What We Should Learn from a Lifecycle Assessment of EVs in the EU

, research and deputy director, Clean Vehicles | October 12, 2012, 4:56 pm EDT
Bookmark and Share

A new study examining the life-cycle impacts of electric vehicles looks at global warming emissions and other environmental impacts from the production and use of vehicles in the European Union. Here’s one media story about the report with a rather damning headline  – Study: ‘Global Warming Potential’ From Electric Cars Twice That Of Conventional. Kind of reminds me of some of the coverage of our State of Charge report (See a Columbia Journalism Review blog on that). It’s stories like this that might lead some casual readers to conclude that electric vehicles are a disaster.

But not so fast….

After reading the study, I found that while some portions of the analysis were surprising, the basic conclusions are not entirely new.

For example,

(1) EVs offer global warming benefits today (20-24% on today’s electricity mix in the EU compared to a gasoline vehicle, according to the authors’ assumptions), but the greatest global warming benefits occur when EVs are paired with cleaner sources of electricity, such as renewables.

(2) The manufacturing impacts of EVs are greater than those of conventional gasoline vehicles primarily because of battery production.   These impacts need to be addressed through the use of greater material recycling and other measures.  (The study does find that manufacturing an EV results in twice as many global warming emissions as a conventional vehicle–which IS surprising. More on that below.)

The impacts of current vehicle production and use are important, but this is only one part of the story when evaluating alternative vehicles and fuels. It’s also critical to understand the potential for reducing those impacts over time. EVs, or any other promising alternatives to the internal combustion engine, shouldn’t be dismissed based solely on an assessment of current vehicle production processes and fuel production (grid electricity in this case). Otherwise we are likely to be tethered exclusively to the gas pump for decades to come.

And misleading media coverage of science journal articles certainly doesn’t advance the conversation.

Now on to some of the substance.

If the emissions of producing an EV are really twice as high as a gasoline vehicle, what does that do to the global warming benefits of EVs?

One finding of the study that caught my attention was the estimate that global warming emissions of EV production are twice that of a conventional gasoline vehicle.  I’ve addressed global warming emissions of EVs in a number of previous blog posts and in our State of Charge analysis, but I’ve focused on the emissions from plugging-in, not vehicle manufacturing.

I ran a quick comparison using two sources on vehicle manufacturing emissions. The two sources are the Argonne National Labs GREET2012 model, which shows EV production emissions are 33% higher than a comparable gasoline model, and the new study results from Hawkins et al., which estimate that EV production emissions are closer to double (200%) those of a conventional vehicle.

The figure below shows the reduction in global warming emissions compared to a 27 mile-per-gallon gasoline vehicle – which is the average efficiency of new compact cars sold in the US.

The columns on the far left  show the State of Charge results without accounting for vehicle manufacturing; an EV results in a 98% drop in global warming emissions when charged exclusively with solar power, a 77% drop when charged on the cleanest US regional electricity grid, and a 19% drop in when charged on the dirtiest US regional electricity grid region.

The second and third set of columns add in the estimates of vehicle manufacturing emissions from GREET2012 and Hawkins et al. respectively.

The numbers show that even in the worst case, on the dirtiest grid and assuming EV vehicle production creates twice the number of global warming emissions as a gasoline vehicle, an EV still has a slight (6%) emission advantage compared to the average new compact.

If the worst case represented the full potential of electric vehicles to reduce global warming emissions, pursuing EVs as part of our solution to oil use and climate change would certainly be questionable.  But it doesn’t.  Even today’s cleaner electricity grids provide substantial benefits and renewables like solar are even better.


By better understanding the impacts of vehicle production we can identify opportunities to reduce them.  The authors of the new study suggest as a first step focusing on recycling of materials and increasing the life of electric vehicles (the longer they last, the better).  That seems like sage advice to me.

We also need to keep up our effort to increase renewable electricity production and move away from high-emission sources like coal. A cleaner grid will enable lower-emission electric vehicles in the future.

And for those not willing to wait (including the 39% of California EV owners with rooftop solar), powering an EV with clean renewable energy is, in fact, an option available today.

