Sir, – Further to “There can be no slowdown in the drive for electric vehicles” (Opinion, April 6th), if we were only considering the local environment where the car was being used, then there is a case to be made for use of electric vehicles. However, when we consider the global environment, electric vehicles, at this point in time, do not make sense. At some point in the future when the use of fossil fuels for generating electricity is eliminated, then electric vehicles will come into their own.
Electric vehicles need to be charge. In Ireland, on average, about 30 per cent of electrical power generated comes from renewable sources.
The remaining 70 per cent comes mainly from fossil fuels (a small percentage comes from imports and the source of that is not clear). Of the fossil fuels used, some comes from coal and some from oil, although these are small amounts – 14 per cent and 7 per cent respectively, with natural gas about 50 per cent. Nevertheless, for the purposes of this discussion, coal and oil have to be considered as the primary source of power to electric cars. One can’t assume that a percentage of the renewable energy goes to charging. The correct way to look at this is that the electric charging can be assumed to be an incremental load.
One then has to consider what source of power generation would be eliminated if that charging load did not exist, ie the fossil fuels burning to be eliminated would be the oil and coal in the first instance.
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To put some numbers on this, when inefficiencies and losses in generation and transmission are considered, only about 25 per cent of the initial energy input from the fossil fuel gets to the user point. If we consider a car burning either petrol or diesel, the actual efficiencies are about 30 per cent and 40 per cent respectively. For electric cars, this translates into a greater emission of CO2 of 20 per cent relative to a petrol car and 60 per cent relative to a diesel car compared with oil burning as a fuel for generating electricity.
For coal-burning generation of electricity, the CO2 emissions would be even higher – 60 per cent and 120 per cent respectively.
Even if we eliminated coal and oil, natural gas would still not be viable – CO2 emissions would be higher by 20 per cent compared with petrol and 60 per cent compared with diesel.
Note that some sources of data yield slightly different figures. Nevertheless, the order of magnitude is correct, so the principle of not using electric cars still holds. Note also that the proposed use of electricity in lieu of fossil fuels for other purposes, eg heat pumps for domestic central heating – suffers from the same misconception. – Yours, etc,
BRENDAN MURPHY,
Sandycove,
Co Dublin.