Electric Vehicles and the Power Grid
By Daniel Potash, Class of 2001
Readers of World-Generation may have been wondering about how much, and when, electric vehicles will impact the power grid. Wonder no more. I attended Plug-In 2008, held in San Jose, California, July 22-24, 2008. All my questions about electric cars were answered, but now I have another question: Why are utilities not more enthusiastic about electric vehicles?
In this article, I will review the status of electric vehicles, and consider the implications for the electric power industry, especially considering opportunities for wind and solar power project developers.
A pure electric vehicle (EV) has a large battery and electric motor, with no combustion on-board. An EV plugs into the grid to charge up. A Plug-in Hybrid Electric Vehicle (PHEV), in addition to a medium to large battery and electric motor, has a gasoline engine.
A Hybrid Vehicle (HV, or HEV for Hybrid Electric Vehicle) is not a plug- in. HV’s have a relatively small battery, and they get charged from conventional gas engine combustion. An HV hybrid has a relatively small battery and does not plug in. The 2008 Prius is an HV with a battery weighing about 110 pounds, and has a range of about 2 miles on electricity alone.
By contrast, GM’s planned Chevy Volt, a Plug-in Hybrid Electric Vehicle (PHEV) will have a 400 pound battery, a range of about 40 miles, and will require 8 kWh to charge up.
You will see battery size quoted variously in terms of kWh and kW, where kW is the instantaneous energy available, and kWh is the capacity to do work.
PHEV and EV Current State of Play
Plug-in’s are not now generally available, and not expected to be generally available until 2010. All-electric vehicles that are now generally available are “neighborhood cars,” with a range of 25-30 miles and top speed of 25 miles per hour. Cars for full use, including highway, are on their way. There are at least 30 “green car” start-ups according to VentureBeat magazine, including some fabulous vehicles. The cars are to die for, but as far as grid impact, it’s not even line noise.
Though PHEV’s or EV’s are not now generally available from manufacturers, there is an interesting grey market of conversion shops and conversion kits. The shops and do-it-yourself kits take a conventional hybrid like a Prius, and add a heftier battery. This gives a boost in electric mileage from about 2 miles to as much as 30 miles. One company claims that their 5 kWh battery will provide 31 miles of range.
To put EV’s and PHEV’s in perspective, I made a survey (see table) indicating that in the next 2-4 years, electric vehicles will comprise only a small percentage of the market.
The top 20 vehicle-makers produced 65 million vehicles worldwide in 2007. GM will start production of its Volt at 20,000 vehicles. Toyota has only recently changed course to address the PHEV market. Mitsubishi appears serious with its iMiEV PHEV, but no production figures are cited. Naturally, manufacturers avoid production forecasts with hard deadlines and GM should be lauded for its time-bound commitment to production volumes for the Volt. My survey shows the amazing high volume of conventional vehicle production and the relative paucity of electric vehicle planned production. Electric vehicles will take a long time to make a meaningful impact via vehicle replacement.
The slow pace of vehicle replacement was addressed at Plug-in 2008 by Andy Grove in his keynote address. He said we should use conversion kits so that, within the next four years, 10 million existing vehicles would be retrofitted to plug-in hybrid. The next day’s keynoter, Andy Frank, University of California, Davis, demonstrated with examples going back 15 years that this type of retrofitting is eminently possible.
No Problem for the Grid
Even assuming an optimistic and aggressive scenario for electric vehicle adoption, the demands on the power grid should be minimal.
Based on the announced 20,000 production level for the Volt and the Mégane, and hints from Mitsubishi about the iMiev, and based on recent scurrying to change tune about electric vehicles (Nissan, Toyota), I guesstimate that 50,000 electric vehicles might be sold in the U.S. in 2010.
Another frame for issue may be gleaned from recent actions of the California Air Resources Board. In March 2008, the ARB issued new rules for “Zero Emissions Vehicles.” ARB requires manufacturers to sell 58,000 clean cars in California in 2012–14, which is out of 1.4 million total cars estimated to be sold. That 3% market penetration rate is consistent with my analysis indicating about 120,000 electric vehicles may be sold in the U.S. in that 2012-14 time frame.
I predict that 1,000 MW for charging vehicles will be required in the entire U.S. by 2017. That is a modest amount of power. The U.S. power grid now has capacity of more than 1,000 GW, according to the DOE’s Energy Information Agency. Last year in the U.S. we added about 15,000 MW of capacity to the grid, of which 5,244 was wind and 227 was solar. Adding 1,000 MW for electric vehicles, by 2017, should be easy, and it could come entirely from renewable energy.
Those interested in more detail about the grid’s capacity to serve the PHEV market may refer to a recent report entitled “Environmental Assessment of Plug-In Hybrid Electric Vehicles.” It was produced jointly by the Electric Power Research Institute and the Natural Resources Defense Council, and is available at www.epri-reports.org.
A significant benefit of PHEV’s and EV’s could come from using off-peak generation. Utility representatives at Plug-In 2008 expressed significant concern about stress on the grid from unpredictable time and place of charging. Existing market forces would seem to favor off-peak charging. I evaluated hourly data for traffic in and out of Manhattan, across the George Washington Bridge, the Holland Tunnel and the Lincoln Tunnel, and plotted that versus aggregate electric power demand in Manhattan. Overall, there is a 76% correlation between traffic and power demand, suggesting that drivers will naturally charge vehicles during off-peak time periods.
Many presenters at the Plug-in 2008 conference debated about the carbon footprint of electric vehicles, using a comprehensive “well to wheels” analysis. Most researchers concluded that electric vehicles were cleaner than gas-powered vehicles, even if they were charged with electricity from a coal-fired power plant.
Christopher Yang (Institute of Transportation Studies, University of California, Davis) presented analysis showing that an ordinary gasoline-powered car has a “Vehicle Carbon Intensity” of 400 grams of CO2 per mile. By comparison, Yang asserts that a PHEV charged by coal power has a Vehicle Carbon Intensity of 356 grams of CO2 per mile. I find that to be a striking statistic, and I am perplexed that coal-fired utilities are not more aggressive in supporting electric cars.
Besides the carbon footprint, there were quite a few analyses presented about using off-peak power. This would seem to argue in favor of maintaining base load resources like coal and nuclear. The nuclear industry hasn’t yet rallied around electric cars as a cause célèbre.
Utilities may be missing a big marketing opportunity. Electric car customers would probably be thrilled to charge up in the middle of the night from dedicated renewable resources.