Small hydroelectric power system can be installed in small rivers or streams and is used as a stand alone power supply (SAPS). They have a capacity of up to 100kW and can be used to supply energy for a cabins and small remote communities that only require a small amount of electricity.
- How a micro-hydro/ water power system works
- Two types of micro-hydro systems
- How to choose the appropriate micro-hydro system
- The advantages of micro-hydro
- Micro-hydro in Australia
A micro-hydro system works on water pressure. Usually water is collected via a pipe in a river or stream. The water then flows down a hill to develop head which gives pressure. At the bottom of the hill, once the water has developed enough pressure, it is then put through a small jet which is directed onto a pelton wheel which is like a series of spoon-shaped cups mounted on a disk.
As the high pressure water hits these cups it turns an alternator around which generates electricity. Usually the alternator is used to charge batteries. The distance is variable, it can range from 5 meters to 50 meters and the wiring has to be sized accordingly to the distance and voltage of the system. The batteries are then being charged and can be used at night or during the day through an inverter to run most of the common appliances.
Two types of turbines exist: impulse and reaction. The impulse turbine is not immersed in water, it runs freely with air and water is then directed onto it by jets. Reaction turbines are immersed in water and sealed in a case. In this case the water passes the turbine and continues to pass through via a pipe back to the waterway.
These two different options of a micro-hydro system depend on low head or high head. The high pressure pelton type of turbine is preferable if you can develop enough pressure due to higher head. If the head is not sufficient to develop good pressure then a high flow, low pressure turbine would be more suitable.
If the head is not suitable, it is better to use the semi-submersed turbine which works on the flow of water in a stream by spinning a paddle-type of alternator.
The other option, the low head, is to use a large diameter pipe in a creek, which can give a high flow rate and be suitable for some specially designed low pressure high flow rate turbine.
The amount of energy produced depends on the head (height from which the water is channeling down) and the flow of the water. The mathematical formula to calculate the available water power is the following: E = mgh, where E = energy, m = mass, g = gravity, h= height
water power = head x flow x gravity
The inverter is mounted near the batteries. The inverter converts the current from DC to AC voltage to run common appliances. As the voltage is very high wiring can be kept to a minimum and the wiring can be run over a longer distance due to the higher voltage.
Micro-hydro systems are a fantastic source of renewable energy and they do not require too much maintenance, the pipes need to be cleaned every once in a while, otherwise they run themselves. A micro-hydro system does a similar job to what a solar or wind system does, which is charge batteries. At times micro-hydro systems are a more cost-effective alternative than a grid connect system.
One advantage of hydro systems is that it can be a more reliable source of power as it can be running 24 hours a day continuously. Another wonderful advantage about micro-hydro systems is that hydropower produces no greenhouse gas emissions, and hence do not contribute to global warming.
Unfortunately, there are very few areas in Australia that have a sufficient amount of running water on properties to make it worthwhile. For this reason, Energy Matters doesn’t stock such equipment; opting