BOLD IDEA Reengineer the grid around electric vehicles.

The first mainstream plug-in hybrids and fully electric vehicles (EVS) are just now hitting the market, and while initial sales have been slow, the Department of Energy predicts there will be 1.2 million of them on the road by 2015. With the EV revolution in full swing, University of Michigan mechanical engineer Jeffrey Stein says the time is now to integrate the electrical grid with the transportation infrastructure and ensure the country's carbon emissions drop as a result of the introduction of electric cars.

Transportation is responsible for 27 percent of America's carbon emissions. Power companies' heavy reliance on coal-fired plants means that electricity generation accounts for even more, about 33 percent "At first it may seem counterintuitive that making cars electric will help us limit greenhouse gases," Stein says. "But in fact we can reduce carbon emissions by adopting vehicle electrification." The keys will be limiting the need for new power plants and engineering the electrical grid to increase the use of clean energy sources.

THE SCIENCE BEHIND IT Designers of both the electrical grid and future EVS will have to take into account when and how owners charge their vehicles. "Eighty percent of charging is expected to take place at home or the workplace," says Genevieve Cullen, vice president of the Electric Drive Transportation Association. Influencing when people recharge their cars could have huge implications for the effect of EVs on the environment.

During off-peak hours, electric companies rely on the base load power generated in large part by carbon-neutral nuclear power plants; when demand rises during peak hours, they bring dirty, coal-fired plants online to meet increased need. "Utilities need to give electric vehicle owners preferential pricing for charging during off-peak hours, when energy is cleaner," Stein says. The other half of the equation, he notes, is engineering a smart power grid that can distribute renewable energy, from solar or wind, for instance, to charge fleets of EVS. "If a power company has the ability to selectively charge groups of vehicles based on when renewable energy resources are available," he says, "it makes electric vehicles useful not only for reducing petroleum consumption but for reducing the amount of greenhouse gases overall that we produce."

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