Electric cars as power buffer

The electrification of transportation demands an upgrade of the current power infrastructure. With innovative smart grid technology, vehicles will no longer just demand but also supply energy.

Artist’s impression of Danish wind demo project. (Illustration: IBM)

“Electricity is the new car fuel, it’s the future,” said Willet Kempton, a professor of Earth, Ocean, and Environment studies at the University of Delaware, while speaking at the annual AAAS (American Association for the Advancement of Science) conference in San Diego. The policy drivers behind electric vehicles are that they diminish dependence on foreign oil and reduce greenhouse gas emissions by using renewable energy sources. President Barack Obama is therefore aiming to have 1 million plug-in hybrid electric vehicles on US roads by 2015.

The problem however is that current power plants are inefficient and slow to respond to frequency regulations, or the differences in the amounts of energy supply and demand, which must now be carefully balanced. Because wind energy is highly unpredictable and the electric grid itself has no storage capacity, there is need for a smarter, more reliable infrastructure.
US researchers strongly believe that vehicle-to-grid technology (V2G) is the answer. Professor Kempton developed V2G, which refers to a two-way flow of electricity and communication between electric vehicles and the electric grid. Instead of merely distributing energy to electric cars, the cars’ batteries can also be used as a source of energy. Electric cars will thus be able to store energy and to return power to the grid.

The rationale behind this innovative idea is this: on average, cars in the United States are only used for one hour each day, and the average distance travelled daily is 60 kilometres. Hence, most storage of electricity remains unused. This means a parked car can be used as a power source for 23 hours, which is the time it will be plugged into the grid. In this way, car drivers would also profit when their cars are parked.

Because the travel behaviour of electric car drivers can be forecasted, the smart grid ‘knows’ the power demand required over the course of the day. Moreover, unpredicted peaks in demand can also be dealt with thanks to the car-based storage capacity. V2G cars will nevertheless not be fully unloaded by the smart grid. According to the researchers, 10 to 20 kW is a reasonable range of power that a car could deliver to a grid.

The theoretical potential of V2G was first studied in 1997. In 2008, researchers first hooked up an all-electric vehicle to the real grid. In order to start serving markets for peak power and storage of renewable electric generation, huge challenges must still be overcome. First, US car companies do not yet produce vehicles with V2G capability. Second, new regulations and policies are needed; for example, such as a new net energy metering system and laws for returning energy to the net.

The University of Delaware has just signed the first license for V2G technology with AutoPort. This major vehicle processing facility will produce the first 100 V2G cars as a proof-of-concept demonstration of the technology this year. After that, business models for electric vehicle interaction with the grid must be established. Promising test beds for V2G are areas with lots of wind energy, such as the Netherlands, Denmark, Texas and California.

In Europe, the Danish island of Bornholm is about to host the first demo project of electric cars powered by wind. The project is called Edison (Electric Vehicles in a Distributed and Integrated market using Sustainable energy and Open Networks) and will start with only 15 vehicles, as a model for the 200,000 electric cars targeted for Denmark by 2020. The project will intelligently use wind power to charge car batteries. Researchers will use simulations and historical data to determine the best way to match supply and demand. IBM and Siemens have joined Dong Energy in the project, as well as the Technical University of Denmark. 

www.ceoe.udel.edu/people/profile.aspx?willett

www.edison-net.dk