Sir – Your correspondents (Messrs’ Bond and Gill, Letters, September 22) believe that Oxfordshire County Council has sold its carbon footprint for a lower price.

Oxfordshire’s councillor Rodney Rose, as reported elsewhere, implies that the electricity companies are ganging up on the county to keep their prices high.

All show a lamentable lack of understanding of the economics of electricity generation.

The bone of contention is the reduction both in carbon footprint and cost that is presumed to occur if street lights are switched off between midnight and 5.30am. This period is precisely that at which demand for electricity is at its lowest.

Because of their design it is impossible to turn many large power stations on and off like light switches.

Because demand is low, it makes good sense to offer the electricity to the market at a low price: a practice used by supermarkets to move goods just before they reach their ‘sell by dates’.

This was the source of the low price from which Oxfordshire benefited.

If the offer is not taken up, the power stations have to continue to operate, the energy is not saved: it is wasted. There is no reduction in carbon footprint or in cost.

There are methods for reducing the carbon footprint, but they all involve either reductions in electricity consumption at peak times, or the use of alternative generation technologies often involving increased costs.

There is ample evidence that good street lighting has many beneficial effects. They include: improved road safety, reduced crime and reduced fear of crime.

Light in the small hours is effectively free: if it is necessary at peak times, then we may as well take the additional benefit at off-peak times.

P Hawtin (Dr) Cumnor