Electric Cars 2 of 4 – Electricity from...?

Electric cars are zero-emission at the point of use, freeing up cities from the pollution of petrol and diesel engines. Instead of cyclists breathing in nitrous oxide, fine black soot and other pollutants to go with their healthy exercise, they will be able to fill their lungs with clean air. This is the way of the future for city living but there is a problem; where does the electricity come from to charge the cars?

I carried out some back-of-the-envelope calculations working out a comparison between the carbon emitted by my E-Mini and my other car a ten-year old Audi diesel. I took into account the Kilowatt hours of electricity used to charge the battery with the range achieved and compared this with the miles per gallon of my old car. The two were comparable in the overall carbon emitted taking into account the carbon dioxide emitted in generating the electricity.

I used an average figure for the carbon intensiveness of electricity in the UK. I did not take the easy option of claiming that the photovoltaic panels that cover both the south and west elevations of my house were charging the car. Not so of course; the car charges at night with the panels generating during the day, but let use consider the overall figures. I generate approximately enough electricity averaged out over the year to cover my electricity needs. I cannot claim the electricity twice; I need it for the house so I do not claim it for the car.

I was on the podium at the Low-Carbon Vehicle Conference last year in a discussion about electric cars. An electric car advocate did not like my comment that until we decarbonise the electric grid electric cars do make a useful contribution to carbon reduction. They are useful in getting part of the future in place, to deal with user-acceptance issues and develop the technology, but no more than that. He claimed that the figure to use in my comparison is the carbon intensiveness of night-time electricity generation when nuclear power stations carry much more of the load. On this basis, my electric car is lower carbon than my old diesel car. However if we all rush out to buy electric cars, the older coal fired power stations will have to come back on power at night. The marginal additional electricity from electric cars will be from high carbon generation.

Meanwhile, it is reported that London black cabs are being brought into service that run on electric power from hydrogen fuel cells. Hydrogen is another clean fuel with only water coming out of the exhaust pipe. One fill and a cab will be able to drive a whole shift driving over 200 miles. This overcomes the range limitation of batteries. This looks like another useful component of the future city transport infrastructure; but where does the hydrogen come from? Answer: Electricity (used to split the hydrogen from water).

There is no avoiding the challenge of decarbonising the electricity supply, without making progress here both the electric and hydrogen car are dead.