Maximizing the Benefits of Plug-in Electric Vehicles

Maximizing the Benefits of Plug-in Electric Vehicles

Advancing electric vehicle charging options and grid readiness reduces oil consumption and vehicle emissions.

A photo of two electric vehicles in a research facility. Enlarge image

Electric vehicle charging stations in NREL's parking garage.
Photo by Dennis Schroder, NREL

Plug-in electric vehicles (PEVs)—including all-electric vehicles and plug-in hybrid electric vehicles—offer the opportunity to reduce oil consumption and vehicle emissions by drawing on power from the utility grid. When the grid uses electricity generated from clean, domestic energy sources, the emerging PEV infrastructure will increasingly maximize petroleum displacement and pollution abatement.

NREL researchers are studying the interactions between PEVs, utility grids, and renewables such as solar and wind. They are also developing strategies and models to further develop electric transportation systems as well as expand generation of renewable energy. To accomplish this work, the lab is collaborating with automakers, charging station manufacturers, utilities, and fleet operators. Together, they are assessing charging communication and control technologies that can help balance PEV power demands with utility portfolio management.

Is the Utility Grid Ready for an Influx of Plug-In Vehicles?

"In most of the scenarios we've explored, electricity distribution transformers have enough excess capacity to charge PEVs," said NREL Engineer Michael Kuss. "Only in extreme cases does vehicle charging have a negative, long-term impact on transformers. In fact, most usage scenarios show that PEVs may actually benefit the utility grid."

A photo of plug-in electric vehicles plugged into charging stations in a parking garage. Enlarge image

PEV charging at NREL's Vehicle Testing and Integration Facility.
Photo by Dennis Schroeder, NREL

An NREL-developed simulation tool, designed to support the Hawaii Clean Energy Initiative, helps utilities in the state evaluate whether its distribution transformers are PEV-ready. NREL analysts combined a wealth of vehicle performance statistics with load data from partner utilities such as the Hawaiian Electric Company and Xcel Energy. The analysts then studied the impact vehicle charging had on the thermal loading characteristics of distribution transformers. After running millions of simulations replicating varying climates and conditions, the simulation tool can predict aging rates for transformers when PEVs are added to existing building loads.

This tool also demonstrates synergies between PEVs and distributed renewables. One example of this is that by supplying loads at the point of consumption, the vehicles get the clean, renewable energy they require while demand on the distribution infrastructure is reduced.

More than a Place to Park—an Example of Localized Energy Production

NREL's state-of-the-art parking garage contains one of the nation's largest PEV charging station installations. This garage is a working example of how electric vehicles and solar power can work together to displace petroleum, improve air quality, and localize energy production. Its photovoltaic system produces more than enough electricity for its 36 PEV charging stations and also meets the structure's other energy needs, while the excess electricity is fed to the utility grid.

Learn more about NREL's vehicles and fuels research.

—Julia Thomas

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