Wind energy is both green and fun, so the idea of building one’s own wind turbine is a good one. The following will give you an idea of what is involved.
Wind energy on a large scale is now competitive with other sources of electricity on a commercial scale. However, small domestic-sized wind turbines have not yet reached this point. The wind is free, but small wind turbines are expensive in relation to what they produce, and cannot realistically compete with mains electricity. Building your own machine saves some of the cost, but please do not underestimate the difficulty of the task. If it were easy to save money by using small wind turbines, then they would be a major feature of the landscape by now.
Most residential locations are not suitable for windpower as trees and buildings break the force of the wind, and create turbulent gusts which can be very destructive. Open hilltop sites or coastal situations with unobstructed views may be suitable for siting a wind turbine. A very tall tower is helpful, but these are not always appreciated by your neighbours.
What size of wind turbine do I need?
Wind turbines work with thin air, so they need to be large in relation to the power they produce. To power a modern home on a good site, the blades would need to span about 5 metres from tip to tip. This is known as the rotor diameter. With careful conservation of energy a smaller machine may suffice. A rotor diameter of 2 metres might yield about 500 kWh of electricity per year, compared with an average annual household consumption of roughly 4,500 kWh.
What sort of generator should I use?
Most small wind turbines are used for charging batteries, to provide a reliable stand-alone power source where grid power is not available. The obvious choice of generator for self-build is the car alternator. However this has major drawbacks. It must be driven at a high shaft speed (over 2000 rpm) to give full output, so you will need to gear it up or modify it in some way to drive it with rotor blades, which typically only manage a few hundred rpm. This reduces the efficiency. In low windspeeds there is very little power available in the wind, and you need a highly efficient generator to capture it. Most, if not all of the power in light winds will be used up energising the magnetic field in the alternator, so the results are disappointing. Nearly all small commercial wind turbines use purpose-built permanent magnet generators for this reason. The DIY enthusiast can make one too, but this is not simple to do. Or you can reuse a permanent magnet motor as a generator. The generator is the key to success or failure of the project, and by far the hardest part to get right.
Can I make my own blades?
The good news is that yes, many beginners have made very useful wind turbine blades, often carved from wood. Or there are sources where you can buy them ready made. If you plan on making your own, it is well worth doing some research and finding out all you can about it in advance. Not only will this save you from ‘reinventing the wheel’ but it will also be safer. Safety is an important issue even with the smallest wind turbines. Never underestimate the destructive power of a runaway windmill rotor in a high wind. Make sure that you have built-in protection against all eventualities. Control systems are as important as any other part of the wind turbine.
Its not easy building your own wind turbine but with skill and dedication it can be very satisfying.
UK: Families can earn £900 a year by installing solar panels on their roofs as part of a new Government scheme to pay people to generate their own electricity.
Under the deal, which will start from April this year, households will be paid for electricity fed into the grid from renewable technologies such as solar, wind or energy from waste.
The most attractive rate of return will be on solar panels, which for an average sized three bedroom home could earn households £25,000 over 25 years.
Ed Miliband, the Energy and Climate Change Secretary, expects one in 10 homes will have installed renewable power on their homes in the next decade expects with the number of homes with solar panels alone rising from 10,000 today to 700,000 by 2020.
He pointed out that the payments would be tax-free and a return of up to 9 per cent annually was better than any bank could provide.
However campaigners said the scheme, that will add around £11 on the average household bill by 2020 as electricity companies recoup the costs from everyone, is just another “green tax”.
The deal, called feed-in tariffs, will ensure that any households or building that invest in installing renewable electricity, should be paid a good rate of return. People who currently have solar panels must do a deal with their electricity company. The panels cannot provide a home’s entire energy needs as they only work in daylight and the energy they generate cannot be stored. When they are generating electricity, any surplus goes straight into the national grid.
“The guarantee of getting an income on top of saving on energy bills will be an incentive to householders and communities wanting to make the move to low carbon living,” said Miliband.
“The feed-in tariff will change the way householders and communities think about their future energy needs, making the payback for investment far shorter than in the past.
“It will also change the outlook for a range of industries, in particular those in the business of producing and installing small scale low carbon technology.”
Solar panels get the best rate of return under the feed-in tariff, followed by wind turbines and hydroelectric.
Installing solar panels, which cover a space of around 10ft x 10ft on an average sized roof, will cost around £12,500 but this will be paid back in10 years because the households will be paid £900 per annum, plus making £140 savings on the yearly electricity bill.
Mr Miliband also introduced a renewable heat incentive that will pay households for producing their own heat from woodchip boilers or an air source heat pump. A ground source heat pump, that costs more than £1,000 to put in, could be rewarded with £1,000 a year and lead to savings of £200 per year if used instead of oil.
John Sauven, Executive Director of Greenpeace UK, welcomed the scheme but said rates are still too low for communities to invest in expensive long term schemes like hydro electric on rivers or larger turbines.
“For many families, generating their own clean electricity will be an attractive investment,” he said. “However, the level of ambition set by the government’s Feed-in Tariff is still far too low if we are to reach the full potential of small scale renewables.”
Landowners and farmers are angry that the Government has set the rate for energy generated from waste or anaerobic digestion, that could be installed on many farms, so low.
