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Drive like the wind

November 2011

PNNL report finds electric vehicles and smart charging can help integrate renewable energy

Results:  


A new PNNL report finds that the Northwest Power system would be able to balance 10 Gigawatts of additional windpower if 2.1 million vehicles, or 13% of the Northwest’s fleet, were electric.

In a new report, researchers at Pacific Northwest National Laboratory show how electric vehicles could help operators more seamlessly add more renewable energy sources like wind into the Pacific Northwest's energy grid. The report finds that the Northwest power system would be able to balance 10 gigawatts of additional wind power if 2.1 million vehicles, or 13% of the Northwest's fleet, were electric. The study also finds consumers would need to have the ability to charge their vehicles during the day, and a small percentage of charging stations would need to be available publicly or at the workplace.

Why it matters: 

The Northwest increasingly is looking to add more wind power to meet growing energy demands and policy requirements to tap more renewable energy sources. In particular, the PNNL report examined the implications of adding another 10 gigawatts of wind to the region's grid by 2019, which regulations such as Washington state's Renewable Portfolio Standards require. "Electric vehicles, coupled with grid-friendly charging, offer a great opportunity right now to help electric companies integrate additional wind power into our electric system," said Michael Kintner-Meyer, PNNL staff scientist and study co-author.

Methods:

The report examined grid conditions in the Northwest Power Pool, which covers Idaho, Montana, Nevada, Oregon, Utah, Washington and Wyoming, many of them home to abundant wind resources and wind energy projects. Although wind power is an increasingly popular source of renewable energy, it is unpredictable and not always available when the grid needs it. On windy days, grid operators have to find a way to use the excess energy or store it. But today, the U.S. grid has very limited storage capabilities.

Many people think of electric vehicles as electricity consumers. But the PNNL researchers say a partially charged vehicle sitting at work or at home represents a potential asset for grid operators; a vehicle's ability to start and stop charging to adjust for varying wind power could serve as a shock absorber on the grid. To explore the feasibility of using electric vehicles to balance wind power, the researchers looked at the driving habits of about 37,000 people - when they were at home, at work or in transit.

The researchers also estimated the ratio of public-to-residential charging stations needed to fully absorb the additional variability from wind power. Based upon existing transportation and driving data, the PNNL team determined only about one of every 10 new charging stations will need to be available to the public or located at the workplace to offer the majority of balancing services to the grid 24/7 if Grid Friendly charging technology is used. Rather than charging a vehicle at a constant rate, Grid Friendly technology can recognize grid conditions and constantly vary the rate at which the battery is charged, based upon a variety of factors, including how much electricity is being generated at any given time. In doing so, the fluctuations in electricity produced by wind farms could be absorbed by a fleet of vehicles starting or stopping their charging cycle, rather than requiring new power plants to provide that balancing service.

What's next:

Researchers at PNNL have developed the Smart Charger Controller, a charging device that uses Grid Friendly technology to automatically recharge electric vehicles during times of least cost to the consumer and lower demand for power. PNNL is a Department of Energy Office of Science national laboratory and has been managed by Ohio-based Battelle since the lab's inception in 1965. Battelle is currently discussing licensing the Smart Charger Controller with charging station manufacturers. PNNL researchers are also actively working on demonstrating the technology in two West Coast electric-vehicle fleets. 

Acknowledgements:

This research was funded by the U.S. Department of Energy. 

References:

Tuffner, F and M Kintner-Meyer. 2011. Using Electric Vehicles to Meet Balancing Requirements Associated with Wind Power. Report prepared for the U.S. Department of Energy.

For more information, see PNNL's news release. The entire report can be read here.


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