All electric? Newer cars should match efficiency of existing vehicles

With reference to ‘Sparking debate: more factors affecting the mass uptake of electric cars’ (The Engineer, 23 November 2009), the issue of recharging electric cars raises further problems. For example, in the UK, burning fossil fuels as a means of generating electricity is the largest contributor to carbon dioxide emissions.

As the bulk of the electrical energy generated in the UK originates from fossil-fuel-based power stations, by the time the electricity has reached that stage suitable for recharging electric cars, more than 50 per cent of the original energy has been lost. When the less-than-perfect recharging efficiency of the battery is added, it is possible that more carbon-dioxide emissions are generated when using electric cars, simply because of how our electricity is generated and transmitted.

In the US, the Fisker Karma petrol electric car follows the railway diesel electric locomotive method: it uses an internal combustion engine optimised for maximum fuel efficiency running at a near constant speed to drive an electric generator, which in turn powers electric motors to drive the wheels. In addition, the motors, when braking is required, are reconfigured to act as electrical generators, so what would otherwise be wasted energy can then be stored and used to supplement the electrical generator when accelerating.

No charging points are needed, there is no demand from power stations, internal combustion engines are optimised for fuel efficiency and fuel economy, driving ranges are at least as good as current cars, with excellent acceleration and top speed, indicative of the best use of electric motors.

The all-electric car may come to be and match the efficiency of current cars, but only when the appropriate infrastructure is in place, and only once electricity-generating systems are in place that are not based upon fossil fuels, and/or have more localised generating points for transportation systems.
Andrew Porter, Hitchin