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Life Cycle Assessment of EVs Reveals Startling Results

| Wednesday June 22nd, 2011 | 15 Comments

Chevrolet Volt: Picture from Chevrolet Volt Web-site

A number of articles published this week paint a negative picture of electric cars based on a British study published earlier this month. The study attempts a comparative life-cycle assessment (LCA) of conventional, hybrid and electric cars and prompted “downer” headlines such as, “Electric Cars May Not Be So Green After All” and “More Bad News For The Chevy Volt.”

The report was undertaken by consulting company, Ricardo and was released by the Low Carbon Vehicle Partnership on June 8th. And contrary to the above headlines, the press release was considerably more upbeat, stating: “Electric and hybrid cars create more carbon emissions during their production than standard vehicles – but are still greener overall.”  Since the headlines suggest a different view of electric cars than the press release, I’ll attempt an objective view of the report’s findings.

An analysis of the full report reveals the study is based on various assumptions. The authors assume projected 2015 vehicle specifications coupled with an in-use period of 150,000 km (93,750 miles). They also assume an electricity carbon intensity of 500 gCO2/kWh. The life-cycle assessment itself covers four distinct “blocks” of a vehicle’s life :

1) Vehicle production – to assess embedded CO2
2) In-use phase – to assess CO2 incurred during the driving life of the car
3) Disposal at end-of-life, and
4) Fuel production and delivery processes – considering both electricity generation and gasoline production, depending on vehicle type

To cut to the chase, the report concludes the following:

Whole Life Carbon Emissions:

  • Standard gasoline vehicle    24 tonnes
  • Hybrid vehicle                          21 tonnes
  • Plug-in hybrid vehicle          19 tonnes
  • Battery electric vehicle        19 tonnes

“Not so green” and “more bad news” for the electric vehicle? No so much! The EVs and hybrids come out ahead. But those negative headlines should prompt the critical person to pay attention to details – because the stories behind the headlines do have a point.

The biggest downside for hybrids – and even more so for electric cars – is the embedded CO2 factored into battery pack production. Whereas the report calculates the total embedded CO2 for the production of a conventional car is 5.6 tonnes, it’s 8.8 tonnes for a mid-size EV. And of that embedded CO2, the EV battery production accounts for 43.1% of the total, equating to 3.8 tonnes. That’s pretty significant.

Detractors of EVs point out that these cars won’t get 150,000 km out of a single battery pack and here, they may have a point. Lithium Ion batteries do degrade with age and with repeated recharging, so at some point, an EV might have to undergo battery replacement. When that happens, we would have to factor in further embedded CO2 for replacement battery production – that is, an additional 3.8 tonnes. But having said that, in an experiment carried out at MIT, an EV battery was subjected to 1,500 rapid charging and discharging cycles, and only lost 10% of total battery life. So, if we consider an EV can go 100 miles per charge, and can withstand 1,500 charge cycles – then that exceeds the mileage assumed in the LCA report. But for the sake of argument, if we concede the worst case scenario, and assume EVs may require a second battery pack, the lifetime CO2 increases to 22.8 tonnes – still better than the projection for a conventional car, if not by a huge margin.

Interestingly, the authors of the report do not try to say whether EVs are better than conventional cars in their conclusion. While they do state embedded CO2 during production is becoming an increasing component of total life-cycle CO2, the main take-away is that further work has to be done to obtain common methodologies and data sets.

My conclusion is, there’s no such thing as a free lunch. Both EVs and conventional cars have a considerable carbon footprint – and there’s no way around this today. Today’s EVs can never genuinely claim to be “zero-emissions,” but this report does not conclude, at all, that they are lesser than conventional cars from an environmental standpoint. EVs offer the advantage that their CO2 footprint can be  mitigated by increasing the balance of renewable energy for recharging, and let’s not forget, the benefits of EVs extend beyond an assessment of CO2 emissions and climate change. Diminishing our dependance on foreign oil is another good reason to encourage the evolution of electric cars.


