HYDROPOWER AND INTERMITTENT RENEWABLE GENERATION
The amount of electricity generation from sources such as wind energy and solar power is increasing in all parts of the world. The output from this type of power generation plant is intermittent, and this causes problems for grid operators who must maintain their grids in balance while absorbing all the energy from these sources when it is available.
The traditional solution to this balancing problem is to maintain fossil fuel– fired plants on standby so that they can be brought into service as the renewable sources fail. Typically some form of gas turbine–based plant will be used to pro- vide this backup. However, where hydropower capacity based on dam and reservoir plants are available, these can often provide both a faster-acting and cheaper means of maintaining the grid in balance.
Pumped storage hydropower plants have provided an energy storage and grid support service for many years (see Chapter 10 on energy storage), but nor- mal hydropower schemes can provide the same service so long as they are operating within their safety limits. A reservoir that is near flood levels will have to lose water whether power is needed or not, and one that is emptied during a dry season may not be able to generate. At other times, however, the plant should be able to stop and start as necessary. Grid support of this type can earn a power plant additional revenue and, as renewable generating capacities increase, hydropower is likely to be seen as increasingly important.