Posted in: Energy, Global Warming, Vehicles Tags: ,

Support from UCS members make work like this possible. Will you join us? Help UCS advance independent science for a healthy environment and a safer world.

Show Comments

Comment Policy

UCS welcomes comments that foster civil conversation and debate. To help maintain a healthy, respectful discussion, please focus comments on the issues, topics, and facts at hand, and refrain from personal attacks. Posts that are commercial, self-promotional, obscene, rude, or disruptive will be removed.

Please note that comments are open for two weeks following each blog post. UCS respects your privacy and will not display, lend, or sell your email address for any reason.

  • Tom Newcomb

    This post is in response to Charles Z’s post, near the bottom of this discussion. He asks

    “So would it be accurate to say that the actual incremental “temporal” response would simply be something within the domain of grid regulation as opposed to unit dispatch,……”

    Yes, this is exactly what I am trying to say. At any point in time there are numerous generators supplying power to the grid. Some (those producing the lowest-cost power) are designated as “base” generation and are operated at “full throttle”, around the clock. Others supply the remainder of the needed power. Some of these may be at full throttle, but several will be at less than full throttle. Only when the system gets too close to being “all-in” will dispatch bring additional source(s) on line. It is these partial throttle generators that respond to changes in load on the grid. Minute adjustments to the fuel flow (coal, gas, oil) are made, based on system voltage and frequency. These changes are probably implemented by PID type controls that can make tiny changes to fuel flow several times per second if necessary. There are thousands of load changes throughout the grid every second. It is the aggregate of these changes that causes the total consumption of fuel to constantly change.

    My whole point is that if you want to know how much GHG your LEAF (or any other electric device) causes, the answer lies in the weighted average GHG/KWH for each partial throttle generator that participated in making the power to charge the LEAF. This leads to the inconvenient fact that nuclear, wind, solar, and most hydro are not used to power your LEAF, because these sources are either base or reserved for peak hours, irrespective of load, in the case of hydro.

    While this data would be virtually impossible to gather, there is an ORNL report that addresses this issue by examining what fuels are actually used by various national grids in the evening and at night. This shows that in Wilmington NC, evening charging uses substantial natural gas and some coal, while night charging uses mostly coal. The LEAF owner is faced with a dilemma; charge in the evening which is “cleaner” and pay more per KWH, ($0.068/KWH plus ~$30/month demand charge) or charge at night, “dirtier” for less ($0.054/KWH, no demand charge). This assumes that you are on a time-of-use rate plan. If you are on the regular Residential plan all power is $0.109/KWH.

  • The EPA is trying to bridge the gap between electric and gasoline vehicles with their MPGe ratings. Here the Leaf get a more realistic 99 MPGe rating rather than 1000 mpg. As a sanity check we can use costs and would expect the electric Leaf to be about 1/4 the cost of the gas powered equivalent.

    Here the 99 MPGe appears close as a Nissan Leaf uses about 340 W/mile (charging losses included) for a cost of about $.037/mile (at $.11/khw). A gas powered Versa, virtually the same size, at the EPA 27 mpg and $3.50 gas is $.13 mile. And .037/.13 is 28% a pretty close comparison.

    I really can not figure where the 1000 mpg could come from. But even at 99 MPGe the Leaf shows as a solid value and is a good step better for the environment.

