Straits Times Forum 14 May 09;
I REFER to Monday's report, 'What green light for electric motoring means', which described the Government's $20 million investment in research on use of electric cars to improve the environment. Contrary to general belief, electric vehicles will actually increase fuel consumption and hence the carbon footprint.
Conventional vehicles convert the energy stored in petrol or diesel to kinetic energy, which runs the vehicles. In this case, only one conversion of energy is involved. In electric vehicles, the batteries in the vehicle are charged by household electric power supply. The electric power is supplied by power stations.
In the power station, natural gas or oil is burned to heat water and generate steam. The steam drives steam turbines which in turn drive generators to produce electric power.
The power is transmitted over transmission lines to homes. To charge the batteries, the AC power supplied is converted to DC power. This involves conversion of energy four times, namely gas or oil to steam, steam to kinetic, kinetic to electric and AC power to DC power. Each conversion of energy results in loss of energy due to conversion efficiency. There is also energy loss in transmission.
Therefore, the overall efficiency of electric vehicles is lower than that of conventional vehicles and the carbon footprint is larger. This is why in Hong Kong, household water heaters are gas and not electric. Even PUB once advertised to encourage use of gas heaters.
Electric vehicles do not pollute the streets and are noiseless compared to petrol- or diesel-driven vehicles. But the overall pollution of the environment will be high since power stations will have to burn more fuel to generate additional electric power to charge the batteries. The pollution is only shifted from residential areas to the atmosphere around power stations.
M.S. Suresh
