If you are lucky enough to have a water course across your property, such as a stream, river, or if you are lucky enough to own an old water mill, water turbines are an ideal solution for providing reliable long-term renewable energy.
Hydropower plants capture the energy of falling water to generate electricity. A turbine converts the kinetic energy of falling water into mechanical energy. Then a generator converts the mechanical energy from the turbine into electrical energy.
Hydro plants range in size from "micro-hydro’s" that power only a few homes to giant dams like Hoover Dam that provide electricity for millions of people.
Hydropower converts the energy of flowing water into electricity or hydroelectricity. The amount of electricity generated is determined by the volume of water and the amount of "head" (the height from the turbines in the power plant to the water surface) created by the dam. The greater the flow and head, the more electricity is produced.
You can easily calculate the available power at your site using the following equation: Power (watts) = Head (m) x Flow (litres/sec) x 9.81 (gravitational constant ‘g’) A typical water to wire efficiency is around 70%, so you should multiply the result by 0.7 to get the actual amount of electricity that you can expect from the site.
Most sites vary considerably in flow between winter and summer, reflecting the differences in rainfall. It is important to make sure that the flow is sufficient to run the turbine, and if you wish extract maximum power from the turbine site, it is often desirable to install two turbines, switching in the second machine, when the water flow allows.
Where They Are Used
We have large range of turbines which are quite flexible in the situations they can be used in. They come in various configurations, low head with high volume, medium head with medium volume and high head with low volume. The smallest turbine (200W) is rated at a flow rate of 3 litres per second and a head of only 10m. We also have a range of high head turbines and as the name suggests these turbines are designed to be used on sites with an above average head of water and a relatively low flow of water.
How They Work
The water enters the turbine from the penstock through a nozzle which directs it into a jet and towards the buckets on the turbines runner. The runner is connected via a shaft to the generator which produces a single phase 230v AC supply. (Some of the larger turbines in the table below may have a three phase output so please check before ordering). Any excess power generated is diverted to a ‘dump load’ ballast heating element in the base of the smaller turbines which uses water-cooling to ensure that the load on the turbine remains constant. The larger turbines heating element will be separate and need fixing in place. These machines may be operated for years with minimal maintenance, although it is necessary to apply grease to the bearings using the grease cap a couple of times a month, to ensure a long life. By reducing the jet diameter on these turbines, it is possible to operate them with heads of over 100m.