  • Tom Newcomb

    Don, thanks for the prompt reply to my earlier comments in which I questioned the use of “average” emissions data to describe the impact of EVs on the environment. In your reply you say:
    “The analysis we performed did use average electricity emissions intensities to estimate the carbon footprint of a plug-in vehicle for an individual consumer. Using an average emissions approach, all the electricity consumption used by a household is treated equally without a distinction between what sources are powered by marginal electricity sources and which are powered by base load sources. This approach, in my opinion, equitably assigns emissions from electricity production to all sources, including plug-in vehicles.”
    While “equity” may be an important consideration in social science, it seems to me that in this instance “accurate” assignment of emissions would be the goal. The “ORNL marginal emissions analysis” that you mention provides the data required to make just such an “accurate” assignment. I was surprised to learn on page 51 that for an EV charged at night (off-peak, cheapest power) in Wilmington, NC in the year 2020, the GHG emissions will be 25% greater than for an efficient hybrid vehicle, (Prius?) running on gasoline. Can the 2012 scenario be much different? The report also confirms my basic premise that EVs are “fueled” almost entirely by coal and natural gas.
    Regarding your comments about emissions intensity of various gasoline sources, you say;
    “When I estimate emissions from new gasoline vehicles, I use the same approach, using the average emissions intensity of a gallon of gasoline despite many new oil sources being more carbon intensive than existing ones. I think this approach makes the most sense when looking at an individuals gasoline and electricity consumption.”
    For proper comparison, gasoline must be treated “marginally”, the same as electricity. However, I think that “marginal” gasoline would not necessarily be the most recently developed source. Oil sands might be part of the “base” supply for the same reasons that nuclear is considered “base” electricity. ( high capital investment and ample, cheap feedstock) Marginal gasoline would be that which is from the highest priced feedstock, such as long distance tanker delivered, or from refineries requiring less-available types of feedstock. I’m not sure where “stripper” oil fits in, but it might be marginal due to the ease of supply modulation, allowing strippers to wait for a better price. In any event, the degree of GHG variation, source-to-source, is less significant than in electric generation.
    I feel bad belaboring this point, but it is important. Your work is shaping the debate. (Why else do you do it?) It can lead to misguided letters-to-the-editor, like the one that led me here in the first place. Please show me where I am wrong. I also welcome the input of anyone else reading this post. Thanks.

    • Thanks Tom. One more point on this. Using your suggested approach to estimating emissions from plugging in a vehicle, no matter how much wind, solar or any other renewable source of electricity that is not a marginal electricity source, the answer would always be that an EV is powered by coal or natural gas. This fails to recognize the complexity and variability of the electricity grid and also suggests that an EV should be treated differently than every other electricity load that the power grid is operated to meet.

      Taking a different tack, one could argue that wind (especially at times in the Northwest where occasionally wind power has been curtailed) is in fact the marginal electricity source and plugging in an EV to the grid is zero emissions.

      There is plenty to debate here, but I think we are losing the forest for the trees.

      Using electricity to power our vehicles offers the unique opportunity to drive using renewable electricity. And as we move our electricity grid towards greater renewable sources and reduce our reliance on coal power which we must do, plug-in vehicles and everything else drawing power from the electricity grid, will get cleaner. Your suggested approach to estimating emissions precludes “cleaner electrons” from ever powering an EV.

      Using average emissions factors isn’t perfect either, but provides a reasonable estimate of emissions for someone plugging their electric vehicle into an outlet today.

      • Tom Newcomb

        Don, I think we know that in the real world, with the real grid, and real people, every decision that every person makes to use more (or less) electricity results in the consumption of more (or less) fossil fuel by the grid. These decisions range from the purchase and use of a 1/2 watt nightlight to the purchase and use of a LEAF. The LEAF decision is different from the nightlight decision because it has the desirable effect of also reducing the consumption of petroleum, vis-a-vis a non-grid-charged vehicle. Lawnmowers, leaf blowers, string trimmers, etc. also fall into this category.
        I say there are three legitimate arguments in favor of the proliferation of grid-charged vehicles:
        Environmental: The net rate of GHG emissions (marginal grid minus gasoline)
        Geo Political: Reduced use of petroleum
        Economic: Reduced cost to the consumer (We need to discuss the ethics of road taxes, but let’s save that for another day.)
        In my opinion, it is unnecessary to exaggerate the environmental impact by using “average” grid emissions. Tell it like it really is. Otherwise, it is like politicians that argue that a reduced rate of spending increase is a spending cut. Some of us know better, and the rest of us should. If more people understood this, we might “waste” less electricity because some people are truly environmentally conscious, to the point they actually change their behavior.

        You did make me question my own position when you said “Your suggested approach to estimating emissions precludes “cleaner electrons” from ever powering an EV.” This raises another question: Who does get to “feel good” for using the “cleaner electrons”? After considerable thought, I conclude that nobody deserves any credit for using these “clean electrons”. To the extent that credit is due, it belongs to those parts of society that caused them to be generated.

