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Wind turbines and small hydro
Wind turbines and small hydro (water) systems are renewable technologies capable of generating electricity at home by using power of the wind or the force of moving water. Choosing to source your energy from renewable sources means you can reduce your household's energy bills.
Wind turbines use the power of the wind to turn a propeller or similar mechanism which drives a generator and produces electricity.
The higher the turbine and the further away from obstructions such as trees and buildings, the greater will be the output of the generator. For this reason wind turbines are usually installed on a tower. This may not be practical for urban areas so wind turbines are typically used in rural areas.
Larger wind turbines are well suited to non-urban areas and are best installed at the top of a gentle rise. The wind generally speeds up going over a rise and more energy can be extracted from the generator. Several large wind turbines clustered together form a wind farm. These feed electricity to the electricity grid rather than individual houses.
Wind turbines don't like turbulence which occurs when wind blows around trees or buildings. They should be installed well away from the house to capture stable winds that don't change speed or direction too often. This will also help to situate the wind turbine out of sight and well away from where its noise could be a nuisance. If the turbine is a distance from the house, you'll need to use heavier cables to connect to the house to minimise energy loss.
Stand-alone and hybrid systems
Wind turbines are usually part of a stand-alone power system where they can be used to charge a battery bank. The house runs on electricity from the battery bank, so the battery bank can be seen as a way of storing energy from the wind. In a stand-alone system you should install a back-up generator for times when the wind isn't blowing.
You can also couple the wind turbine with a solar power system giving you a hybrid system with energy supplied from three sources: the wind, the sun and the back-up generator. You'll generally find that it is either windy or sunny or sometimes both and you may not need to run the back-up generator very much at all.
Depending on where you live, you can connect some systems to the mains power grid to feed-in excess electricity.
Before deciding on installing a wind energy system you should undertake some wind speed monitoring to make sure that you have sufficient wind to provide your energy services. Speak to a certified installer for advice. Ensure your installer is endorsed for wind and stand-alone systems. With knowledge of your available wind, a system designer can advise on the position, size and type of wind turbine to maximise your available electricity.
Where a suitable water supply is available, a small hydro energy system can be a very reliable and economic option for providing power to your home. Small (sometimes called micro) hydro systems are generally used in rural areas, and due to the need for a supply of running water, the ability for most households to use this type of energy supply is limited. If you have a permanent stream, creek or river close to your home you may be able to take advantage of this affordable energy source.
As every site is different, small hydro systems vary in how they are set up. However there are general principals—every small hydro system will have a way of collecting the water, feeding it to a turbine, connecting the turbine to a generator, and either running power to the house directly from the generator or by charging batteries before finally returning the water to the stream.
Some (less common) hydro turbines are suspended in large streams, rather than taking the water from the stream.
In each case the power you're able to produce is determined by the flow rate and the head—the height from which the water is falling.
How much power can a hydro turbine produce?
Hydro turbines come in a variety of types and sizes and an experienced system designer can recommend the most appropriate for your circumstances. However, for the majority of turbine types there are two components which together produce a useful output for your system:
- Flow rate. This is generally measured in litres per second and you should undertake a test to measure the flow rate of your water supply while planning your system. The greater the flow rate, the better.
- Head. This is the height from which the water is falling. The greater the height, the more 'push' there will be on the blades of the turbine.
How much water do I need on site?
There generally needs to be a water supply or 'feed stock'. This will normally be a small dam situated as high as possible above the site for the turbine. The inlet to the pipe should include a filter to stop leaves, twigs, and even fish, from entering the pipe. The pipe from the feed stock to the turbine needs to be as large in diameter as is practical and as straight as possible to avoid friction on the bends which slows the flow.
The turbine is connected to a generator and electricity from the generator can be used to run household functions directly (if the generator has enough capacity) or to charge a battery bank. If you're using a battery bank you then connect this to an inverter to supply power to the house.
One of the great features of a hydro energy system is that the water is returned to the stream after passing through the turbine. The environmental flow (the amount of water needed in a watercourse to maintain healthy ecosystems) is maintained. Any water loss will only occur between the feed stock and the point where the water is returned to the stream.
As these systems are located at the stream, the turbine and generator are generally a distance from the house. This minimises any noise but care must be taken to choose heavier cables to minimise energy loss between the generator and the house or battery bank.
Do your research to find out about the right small hydro system for your situation. Contact suppliers about the options available and ensure you get several quotes so you can compare prices and systems. It's a good idea to talk to other people in your area who already have a small hydro system in place.
Rebates are available to help with the cost of installing wind turbines and small hydro. Renewable power incentives in the form of Small-scale technology certificates (STCs) can save thousands on the cost of a new system. Small-scale wind and hydro systems are classified as small generation units (SGUs) and have the same guidelines as solar panels apart from eligibility requirements—see the Australian Government website for more information.
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