A micro-hydro system generates electricity from flowing water in a stream or river. These systems are typically used as standalone power supplies (SAPS) for off-grid homes, cabins, farms, and small remote communities. Micro-hydro systems usually produce up to 100 kW of electricity, although most residential systems are much smaller.
Unlike solar or wind power, micro-hydro can generate electricity continuously as long as water is flowing. Because of this, even a small system can produce a reliable amount of energy over time.
Micro-hydro systems are most suitable for properties with a consistent water source and sufficient elevation drop. In Australia, these conditions are relatively rare, which is why micro-hydro installations are far less common than solar systems.
- 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
How a micro-hydro system works
A micro-hydro system works on water pressure. Usually water collects 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 develops 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 charges batteries. The distance is variable, it can range from 5 to 50 meters and the wiring is sized accordingly to the distance and voltage of the system. The batteries then charge and can perform at night or during the day through an inverter to run most of the common appliances.
Two types of micro-hydro / water power systems
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.
How to choose the appropriate micro-hydro system
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. That can be suitable for some specially designs of low pressure high flow rate turbines.
The amount of energy production 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 is minimal, and the wiring can run over a longer distance due to the higher voltage.
The advantages of micro-hydro / water power
Micro-hydro systems are a fantastic source of renewable energy. They do not require too much maintenance. The pipes need cleaning every once in a while. Otherwise, the systems 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. Hence they do not contribute to global warming.
Micro hydro in Australia
Unfortunately, there are 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 to focus on providing components and systems for renewable resources such as solar power and wind energy which are both plentiful in Australia.
