Alternative Fuel and Transportation

Published on April 27th, 2009 | by Derek Markham

Just How Green is That Electric Car, Anyway?

With the push to reduce the carbon emissions from transportation, sometimes the newest developments, the latest technology, gets the spotlight. By putting more hybrid and electric vehicles on the road, though, are we really getting “greener” vehicles? A report by an independent UK transportation group, Transport Watch, may have some surprising information for electric car aficionados.

Photo: frankhElectric Car

Electric Car

If your electric vehicle is charged with electricity from a coal-fired power plant, then the CO2 emissions to fuel your EV are about double the amount emitted by a diesel engine, due to the inefficiencies in electrical power generation and transmission.

According to Transport Watch, only about 30% of the energy generated by the power plant actually reaches the vehicle because of losses in the transmission route. Of the energy delivered to the vehicle, 20% is then lost to the batteries and electric motor. This means that most EVs are only about 24% efficient.

Contrast that with a modern diesel engine, which achieves an efficiency of 40-45% on the fuel burned by the vehicle. Granted, the internal combustion diesel engine does emit CO2 at the tailpipe, while an EV does not. However, the CO2 emitted by the EV is not seen at the curb, leading to the assumption that electric cars decrease CO2 emissions overall.

“We conclude that the notion that electric cars will reduce emissions is a fiction unless we hypothecate that the UK electricity generating industry will be de-carbonised.” – Transport Watch

If a true low-carbon transportation initiative catches on, we might be seeing more diesels and less electric vehicles on the road, simply because of efficiency. Coupled with the fact that manufacturing new EVs takes new technology, materials, and factory re-tooling, the CO2 emissions factor could mean that diesels are the cleanest transportation option we have right now.

If large-scale renewable energy electric power plants start feeding the grid, and EV owners can opt to choose clean energy for their cars, then a shift to an electric vehicle economy will begin to make the most ‘green’ sense. Until then, however, EVs are still coal-powered vehicles…

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About the Author

lives in southwestern New Mexico and digs bicycles, simple living, organic gardening, sustainable lifestyle design, slacklining, bouldering, and permaculture. He loves good food, with fresh roasted chiles at the top of his list of favorites. Catch up with Derek on Twitter, RebelMouse, Google+, or at his natural parenting site, Natural Papa!

16 Responses to Just How Green is That Electric Car, Anyway?

  1. Lorie Maguire says:

    Hi, I’d be interested to know which “independent UK transportation group” did this study? I have read a similar story on how the Hummer is eco superior to the Prius up to the build.

    Where is the breaking point of both gas and emissions savings during the life of the vehicles? If on the road for ten years does the hybrid / or electric car ultimately become the better choice?

    Do we need to consider these ineffeciencies in building eco friendly systems such as wind farms and solar technology?

    • The group is called Transport Watch and the link to the study is in the article above. The point is that the efficiency of a modern diesel is much higher than an electric car, and electric cars are usually charged from the coal-powered grid, which is inefficient. Couple that with the feel-good piece of “It’s electric, so driving is now green and clean.”, and emissions may not drop at all.

  2. Tim says:

    I think it’s also important to think about the times of day when the bulk of the electrical load from plug-in electric vehicles will be put on the grid. I think most models show that cars are most likely to be plugged in at night, when electricity demand is lowest and the prices are cheapest. Certainly, if we transitioned to a large electric car infrastructure where cars are plugged in all over town all times of day and night, we would definitely have to consider the increase in demand and addressing that demand with new clean power sources.

  3. Lorie Maguire says:


    I found some more specific information on the electric car’s efficiency:

    The Transport Watch UK’s data is expanded on quite a bit.

  4. Ed says:

    This article assumes that 100% of the power used to charge an electric vehicle is produced from burning coal. I think that would be the exception rather than the rule. I live in Maine and roughly 40% of our electricity comes from non-co2 emitting sources (wind, solar, hydro and nuclear). In the example above, this would put the electric car on par with a diesel powered car.

    As time goes on and the price of fossil fuels increases (there is a finite supply of coal and other fossil fuels – the price will increase) the percentage of non-co2 emitting power sources will increase as they will be more competitive in terms of cost. This being true, electric cars need to be a developed and tested technology that can really begin doing the workload of the populations personal transportation needs.

    Full disclosure: I’ve built an electric car myself – sadly, economics was my major motivation behind the project. It’s simply much cheaper to operate an electric car.

