Power Electronics

Studies Examine How Plug-In Hybrids Will Affect Power Grid

As plug-in hybrid electric vehicles (PHEVs) move toward commercialization, utilities, research institutions, and other organizations are attempting to analyze the possible impact that these new, high-power loads could have on the electric grid in the future. One example is a recent study conducted by Oak Ridge National Laboratory, which found that recharging habits on the part of vehicle owners will determine whether PHEVs demand additional power generating resources. That study aims to look into the future, making projections for 2020 and 2030 when PHEVs are expected to achieve significant market share.

Meanwhile, a recently announced partnership between the Electric Power Research Institute (EPRI) and Ford Motor Company aims to develop and evaluate technical approaches for integrating PHEVs into the nation’s electrical grid system. This study will gather data using actual vehicles—Ford Escape PHEVs. In addition, one governmental organization, the Michigan Public Service Commission (MPSC), has announced a pilot program designed to integrate PHEVs into Michigan's electric grid, as part of the MPSC's ongoing smart grid collaborative.

Released last month, the Oak Ridge National Laboratory (ORNL) study examined how an expected increase in ownership of hybrid electric cars and trucks will affect the power grid depending on what time of day or night the vehicles are charged. The study concluded that a growing number of plug-in hybrid electric cars and trucks could require major new power generation resources or none at all— depending on when people recharge their automobiles. Some assessments of the impact of electric vehicles assume owners will charge them only at night, says Stan Hadley of ORNL's Cooling, Heating and Power Technologies Program.

"That assumption doesn't necessarily take into account human nature," says Hadley, who led the study. "Consumers' inclination will be to plug in when convenient, rather than when utilities would prefer. Utilities will need to create incentives to encourage people to wait. There are also technologies such as 'smart' chargers that know the price of power, the demands on the system and the time when the car will be needed next to optimize charging for both the owner and the utility that can help too."

In an analysis of the potential impacts of plug-in hybrid electric vehicles projected for 2020 and 2030 in 13 regions of the United States, ORNL researchers explored their potential effect on electricity demand, supply, infrastructure, prices and associated emission levels. Electricity requirements for hybrids used a projection of 25 percent market penetration of hybrid vehicles by 2020 including a mixture of sedans and sport utility vehicles. Several scenarios were run for each region for the years 2020 and 2030 and the times of 5 p.m. or 10:00 p.m., in addition to other variables.

The report found that the need for added generation would be most critical by 2030, when hybrids are expected to have been on the market for some time and become a larger percentage of the automobiles Americans drive. In the worst-case scenario—if all hybrid owners charged their vehicles at 5 p.m., at six kilowatts of power—up to 160 large power plants would be needed nationwide to supply the extra electricity, and the demand would reduce the reserve power margins for a particular region's system.

The best-case scenario occurs when vehicles are plugged in after 10 p.m., when the electric load on the system is at a minimum and the wholesale price for energy is least expensive. Depending on the power demand per household, charging vehicles after 10 p.m. would require, at lower demand levels, no additional power generation or, in higher-demand projections, just eight additional power plants nationwide.

To read the full study, see www.ornl.gov/info/ornlreview/v41_1_08/article21_web_only.shtml.

Paving the Way For PHEVs

The Electric Power Research Institute (EPRI) and Ford Motor Company have announced a three-year agreement to develop and evaluate technical approaches for integrating plug-in hybrid electric vehicles (PHEVs) into the nation’s electrical grid system, a key requirement to facilitate widespread adoption of the vehicles.

EPRI will form a collaborative of utilities in the New York-New Jersey area that will test Ford Escape PHEVs. Subsequent trials will be conducted with customers of the participating utilities.

Ford, which is also working with Southern California Edison (SCE), is said to be the first automotive manufacturer to partner with the utility industry to facilitate advancing PHEVs. The EPRI-Ford program will build on the ongoing Ford-SCE partnership and help determine regional differences in how the operation of PHEVs will impact the grid.

“This partnership represents a concerted effort by the transportation and electric sectors to work together in advancing PHEV technology,” said Mark Duvall, EPRI’s program manager for Electric Transportation. “This effort should accelerate the pace of PHEV development while enabling the utility industry to prepare for the introduction of these vehicles.”

Ford has designed and is building 20 Escape PHEVs for testing in the Los Angeles area under the Ford-SCE partnership. With this new EPRI-Ford agreement, Ford is able to expand the evaluation and demonstration program to include other utilities.

“PHEVs have great promise, but still face significant obstacles to commercialization, including battery costs and charging strategies,” says Nancy Gioia, director of Sustainable Mobility Technologies at Ford. “ Ultimately such vehicles must provide real value to consumers.”

EPRI, Ford and SCE’s research and analysis on the Ford PHEVs will include data from four primary areas: battery technology, vehicle systems, customer usage, and grid infrastructure. The analysis will also explore possible stationary and secondary usages for advanced batteries.

Another effort in this area is a pilot program initiated in March by the Michigan Public Service Commission (MPSC). Its program is designed to integrate PHEVs into Michigan's electric grid, positioning the state to become a leader in this technology. The pilot program will be part of the MPSC's ongoing smart grid collaborative.

"As the automotive leader of the world, Michigan is uniquely equipped to lead the effort to integrate plug-in hybrid vehicles into its electric grid," said MPSC Chairman Orjiakor Isiogu, a member of the Smart Grid Collaborative effort between the Federal Energy Regulatory Commission (FERC) and the National Association of Regulatory Utility Commissioners (NARUC). "The widespread adoption of PHEVs has the potential to significantly reduce gasoline consumption, while reducing the overall greenhouse gas emissions produced in the state.

"The success of plug-in hybrid vehicles is dependent on the deployment of intelligent grid technology. So, this represents a unique opportunity for Michigan's electric utilities to expand sales, without contributing to system peak, while simultaneously reducing the overall level of greenhouse gas emissions from the transportation and utility sectors.

PHEV technology also has the potential to provide peak load power during high demand periods, if a utility's electric distribution system provides vehicle-to-grid (V2G) capability through smart grid technologies.

The Commission notes that achieving a high penetration of PHEVs that retains the stability of the electric grid is dependent on smart grid infrastructure research and development. Therefore, the MPSC is requiring all regulated electric distribution companies to participate in the smart grid collaborative, expanded by the MPSC's order to include PHEV pilot projects.

The MPSC encourages other interested parties to participate as well.For more on this program, see http://michigan.gov/mpsc/0,1607,7-159--187335--,00.html.

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