A compilation of studies (*) carried out by Chalmers University of Technology in Sweden shows that electricity generation is the single biggest contributor to the environmental impact of an electric car. In fact, if an electric car is charged with electricity generated by coal power, the emissions caused by the car exceed those of an eco-class petrol or diesel car. In contrast, the emissions of an electric car charged purely with wind-generated electricity are up to 140 times less than from a petrol-powered car. Most e-cars are charged with an energy mix that lies somewhere in between.
“Very few cars in Europe, and in the world, are charged with 100 per cent coal power. An electric car charged with the average EU energy mix currently offers a better alternative to almost all petrol and diesel powered cars,” says Anders Nordelöf, a PhD student at Chalmers University and project manager at the Swedish Hybrid Vehicle Centre. “In addition, electricity generation is becoming increasingly cleaner, so that at the end of its life an electric car will have performed even better in terms of greenhouse gases.”
MORE THAN ENGINE EXHAUSTS
It is well known that cars contribute to poorer air quality and emit greenhouse gases. But the exhaust pipe is not the only source of emissions: fuels like petrol and diesel oil have to be pumped out of the ground and transported to petrol stations; and the electricity for an electric car can come from a coal or oil-fired power plant, which in turn emits large amounts of carbon dioxide.
“All of the studies we examined point in the same direction, namely that electric cars can only reach their full potential in mitigating global warming if global electricity generation becomes free of fossil carbon emissions,” Nordelöf says. “If so, they can become almost completely emission free, in particular as regards carbon dioxide.”
This is actually already a reality in Sweden as well as other countries that have a low proportion of fossil-based electricity generation.
“This shows that the development of electric cars must go hand in hand with the development of renewable energy sources,” says Annika Ramsköld, Head of Sustainability at Vattenfall. She is convinced that electric cars also have other important benefits compared to cars powered by internal combustion engines, irrespective of the power source used. “Electric cars produce significantly less noise and no local emissions of pollutants such as nitrogen oxides and particles – so they are always winners for urban environments!”
ELECTRIC CARS ARE HEALTHY
A research team from the University of Minnesota, in the US, focussing on air pollutants and particles, showed that the way the electricity for e-car charging is generated determines its environmental and health performance.
“We estimate that, in the US, an electric vehicle charged with electricity from natural gas can decrease negative health effects among humans by 50 per cent compared to a petrol car. With wind, water or solar power, the impacts decrease by 75 per cent in comparison,” Christopher Tessum from the University of Minnesota explains. “However, electric vehicles charged with electricity from coal power can lead to three times as much health damage in humans compared to petrol vehicles.”
Yet, even electric cars charged with electricity generated with low emissions have a certain negative health impact.
“The largest part of these effects comes from the production of the batteries, and a smaller share from the wear of brakes and tyres,” Tessum says.
BATTERIES ARE A PROBLEM
Nordelöf agrees that electric car batteries are an environmental issue, partly because their manufacture involves a lot of fossil energy and partly because some battery types cannot be easily recycled.
“More renewable energy will lead to cleaner battery production in the future. But electric cars will only become completely clean when we also get an efficient system for recycling the batteries. While the recycling of lead batteries already works well, there’s still a lot to be done as regards the lithium-ion types. Some studies show that completely efficient recycling will make it possible to halve the energy consumption used for battery manufacturing.”
To reach their conclusions, the US researchers looked at the whole life cycle of various types of fuel and how it impacts the amounts of ground-level ozone and other atmospheric pollutants. The researchers also examined patterns of habitation and used mathematical models to calculate how many people were exposed to emissions from both fuel production and from the actual driving of the cars.
(*) These studies compared the EU’s target for private cars sold in 2012, which also forms the basis of the Swedish eco-car classification.
Video - Christopher Tessum summarizes the study