        In the case of hydo, credit the politicians that pushed for these massive projects, and the taxpayers that paid for them. Most of this was done at a time that GHG wasn’t even on the radar.

        In the case of nuclear, credit the utilities, the nuclear industry, and the Public Utility Commissions that took the heat from the environmentalists and the peaceniks, and pushed these projects over the goal line.

        In the case of wind and solar, credit the State and Federal politicians, the Green lobby, and the Public Utility commissions for creating tax and utility policies that cause these technologies to be deployed in spite of their dismal economics. I suppose the taxpayers and utility customers deserve some credit, in the sense they didn’t revolt against this attack on their pocketbooks, but I suspect this is more a result of ignorance and apathy than an embrace of environmentalism.

        Man can’t make the wind blow, or the sun shine, or the rain fall, so there is no way that these clean energies can become the “marginal” portion of the grid’s energy supply. We are stuck with hydrocarbon fuels to handle the marginal load. Biomass has potential in this regard, but that doesn’t seem to get much play. More nuclear, replacing coal, is the most practical, economical path to a serious reduction in GHG, but nobody wants a reactor in their back yard. Combined-cycle natural gas would appear to be the technology-of-choice to replace coal at this time. Is that what’s happening in the real world? How much longer will the public subsidize wind and solar? What is the upper limit on the role that wind and solar can play? These public policy issues are independent of someone’s decision to purchase a LEAF and then charge it starting at 6:00 PM to the detriment of some Saudi Prince, with a modestly favorable impact on GHG, and an eight(?) year payback on his investment.

  • I’m puzzled by the claim that electric cars are so much more energy intensive to produce. According to table D3 in the National Academies study– http://www.nap.edu/openbook.php?record_id=12794&page=438 — manufacture of a conventional car results in 47 grams/mile of CO2. The same table (figures provided by GREET) shows an electric vehicle resulting in 50 grams/mile. Have the NAS/GREET numbers been changed?

  • The EU report on EVs is not a correct assessment of the impact that EVs and plug-ins will have on cleaner air. One assumption the report makes by looking at air pollution in aggregate is forgetting that air pollutions greatest affects are felt most locally, when closest to the source. If you put your head in the smokestack of a coal fired power plant the affects of the pollution from that plant are immediately apparent. However, if you move several miles away from that plant into a city the affects to your breathing are much less than the internal combustion engine’s smokestack located much closer to your lungs.

    The other assessment that the report fails to take into account is the French example. I don’t agree with using nuclear for electric production, but the reality of the situation is that France’s electricity comes from nuclear right now. EV’s in France may create other hazards, but they don’t produce greenhouse gasses as part of their operation. The United States has put to bed nearly one fifth of its coal use as natural gas has proved to be cheaper and cleaner in the last few years. Natural gas production keeps increasing and pressure to reduce emissions from coal keeps growing. The switch to natural gas trend will continue and the energy produced will be much lower in carbon and other pollutants. As cleaner fuels grow in popularity such as wind, solar, geothermal and hydrokenetic and grab greater amounts of the energy sector EVs become cleaner yet.

    I purchase the electricity for my Volt from a renewable program with my utility. You can do this as well. There are hundreds of similar programs at nearly every utility in the United States. My Volt is a virtual emissions free vehicle because its electricity comes from wind, solar and other renewable electricity sources. Using EVs and other plug-in vehicles and getting your electricity not only for your vehicle, but for your home as well from renewable sources are things we all as consumer can do. Making the choice to make changes in our use of energy will expand markets for renewables, which will directly impact EVs and plug-ins. No slight increase in pollution in manufacturing can overcome the overwhelming benefit of driving pollution free now and for the life of the vehicle.

    So, if you are thinking of buying an EV to benefit the air, don’t listen to the naysayers. EVs and plug-ins are really good now. The more of them we have now the greater the competition. The greater the competition the lower the prices of the vehicles. If you buy plug-ins and EVs now, the faster the manufacturers will get to economies of scale that will help them reduce their costs, which with competition will lead them down the road of reducing the prices on these vehicles and therefore making them more affordable, which will allow them to reach greater numbers of consumers, which will increase the economies of scale again, etc. etc. The greater the competition the more manufacturers will want to advance the technology to create differences between their products and the others. Things like, longer ranges on plug-ins, more efficient motors, better regenerative braking schemes, greater energy density in batteries and more. Purchasing plug-ins in greater numbers puts into effect the virtuous circle of ever improving products with lower and lower impact on the environment. EVs displace fossil fuel vehicles. They give us a place to put over generation of renewable energy like when the wind blows at night or when there have been heavy rains for hydro.

