Hydropower, and small hydropower (SHP) in particular, is recognized as a flexible and affordable renewable energy source. Its role in electricity generation, especially in rapidly developing countries, is crucial. The World Commission on Dams (WCD, 2002) focused attention internationally on the negative environmental and social impacts of large dams, which raised questions about the environmental sustainability of large hydropower projects. However, only about 25 percent of the world’s large dams are involved in producing hydropower. The rest were built for other purposes, mainly for irrigation, but also for water storage, for recreation and for assisting in river transport. Conversely, many large hydropower projects are run-of-river projects, which do not necessitate the building of a dam, while the role of small, mini- and micro-hydropower schemes is becoming increasingly important in the energy security of many countries, led by the example of China. It is therefore important to disassociate a discussion of the role of hydropower from the debate over large dams, while not glossing over the environmental and social considerations involved in the choice of technology.
■ Pumped storage: This involves pairs of reservoirs with
a significant height difference. Water is pumped when
there is spare capacity in the network and then allowed
to flow down again and generate power at times of
peak demand. It uses more power than it generates,
but is essential as a flexible reserve and can make an
electricity network more efficient.
Run-of-river: This form of hydropower uses the stream’s flow and has little or no reservoir capacity or storage or regulation. In social and environmental terms, it is seen as preferable to reservoir construction. Smaller hydropower schemes (including micro- and pico-hydro) are usually run-of-river projects, but the technology is increasingly being applied in large schemes where the topography makes it feasible, as fast-flowing water is required.
Other Two types are
Reservoirs: This type of hydropower involves the
construction of a dam (large or small) and the
formation of a reservoir. Such construction is usually
multi-purpose, both for water supply and for electricity
production. This type of hydropower brings maximum
flexibility of supply and maximum efficiency.
construction of a dam (large or small) and the
formation of a reservoir. Such construction is usually
multi-purpose, both for water supply and for electricity
production. This type of hydropower brings maximum
flexibility of supply and maximum efficiency.
■ Pumped storage: This involves pairs of reservoirs with
a significant height difference. Water is pumped when
there is spare capacity in the network and then allowed
to flow down again and generate power at times of
peak demand. It uses more power than it generates,
but is essential as a flexible reserve and can make an
electricity network more efficient.
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