  5. Stephanie says:

    In Washington State, new legislation was passed last week to encourage development of the infrastructure necessary for EVs to be successful. Most, if not all of the recharging stations will be powered with solar and/or wind energy. Now, that is a clean answer, in my opinion!

    Also, smart grid technology will allow off-peak charging and credit consumers that do so on their electric bill. This is truly the next generation’s vehicle model.

  6. Alexa says:

    Was just reading a related article that Stephanie refers to over at Buildbabybuid:

    It seems to me like the U.S. just isn’t quite with it yet in terms of thinking “clean.” I just traveled to Europe and they seem like they’re light years ahead when it comes to adopting cars that are more fuel/energy efficient.

  7. Lya says:

    It’s a shame that these people (EVs producing companies) told the whole world that the cars did no harm to the environment! I mean, the cars are powered by coal-fired power plants and they(the power plants,actually) emits CO2 just like any other diesel-powered vehicles!! Is that what they call a ‘GREEN TECHNOLOGY’??! wake up everybody…

  8. Lorie Maguire says:

    – In the U.S. 70% of energy to make electricity comes from fossil fuels.
    – 70% of this energy is wasted generating the power that comes to your door.
    – Electric cars use fossil fuel at 20 to 25% efficiency.
    Internal – combustion cars operate at about 15% efficiency (yes that means LESS efficient).
    – Electric vehicles use 0.18 – 0.46 kWh per mile.
    Conventional vehicles (25MPG) use 1.35 kWh per mile. (less efficient).
    – Electric vehicles offer fuel economy equivalent to as much as 188 miles per gallon.

    “Now let’s talk pollution. A huge advantage of PHEV and BEV cars is that their energy can come from renewable sources, such as hydroelectric, wind, or solar. Even if the energy source is fossil fuel, installing state-of-the-art emission controls on a few big power plants is way easier than installing ’em on hundreds of millions of motor vehicles. What’s more, since many electric plants use natural gas, CO2 emissions from power generation are a modest 1.27 pounds of CO2 per kWh — 1.9 pounds per productive kWh once we account for losses during battery charging and so on. Compare that to gasoline, which produces the equivalent of 3.9 pounds of CO2 per productive kWh.”
    From: The Straight Dope, Cecil Adams

    A great documentary (I got it from Netflix) is Who Killed the Electric Car.

  9. Daniel says:

    But what about the non-renewable resources used in electric vehicles?

    I’ve read many interesting articles covering where the energy for electric vehicles comes from. I’ve even read some that talk about the environmental hazards of an electric car that has finished it’s life (Conventional vehicles are much easier to recycle).

    Lithium is expensive due to mining difficulties at the moment, but the high price will drive a new mining industry and since lithium does not exist in large quantities alone, we’ll see a lot of environmental destruction like the strip mining of the past for coal.

  10. Lorie says:

    One source says that we have 15,112 days until we’ve depleted our oil supply. That’s scary even if it’s double that.

    Here is an excellent article by Treehugger that goes step by step on how electric car battery cells are recycled.

  11. d says:

    snt electricity fueled by gas? I dont get how electric cars are green when green deters people from using conventional energy. Here’s a creative thought a waterless car wash

  12. David Wallace says:

    So if the goal is to reduce carbon emissions, is it easier to monitor and clean up 1 power plant or 100,000 cars?

  13. Ivy says:

    As far as I knew GM had to get ride off all the electronic cars the put in the market a few years ago…and the reason was because the biggest petrol companies pushed them to do it….so I am wondering now..what made them change their minds? when is they change their minds again?

  14. Stephen says:

    There are so many factors to allow for when comparing these two methods of propulsion.

    The carbon intensity and efficiency of the power source, natural gas power stations are only about half the carbon of coal stations and far more thernally efficient as well

    The extra carbon used for refining the petroleum

    The extreme inefficiency of internal combustion engine operation during urban driving

    The ability of electric cars to operate efficiently at low loads and speeds and regenerate the kinetic energy lost in braking

    When all this is allowed for the amount of carbon released in the UK would be about half that of a gasoline engined car, and of course no tailpipe emissions.

    In practice electric cars would be mainly used for town driving, not highway. I think there are far better solutions for electric cars than driving them as an isolated product.

    This spreadsheet is just for highway (constant speed driving) go to honda insight or audi

    Hope you find this useeful

  15. myna lee johnstone says:

    as a pedestrian and human i would opt for electric to spare us all the NOISE and toxic fumes from diesel run vehicles
    it is hard to escape the daily noise of traffic and engines starting
    i also think that drivers of electric cars just might be more mindful of their driving habits

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