Hydro

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Electricity is generated using the energy of water flowing in rivers or streams to rotate a turbine, driving a generator that produces electricity. Water can be stored in reservoirs for use when needed, making this energy source both reliable and stable. Micro hydroelectric plants often have no reservoir and instead divert part of a watercourse for a short distance. If there is no reservoir the power output depends entirely on the water flow, which varies with precipitation and snow melting. It should then be connected to the grid, so that excess electricity production can be sold and shortfall met by the grid.

Types

• Micro-hydro (from 1 to 100kW ) up to very large scale generation

Other components 

• Turbine housing
• Dams and/or diverted watercourses
• Electricity meter that allows electricity export to grid
• Battery if not grid-connected

Typical saving

Zero carbon renewable energy source. Electricity output and savings depend on height difference (head) in the watercourse and the flow. A small hydro system (1 to 3kW) could meet the annual equivalent of a typical household’s annual electricity requirements.

Indicative cost

Can be cost intensive to build and maintain, but have a long life time. Lower cost turbine-generator units have now been developed for a wide range of heads and flows. These are manufactured in the UK and available at prices of less than £2000 per kW.

Main issues affecting feasibility

• Local hydro resource: Requires sufficient flow of water, eg mountain stream, dammed watercourse or mill race. Sites have been identified in the Y&H region.
• Licence to use watercourse: Required from the Environment Agency.
• Ecological impacts: affecting natural and cultural heritage, water regimes, fisheries, aquatic habitats and species.
• Social impacts: including population displacement for some large schemes.

Further information

www.energysavingtrust.org.uk/Generate-your-own-energy/Hydroelectricity