windows Vista operating system. But it is at A123 Systems, the company he founded with Chiang in 2001, that Fulop has had his greatest success. Now the company’s vice president of business development, he has helped A123 raise over $250 million, including investments from Sequoia Capital, GE, and OnPoint, the venture capital initiative of the U.S. Army. A123’s batteries can already be found in power tools, airplanes, and hybrid buses.

Fulop dropped out of college to found one of his companies, only to return for an MBA after starting A123. But despite a lack of academic training in materials science, he is quick to grasp technical details. He spent months scouring scientific journals, attending conferences, and picking the brains of university technology licensing officers before his search led him to Yet-Ming Chiang. And thanks to this preparation, it took just one meeting to convince the MIT professor that Fulop’s idea for a battery company was sound.

Commercializing battery technology, especially for new cars, is a capital-intensiv­e and risky business. To help jump-start the company, Fulop helped negotiate a deal with Black and Decker to supply batteries for the power-tool market. Not only did the agreement give A123 an early and much-needed source of revenue from an industrial customer, but it was an ideal way to start testing its production technology for the much larger automotive market. In 2006, partly on the strength of the com­pany’s success in reliably producing millions of battery cells a year for power tools, Fulop and his partners persuaded GM to give A123 a chance. The automaker is testing two different battery technologies for its Volt, with a decision expected by the end of the year. If GM does select A123’s technology, Fulop will have played a key role in making possible the United States’ first mass-produced electric car.