IVL Swedish Environmental Research Institute was commissioned by the Swedish Transport Administration and the Swedish Energy Agency to investigate litium-ion batteries climate impact from a life cycle perspective. There are batteries designed for electric vehicles included in the study. The two authors Lisbeth Dahllöf and Mia Romare has done a meta-study that is reviewed and compiled existing studies.
The report shows that the battery manufacturing leads to high emissions. For every kilowatt hour of storage capacity in the battery generated emissions of 150 to 200 kilos of carbon dioxide already in the factory. The researchers did not study individual brand batteries, how these were produced, or the electricity mix they use. But if we understand the great importance of the battery here is an example: Two common electric cars on the market, the Nissan Leaf and the Tesla Model S, the batteries about 30 kWh and 100 kWh.
Even before buying the car emissions occurred, corresponding to approximately 5.3 tons and 17.5 tons of Carbon Dioxide. The numbers can be difficult to relate to. As a comparison, a trip for one person round trip from Stockholm to New York by air causes the release of more than 600 kilograms of carbon dioxide, according to the UN organization ICAO calculation.
Another conclusion of the study is that about half the emissions arising from the production of raw materials and half the production of the battery factory. The mining accounts for only a small proportion of between 10-20 percent.
The calculation is based on the assumption that the electricity mix used in the battery factory consists of more than half of the fossil fuels. In Sweden, the power production is mainly of fossil-nuclear and hydropower why lower emissions had been achieved.
The study also concluded that emissions grow almost linearly with the size of the battery, even if it is pinched by the data in that field. It means that a battery of the Tesla-size contributes more than three times as much emissions as the Nissan Leaf size. It is a result that surprised Mia Romare.
- It should have been less linear as the electronics used is not increased to the same extent. But the battery cells are so sensitive as production looks today, she says.
- One conclusion is that you should not run 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 find out what quality they are. They have in many cases been forced to conclude that it is difficult to compare existing studies together.
- We've been frustrated, but it is also part of the result, says Lisbeth Dahllöf.
His colleague, Mats-Ola Larsson at IVL has made a calculation of how long you have to drive a petrol or diesel before it has released as much carbon dioxide as battery manufacturing has caused. The result was 2.7 years for a battery of the same size as the Nissan Leaf and 8.2 years for a battery of the Tesla-size, based on a series of assumptions (see box below).
- It's great that companies and authorities for ambitious environmental policies and buying into climate-friendly cars. But these results show that one should consider not to choose an electric car with a bigger battery than necessary, he says, noting that politicians should also take this on in the design of instruments.
An obvious part to look at the life cycle analysis is recycling. The authors note that the characteristics of the batteries is the lack of the same, since there is no financial incentive to send batteries for recycling, as well as the volumes are still small.
Cobalt, nickel and copper are recovered but not the energy required to manufacture electrodes, says Mia Romare and points out that the point of recycling the resource rather than the reduction of carbon emissions.
Peter Kasche the report originator Energy Agency emphasizes the close of the linear relationship between the battery size and emissions is important.
- Somehow you really get to see so as to optimize the batteries. One should not run around with a lot of kilowatt hours unnecessarily. In some cases, a plug-in hybrid to be the optimum, in other cases a clean vehicle battery.