by MarkR » Sun 05 Dec 2004, 08:33:04
This is a very sensible way of improving efficiency.
Currently, electrical demand varies greatly over the course of the day. From very low at night, to very high on a Summer afternoon (when ACs are running full on).
While the bulk of the electricity is supplied by big efficient power plants, the 'peak' electricity is supplied by 'peaking' plants which are, by nature, much lower efficiency and produce electricity at much higher price, both financial and environmental.
Plus, to put it simply, the higher the peak, the more power stations and more transmission lines needed to carry the power.
Peak-shaving has been an established technique - it makes more effective use of large high-efficiency generation and the power grid, and reduces the need for peaking plants - which still need maintenance and staffing, even though they may run only 100-200 hours per year.
In some countries, this is done by using variable priced electricity - e.g. Economy 7 (UK) - electricity supplied at 60% discount between midnight and 0700. Mainly used by storage heaters, which provide 24 hours of heating with 7 hours of electricity.
France has much greater problems because of it's high nuclear capacity - they have 'Tempo' which offers 6 different prices depending on time of day, expected demand on that day (given a colour: red, white or blue). So peak-electricity on a red day, might cost 15x as much as off-peak electricity on a blue day.
These tiered pricing systems put the onus on the consumer to regulate their consumption depending on demand, and they work to some extent. However, additional benefit can be obtained if some demand is under control of the suppliers.