How electric vehicles that feed the grid will pay off

Compass

Just like the two-way street, car innovators are focusing more than ever on the two-way plug that could revolutionize cars’ relationship with the grid. The idea is to give plug-in cars the ability to feed energy back into the grid when parked. And part of the vision includes small payments to people whose vehicles become energy providers when the grid is in need of balancing during peak hours. This innovation will be particularly useful for backing up energy sources like wind and solar that can vary by time of day or weather.

Using 15 plug-in Mini E’s donated by BMW, the idea is being explored by Professor Willett Kepton of the University of Delaware. These days cars sit idle and unused for a large majority of their lives. Creating back-and-forth capabilities with the grid – and the home – would sharply increase the car’s efficiency and role in our lives while challenging the traditional energy provider and consumer relationship.

Dubbed the “cashback car,” the consumer-friendly technology could make EVs even more appealing to people who are tired of burning funds at the gas pump. As Autoblog Green explains:

Kempton estimates that in the high-value grid markets, an EV at a charging point with the capability to charge or discharge at 10kW can generate $2,000 or more each year. It’s a very appealing proposition to go on vacation while leaving your car at home in the garage generating a paycheck for when you return. And, over a typical 5-10 year ownership period, it’s enough to pay for the cost of the battery and still provide you the benefit of EV motoring at its spectacular two- to three-cents-per-mile operating cost.

In this world, the rules of car ownership change dramatically. Drivers can quit oil, provide clean energy to the grid, and get paid for it.

This article was originally published on the Union of Concerned Scientists’ Compass blog. Reproduced with permission

Comments

8 responses to “How electric vehicles that feed the grid will pay off”

  1. Bob_Wallace Avatar
    Bob_Wallace

    This idea has been around for a while and there is at least one project giving it a test.

    I doubt this is the route we’ll go for grid power. EV batteries are likely to be much more expensive than grid storage batteries since the have to be smaller and lighter per unit electricity stored. Right now the ‘most optimistic’ prices I’m hearing for the LEAF batteries is $300/kW. Eos is advertising a zinc-air grid storage battery for $160/kW. If Ambri’s liquid metal battery scales up then grid storage is going to be very cheap.

    The important role for EVs is as dispatchable load. EVs will need, on average 1.5 hours per night charging. Once the grid is smart enough grid operators can charge a whole bunch at once when demand for other uses drops well under supply (the wind starts blowing hard late at night) or can spread them out over many hours to lower overall demand. People who drive less than average can soak up a lot of power some nights and not charge at all on others.

    EVs are likely to make wind more profitable as they will provide new markets for off-peak production. That will bring more investment in wind turbines and increase the amount of wind available during peak hours.

  2. Miles Harding Avatar
    Miles Harding

    There are a few problems with this concept:

    a) The trend with EVs is more likely to be to smaller, cheaper and lighter batteries as the motoring press ‘rage anxiety’ invention disappears. There will be limited energy on-board.

    b) The marginal energy storage cost on batteries (cost per kwh stored) is currently about 20 cents, so a charge to discharge differential of more than this would be needed for this to make sense. The differential in Australia is currently about minus 20 cents, so no point here.

    c) vehicle batteries are necessarily high performance and low weight, so the likelihood of them becoming as cheap as some projections indicate is low. Also, there are very few EVs on the roads, so no materials shortages haven’t been experienced.

    For these reasons, I agree with Bob_Wallace, below.

    Stationary batteries are the most likely candidate for grid buffering and have the advantage of always being at home and plugged in. There are many more options when weight and size are removed from the battery requirements.

    In a recent conversation, I was describing water based storage for time shifting an air conditioner to off-peak. My associate suggested using a battery to achieve the same in a normal mass market air conditioner.

    1. Bob_Wallace Avatar
      Bob_Wallace

      I don’t agree that EV batteries are likely to decrease in range across the board.

      I can see the possibility of a bifurcation into sub 50 mile EVs which are designed for ‘second car’ commuting and ‘first car’ EVs moving to the 200 mile range.

      A small, inexpensive ‘zip to work’ EV could be very popular. It should be capable of driving at highway speeds and be safe in collisions (doable).

      A 200 mile range with <20 minute recharging gives one a 'drive all day' capability. If/when EVs drop in price to ICEV levels I think most people are going to pay for the long drive potential.

      Water is likely to stay cheaper than battery chemistry. Insulated containers are cheap to build. And you can store a lot of energy in a small space. I would think that heating and cooling done with a heat pump using water/salts storage would be a good solution for many.

      Use cheaper off-peak electricity to store 'cold' for peak hour use.

      If you live somewhere that has hot days and cooler nights then cooling down a storage vat would be efficient. Much easier to dump heat into cool air.

      In some situations it would pay to use solar water heater panels during the day to heat up the storage vat and then use that stored heat to assist nighttime space heating.

      This is already being done in commercial buildings. I don't know if it is being installed in residences.

      1. Miles Harding Avatar
        Miles Harding

        Curtin University has a very large cold store tank (>>100KL). I started out considering water buffering to be a good air conditioning solution, but water-based systems are almost totally unavailable in typical domestic sizes.
        Batteries are flexible, so the same battery can potentially be used for lighting, cooking, even fast charging an EV. Once these other uses are considered, the occasional air conditioning use (good design and thermal mass minimises the need for it) makes a water-heat storage system less attractive.

        I currently drive an EV with a 120km range (Mitsubishi i-Miev) and have found it to be very good in the urban environment. Apart from road trips, the Holden ICE rarely gets used.
        I have an associate who commutes 80km each way in the same model EV, although he requires a charge at work to get home. He chose the I-Miev over the Nissan Leaf (the other EV on the market) because the range is adequate and battery is smaller** and more compatible with work-based as well as solar and wind charging on his property.

        **A fairly linear relationship exists between per-km energy use and vehicle weight.

        1. Bob_Wallace Avatar
          Bob_Wallace

          We’re talking long term solution, I believe. There may not be a residential sized water-exchange heat pumps on the market now but that doesn’t meant there won’t be.

          Actually there may be. There are small water-exchange heat pumps being used in geothermal heating/cooling.

          Geothermal heat pumps are a third solution that needs to be considered. It’s not clear that energy storage for space heating/cooling will yield a one size fits all solution.

          There aren’t any battery systems which are affordable at US grid prices. In a few places such as Australia or Germany batteries may be affordable. The cheapest lead-acid storage options add about $0.20/kWh to the price of electricity.

          EV batteries are likely to become smaller. And they almost certainly will become cheaper.

    2. Ronald Brak Avatar
      Ronald Brak

      The wholesale price of electricity is currently expected to be over $12 a kilowatt-hour tomorrow evening in South Australia. At the moment it’s zero. I think that’s an arbitage opportunity that would more than compensate for any wear on tear on a battery pack.

  3. James Hilden-Minton Avatar

    In ten years, there will be a lot of retired EV batteries piling up. They’ll have a lot of life left in them, but will not be as attractive for use in their original car as a newer replacement. I think we need to develop secondary markets for these batteries. Paving the way for these markets now would improve the economics of EV ownership and encourage quicker adoption. Your EV battery needs a retirement plan today.

  4. Nat Treadway Avatar
    Nat Treadway

    There is a confusion, at times, between the value of the electric commodity (usually stated in cents per kWh), and the value of ancillary services that are a necessary part of grid operations. (The article refers to “balancing power.”) Car batteries can provide very small amounts of power at critical moments. It’s the timing and point-of-delivery that matter. These have relatively little to do with average commodity price.

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