    Purchasing plug-ins is a fundamental change that our society can make towards the greater good of having all our energy come from pollution free renewables. It begins today with you purchasing a plug-in. Reports such as this EU one just confuse things. We have our hand on the hot plate of global climate change. While electric vehicles may seem like just pulling away the palm from that hot plate while the fingers are left behind, it is necessary for us to lift the palm as a precursor to lifting the entire hand. Cursing that lifting the palm first because it doesn’t solve the entire problem and therefor we need to leave the entire hand on the burner of the hot plate, is illogical. And yet that is what these types of reports seem to be doing. The journey of 1,000 miles begins with just a single step. We have good shoes on with electric vehicles. How about we just start walking.

  • David Kennington

    Your analisis ignores another factor, according to the DOE production of 1 gallon of gasoline requires 6kwhr of electricity. So if I replace a 28.8 mpg car with an EV getting 4.8 miles/kwhr no additional electricity is used. (this is my actual number driving my Leaf) Since this is a higher number than the optomistic 27mpg I propose that the GHG reduction is actually over 100% for the fuel side of the equation.

    • Hi David, thanks for your comment. Just to clarify, our analysis does include the emissions associated with refining oil into gasoline. So the emissions from electricity used to produce the gasoline is accounted for.

  • Tom Newcomb

    Dear Don,
    I arrive at your blog, oddly enough, as a result of an on-line Letter-to-the-Editor in the Wilmington NC StarNews, written by Ronald Cochran, who is a recent contributor to this space. His letter is copied below for reference. His statement that “I own a Nissan LEAF Electric Car, and I calculate that it produces (via electricity use) the Greenhouse Gas equivalent of a standard gasoline car that gets over 1,000 mpg.” amazed me.

    His letter led me to take a look at your report. I retired after a 41 year career as a process development engineer with GM’s foundry division. We used a LOT of energy, and I know a little bit about energy conservation. I disagree with a basic premise of your report; that the “average” greenhouse gas emissions of power generation is the appropriate measure of the impact of charging an EV. “Marginal” emissions, as you define then, aren’t right either. In my opinion, the correct approach is what I call “temporal” emissions; the incremental emissions resulting from the incremental increase in load, at the point in time the load is imposed. You seem to dismiss this approach in the last sentence of
    Appendix A: Calculating Emissions from EV Charging:

    This approach [average] ignores the impact of any changes in electricity production that may be caused by a single individual plugging in an EV—an impact that is virtually imperceptible.

    You seem willing to ignore the very real changes to the grid that result from each added load because the load is “virtually imperceptible”. In other words, that which is imperceptible is therefore not “real”.

    Common sense dictates that for every increase in load on the grid, whether a Nissan LEAF being charged, or a 100 year old incandescent light bulb being turned on, there will be an increase in the amount of energy that must be input to the grid to maintain the desired voltage in the system. This will be accomplished by one or more of the power sources that are actively powering the grid, at that moment, increasing their output to satisfy the increased load.

    Only those power sources that are operating at less than 100% capacity can participate in this reaction to the increased load. Nuclear, wind, and solar power systems are typically operated at 100% due the low variable cost per KWH and the high fixed cost of the facility. Hydro that is water-limited is likely reserved for peak-demand generation, and thus not directly responsive to incremental load. Fossil fueled power plants have higher variable cost/KWH (mainly fuel cost) and by their design are readily throttled to operate at partial capacity. Increased load results in increased consumption of fossil fuel in virtually every instance. At best, the increase may take the form of (cleaner) additional natural gas consumption, but often it will be coal or oil consumed by an older, less efficient generating plant.

