3 Responses

1. No carbon is consumed.

2. Once a dam is constructed, electricity can be produced at a constant rate.
   If electricity is not needed, the sluice gates can be shut, stopping electricity generation. The water can be saved for use another time when electricity demand is high. The build up of water in the lake means that energy can be stored until needed, when the water is released to produce electricity.
   Dams are designed to last many decades and so can contribute to the generation of electricity for many years / decades.
   The lake that forms behind the dam can be used for water sports and leisure / pleasure activities. Often large dams become tourist attractions in their own right.
   The lake’s water can be used for irrigation purposes.
   When in use, electricity produced by dam systems do not produce green house gases. They do not pollute the atmosphere.

3. You’ve already received one quite reasonable, if not complete, answer.

   The main attractions of hydro plants, at least for those associated with building them are:
   1. The fuel (rainfall) comes free of charge and there’s no risk exposure to future fuel prices.
   2. The machinery runs at low temperatures and can therefore be started, stopped and loaded or unloaded very fast to respond to sudden changes in load demand or the loss of other generation on the network.
   3. The river which runs out of the plant can be much better controlled than without the dam. With proper water management, floods can be prevented during the wet season and water stored to provide flow and irrigation during dry periods.

   Those who build them are not particularly motivated by saving carbon emissions – but it does make good publicity sometimes.