Academics in Norway have published a study arguing that electric cars can be more polluting than is widely assumed. Leo Hickman, with your help, investigates. Post your views below, emailor tweet

9.40am: A study by engineers based at the Norwegian University of Science and Technology has questioned some common assumptions about the environmental credentials of electric cars.

Published this week in the Journal of Industrial Ecology, the "comparative environmental life cycle assessment of conventional and electric vehicles" begins by stating that "it is important to address concerns of problem-shifting". By this, the authors mean that by solving one problem, do electric cars create another? And, if so, does this environmental harm then outweigh any advantages?

The study highlights in particular the "toxicity" of the electric car's manufacturing process compared to conventional petrol/diesel cars. It concludes that the "global warming potential" of the process used to make electric cars is twice that of conventional cars.

The study also says - as has been noted many times before - that electric cars do not make sense if the electricity they consume is produced predominately by coal-fired power stations. "It is counterproductive to promote [electric vehicles] EVs in regions where electricity is produced from oil, coal, and lignite combustion," it concludes.

So, should this new study make us reassess the environmental credentials of electric cars? Or does the analysis and data help us, as the authors insist, improve the environmental performance of electric cars? As they say:

Although EVs are an important technological breakthrough with substantial potential environmental benefits, these cannot be harnessed everywhere and in every condition.

Please leave your thoughts below. If you are quoting figures or other studies, please provide a link through to the original source. I will also be inviting various interested parties to join the debate, too. And later on today, I will return with my own verdict.

10.09am: There has already been some reaction via Twitter asking if the study is "well-to-wheel", namely, does it also include the emissions caused during the extraction/production of petrol/diesel?

I have just received an email from Guillaume Majeau-Bettez, one of the authors, answering this precise point:

Yes, our study covers the whole production chain of the cars and of the fuels, the use phase, and the end of life.

P.S. I have asked the authors of the paper to monitor this debate and respond to any other queries from readers.

10.32am: It's probably worth highlighting, just in case you missed the link above, that the paper in question can be read in full here. Here's the key conclusion:

The production phase of EVs proved substantially more environmentally intensive. Nonetheless, substantial overall improvements in regard to GWP [global warming potential], TAP [terrestrial acidification potential], and other impacts may be achieved by EVs powered with appropriate energy sources relative to comparable ICEVs [internal combustion engine vehicles]. However, it is counterproductive to promote EVs in regions where electricity is produced from oil, coal, and lignite combustion. The electrification of transportation should be accompanied by a sharpened policy focus with regard to life cycle management, and thus counter potential setbacks in terms of water pollution and toxicity. EVs are poised to link the personal transportation sector together with the electricity, the electronic, and the metal industry sectors in an unprecedented way. Therefore the developments of these sectors must be jointly and consistently addressed in order for EVs to contribute positively to pollution mitigation efforts.

10.38am: In the comment below, @MartynW asked:



Does this study take account of cars being one of the most recycled products we use?

Guillaume Majeau-Bettez, one of the paper's authors, has just emailed me this in response:

The crucial importance of recycling is one of the conclusions of our analysis. There are different ways to account for recycling in Life Cycle Assessment. We have chosen to analyse a "first wave" of electric vehicles, made from average metal mixes (a fraction virgin and a fraction from recycling). Hopefully, subsequent "waves" of electric cars would be made with a higher fraction of recycled metal (ecars made from ecars, cradle-to-cradle...), but the industry is not there yet.

11.24am: Many thanks for the great response from readers so far. Here are a few interesting observations that I thought worth highlighting here "above the line"...

Dr Simon Evans:

While we can expect petrol/diesel cars to become more efficient I would have though the same will be true of electric car manufacture, plus grid mix carbon intensity is going to fall through the floor if carbon targets are met - at least inthe UK. This will make electric cars an even better proposition in CO2 terms

ikd:

The place that most of these studies fall down is that they don't properly account for the toxic air pollution benefits of EVs and in particular it's spatial dependence. The effects of pollution on health are much higher pro rata in highly polluted city centres (like London) than in less polluted, smaller cities or rural areas.

madkiwi:

While EVs currently rely on polluting power stations, in the future, these can become friendlier, as alternative sources are developed. I see EVs as not being perfect, but they have a lot more potential than IC cars that will always be polluting, no matter how efficient they are.

Guess11:

The study does not go beyond looking at 'average use' of vehicles in calculating it's numbers. No comparative numbers for predominantly low speed, urban, stop-start use. All of these factors will significantly favour electric.

