Hydroelectric power generates about 10% of the nation’s energy.
Flowing water creates energy that can be captured and turned into electricity. This is called hydroelectric power or hydropower.
The most common type of hydroelectric power plant uses a dam on a river to store water in a reservoir. Water released from the reservoir flows through a turbine, spinning it, which in turn activates a generator to produce electricity. But hydroelectric power doesn’t necessarily require a large dam. Some hydroelectric power plants just use a small canal to channel the river water through a turbine.
Another type of hydroelectric power plant – called a pumped storage plant – can even store power. The power is sent from a power grid into the electric generators. The generators then spin the turbines backward, which causes the turbines to pump water from a river or lower reservoir to an upper reservoir, where the power is stored. To use the power, the water is released from the upper reservoir back down into the river or lower reservoir. This spins the turbines forward, activating the generators to produce electricity.
A small or micro-hydroelectric power system can produce enough electricity for a home, farm, or ranch.
Hydroelectricity is based on the power of gravity. Water in rivers and streams flows downwards towards the sea; as the water passes through a hydropower system, the energy in the water drives a turbine which turns a generator and energy is produced.
The power of the system will depend on the strength of the water passing through, as well as the efficiency of the system.
There are three standard types of hydropower systems. The first is a standard ‘run of river’ system, which uses the existing flow of the river. Water is typically redirected to pass through the turbine and the water is passed back into the river or stream.
While this system is the most straightforward, it also has the disadvantage of being entirely dependent on the river strength. If your river goes dry due to drought, your system will not run.
However, due to its simplicity it is also the most typical to use for domestic or community systems.
The second type is a storage system, or dam, which is the most common form. Dams are used for large-scale hydroelectricity projects around the world, but can also be used for smaller systems.
A reservoir stores the water from the river and lets it through gradually. This offers a greater degree of control because the system can still work if the river runs dry.
The final type is a pumped system, which uses cheaper, off-peak energy to pump stored water back up to a higher point to generate energy at peak times.
Is domestic hydropower practical?
Hydropower’s practicality depends entirely on your access to running water. But, even if you have a river or stream nearby, it doesn’t mean you can automatically consider hydropower.
If you think you may be eligible, you should contact a certified hydropower installer who can take a look at your site. Whether it is suitable or not will depend not only on your location and access, but also how steeply the river flows and how much water passes through.
You should also consider the seasons. Your river’s lowest level will determine how feasible your site is more than your river’s highest level. This in turn will vary year by year depending on rainfall levels.
The Energy Saving Trust recommends hydropower as an excellent community development project. This will lower installation costs and give you greater flexibility around installation.
How much does it cost?
The cost of a hydroelectricity system depends almost entirely on its size and where you put it.
The costs are likely to be significant either way. A typical 5kW system to power one home will cost around £25,000, but it could be more or less. The good news is that once the system is installed it requires very little upkeep.
How much energy the system will generate, and hence what your savings will be, is even harder to estimate as it will depend not only on the system, but also how long it is able to operate at full efficiency, which in turn depends on the water levels in your area.
What are the advantages and disadvantages of hydroelectricity?
The pros include:
- A clean, renewable resource perfect for a wet climate like the UK
- Almost maintenance free; a system life expectancy of up to 50 years
The cons include:
- Installation costs are high
- Suitability depends entirely on location and other factors
- Energy generated can be easy to predict, but will be highly seasonal