Select Committee on Environmental Audit Written Evidence

Memorandum submitted by Tom Midgley

  An objection often raised against the widespread use of renewable power sources is that they are not guaranteed to be constantly available. I would like to put to the committee the thought that matching supply to demand is inevitably a complex business, and that while variable supply increases that complexity it is not beyond the wit of man.


  Our electricity supply system has been built around the reality that demand for power varies through the day, from day to day, geographically, and with the seasons. The current design of the electricity system assumes that supply will be constantly available and—for the most part—controllable[204].

  This is not a necessary assumption. Many of the natural power sources available to us—wind, wave, solar—are neither constant nor controllable, and if we are to make best use of them rethinking and redesign will obviously be necessary.

  If we move from a few, large, controllable generators to a many, smaller sources with time-varying outputs, it becomes a statistical question what mix of technologies will best provide electricity at an appropriate service level.

  It might be for example that a certain mix of wind and solar power would require backup from coal-fired stations on 14 days of the year to meet demand, but that by substituting some wave power this would be reduced to five days.

  I would hope that this committee would be able to recommend that analytical tools should be developed, able to establish the optimal mix of power sources to provide a defined level of security of supply, taking into account the statistical distribution of the supply technologies—wind, wave, solar—and the daily and seasonal demand for electricity.

  Whilst our requirement is to perform this analysis for the UK, the optimum mix will be very different in other parts of the world, and we would render the world an enormous service if our analysis were done in such a way that the different parameters of each country could be simply "plugged in". Thus, in the UK an important factor is the wintertime correlation between the high demand for heat and the peak availability of wave power, in Bahrain the simultaneous demand for air-conditioning and the availability of solar electricity would be more significant.

22 September 2005

204   The exception of course is Nuclear Generation which is extremely inflexible, hence the millions of night-storage heaters which were installed to try to use the output at times of low demand. Back

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