12 March 2011

Carbon confusion: Just how green are electric vehicles?
The UK's electricity supply relies heavily on fossil fuels, so just how eco-friendly are electric cars?

Direct carbon emissions from electric cars are zero, but trace the electricity back to its source and you'll find a different story. Gas and coal-fired power stations still generate the majority of the UK's electricity supply. Given this heavy reliance on fossil fuels, how green can electric cars actually claim to be?

"Driving an electric car under the UK's current generation mix is not particularly clean," says Adrian Gault, chief economist at the Committee on Climate Change (CCC), the government's climate-change advisers.

This is because electric vehicles, run on the UK national grid, are powered by a mix of gas (45%), coal (28%) and nuclear (17%), with a few renewable sources such as wind and hydro thrown in (6.6%), according to the Department of Energy and Climate Change's most recent figures. In other EU countries such as Austria, which has more than 70% renewable energy, electric cars are significantly cleaner.

However, even on the current UK electricity supply, electric cars are greener than many conventional motors - partly because they are incredibly efficient. "Of the energy you're putting into an electric car when you plug it in, you probably get 80% to 90% translated into useful power at the wheels," say Professor Roger Kemp, author of a Royal Academy of Engineering (RAE) report on electric cars. "And that's really very good, because in a conventional car it's more like 20% to 30%, with the rest coming out as heat through the radiator and the exhaust pipe."

So how do electric cars compare with similar petrol and diesel cars when it comes to carbon emissions? According to the RAE, electric vehicles emit about 100g of CO2/km. Kemp argues that it is unfair to compare electric cars with large gas-guzzling cars such as 4x4s. If we look only at the three smallest categories of conventional car, average exhaust pipe emissions from new cars in 2009 were about 130g CO2/km. Emissions from producing the fuel (extracting and refining the oil) typically adds another 10% to 18% on top, bringing the total for new small cars in 2009 to 145-155g CO2/km. Based on these figures, electric cars currently emit about a third less carbon on average than small conventional cars.

In terms of air quality, electric cars are streets ahead, because they don't release harmful pollution in densely populated city centres where it does most harm (although there is pollution from the power stations themselves). This is important since London, for example, is in breach of EU standards on dangerous airborne particles, and pollution causes more than 4,300 premature deaths a year in the capital.

But focusing on current performance misses the fundamental point, which is that electric cars have the potential to be dramatically cleaner in the future.

Dale Vince, founder of green energy firm Ecotricity calls electric cars "wind cars" to emphasise their ability to run on clean energy instead of oil. Thanks to our legally binding target to cut greenhouse gases by 80% by 2050, a huge shift towards low-carbon generation is required over the next 10 to 20 years. The UK has also committed to generating 15% of all energy and 30% of electricity from renewable sources by 2020.

The CCC suggests that in order to meet the 80% target by 2050, carbon emissions from electricity generation (which are easier than other sectors to reduce) need to decrease by about 90% by 2030, at which point "emissions from electric cars could become almost zero".

It's because of this promise of very low emissions in the future that the CCC is recommending an "ambitious trajectory for electric-car uptake", starting now. The CCC advises that to meet our climate-change targets, 16% of new cars should be electric by 2020, rising to 60% by 2030. By 2020 they recommend the UK has 1.7m electric cars on the road.

For the full news article and to be taken to the website, click here