No, Electric Vehicles Won't Bring Down the U.S. Power Grid

Follow John

Power lines by Flickr user achouro

Power lines by Flickr user achouro

Enlarge Photo

Last week's heat wave prompted another eruption of that perennial question: Won't electric cars that recharge from grid power overload the nation's electricity system?

Or put more bluntly: Will electric vehicles bring down the U.S. power grid?

The answer, equally bluntly, is: No. They won't.

(And we rather wish that certain news organizations--we're talkin' to you, The New York Times--could add a bit more perspective before writing about the topic in the predictable maybe-yes-but-maybe-no format.)

Study by unlikely partners

A comprehensive and wide-ranging two-volume study from 2007, Environmental Assessment of Plug-In Hybrid Vehicles, looked at the impact of plug-in vehicles on the U.S. electrical grid. It also analyzed the "wells-to-wheels" carbon emissions of plug-ins versus gasoline cars.

The study is well regarded, in part because of its authors. It was a joint effort by two somewhat unlikely partners: the Electric Power Research Institute (EPRI), which is the utility industry's research arm, and the Natural Resources Defense Council (NRDC).

It looks at the consequences of drivers charging plug-in vehicles at different times during the day. And it assumes a gradual rollout of electric vehicles into the current U.S. fleet of 300 million vehicles. GM, for example, will only sell 10,000 Chevy Volts during all of 2011.

1 EV = 4 plasma TVs

In practice, this means electric cars will only impose marginal increases on the electric grid. The load of one plug-in recharging (about 2 kilowatts) is roughly the same as that of four or five plasma television sets. Plasma TVs hardly brought worries about grid crashes.

Auto analyst J.D. Power projects that by 2015, global production of plug-in electric vehicles--for all markets, not just the U.S.--will total 500,000 per year, half in China. If they all charged at the same time, that's no more than the load of 2 million plasma TV sets, globally.

Even if the U.S. alone has half a million plug-ins to recharge (out of 300 million vehicles on the road, remember) within a few years, utility executives aren't losing any sleep. In fact, they're happy. They love the idea of selling you "fuel" for your vehicle.

Off-peak charging incentives

They will, however, offer strong incentives to get you to charge overnight, when demand on their generating capacity plummets. They have tons of unused power capacity then, and they'd like nothing better than to sell you some of that power, even at special cheap rates.

Even before "smart grid" applications arrive, owners will be able to direct their electric cars when to recharge. The driver of a 2011 Volt, for example, can plug it in as soon as she returns from work, but set the car to charge only when cheaper nighttime rates kick in--after 11 pm, say.

Knowing all this, the EPRI-NRDC study concluded--not surprisingly--that plug-in vehicles won’t strain the grid. Two earlier, more limited studies from the Pacific Northwest National Laboratory and Oak Ridge National Laboratory concluded essentially the same thing.

'Prius clusters' a worry

A more realistic worry for utility executives is that early adopters who buy plug-in vehicles will live in concentrated groups, informally known as "Prius clusters" (more than half the buyers who've put down deposits on the 2011 Nissan Leaf now own Toyota Prius hybrids).

The result is that neighborhood transformers may have to be upgraded if, for example, two or three homes on a particular cul-de-sac install EV chargers.

Upgrading local distribution equipment is a manageable problem, one that utilities plan for all the time as household electric usage inches up due to new consumer electronics and other equipment.

Knowing where it may occur is key, which is why utilities are working hard asking likely EV buyers to raise their hands ahead of time.

But in short, the extra load on the grid from charging upcoming plug-in cars will be relatively slow to grow, predictable, and highly localized in its early years. Electric vehicles will not "bring down the grid" under any circumstances.

[IEEE Spectrum; photo by Flickr user achouro]

Follow Us

Comments (15)
  1. John,
    Thank you for putting the EVs plugging into the grid issue into proper perspective. I love the plasma TV comparison!
    I wonder if those pushing all the anxiety about EVs plugging in have ever worried about "Plasma TV clusters". I bet not. ;-)

  2. Good article. Another thing to consider... Early adopters of EV's are likely to also be folks who are more likely to already have or plan to get solar power for their homes.

  3. Great article John. I have heard "Electric vehicles use about the same amount of electricity per mile as gas cars do! Yes that is right, gasoline has to be pumped and refined, that process takes energy. Electric cars just cut out the middle man." Do you know of any study that confirms or denies this?

