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Clean Power Some EVs can signifiantly outperform EPA mileage ratings

Published on January 28th, 2014 | by Silvio Marcacci

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Controlled EV Charging Cuts Power Costs 50% (Even More With Wind Energy)

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January 28th, 2014 by  

Two truths are clear about electric vehicles today: Charging them is cheaper than filling up with gasoline, and they hold immense potential to boost renewable energy integration by serving grid operators as countless energy storage units. So what if those benefits were combined? 

The answer, say researchers at Carnegie Mellon University, is at least a 50% reduction in EV charging costs – and an even higher cost reduction in areas with high levels of wind energy capacity.

According to the study of various EV charging scenarios modeled across New York State’s regional grid, controlled EV charging by grid operators holds the key to unlocking the combination of lower power prices, higher wind energy integration, and more emission-free vehicles on the road.

EV charging image via CleanTechnica

EV charging image via CleanTechnica

Misplaced Fears Of EV Charging Spiking Power Costs?

It stands to reason as more EVs plug into the grid, grid operators will have to dispatch more generation to keep all those Leafs and Teslas juiced up. “If owners regularly plug in these electric vehicles when they get home from work, this would add to greater demand when the most expensive power plants are running,” said Allison Weis of CMU.

Even though the number of EVs on American roads (and their associated power demands) may still be relatively low, their numbers grow exponentially larger every year, giving grid operators one more factor to fret about for long-term capacity planning and reliability forecasts.

Not necessarily so, found the CMU researchers. “Controlled charging can shift loads later in the night when cheaper power plants are again available,” said Paulina Jaramillo of CMU. In this case, controlled charging means shifting generation to cheaper plants and off-peak hours, and can run from full to partial charging speeds.

Controlled Charging + Wind Energy = Big Savings

If grid operators have the ability to control when and how fast EVs are charging across the grid, the CMU researchers reported power generation costs would be reduced $65-110 million per year compared to uncontrolled charging.

That’s roughly 1.5-2.3% of total modeled system costs, between 54%-73% the cost of integrating plug-in hybrid electric vehicles, and roughly $100 annually per vehicle when EV penetration reaches 10%. Variations in overall costs resulted in different capacity scenarios, where more or less generation was available for use.

However, regardless of power generation capacity scenarios, EV charging costs fall even further when large amounts of wind energy are present on the grid. In fact, when wind penetration reaches 20%, controlled charging creates an additional 6-13% in cost reductions.

That level of wind penetration isn’t typically sustained on U.S. grids, but it has absolutely been reached with growing frequency on regional grid systems in Texas and the Midwest – meaning the CMU results could already be manifesting themselves if proper vehicle-to-grid controls were in place.

Even better, the CMU research underlines the value EVs can have on maximizing renewable energy when it’s available. “Controlled charging could also help manage fluctuations from renewable energy sources like wind and solar power,” said Jaramillo.

Wind turbine & EV in field via Shutterstock.

Wind turbine & EV in field via Shutterstock.

Accelerating Toward A Smarter, Cleaner, Cheaper Future

While the researchers noted additional studies were needed to fully understand the total cost and emissions implications of EV charging, the CMU study is yet another example of how important EVs are to our clean energy future and adds to research showing the the grid can handle EV integration without crashing.

Considering NREL’s recent report that wind energy could increase grid reliability, the link between smart grids, clean cars, and renewable electricity just keeps getting clearer and clearer.

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About the Author

Silvio is Principal at Marcacci Communications, a full-service clean energy and climate-focused public relations company based in Washington, D.C.



  • Will E

    what about solar panels on the garage and fill up with your own electricity.
    use the car as mobile storage battery for your solar electricity.
    clean, easy, cheap, add your solar with grid wind turbines and it adds up to
    beyond expectations. energy is for free, just take it from sun and wind.
    why people still discuss this?—– and want to dig for coal and want to pump oil to burn it. buy and burn economy crisis.
    It is all in the air, everywhere for free. just catch it.
    using TESLA car as free storage for renewables.

    • Gary Richardson

      You go to work during the day, you will need storage to transfer that to your EV when you get home. Though you will probably get some mid afternoon solar if you are home soon enough. The other issue is powering your AC 30 minutes before getting home and until the weather cools. Hopefully there will be enough wind power for evening and early morning gusts to fill remaining charging needs.

  • Jouni Valkonen

    It is very bad and unpopular idea to let grid operators to decide when charging. It is not even in their monetary interests, because intelligent EV charging will reduce their profits. Instead e.g. Tesla can do intelligent charging without consent of the grid operators and although not to profit from the deal, at least they can do harm for the grid operators business models! Here I outlined a simple method how Tesla owners can intelligently charge their cars without compromising battery longevity:

    Using Tesla car as free storage for renewables
    http://www.teslamotorsclub.com/showthread.php/25158-Using-Tesla-car-as-free-storage-for-renewables-%97-feature-suggestion

    • Bob_Wallace

      Grid operators make money by selling electricity. EV charging will be a new profit base.

      EVs will be an asset aside from the market value. Having a lot of demand that can be controlled will make it much easier for the grid to operate. As we move into higher range EVs it will be possible for many EVs to skip one or more nights of charging. The grid will have a great place to dump (sell) surplus generation and the ability to avoid having to purchase expensive peaking power when supply is short.

  • JamesWimberley

    It’s a truly terrible idea to let utilities start controlling what householders switch on and off. Big Brother! Instead they should (a) create tariff structures that give an incentive to householders to switch appliances, including EV chargers, on and off according to the cost and carbon intensity of the marginal grid generator, (b) provide them with appropriate information on system cost and carbon intensity. It can all be brought together by a domotic home controller on the householder’s side of the meter – a slave of the householder, not the utility.

    • RobS

      If participating in Demand response was compulsory then I would totally agree with you, however as long as it remains voluntary and you simply offer households the opportunity to receive discounted tariffs if they give control over certain loads like EV charging and hot water heating to utilities then I see nothing Big Brother about it as it simply offers consumers an option.

    • Sean

      ha! big brother indeed.
      the joke is that these are two sides of the same coin, no consumer is going to give up convenience without financial benefit.

      modify your plan such that everyone is on a market based system, demand high? Price high, demand low? price low, with pricing information made available to a computer at the customer’s house, which they can set price triggers to activate different appliances.

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