Water Energy

Water is a key player in the renewable energy field.  Water is used in many renewable energy technologies as a medium to transfer either the energy of the sun, the earth, or biomass to heat space, water, or generate electricity.

Waterwheels
Before water was used to generate electricity, it was harnessed to produce mechanical power.  Mills for grinding grains or sawing wood, or billows in a blacksmith forge where powered by a waterwheel.  While these uses are not as common now, they are still viable applications. 

Large Hydro
There are massive amounts of energy flowing through rivers.  Even though large hydro projects are known to have adverse environmental impacts on river ecology, they have come to account for a percentage of the electricity generated in Canada.  Huge dams create a reservoir and height for the penstock through which water flows to turbines.  Mactaquac, a 672 Megawatt installation, and Beechwood, a 113 Megawatt installation, are just 2 of the 7 sites that generate hydroelectricity in New Brunswick.  Both are on the St. John River, 19 km and 160 km north of Fredericton respectively.

Micro hydro Electricity
Micro hydro has a very loose definition as it includes operations under 1kW or even up to 100kW.  Similar in theory to large hydro, micro hydro is one of the most environmentally friendly ways to make electricity because the scale of the intake system and the turbine do not have a big impact on the river ecology.  If the conditions are good, meaning the source will be flowing 24 hours a day 365 days a year, hydro can be cheaper and a more consistent producer of electricity than solar or wind.
Micro hydro turbines can be built to different specifications tailored to the site, which are divided into two basic categories.  One turbine is low flow, high head for smaller streams that are on the side of a steep hill.  The other is high flow, low head, which would be more appropriate for a waterway that has a very low grade of slope but a lot of water flowing.

Because of the higher density of water, similar outputs to wind can be achieved with much smaller turbines. The turbine itself may be as small as 10 centimetres in diameter, and consists of spoon-shaped cups arranged around the centre of a wheel. The wheel is mounted on a shaft that turns smoothly on sealed bearings. A small amount of water is diverted from the stream into the penstock, a pipe that amplifies water pressure and directs jets of high-pressure water onto the turbine fins causing the wheel to spin at high speed. The spinning shaft can be used to power a variety of machines, including electrical generators, woodworking tools, pumps, fans, and more. 

Some basic definitions of the terms involved in micro hydro:

Intake:  The point where water is diverted from the water way.
Penstock:  The pipe down which water is directed to the turbine.
Turbine: The waterwheel that turns the generator.
Flow:  The amount of water flowing past a given point in a given period of time.
Head:  The distance between the intake of the penstock and the turbine.