Hydroelectricity generation explained

This is how hydroelectricity systems use flowing water to generate electricity:

1. Water from streams and rivers flows downhill. The higher the water source, the more potential energy it has and the more electricity the system can generate.
2. Flowing water passes through a narrow tunnel called a penstock. This turns the water’s potential energy into kinetic energy.
3. Water rushes through a turbine, causing it to spin.
4. The turbine powers a generator to produce electricity.
5. Electricity runs through a transformer to turn it from direct current (DC) to alternating current (AC).
6. The electricity generated can power your home or you can sell it to the grid.

Whether you can install a hydroelectric generator very much depends on the site itself. Most homes won’t have access to a suitable site even if they have a watercourse running nearby.

If you think you have a suitable site nearby, speak to your environment agency first. For more information, visit GOV.UK.

A suitable site needs a water source with a combination of:

• Flow – how much water is flowing through the system.
• Head – the difference in height between the water at the top of the system and the bottom.

It’s also important to consider what happens to the watercourse in summer. How much water flows during dry periods is usually the deciding factor in whether a site is suitable. Even if a river looks impressive at full flow, its ‘minimum flow’ is what assessors will consider.

If there’s a good hydro resource in your community, it might be worth developing it as a community energy project.

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

Yes, all hydropower systems need planning permission. You should get in touch with your local authority as early as possible to make sure you get the right permissions.

If you’re in Scotland, you may also need to apply for a water abstraction licence.

Costs for installing a hydro system are very specific to the site, so it varies depending on:

• where you want to install it
• what equipment you need for the installation

According to the Centre for Alternative Technology, expect a hydropower system to cost around £5,000 to £6,000 for a small, 1kW off-grid generator, plus installation costs.

Your savings will depend on the amount of electricity the system generates. This depends on:

• the number of hours the turbine can run in a year
• how often the level of the water 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.

Yes, you can. If you sign up for the Smart Export Guarantee, you can get payments for the excess electricity you export.

The Smart Export Guarantee doesn’t apply to Northern Ireland. Instead, speak to your energy supplier direct and ask if they offer an export tariff.

Most hydropower systems can last for 40-50 years, with low running and maintenance costs. If they’re well maintained, they could last even longer.

There is potential for damage by debris that’s carried downstream during flooding. But you can add a screen to the system to minimise this risk.

Hydroelectricity might not be suitable for everyone. However, there are other options available to generate your own energy:

• Solar panels: Sunlight is free, so why not reduce your energy bills with a solar panel system?
• Wind turbines: If you live in an open, exposed location, a wind turbine can turn the lightest breeze into electricity for your home.