If you are fortunate enough to have a stream running through your property, you might be able to generate hydropower. Microhydropower is a term used to describe very small hydropower systems. The definition of microhydropower varies, but is generally below 300 kilowatts. At this size, the system can be operated as a “run of the river” installation, without the need for significantly altering the site with dams for water storage.
Microhydropower systems use water pressure to move a mechanical device (the turbine), which then drives a generator to produce electricity or performs work directly. The advantages of microhydropower systems are that they run continuously and the energy produced is predictable. However, river flows vary across the seasons, and year-to-year, so accurately determining the resource is very important.
The key determinates of the available resource are head and flow. Head is the vertical distance the water falls. Flow is the volume of the water. The power generated by a hydropower system is the product of the head, the flow, and the efficiency of the equipment.
The major components of a typical microhydropower system include the intake from the river, the penstock, the turbine, and the generator. The penstock delivers the water to the turbine, which rotates and powers the generator. Batteries may be used for storage. Most microhydropower systems use a DC generator to charge a battery bank. An inverter may be used to produce AC electricity.
A dealer will want to know the head and flow at your site. You can hire someone to assess your site resources or do it yourself.
You’ll need to know the vertical distance from the water intake to the turbine. If you do the assessment yourself, you will need to make some decisions about where to locate the water intake and turbine. If you hire a dealer, they will determine the system location and measure the head for you.
There are a number of ways to measure head, using surveying techniques, altimeters, or a simple water-filled tube and pressure gauge. Whichever method is used, three separate measurements should be taken at your site to verify accuracy.
Determining flow at a site is much more difficult to measure. Flow varies throughout the year; therefore, a one time measurement is not very useful. Ideally, a hydrological study should be performed, which involves checking records of regional rainfall and water flows.