▼▼▼      15 Comments     ▼▼▼

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  1. June 22, 2011 at 6:00 am PDT | Ben writes:

    Very interesting. I have heard that car batteries are 95% recyclable. can most of the embedded energy be saved for the next battery… and the one after that?

    If so, 1 battery could last several cars.

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  2. June 22, 2011 at 6:07 am PDT | Bob Siegel writes:

    Production efficiencies do tend to improve with time. Now that these new vehicles are out there on the road, suppliers will continue to work to reduce embedded CO2, especially if the world is paying attention.

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  3. June 22, 2011 at 7:58 am PDT | Andrew Keenan writes:

    We need a similar study in the States. Luckily, places where EVs are most likely to be sold and used will be in states where the power grid is cleaner–think California and Florida.

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  4. June 22, 2011 at 11:30 am PDT | David Nix writes:

    Actually the battery is likely to outlast the car. DBM Energy claims their lithium polymer batteries last more than 5000 charge cycles with little loss in capacity. That’s 14 years of one 300 mile charge a day.

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  5. June 22, 2011 at 11:47 am PDT | Bill Webb writes:

    In response to the question Ben raised:

    Lead-acid battery materials are about 95% recoverable in recycling. That of lithium batteries is not.

    Unfortunately, although all four of the metals used in lithium batteries can be recycled, the value of raw recycling material is about $100/ton. Leaving out any incentive with respect to environmental issues, there just isn’t much reason to recycle them commercially because the cost of the process would exceed the worth of the materials recovered.

    Hopefully this may change with advances in reclamation technology. For now, however, we’re looking at major waste. Furthermore, if we assume that the original EV is driven until the batteries’ capacity is pretty much degraded, reuse of the battery packs is problematic.

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  6. June 22, 2011 at 12:15 pm PDT | Alison Tottenham writes:

    From the figures given above, there does seem to be a just worthwhile saving in CO2 over the life of the vehicle. However, that is really only worthwhile if a very high % of cars were EVs; at the current cost of EVs plus their very short range and the time needed for charging, it seems that few folks will actually buy them.

    The other point of concern is that their use would put a further strain on our electricity supply from existing fossil hydrocarbon and encourage the hurried building of more nuclear power stations. This might be what the UK government would like to see. But it is definitely not in the interests of our developing Renewable Energy generation network. e.g. Ireland appears to have decided where their charging points will be located, but do not seem to have realized that this will put a much greater strain on their remaining turf burning power stations; and I do not think that they really intend to suddenly go in for nuclear! Maybe they feel that their wind and solar power infrastructure is already strong enough for this extra demand; but I can’t help wondering whether it has been properly thought through.

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  7. June 22, 2011 at 12:39 pm PDT | Daniel Sotelino writes:

    Thanks for this informative article. Just for the sake of argument: Let’s assume that mileage of conventional vehicles will continue to improve over time. Do these studies take that into account? Second, I also suspect that biofuels may continue to play a larger role; it is debatable that they reduce emissions as compared to petroleum fuels, but assuming that the role of biofuels continues to expand (and that biofuels do in fact have a smaller carbon footprint than petrofuels [debatable]), and that the efficiency of conventional vehicles continues to improve, might not conventional fuel vehicles be a better option in the long run? Of course, if EVs only charged during off-peak hours, those emissions would be burning anyway, so EVs would simply be capturing energy that would otherwise go to waste, which is another matter to consider. It doesn’t really seem fair to charge the EVs with the emissions that would be occurring anyway (ie those captured during off-peak hours). If on the other hand, EVs charge during capacity or peak hours, the marginal cost of electricity increases, and natural gas peakers are more likely to be involved in their charging, thus resulting in increased emissions. I don’t think that there is a simple answer here. I think these numbers will continue to be refined over time, and that optimal energy sources for vehicles may vary by geographic location and type of vehicle use (for example, larger vehicles may be better off as conventional petrovehicles, while smaller vehicles in urban areas may be better off as EVs, and smaller vehicles in suburban areas with longer commutes may be better off as hybrids). Ultimately, I do appreciate this Mr Covington’s efforts at putting down some hard numbers we can compare.