11.40am: Here's another email from Guillaume Majeau-Bettez, one of the paper's authors who is following the reader reaction below:

Your readers are sharp critiques! The recycling question is central (see my previous email). @ikd: The absence of urban air emissions is certainly a strong argument in favour of electric cars. For human toxicity, our study partly addresses the difference between emissions to densely populated and less populated areas, though this could certainly be improved. However, we cannot think only of the toxicity on humans; we also address toxic impacts on aquatic life and ecosystems. @Seb: This is one of our core finding: because the production of an electric car causes roughly twice the climate impact of producing a comparable conventional car, it must run on rather clean electricity to "make up" for the initial climate impact.

Further on @Seb: All use phase energy requirements were based on industry performance tests with the New European Driving Cycle, following the UNECE 101 regulation (UNECE 2005). These tests combine four elementary urban

driving cycles and one extra-urban driving cycle, with regenerative charging and energy losses during overnight charging included for EVs. @Guess11: Following industry standard, we based our assessment of the use-phase on the "New European Driving Cycle", which includes a typical share of stop-start. As many readers point out, the electric car industry is young and will likely improve in the future. We studied the present generation of electric car, we refrained from making predictions. good dialogue.

11.52am: I've just received this reaction from a spokeswoman at the Society of Motor Manufacturers and Traders:

Electric vehicles represent one option within a range of technologies that help motorists to lower their emissions. The automotive industry manufactures – or is developing – a broad array of low and ultra-low carbon vehicles, from highly efficient petrol and diesel models, through gas, biofuel and hydrogen, to hybrid, plug-in hybrid, pure-electric and fuel cell vehicles. Every year, the latest drivetrain technologies see emissions reduced, with today's new cars emitting on average 20% less than their 10 year old counterparts. Significant investment is ongoing, with worldwide R&D powering the continuous improvement of existing technologies and the introduction of other low carbon innovations.

In terms of the lifecycle emissions of electric vehicles, the energy industry in Europe is constrained by legally binding limits on the total amount of CO2 emitted each year, up to 2020 (EU Emissions Trading Scheme 2009/29/EC). This limit reduces year-on-year to achieve an overall reduction in CO2 emissions. This means, in practice, that if overall energy demand increases as a result of electric vehicles (or for any other reason) then the increase in demand must be met with electricity from renewable or zero carbon generation sources.

In addition, measures such as the EU's Renewable Energy Directive, which requires 20% of renewable energy by 2020, are positive strategies to achieve CO2 reductions while the European Emissions Trading Scheme requires electricity suppliers to reduce their overall CO2 emissions.

12.11pm: Robert Wilson, from the University of Strathclyde's department of mathematics, raises an important point below the line:

Simply decarbonizing electricity assuming no increases to demand appears to be a massive challenge. Our choice on transportation appears to be between increased fuel efficiency, a switch to "cleaner" fossil fuels and a push for increased public transportation, or aiming for something like 100% electric cars. The first approach is guaranteed some level of success. The second, however will fail completely if the electricity grid is not fully decarbonized. What we really need to do here is reframe this question, and instead ask not whether electric cars are bad for the environment, but how many of them are bad for the environment.

12.15pm: Touching on the same themes as this week's paper, Time magazine ran this feature last February on why the use of electric cars in China - where "about 85% of the country's electricity is powered by fossil fuels, of which 95% is coal" - is causing an environmental headache:

Kilometer per kilometer, electric cars in China beat out conventional vehicles as among the worst environmental polluters. On average, the fine particulate emissions per passenger-km are 3.6 times greater for electric cars than for gasoline cars. That's better than for diesel cars but on par with diesel buses, which can spread their environmental impact across the number of passengers they carry. "If we compare gasoline car emissions to electric car emissions, the electric cars look very, very bad," says Christopher Cherry, an assistant professor of civil and environmental engineering at University of Tennessee. "So the point is that you have to consider the emissions exposure when the exposure source is far apart — the electrical power plant as opposed to the tailpipe of a car."

12.30pm: As background reading, I have examined the issue of whether "electric cars really produce fewer emissions" before. I have also investigated the issue raised by uhf101 regarding "range anxiety".

12.36pm: Here's some reaction via Twitter...

@leohickman you may find this information on electric vehicle battery recycling useful autom.tv/T4XCRz — Tom Callow (@au_tom_otive) October 5, 2012

Re @leohickman's eco-audit's Q, what % increase in UK electricity demand would result from 100% electric cars? From memory it's 50% in US. — Robert Wilson (@PlanktonMath) October 5, 2012

@planktonmath @leohickman King, 2007: "total conversion of UK car fleet to electricity = 16% of current demand" (out of date?) — David Powell (@powellds) October 5, 2012

@powellds @leohickman If overnight when demand is low, less new capacity is needed. Some argue (optimistically) you need no new capacity. — Robert Wilson (@PlanktonMath) October 5, 2012

@powellds @leohickman IEA put the global figure at 20%. Referenced in a book I have open, but can't find it online. — Robert Wilson (@PlanktonMath) October 5, 2012

12.48pm: It's a few years old now (2008), but here's what the UK government has to say (pdf) on the issue of the "lifetime vehicle carbon use" of EVs compared to vehicles with internal combustion engine:

EVs have the potential to offer significant carbon dioxide and greenhouse gas emissions reductions compared to conventional petrol/diesel fuelled internal combustion engines. This applies over a full life cycle, taking account of emissions from power generation and emissions relating to production and disposal. Based on the current UK grid mix there are already significant benefits of the order of approximately 40% reduction; these benefits have the potential to become much greater with further decarbonisation of the UK power mix.

