Hydroelectricity

All streams and rivers flow downhill. Before the water flows down the hill, it has potential energy because of its height.

Hydropower systems convert this potential energy into kinetic energy in a turbine, which drives a generator to produce electricity. The greater the height and the more water there is flowing through the turbine, the more electricity generated.

The amount of electricity a system generates also depends on how efficiently it converts the power of the moving water into electrical power.

Hydropower is very site specific. Most homes will not have access to a suitable resource even if they have a watercourse running nearby.  If you might have a suitable site, the next step is to contact a certificated installer, who will assess your site.

To be suitable for electricity generation, a water source needs to have a combination of:

• Flow – how much water is flowing per second.
• Head – a difference in height over a reasonably short distance.

Find out more about hydropower systems and the planning permissions and licences required.

It’s also important to consider what happens to the river in summer. The minimum flow during dry periods is usually the deciding factor, no matter how impressive the river looks when it’s in flood.

If there is a good hydro resource in or near your community, it might be worth developing it as a community energy project, rather than as a system to supply just one home.

If you live in Scotland, find case studies and examples of homeowners who have installed a micro hydro system using our Green Homes Network tool.

Costs for installing a hydro system vary, largely depending on the location and equipment required for install.

Maintenance costs also vary but are usually low. Hydro systems are very reliable.

Savings will depend on the amount of electricity the hydro system generates. This is affected by the number of hours the turbine can run in a year, which in turn depends on how often the level of the river is high enough to supply the system. Your installer will predict this for you and provide estimates on the amount of electricity you can expect to generate.

Signing up for the Smart Export Guarantee tariff means you can receive payments for exported electricity for qualifying systems. Please visit our Smart Export Guarantee page for more information.

Hydro systems were eligible for Feed-in Tariff scheme (FITs) payments. The FITs scheme closed to new applications on 31 March 2019. If you have already installed your hydro system on or before 31 March 2019 you may still be able to apply. For more information about the FITs scheme and recent changes please visit our Feed-in Tariff page.

Once installed, most systems can last for 40-50 years, with low running and maintenance costs and could last for longer if well maintained.

There is potential for damage by debris carried downstream at times of flood, however screening the intake should minimise this risk.