Why Electric Cars are Really Coal Cars

I saw a wonderful play at the Royal Court Theatre in London recently: "The Heretic" by Richard Bean. In a nutshell, the plot centres on a female academic, Dr Diane Cassell, who is researching sea-level rise. She finds none at some measurement point in the Maldives, but realises that both land and sea are rising together. Thus, while sea-levels are indeed rising, the islanders are unlikely to be forced from their lands by them. If she publishes her results, the department stands to lose a very lucrative contract from an insurance company and so her Head of Department forbids her to go public which she does, and on national television at that, so getting fired from her job. The Human Resources person is grimly hilarious.

In the play, one of her students with utterly green credentials including eating lots of garlic to apparently curb his own bodily greenhouse-gas emissions, refuses to go on a field trip in the university minibus on the grounds that it runs on fossil fuels, preferring instead to cycle forty miles there and forty miles back.

Diane asks him: "In your green future, how would we get fourteen students fifty miles to the North Yorkshire Weather Station?"
He replies: "There should be like an electric car/minibus. Electric cars don't have any emissions."
Diane responds: "Electric cars should be called coal cars. 30% of our energy comes from coal. Electricity is not naturally occurring in nature."

Now this does raise an issue about the "cleanliness" of electricity, which is all the more salient in view of the U.K. government's aim to install thousands of electric charging points around the country for electric cars with the aim to "wean us off imported oil". However, the majority of electricity in the U.K. is generated using power stations fired by coal (28%) and gas (45%), and hence even if a substantial substitution of the present 30 million British oil-fuelled cars by electric vehicles could be made, it would entail the consumption of vast quantities of these other fossil fuels instead to provide the additional electricity for them.

It is claimed in a Royal Academy of Engineering (RAE) report on electric cars that they are in any case cleaner because 80 - 90% of the energy put into them in terms of electricity is recovered in terms of useful power at the wheels, to be compared with 20 - 30% in a conventional oil-powered car. Well, that sounds good, but the reality is that only about one third of the energy in the coal or gas actually ends-up as electricity because of the Second Law of Thermodynamics and the Carnot Cycle limit - the other two thirds being thrown away as heat. Thus the electric car is harvesting in terms of well-to-wheel miles only about 27% of the original fossil fuel energy, so not that much better than the standard car running on petrol or diesel. The difference is merely whether about the same quantity of waste heat energy is thrown away at source or in the vehicle.

The green energy company, Ecotricity refers to electric cars as "wind-cars", to stress that they could run on electricity made from green sources such as wind. Indeed, the U.K. has made the decision to focus on wind-energy to meet its carbon-emissions targets, and plans to build offshore wind-farms on an impressive scale to do the job. It is advised by the Committee on Climate Change that by 2020, 1.7 million electric cars should be on Britain's roads, or just over 5%, which I don't honestly see would make a serious hole in our demand for imported crude oil.

To decarbonize the national grid would require another 30 - 40 GW of green generating power, or "the equivalent of a hundred large offshore wind-farms," according to the chief economist of the CCC. These would need to be large indeed. Assuming a rated capacity per turbine of 5 MW, and a capacity factor (actual output) of 30%, we have 1.5 MW for each. Thus we need around 20,000 - 27,000 turbines to produce 30 - 40 GW of power. So that means 100 wind-farms with 200 - 270 turbines each. If one turbine per day were manufactured, no mean feat given present manufacturing capacity, the process would take 55 - 74 years to complete, with the installation of them as a separate effort. As noted in previous posts, there is the further question of whether there will be sufficient quantities of rare earth elements (REEs) available on the world markets to make the turbine magnets which need about one tonne of neodymium per 4 MW of rated capacity.

Clearly, we have a serious problem in switching from dirty oil cars to green electric cars, which will need to be built themselves. There are many issues of the materials needed per se, and a hybrid car e.g. a Prius needs 1 kg of praseodymium for its motor plus 15 kg of Lanthanum for its battery, while a fully electric vehicle will require much more of each. Personal electric cars are still a far better option than personal hydrogen cars for all kinds of reasons, but if governments are serious about introducing electric transportation in place of oil, the creation of electrified mass passenger transport, e.g. trains and trams would be the better way to go.

By. Professor Chris Rhodes

Professor Chris Rhodes is a writer and researcher. He studied chemistry at Sussex University, earning both a B.Sc and a Doctoral degree (D.Phil.); rising to become the youngest professor of physical chemistry in the U.K. at the age of 34.
A prolific author, Chris has published more than 400 research and popular science articles (some in national newspapers: The Independent and The Daily Telegraph)
He has recently published his first novel, "University Shambles" was published in April 2009 (Melrose Books). http://universityshambles.com