Hydroelectricity

Hydroelectricity is the extraction and conversion of energy from water into its most useful form; electricity. Where water flows from a high level to a low level, turbines are used to capture the energy in this flow to drive a generator to produce electricity. This can be done in two main ways. The first simply uses the direct flow of water in a river and extracts energy according to how high or low the flow is through a water wheel connected to a turbine. The second dams the river to capture and store the water until it is needed.

Water wheels can be used on a domestic scale if a river or stream with enough water or with a high drop is present on the property, though planning permission is needed for this in most areas, it may not be required. Excess electricity produced can be sold back to the grid.

Before connecting your turbine to the electricity grid, you will need to meet the regulations of your local electricity distribution company. This varies with the installation size - if your turbine is rated at under 3.6kW for a single phase supply (or 11.2kW for a three phase supply) then you will only need to complete a G83 form that certifies that the system meets the applicable standards. These forms should be supplied by your installer or may be obtained from the local electricity distribution company. You should then have an automatic connection to the distribution network as long as you can comply with the terms set in G83. If your turbine is larger than this, you will need to contact your distribution company and negotiate directly for a connection.

You may also be eligible to earn additional payments for renewable electricity generated through the Government’s Renewables Obligation, by selling Renewable Obligation Certificates (ROCs). These ROCs are granted by the energy regulator, Ofgem, for every megawatt hour (MWh) of power generated from a renewable source. Each Certificate may be traded, and they currently have a value of around 3p per kWh, with the exact value dependent on the demand for, and availability of, renewable electricity. Some electricity companies, such as Good Energy, will aggregate renewable electricity production from their domestic customers, and pay you the value of the ROCs that they are able to sell on your behalf from this process on an annual basis. (A typical building-integrated renewable system will not generate enough electricity to earn a whole ROC in a year). There is normally a charge by the electricity company for acting as your agent in this aggregation process, and all small generators seeking ROCs must have a total generation meter approved by Ofgem. If your turbine system installed is very small, it may not prove economic to claim ROCs.