Vehicle-to-grid technology gains some traction

As American car buyers prepare to kick the tires of the first new generation of electric cars to arrive since the 1920s, Willett Kempton already has bigger plans for these vehicles.

Kempton, 61, directs the Center for Carbon-free Power Integration at the University of Delaware. He is the originator of a concept that would make electric vehicles a boon to today's electricity grid, and a potential solution for one of the biggest climate-related question marks hovering over the grid's future: how to store renewable energy.

The idea is to allow electric vehicles not only to draw power from the grid, but to send electricity back into it, as well. It effectively would use the cars' batteries as a big storage system to help buffer the constantly fluctuating balance of electricity in the system -- ups and downs that are expected to become steeper and more unpredictable as the share of renewable energy rises.

While electric cars are a new idea to most people, Kempton, who teaches renewable energy policy, has had these ambitions since the mid 1990's. While he was mulling over the problem of how to extend the use of solar power when he happened to attend a discussion of electric vehicles in Washington, D.C. Suddenly a light bulb went on in his head. "There's going to be batteries everywhere there's a garage or a driveway," he recalls thinking.

His lab has been researching the idea since then and more recently testing it. Now he has applied for a grant from the U.S. Department of Energy to launch the first field-scale demonstration of the concept. His new project will come in an environment that has become markedly more serious about the idea of electric vehicles, and where increasingly large players are investigating the potential of his concept, which is called vehicle-to-grid, or V2G, for short.

"The electric system in the country is one of the biggest, most complex just-in-time delivery systems that exists today," explained Sunil Chhaya, senior project manager of the plug-in hybrid vehicle program at the Electric Power Research Institute in Palo Alto, Calif.

"The way I see whether this technology is a serious contender or a serious technology for the future is to see if the mainstream players get involved," he added. "And now that is happening."

In an indication that they expect -- or at least hope -- electric vehicles can reach mass-scale market penetration, auto manufacturers have begun collaborating with utility companies to investigate the implications of connecting these two industries that have been almost entirely separate since their births.


Meanwhile, pilot projects are springing up across the country, following Kempton's lead. Companies are seeking to commercialize the necessary technology and governments and utilities have begun to ponder regulatory frameworks that will be necessary for the shift.

Helping the grid handle its ups and downs

Vehicle-to-grid would benefit the grid because under the current system electricity supply must match demand, immediately. Otherwise, there is the possibility for temporary brownouts, even blackouts.

"Right now, electricity is a product that is produced and consumed at the same time," said Steven Letendre, a professor at Green Mountain College in Vermont who has modeled the economics of vehicle-to-grid.

Because demand stems from the activities of consumers, and these activities fluctuate constantly, the grid must adjust continuously. That's not only to ensure a continuous power supply, and not waste excess electricity, but also to keep power flowing at the right frequency.

The grid sends signals to power plants every 4 seconds to tell them to make the minute up-or-down adjustments to their generating capacity, based on the needs of the grid.

Vehicle-to-grid proponents say this could just as easily be done by drawing electricity from or putting it into storage. "Right now, the power grid has ... virtually very little storage," Letendre said.

Studies show that electric vehicles could be plugged into the grid as much as 20 hours a day on average. If enough of the cars were out there, they would be a ready source of storage.

The second-to-second adjustments are called frequency regulation, and utility regulators pay power generators to provide the service. Typically, the units added to balance the grid must be at least 1 megawatt.

In 2007, the Federal Energy Regulatory Commission issued an order that would allow electric storage facilities to be treated equally to generation.

In Kempton's plan, cars would be aggregated so that their batteries would collectively form 1 megawatt of capacity. Together, they would constitute a frequency generation unit and they would get paid. Letendre estimates that a single electric car owner could earn $2,000 to $4,000 a year by selling power from his car back to the grid.

That would not only benefit electricity consumers, but effectively lower the price of the vehicles to buyers. Experts say the cars' relatively high prices are the largest barrier to their entry into the market.

A longer-term application would be for the cars to provide storage for wind and solar energy, which are intermittent. That would eliminate the need for renewable energy plants to be built with back-up fossil-fuel generators -- but also prevent excess energy during times of high wind or solar availability from being wasted. For example, the wind often blows most strongly at night, when power demands are low.

"It's kind of a way of increasing the amount of renewables we can use, we can tap into," said Jon Lilley, the vehicle-to-grid project coordinator and a graduate student in Kempton's lab.

Last month, Denmark announced a plan to use vehicle-to-grid to help an island of 40,000 people become entirely wind-powered. Kempton was a key adviser on the project.

A stimulus to get the juice flowing

Though interest in V2G has been around for years, few cars have been hooked up. Isolated tests have been done by companies like the large West Coast utility Pacific Gas and Electric and AC Propulsion of San Dimas, Ca., the electric vehicle manufacturer that supplied Kempton's first car.

Now interest is beginning to grow. In Boulder counto, Co., three plug-in hybrids -- converted Toyota Priuses -- will begin sending electricity back to the grid in the fall, under the county's smart grid progrm. Talks of pilot projects are taking place in Maine, Vermont and Rhode Island.

This year, two utility companies in Delaware were the first in the country to authorize vehicle-to-grid.

Kempton, meanwhile, has put in an application for $29 million of federal economic stimulus funding that would be used to fund a demonstration project of 450 vehicles. Much of the money would go toward subsidizing vehicles from AC Propulsion, a company that currently sells cars for $70,000 down to $40,000.

Kempton says this will make a big difference for increasing the volume of the vehicles. Less than 20 have been sold so far.

"I'm quite confident that we can sell 450 at that level," he said.

Those 450 vehicles would be aggregated into frequency regulation units in the mid-Atlantic region, New England and California. In exchange for the subsidy, buyers would be required to participate in the vehicle-to-grid program.

Kempton says the major auto companies have not expressed serious interest in vehicle-to-grid. "It's ridiculous," he said. "These Fortune 500 companies are scared to try this stuff out."

"We think the best way to get this rolling is to ... show them that it works," Kempton says.

Automakers interested but uncertain

Paul Denholm, an expert on the grid and electricity storage at the National Renewable Energy Laboratory, said it's too early to tell just how good a technology vehicle-to-grid is.

"There's a lot of uncertainty about the role of vehicle-to-grid," he said. "You're going to find a lot of people out there that have some legitimate concerns about the difficulties of making a business case for vehicle-to-grid. This is not an easy technology to implement. This is going to take a lot of work for it to get out there."

For example, he said, many auto companies are concerned that increasing the charge and discharge cycles on a battery will shorten its lifetime.

Furthermore, there have to be regulatory changes and, more importantly, a computerized system for coordinating the communication between the cars and the grid.

Then there's the fact that electric vehicles are not even on the mass market yet.

Tony Posawatz, vehicle line director for General Motors Corp.'s Chevrolet Volt, agrees that vehicle-to-grid is a far cry from commercialization. But he says that GM is interested.

A year and half ago, GM began partnering with EPRI and 50 utility companies around the country to start researching questions surrounding putting cars onto the grid. Ford Motor Co. and Daimler AG have similar, if smaller collaborations. Chhaya -- who previously worked on hybrid and plug-in-hybrid vehicles for 10 years at GM -- would not give the names of other companies EPRI has spoken to. But, he said, all major companies "that we have spoken with have shown interest."

Posawatz said that GM's first priority is to get the cars on the market and to test the integrity of the battery, which it wants to have a 10-year lifetime.

"Once you have these vehicles in the marketplace for other reasons, if they can stand on their own, then it makes sense to have this additional application," Chhaya said.

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