  4. This is comical. FACT - 54% of electricity produced in the U.S.A comes from coal burning plants. COAL !

  5. john, true just over half of U.S. electricity comes from coal, but #1 - coal powered electric car is still cleaner than gas powered car, #2 many states (like WA where I live) hardly use coal at all (don't quote me on this, but I think between 10 - 20% in our state, but for definitely somewhere around 60% comes from hydro, another 10 - 15 from wind, solar, biomass, geotherm and the rest from natural gas), #3 as someone already said, a huge portion of the first 500,000 people buying these electric cars are going to people who have solar/wind or other cleaner sources of power production either on their property or are directly subsidizing through Green Power Programs (paying extra to, in theory, purchase power from renewable sources). So... even though we get a lot of power from coal, it is still far better to drive electric than driving ANY gas car.

  6. Hey, since these electric cars will use less parts, might that mean that those of us who like to do some of the work(maintenance)on our cars will get more of a chance on these cars? Than on the new ICE cars? That would be another real plus to owning all-electric cars, I would think.
    A lot of the routine stuff we have ta do on our ICE cars won't translate over to all-electrics because the electric cars won't have all those hundreds of parts, a lot of which need routine maintenance at periodic intervals.

  7. @Patrick: Thanks for the good words. To your question, the so-called "wells to wheels" analysis for oil v electricity takes into account all of the energy expended in refining, transportation, etc. as well as the actual energy content of the fuel and the vehicle efficiency in taking it from the "tank" (or battery) to the drive wheels.

  8. If every car in the US were a Pluggable Electric Vehicle, a 30% penetration of wind power could provide all the charging electricity. Wind is mainly an overnight resource, and PEV charging will be mainly overnight. In addition, the PEVs can produce benefits for the grid. They can use their storage capacity to balance out the variability of wind, other renewables, and load. Using storage to perform that function will minimize the need for conventional plants to do it, also eliminating the need to generate at the minimum limits of those plants that can't be used for balancing.

  9. Why do we have journalists analyzing this issue instead of engineers? If you make VERY conservative estimates at engine efficiency, look at the amount of gasoline consumed by cars alone, and factor in the energy content of that fuel, you're looking at a bare minimum of ~110 GW of increased electric capacity. That's more than 100 brand new high-capacity nuclear plants. How are we going to account for this massive new increase in demand when we're getting reports that the electric grid was almost strained to the max due to increased AC loads during last week's heatwave?
    You're going to have to change American driving habits before anything else. Some environmentalist-types might not mind driving around in their tiny smart-car with 20 horsepower, but your average driver isn't going to have any part of that.

  10. The grid is strained to the max only for a few hours per day on the hottest afternoons. Unless large portions of PEV marked are driving the maximum distance to work or shopping there won't be much charging demand during daylight. At other times the electric suppliers would LOVE to sell more of their excess capacity.
    On another note, hydrocarbons are a great (one of the best) portable fuels. The focus should be converting households to geothermal HEAT PUMPS, these use less electricity than conventional air conditioners, the utility can sell you electricity all winter, and there is no 'fire breathing dragon' in your basement. My system on a 2000 sf house is in MD ±$1,000 per year cheaper than heating oil/diesel. Almost as cheap as wood!

  11. @John & Tinman,
    In some cases you will have to dig deeper then just what is reported for the state as a whole. As many states have more then one electric utility. If you contact your local provider, they should be able to give you a breakdown of what their generation mix is. Generally speaking most of the coal power is in the midwest and east coast. The current issue of Scientific American ( has a good article on this as well.

  12. The article seems to assume that changing localized transformers is easy and done on a regular schedule, but that is usually not the case. The cases with two or more neighbors getting EV is complicated and it is most likely to be localized power outages on the local transformer level(3 or 4 neighbors without power), but yes not the mass black outs. Many local transformers need the night low to cool thus smart grid could hurt these neighborhoods when neighbors plug it together to recharge at 11. The true fear of companies is the quick charge 3-phase plugs (which charge in only 3 hours). If two neighbors want the quick charge and plug in together a lot more damage can be done.

  13. John, I wish your conclusion was correct, but it is not. Unless the US starts seriously planning for electric cars, we will have a serious problem. Do the math. Charging 400,000 cars (0.3% of USA) drawing about 1KW (Chevy Volt) = 400MW. That is about how much a small nuclear reactor puts out.

  14. i do not get it yet, unless we move to nuclear power, we still use oil

  15. Precisely David. These things are the WORST for the environemnt. We will now be powering our automotive needs with those nice, clean burning, coal fired electric plants. Not to mention all the environmentally friendly batteries we will eventually have to deal with.

Commenting is closed for old articles.

Get FREE Dealer Quotes

From dealers near you

Find Green Cars


© 2015 Green Car Reports. All Rights Reserved. Green Car Reports is published by High Gear Media. Send us feedback. Stock photography by izmo, Inc.