1.00pm: I've just received this response from Robert Llewellyn, probably best known as Kryten in Red Drawf but also something of an electric car obsessive, as evidenced by his dedicated blog:

I'm trying not to be dismissive of yet 'another report' which 'proves electric cars are more polluting than diesel' because it raises a very important points. We need to know the facts about electric cars, their true total impact. Here I will point out something, we still don't know the true impact of the internal combustion cars and the fuel they use. This information is obfuscated by historical habit, for 100 years no one wanted to know. For example, how much electricity from coal burning power plants goes into refining oil? Try and find out how much per gallon? I've asked when filming at a massive oil refinery that had it's own set of pylons coming from a nearby coal burner. No one wants to tell you. (estimates range from between 4 -7 kWh per gallon) We know we need to change the way we generate electricity, with or without electric vehicles this is vitally important. We know what comes out of the tailpipe of an ICE car, toxic and carcinogenic gasses which cause untold levels of harm to human beings. We do know that 100 miles in an electric car uses around 24kWh, in an ICE car around 110 kWh. So from a global energy perspective that's a massive reduction in energy needs.

We do know that most EV drivers charge the car at night when the amount of coal burnt to produce electricity is at it's lowest, we know that coal makes up under 30% of the UK grid supply during peak times. We know that most people who drive EV's also install solar panels, I have. In one year, my Nissan Leaf used 5,340 kWh and my solar panels produced 3,555 kWh. We know that an electric car can run on electricity from any source, a fossil burner can only burn fossils.

So what about the battery toxicity? Are we just going to throw away the battery after the car has done 150,000 miles? No, of course not. Nissan are about to open a massive battery re-cycling plant at their Sunderland works. What about the massive piles of worn parts the traditional motor industry produces, clutches, waste lubricating oil, the platinum in catalytic converters, filters, pumps, the list goes on and on. Are they thrown away? of course not, they are recycled. What about the materials that go into making traditional cars, sourced and shipped from all over the world. The true well to wheel argument is a minefield, and this report has dived in feet first. Good luck to them.

1.10pm: Here's another email from Guillaume Majeau-Bettez, one of the paper's authors, this time on the question that I put to him about whether they had also looked at regional variations when it came to the carbon intensity of electricity production. For example, in terms of reducing emissions, is the US grid better or worse than Europe's for charging electric cars?

This is outside the original scope of our study. We did not address electric vehicles on a region-per-region basis, but rather on a per-electricity-source basis. This can get quite complex; the electricity mix in any given point can differ from the average (national, regional) mix, and will also fluctuate with time (time of day, season, etc.) Speaking in general terms, however, the average US grid is more fossil fuel and global warming intensive than the European grid. Referring to the latest "Life Cycle Inventories of Electricity Mixes and Grid", the US mix causes roughly 800 gCO2-equivalent per kWh of low voltage electricity at grid, compared to roughly 500 for the European mix. (see http://www.esu-services.ch/fileadmin/download/publicLCI/itten-2012-electricity-mix.pdf - p. 207)

2.12pm: Dr Marcello Contestabile, a research fellow at the Centre for Energy Policy and Technology at Imperial College London who specialises in battery technologies "in the context of road transport", has emailed me his thoughts:

In the last few years there has been a lot of hype around electric vehicles and as a result their environmental credentials have often been somewhat overstated. However, experts are well aware of the fact that well-to-wheel carbon emissions of EVs are strongly dependent on the carbon intensity of the electricity used, and that in extreme cases these could even be higher than those of conventional internal combustion engine vehicles. Lifecycle environmental impacts of electric vehicles are comparatively less well understood and hence studies such as Hawkins et al are needed.

In a recent consultancy piece I have conducted with other colleagues at Imperial College (http://www.lcaworks.com/EV%20Lit%20Rev%20FINAL.pdf), we arrive at results that are largely in agreement with Hawkins et al. In particular, we have focused on greenhouse gas emissions and we have reviewed previous studies showing that manufacturing of electric vehicles, and particularly batteries, is likely to be more energy intensive than that of conventional internal combustion engines. However, this can be more than offset over the lifetime of the vehicle if the latter is powered by low carbon electricity and the battery lifetime is comparable to that of an internal combustion engine.

