Large emissions from electric car batteries

Large emissions from electric car batteries 

2017-05-29 10:00 

Johan Kristensson 

248 Enable Talking Web 

Huge hopes are attached to electric cars as the solution to the car industry's climate problems. But electric car batteries are environmental culprits in manufacturing. Several tonnes of carbon dioxide have been emitted, even before batteries leave the factory. IVL The Swedish Environmental Institute has, on behalf of the Swedish Transport Administration and the Swedish Energy Agency, investigated the climate impact of lithium-ion batteries from a life cycle perspective. The batteries intended for electric cars are included in the study. The two authors Lisbeth Dahllöf and Mia Romare have done a meta-study, ie reviewed and compiled existing studies. The report shows that battery production gives rise to emissions of 150-200 kilos of carbon dioxide equivalents per kilowatt hour of battery produced. The researchers have not studied the individual car brands' batteries, how exactly these were produced or which electric mix they use. But for the understanding of the importance of battery size, let us take an example: Two ordinary electric cars on the market, Nissan Leaf and Tesla Model S, have batteries of approximately 30 kWh and 100 kWh, respectively. Already when you buy the car, emissions have occurred corresponding to about 5.3 tons and 17.5 tons, respectively, for batteries of these sizes. The numbers can be difficult to relate to. For comparison, a trip for a person round trip from Stockholm to New York by plane causes emissions of just over 600 kilos of carbon dioxide, according to the UN organization ICAO's calculation model. Another conclusion in the study is that about half of the emissions occur during the production of raw materials and half during the production of the battery itself in the factory. The mining itself accounts for only a small part of between 10-20 percent. Read more: Read more: "The potential advantage of electric cars" The calculation is based on the assumption that the electricity mix used in the battery factory consists of just over half of fossil power. In Sweden, power production consists predominantly of fossil-free nuclear and hydropower, which is why lower emissions could have been achieved. The study also concludes that emissions grow almost linearly with battery size, although data in this area is scarce. This means that a Tesla-sized battery contributes just over three times as much emissions as a Nissan Leaf-sized one. It is a result that surprised Mia Romare. - It should have been less linear because the electronics used do not increase to the same extent. But the battery cells themselves are as influential as production looks today, she says. - One conclusion is that you should not drive around with unnecessarily large batteries, says Mia Romare The authors emphasize that a large part of the study has been about finding out what data is available and finding out what quality they hold. In many cases, they have been forced to state that it is difficult to compare existing studies with each other. - We have become frustrated, but it is also part of the result, says Lisbeth Dahllöf. Colleague Mats-Ola Larsson at IVL has made a calculation of how long you need to drive a petrol or diesel car before it has emitted as much carbon dioxide as battery production has caused. The result was 2.7 years for a battery the same size as the Nissan Leaf and 8.2 years for a Tesla-sized battery, based on a series of assumptions (see fact box below). - It is great that companies and authorities introduce ambitious environmental policies and buy climate-smart cars. But these results show that one should consider not choosing an electric car with a larger battery than necessary, he says and points out that politicians should also take this into account when designing instruments. An obvious part to look at in life cycle analyzes is recycling. The authors of the report state that what characterizes batteries is the lack of them, as there is no financial incentive to send the batteries for recycling and the volumes are still small. Cobalt, nickel and copper are recycled, but not the energy required to manufacture the electrodes, says Mia Romare and at the same time points out that the point of recycling is resource management rather than reduction of carbon dioxide emissions. Peter Kasche from the report client The Swedish Energy Agency highlights the close to linear relationship between battery size and emissions as important. - Somehow you really have to make sure that you optimize the batteries. You should not drive around with a lot of kilowatt hours unnecessarily. In some cases a plug-in hybrid may be optimal, in other cases a pure battery vehicle. That's how IVL counted Mats-Ola Larsson has made a number of assumptions when calculating that the emissions from a battery the size of a Nissan Leaf and a battery the size of a Tesla take 2.7 and 8.2 years, respectively, to "drive together" with a normal petrol or diesel car: The average value of emissions for new Swedish cars in 2016 was 126 grams of carbon dioxide per kilometer. That value has been corrected to 130 so that some of the cars that at