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  8. June 22, 2011 at 14:26 pm PDT | John Countryman writes:

    Two things: 1. Unless the power grid is upgraded or some kind of rotational charging is used, the transformer sitting on the pole in your neighborhood is likely to blow if everyone has and EV and starts charging it at the same time.
    2. Reducing dependence on foreign oil here in the US is something that is becoming more important every year.

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  9. June 22, 2011 at 14:31 pm PDT | Hillel Hammer writes:

    A few important points:
    1. The 500 gCO2e/kWh is crucial to the analysis, and this will vary greatly from place to place. E.g., NY state is closer to 350, making electric much more attractive today.

    2. One of the reasons for moving toward electric is that it doesn’t dictate the power source, leaving the market open for all sorts of renewable sources, which will increase and improve over time. Therefore, shifting the market towards electric is an investment in the future, even more than it is a benefit today (which it is).

    3. The biggest benefit of electric vehicles is completely overlooked: urban air quality. This is a HUGE issue today, largely driven by on-road pollution near exposed population. Even biofuels, at their lowest carbon content, continue to emit pollutants.

    4. Electric vehicles will not present a problem for the electric grid because the growth is not expected to be explosive but rather gradual. Furthermore, since most of the charging can be done at off-peak, there may be benefits in terms of balanced use and with smart grids there may even be storage opportunities to balance out the grid.

    5. Although I have not reviewed the study in detail, the numbers seem extremely low. They are using 130g/m as a fleet average, which is 5-10 times lower than numbers I see for actual on-road simulation in the US–I know EU cars are cleaner, but not by that much on average. Combining this with my comment above for electricity would indicate that this is biased towards conventional vehicles, making the EV benefits even higher than presented.

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  10. June 22, 2011 at 14:39 pm PDT | Anonymous writes:

    What about repair and maintenance costs? EVs are expected to have drastically fewer costs overtime that can often rival the initial purchase of the vehicle. Plus longer vehicle lifespans.

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  11. June 23, 2011 at 9:33 am PDT | T. Caine writes:

    Another point I don’t see brought up is the opportunities for EV battery reuse that are already being coordinated, specifically the option for renewable energy storage at the utility scale.

    EV batteries are projected to lose their charging capacity over time and there is a threshold for how that relates to their usefulness in providing power for the car. However, even if batteries fall beneath capacity for automotive use, they can still be markedly successful in helping to offset the variability in renewable power sources.

    Not only could would this ultimately be extending the lifecycle of these battery components (and helping them offset more carbon in the process) but it could also create a secondary market for them that would effectively be lowering the price of the cars as well.

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  12. February 08, 2012 at 12:44 pm PDT | Aptaphoto writes:

    Does this analysis include the impact of producing the electricity which powers the car?  So in the US, most often a coal-fired power plant?

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  13. March 31, 2012 at 19:07 pm PDT | Guest writes:

    A few comments;
    What about the energy that would be needed to upgrade the power grid that would be needed as more and more electric vehicles are adding their demands on the grid. This should be factored in when looking at the overall impact. What countries in the world have the largest deposits of lithium? Will we be exchanging are dependence on a resource from one foriegn country to another. As more and more batteries are required what impact will the increased mining activities have on the enviroment?    

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  14. July 02, 2012 at 10:49 am PDT | Auke writes:

    This article does not take into account the toxic waist produced during the production of the materials for the batteries, plus of course the waist batteries. We try to improve the CO2 emission and produce another environmental diaster. Time to look further for other solutions.

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  15. November 15, 2012 at 22:10 pm PDT | Phil writes:

    Seattle City Light provides customers like me 100 percent hydropower generated electricity, so that reduces the carbon footprint to 25% of a gas-powered car.

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