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Peter Cochrane's Hard Drive 1998 When the people demand power AT the start of a major sporting event such as a World Cup match, or a televised quiz show or song contest, millions of TVs are switched on within minutes of each other. When it's over - or when the late evening news comes on - a large percentage of the population immediately gets up, goes to the kitchen, and makes coffee or tea. Millions of taps and kettles are turned on within a few minutes and several million lavatories are flushed. The sudden demand for extra water adds to the impact on energy demand as thousands of supply pumps kick in. (Exceptionally, England's exit from the World Cup was followed by a conspicuous lack of demand for power, attributed to the shock of the result). How does the power grid cope with these surges? In many countries the base power load is generated by a combination of huge (billions of watts) nuclear and coal-fired power stations. Economically these stations are best operated flat out at a constant supply level. The peaks of energy demand are often satisfied by pump storage water, hydroelectric, oil and gas-fired units that can be rapidly brought on line. In America they adopted a strategy of introducing more advertising slots on TV to spread out the demand for electricity. Beyond this of course there is the impact of weather, which creates huge demands for extra energy when we get a cold period, and of course the need for more light in winter. So the people who supply our energy have to follow the weather forecasts, keep in touch with TV schedules and much more to be prepared to compensate for the synchronised actions of huge populations. Now all of this might seem sophisticated, or not, depending on your point of view, but either way it has served us well for decades. So, what of the future? In recent years we have seen the remote control of domestic central heating using radio broadcast channels to turn sectors of the country on and off for short periods to help even out the peak demand. People signing up for this option get a better tariff and pay less as a result. Unfortunately, we cannot all benefit from this system as it is implemented today. However, electronics and telecommunication now offer the opportunity to introduce the smart appliance. Instead of the kettle just using a crude heating element, electronic sensors could detect the supply voltage and frequency. If they are low the kettle could demand less current and take longer to boil. On the other hand, if they are high, the kettle could demand more current to boil the water faster. In this manner the problem of over and under loading of the supply can be eased considerably. This also applies to washing machines, dryers, dishwashers, vacuum cleaners, lawn mowers, and other appliances that use high levels of energy. Another opportunity to even out demand is now on offer with telecommunication links controlling appliances, heating systems and water pumps. Go to bed and sometime during the night the dishes and cloths are washed. Who cares when, or who, switches them on? Peter Cochrane holds the Collier Chair for the Public Understanding of Science & Technology at the University of Bristol. His home page is: |
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