In our piece we also argue that the fact that battery technology is still evolving could help mitigating the problem. In fact, for electric vehicles to gain a significant share of the market the cost and weight of batteries need to reduce significantly and their durability increase. Reducing costs involves using cheaper materials, and hence those based on less energy intensive materials would be favoured; reducing weight means using lighter but also less material per unit energy stored, which again could reduce the overall environmental impact of battery manufacturing.

In conclusion, it is plausible that the currently higher environmental impact of manufacturing electric vehicles will naturally reduce somewhat if these are adopted on a large scale; at the same time, decarbonising power generation is imperative and it is in this context that electric vehicles should be considered. However, both my analysis and Hawkins et al also suggest that more research on lifecycle impacts of electric vehicles (and indeed any other vehicle technology) is necessary and that road transport policies need to better account for these impacts in order to provide a level playing field where more environmentally benign technologies are adequately rewarded.

2.24pm: Andy Heiron, Renault UK's head of electric vehicle programme, has sent me his thoughts:

Most of the environmental impact of a car comes in use and in this respect EV's already offer a significant 'well to wheel' advantage, even with the relatively 'dirty' grid mix in the UK. Taking into account the proposed Committee on Climate Change target of 300g/KWh, this would equate to w2w for ZOE (210km range, NEDC) of 31.4g/km, and I cannot see ICE technology getting close to that level by 2020.

Without access to, or the time to study, this report, it's difficult to add much on the production impacts, but the statement the production of EV's has twice the global warming impact seems high, and perhaps, as one of the authors admitted, reflects the current reality of (low volume) production. Again, I can only comment on the Renault situation where EV's are built in the same factories alongside ICE products and so suggest that a difference of this magnitude seems unlikely.

2.44pm: Doug Parr, Greenpeace UK's chief scientist and policy director, has responded:

Whilst unable to go over the report with a fine toothcomb, the broad conclusions seem right in that: 1. Ricardo research for LowCVP showed that the climate costs of production of electric vehicles are significant, in particular, in relation to the battery. Policy that ignores this could create perverse incentives. 2. Electricity is a carrier of energy, not the primary energy itself. Once fabricated, running electric vehicles off a power system run by lignite will generate increased emissions rather than savings, and generally will off coal too. 3. Element Energy have calculated that in 2030, even with EVs representing three-quarters of the total car stock, the additional demands are less than 10% of forecast electricity demand at that time for all end uses. 4. It remains an environmental imperative to conserve scarce resources like the minerals and rare earths necessary for battery fabrication. Saving CO2 does not justify laxity on mining standards or waste management. 5. The importance of electric vehicles – and hydrogen-fuelled ones - is that they provide a way of moving away from a hydrocarbon based transport system. Electric vehicle development and mass-production cannot just be switched on and off overnight. So EVs can be supported if there is a broad consensus that decarbonisation of the power system will take place, and a strong implementation plan in a country. 6. However, the longer term options of technology change should not obscure the fact that in the short term most of the emissions savings in transport will come from better efficiency of petrol and diesel vehicles. Emissions standards for cars and vans, as are being discussed in Europe and member states this autumn, are the most important measure for reducing emissions over the next decade. Changes in vehicle technology and production that these standards require will generally be helpful in making EVs a more attractive commercial proposition.

4.37pm:

My verdict

The authors of this new paper are evidently not saying that electric cars are "bad" for the environment in all circumstances, but they are confirming what many already knew: that as electric cars become more popular - which is being encouraged by policymakers across many countries - we mustn't lose sight of the fact that the carbon intensity of the electricity used to power them is key. Another crucially important factor to monitor (and, hopefully, ameliorate) is just how energy- and resource-intensive the production of these vehicles can be.

The problem for electric cars is that they will only increase their environmental credentials (compared to "conventional" cars) once more and more of them are made and used, which, in itself, will drive faster and deeper innovation in battery technology, production efficiencies and end-of-life recyclability. It's somewhat unfair to compare them to conventional cars at present because they are an immature, fledgling technology, but the opportunity for increased efficiency throughout their lifecycle seems significant as/if they become more popular.

But a bigger problem, perhaps, is that their environmental "success" hangs largely on factors beyond their manufacturers' control. As has been shown in China, electric cars powered by electricity generated through the burning of coal and oil make very little environmental sense. They need to run off a low-carbon, "smart" grid where renewables and nuclear do much of the heavy lifting. So policy-makers have a twin challenge if they want to see more people driving electric cars: they need to ensure a low-carbon, smart grid is delivered and they need to assist manufacturers in bringing down the cost of these vehicles. Doing that in a synchronised and timely manner is going to be hard, but a prize worth reaching for.