TABLE OF CONTENTS Part of the reason why the electricity system requires such careful management is that electricity is not a storable commodity. If a peak in demand is on the way, or may be on the way, it is not possible to store up a pile of electricity and release it at the right moment.
This has important implications for managing the electricity grid. Electricity demand is not constant. It tends to go up and down depending on the time of day and of year, as different groups' electricity requirements begin and end. The biggest peak is generally on a winter evening, when domestic demand for heating, lighting and other uses is highest. A summer night has the lowest energy use.
Since it is not possible to store electricity, the aim for an electricity supply company has to be to invest in a diverse range of generation that will give it the best opportunity to match supply and demand.
A mixed system makes the best use of the different types of generation. Some forms of generation are slow to start up and have little flexibility in operation, but in continuous generation they are cost-effective. These plants would typically be operated continuously to supply 'base load' the electricity required even on a summer's night, maybe 30 per cent of the average load. Forms of generation that can be started up within minutes or hours and cycled up and down to provide more or less power...
