July 26, 2010 By Kahliah A. Laney
"Change we can believe in" was President Barack Obama's campaign slogan, and whether anyone believes in it, change is exactly what the U.S. is getting. One example is the federal government's policy on energy. The Obama administration crafted the comprehensive New Energy for America Plan, the centerpiece of which is putting 1 million electric vehicles on U.S. roads by 2015. But that aggressive plan raises a concern: Can the country's aging electric grid support these new plug-in hybrid electric and plug-in electric vehicles?
Experts would say yes. In fact, with the right technology, electric vehicles could do more to help the grid than harm it. Through vehicle-to-grid (V2G) technology, plug-in vehicles are capable of adding power capacity to the grid during high demand - known as peak shaving - and also storing renewable energy that can be returned to the grid during peak hours. V2G technology also may benefit consumers who could sell that excess power back to grid operators.
For V2G technology to work, however, plug-in electric vehicles must be grid-integrated. This would require car manufacturers to make vehicles with two-way connections that let them take energy from the grid for charging and give back excess power. They'll also need a control system that grants grid operators access to vehicles' batteries and a way to track energy exchange between the vehicle and grid. Finally concerns remain about the electric grid's stability, despite demonstrations of how the grid and plug-in vehicles can have a mutually beneficial relationship.
Photo: Cadillac Converj concept car/Photo by Kenavt/Wikipedia
The nation's power grid is designed to support peak energy loads, so when electricity demand is low - typically between midnight and 6 a.m. - unused energy is produced by coal- and gas-fired power plants. Charging plug-in vehicles during off-peak hours could use that excess energy, which is what some researchers call "filling the trough." And if plug-in vehicles charge while demand is low, it wouldn't be necessary to increase the grid's delivery capacity.
Additionally grid-integrated vehicles would include a timer to control when charging cycles begin and end. Controlled charging would mitigate too many people charging at any given time, which could overwhelm the grid. "If you have some kind of controlled charging, impacts on the grid will largely be positive," said Paul Denholm, a senior energy analyst for the National Renewable Energy Laboratory.
Willett Kempton, a University of Delaware professor and father of V2G technology, said a Super Bowl broadcast will tax the grid more than plug-in vehicles. "On average a vehicle pulls something like 400 watts, which is about the same as a plasma TV," he said. "The thing about the Super Bowl is everybody turns their TVs on at the same time ... more of a problem than cars, which are plugged in at varying times throughout the day and night."
So the question isn't just if the grid is up to supporting plug-in vehicles, it's also whether these vehicles are up to supporting the grid.
Cars have come a long way since Henry Ford's first Model T produced in 1908. The modern array of energy-efficient vehicles is a showcase of technological advancement.
Plug-in hybrids, like the Chevrolet Volt, have an electric motor and an internal combustion engine, similar to conventional hybrid vehicles. But they differ because their high-capacity lithium-ion batteries can be recharged through an external electrical outlet. The internal combustion engine kicks in when the batteries are depleted, giving the vehicle more range. Full electric plug-in vehicles, like the new Nissan Leaf, are powered solely by rechargeable lithium-ion battery packs, which are recharged by an external power