    An electric vehicle is likely to be re-charged in the evening, and ideally during off-peak hours. (after 9 PM in NC) This can minimize the owner’s electric cost if they are enrolled in the time-of-use rate plan. This is also environmentally favorable, as the utility is likely using its most cost effective fossil fuel systems at that time. If the EV is charged during midday the incremental power is produced by higher cost, and probably less fuel efficient fossil fuel systems. (I am on the time-of-use rate and achieve a nice savings, even without an EV)

    While the decision to purchase an EV can be a good one for the environment, the environmental impact is not as great as your report leads one to believe, and indeed, EVs “run on” fossil fuel, now and into the foreseeable future.

    The true environmental impact of an EV can only be assessed by taking a number of factors into account. For example, what time of day is it recharged? Are more miles being driven to accomplish the same tasks due to the limited range of the vehicle? (For example, are two 50 mile trips undertaken to accomplish what could have been accomplished in a single 75 mile trip, because the range of the vehicle is 60 miles?) Are additional, unnecessary, miles driven because the owner thinks it is “affordable” or “not so bad” for the environment? What is the alternative mode of transportation if the EV were not an option? This is a complicated subject, not well served by simplistic or biased analysis.

    I’m not against EVs or credible environmentalism, but I am against baseless hyperbole and over-reaching by either side of any argument.

    Here is what I am requesting:
    1. Critique my “temporal” approach in a factual way.
    2. Contact Ronald Cochran to make him aware of my post, and give him my email address. I would be happy to buy him a beer at Whiskey Creek, as I live just a couple of miles north of him, on Barksdale Rd. (I could Google his address, but not email or phone…)

    Ronald Cochran’s letter:

    Published: Friday, October 19, 2012 at 1:23 p.m.
    Last Modified: Friday, October 19, 2012 at 1:23 p.m.
    Mr Editor – I have no landline phone. I have been to your offices to show ID.
    NO! THEY’RE CLEANER! Americans seem to see a never ending stream of articles in the public media that cast doubt on the notion that Electric Cars are cleaner than standard cars. The common accusation is that Electric Vehicles (EV’s) simply transfer their emissions to the electric power plant that generates their electricity. A Senior Scientist at the Union of Concerned Scientists has recently calculated that Greenhouse Gas emissions caused by EV’s are lower than those from an average US compact car, even if the EV’s electricity is produced exclusively by burning coal. That means that EV’s are much cleaner than the average car on American roads, many of which are far dirtier than a compact. EV’s will also get even cleaner with time, as more Green Energy sources come on line.
    Furthermore, in the Wilmington area about half of our electric power comes from the Brunswick Nuclear Plant, which produces zero Greenhouse Gas emissions. I own a Nissan LEAF Electric Car, and I calculate that it produces (via electricity use) the Greenhouse Gas equivalent of a standard gasoline car that gets over 1,000 mpg.
    If you want to know about Electric Cars, just ask one of us EV owners. My wife and I love our LEAF for around town driving. I also know many other EV owners in the Wilmington area, and every one of them would strongly recommend their cars. Don’t believe everything you read!

    Ronald L. Cochran

    • Tom, thanks for your detailed comment regarding our approach to estimating emissions from electric vehicles. As you note, this is a not a simple subject and there are differing opinions on approach. The analysis we performed did use average electricity emissions intensities to estimate the carbon footprint of a plug-in vehicle for an individual consumer. Using an average emissions approach, all the electricity consumption used by a household is treated equally without a distinction between what sources are powered by marginal electricity sources and which are powered by base load sources. This approach, in my opinion, equitably assigns emissions from electricity production to all sources, including plug-in vehicles. When I estimate emissions from new gasoline vehicles, I use the same approach, using the average emissions intensity of a gallon of gasoline despite many new oil sources being more carbon intensive than existing ones. I think this approach makes the most sense when looking at an individuals gasoline and electricity consumption.

      However, marginal emissions analysis is the approach needed to evaluate how the electricity grid responds to new demand and I agree with you that doing so on a temporal basis is important given how the electricity grid changes throughout the day. If tens of thousands of EVs are going to plug in at night, how is the grid going to respond? What power plants will provide the additional power? Marginal analysis helps answer these questions. But its important to consider not only the immediate response of the grid, but what the longer term response is well. For example, how is the electricity grid changing over time as plug-in vehicles grow in number? A marginal emissions analysis by researchers at Oak Ridge National Lab is one example of looking at the marginal emissions impact of plug-in vehicles over time.

