Common Tragedies

Thoughts on Environmental Economics

Coal-fired car

Posted by Daniel Hall on October 29, 2007

Ryan Avent points us to today’s NYTimes and says:

It’s clear that partially or completely electrifying our automobile fleet would be a great way to reduce our output of carbon emissions. An electric car is cleaner than a gas-powered one, even if the electricity is produced by a coal-fired power plant.

Really? Would an electric car run completely on coal-fired electricity actually involve fewer carbon emissions than a conventional internal-combustion engine car?

My web search found this site, summarizing a lifecycle analysis paper I cannot find, which seems to indicate that, yes, it would, although it is a close thing.

Lifecycle CO2 emissions

Note that an electric car involves quite a few more emissions during manufacture, but less during use, even if all the electricity is from coal.

My questions: Does the paper include emissions from disposal? (My guess is that batteries are not just energy-intensive to manufacture, but also to recycle.) What is the assumed time to replacement? Do the compared cars offer (nearly) identical “services” (power, range, passenger space, etc.)? What is the sensitivity of results to the size of the car? If the per-mile cost of operating an electric car is lower than a gasoline car, how much extra driving will people do?

Clearly electric cars look much better from the standpoint of carbon emissions if other forms of generation are used or if we can successfully use carbon capture and storage. Electric cars would also presumably be better for local air pollutants like ozone, NOx, particulate matter, etc., since we can locate generation facilities outside of major urban centers.

Finally, do read the rest of Ryan’s post, there are several cogent thoughts.

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5 Responses to “Coal-fired car”

  1. Mathias said

    Daniel,

    You should check out this ERPI/NRDC that was released this summer. A phev powered by current coal technology has GHG emissions 28 to 34% lower than a conventional vehicle.

    link here

  2. Daniel Hall said

    Mathias,

    Thanks for the pointer.

    I’ll note the EPRI/NRDC study is not a life-cycle analysis and that their results (p. 7 of the exec summary) seem to basically comport with the chart I’m showing here. It’s hard to tell what the exact result from the chart above is, but it appears that the “use” emissions from an electric car run on coal-fired electricity are basically about 30% lower than for a gasoline vehicle. It’s the manufacturing where you give back a lot of that gain, and that would presumably apply to the cars in the EPRI/NRDC study as well.

  3. Mathias said

    Daniel,

    I tried to do the same thing by eyeballing the data in the chart above. To me, it still seems to vary significantly from the ERPI/NRDC. In the figure above, the “use” numbers are about 20 mgCO2 for gasoline and 17 for the coal-powered phev.

    I also don’t understand why the emissions from manufacturing (from a 2001 study) are 100% higher for what was then a completely conceptualized vehicle. Maybe I should try to track down the full paper.

    Nevertheless, the main point is still clear. Electric vehicles are much, much better for reducing emissions if they are powered by renewable energy.

  4. Daniel Hall said

    Mathias,

    Yeah, good catch, I was thinking 17/21, which somehow I divided to get 30% instead of 20%.

    In terms of the vehicle being conceptual, weren’t there electric cars prior to 2001? If you get ahold of the full paper let me know.

    Also, I wonder if much of the difference is explained by the differences between a fully electric car and a PHEV?

  5. Susie said

    Even before this favorable GHG analysis, electric motors blew away internal combustion engines in almost any category. They’re more efficient, smaller and lighter, quieter, don’t have any direct emissions, and are capable of regenerative breaking. They don’t even need a transmission. But before we get ahead of ourselves, we should remember that the engineering hasn’t quite caught up to make them competitive in the mainstream market. (Kind of like, sure, fuel cell vehicles sound great, but the reasons why they’re great don’t mean much if I’ll never be able to drive one.) As far as I know, all commercial electric cars to date have had a range of only ~60 miles before needing another charge. But some good news that may (happily) discredit what I’ve commented above: the Tesla Roadster, to be released in 2008, is an all-electric car that claims a range of 250 miles.

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