Hydro Power
Hydro power is perhaps the most long-established renewable energy technology. The first water wheels - used in irrigation - were developed in the far-east over two-thousand years ago. Later, waterwheels were applied to milling (hence watermills); by the time of the Industrial Revolution the use of waterwheels was extensive: working the bellows in foundries and forges, driving the machinery of factories. Mechanical outputs ranged from a few hundred watts to a few tens of kilowatts. Towards the middle of the 19th Century the first water turbines were developed. The turbine was distinct from the wheel in that it was smaller, more compact, more efficient, and ran at a higher speed. The latter qualities made the water turbine particularly suited to use in electricity generation.
Hydro power systems use running water turning a turbine to produce electricity. A micro hydro plant is one that generates less than 100kW. Improvements in small turbine and generator technology mean that micro hydro schemes are an attractive means of producing electricity. Useful power may be produced from even a small stream.
For houses with no mains connection but with access to a micro hydro site, a good hydro system can generate a steady, more reliable electricity supply than other renewable technologies at a lower cost. Total system costs can be high but often less than the cost of a grid connection and with no electricity bills to follow.
It should be noted that in off grid applications the power is used for lighting and electrical appliances. However, space and water heating can be supplied when available power exceeds demand.
Hydro power systems convert potential energy stored in water held at height to kinetic energy