  • Ronald Cochran

    As a LEAF owner I appreciate your points about this paper being a bit lopsided. A couple more points that you might want to consider are:

    – Given the current range of BEV’s, they are almost exclusively driven in the city. Yet you assume 27 mpg as your average ICE comparison. It it’s unlikely that your average American new car gets that in the city. I would guess more like 16 mpg.

    – Also the subject paper assumes an EV life of 200,000 Km, only 124,000 mi. I would guess that a more realistic value for a BEV might be 225,000 mi. or 363,000 Km. This difference is a big deal, because a realistic lifetime trends to dilute the emissions from manufacturing the BEV/battery.

    • Thanks for the comment and suggests Ronald. I haven’t seen a split of city and highway driving for EVs currently in use, but your point about EVs being mainly used in city driving may be right. I used the average efficiency of new compacts sold in 2011 for comparison – which is a combined city/hwy rating of 27 mpg – based on the fact that the BEVs on the market today mainly fall into that vehicle segment. I’ll keep an eye out for more EV driving data to see about refining that further.

      I agree that the lifetime miles used in the study was on the low side. The authors looked the the sensitivity of their results to longer lifetimes and did show that with manufacturing impacts averaged over more lifetime miles, they become less significant. In my calculations I used 150,000 life time miles – which is more inline with your suggestion.

      • Charles Z.

        Hi Don, Ron, and Tom,

        Thanks for the clear differentiation between marginal and average grid mixes.

        I have been thinking about the difference between marginal, average, and
        “temporal” grid mix for a while. I agree on the concept of incremental load but am curious as to what generation sources actually switch on to a LEAF/Volt being plugged in.

        My thoughts were that in the instances of one/two/three Volts/Leafs being plugged into a neighborhood grid, the incremental load is usually less than 5 kW (assuming for example, one Level 2 AC and two Level 1 AC chargers). This is less than the peak use of one house. The switch-on of a natural gas, oil, or coal unit occurs in quanta (I believe its much larger than 5 kW but I’m unsure). So would it be accurate to say that the actual incremental “temporal” response would simply be something within the domain of grid regulation as opposed to unit dispatch, e.g. ancillary services, decreasing resistance, etc?

        Obviously, once you have a sufficiently high penetration of PEVs in a neighborhood, the picture changes, but when there’s only a couple on the block, I’m curious as to what is the actual effect on generation sources.


    • Mark Whyte

      Hi Ronald,

      I read an article on this report elsewhere and if memory serves correctly the reason the EV life was set at such a low figure was due to the authors belief that batteries would require replacement at this interval. Should that be the case it puts more emissions back into the manufacturing side of the equation. There was also some of the old ‘batteries into landfill’ talk.

      It was slanted in such a way that if replacement batteries and junking of the old ones was taken into account the outlook would be even worse for EV’s and he was doing them a favour by not including this data. Another in the long list of ‘cheap shots’ at the EV industry.

      By the way, excellent point on the fuel consumption comparison. I’ve always compared against average fuel consumption figures which as you point out when comparing the vehicle usage isn’t the fairest benchmark.

  • Richard

    I feel that EV naysayers will alway use change to spread fear.The bottom line is we need a cleaner grid through the use of renewable. If all EV owner purchase and used Solar or received credit for purchasing solar for there EV vehicles the benefits like cleaner air,less imported oil,and less use of coal would start to grow exponentially. So less CO2 Carban dioxide levels in the Earth’s atmosphere are not the goal ? I’am no the oil companies will show us the way.

  • I see that, once again, the EV naysayers are spreading their petrolganda far and wide. And what alternative are they suggesting? Just keeping burning fossil fuels until they run out? They will, you know, and the rate of consumption just keeps growing exponentially. Readers would do well to consult this study, then use the tool at the end to perform their own calculations and compare how EVs and ICEs impact the environment: http://bit.ly/AwvJ83