Support for domestic wind turbines has blown hot and cold in the past few years, but recent improvements in industry standards mean that it’s now easier to be sure whether wind power is the right choice for you.
The stats are impressive. The UK is the windiest place in Europe, claiming a hefty 40 per cent of its wind energy, and even sober voices talk of it creating thousands of jobs over the next 10 years. But for all its promise of clean electricity as we face up to climate change, controversy clings to wind power like a limpet to a rock. Leaving aside the rows over giant turbines in beauty spots, wind for the home has had more flak than all other renewables put together. Anyone would think its advocates were trying to sneak in nuclear waste by the back door. First, there were media claims that domestic turbines in cities couldn’t power a hairdryer. Then this year, came the downbeat results of the Warwick Wind Trial study. This described the technology as making ‘a tangible contribution to energy and carbon saving only on the most exposed sites and tallest buildings’.
The truth is much more complicated, says trade body the British Wind Energy Association (BWEA; bwea.com). The industry has moved on ‘in leaps and bounds’ since the negative headlines of three years ago. Then, a windmill on your chimney pot was billed as the ultimate green accessory, and David Cameron announced he was getting one on his London home. Unfortunately, especially for those urbanites who bought into this, the performance figures claimed for the machines were often unrealistic. For example, it was common for a sales pitch to assume an average wind speed of 12m per second (m/s), when this notoriously difficult figure is more like 5m/s across Britain, and nothing at all like this in built-up areas. ‘The media saw the performance of the turbines and said they didn’t work. But if you were looking at the detail you’d realise they were put in the wrong place,’ says Alex Murley, small systems manager at the BWEA. ‘In the same way solar panels wouldn’t do much if you put them in a cellar,’ he says.
Now, says Murley, there have been reforms in the way wind is sold. ‘There are industry standards for the advice that consumers get. This means we can probably kiss goodbye to salesmen in urban and many suburban areas where micro wind is unlikely to work,’ he says. Improved standards now mean that manufacturers publish ‘noise maps’ for their products, for example, so it’s possible to work out how far your turbine needs to be sited from your neighbour’s property. Murley estimates you will need to be 5m away for a 1.5 kilowatt (kW) turbine; larger systems should be 40m away. ‘remember that when it’s windy, there’s background noise, too,’ he says.
But for properly positioned turbines, there is huge potential. The BWea has done some research in the north-west and south-west regions of the uK, which Murley describes as the ‘typical hunting grounds for wind’, and estimates that 48,000 homes have suitable sites. so where do you start? Wind turbines are, of course, a godsend for people living without connection to mains electricity, who will use their machine to charge batteries they can draw upon. Most of us, however, are ‘grid tied’ to the national grid and will need a turbine, mounting system, fuses, a suitable meter and a grid tie inverter to convert the power you are generating to that appropriate for connection to the mains.
The first thing to do is to work out your site’s wind speed. you’ll get a rough idea by checking out the government’s wind speed database (berr.gov.uk), though it must be stressed that this is only a rough guide. Local speeds will be affected by nearby buildings and trees. However, if the figures are promising (you’re looking for an average wind speed of 6m/s or more), plus you have an open site, you should really try to be more specific.
You could contact a supplier who can put you in touch with a consultant. you’ll find suitable installers and products at microgenerationcertification.org, a government-supported scheme that requires consistent standards. However, a consultant is likely to be expensive. A much cheaper option would be to buy an anemometer to measure the average wind speed. The longer the period over which you take your readings (months, or a year, as opposed to hours), the more accurate they’re likely to be. at bettergeneration.co.uk, anemometers with readouts start at £40, with mounting poles around £17. you’ll need planning permission, too, so a call to your local authority is required.
A typical domestic turbine is between 1 and 6kW. Confusingly, the industry describes ‘micro’ turbines as being 1.5kW or below, and ‘small’ extending to 50kW. At the lower end of the domestic scale, you’ll be making a dent in your electricity bill, the size of which will depend on the amount of wind in your area and your electricity usage. at the top end, you could be producing enough annual electricity for two-and-a-half homes (around 10,000kW hours). This means you could be exporting some of the electricity you generate and earning money from that, as well as qualifying for rOCs (renewable obligation certificates) for generating renewable electricity, which can be exchanged for cash with the electricity regulator Ofgem.
Expect to pay around £1,500 for a 1kW turbine, and £11,000-£20,000 for a 2.5-6kW set-up. Blades of 5m diameter are typical of a larger domestic system, which will be mounted on a mast. in fact, most domestic turbines are mast-mounted, typically between nine and 15m high. The higher the mast, the more exposed you are to the wind. Mounting on houses (as opposed to blocks of flats) remains very controversial because of possible damage to properties, noise levels and interference from nearby buildings. ‘We don’t recommend it,’ says david sharman, managing director of turbine company, ampair. an honest statement from the turbine industry. It’s good to hear.
Words: Dominic Murphy