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The Facts About Wind Power

By: Dr Gareth Evans - Updated: 27 Feb 2012 | comments*Discuss
 
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Britain is home to about 40% of Europe’s wind resource, so it’s hardly surprising that when it comes to discussions of renewable energy and sustainable development, wind power is something that gets a lot of interest.

However, despite all the obvious benefits of having such a major source of free energy quite literally on our doorsteps, planning proposals for wind farms and offshore turbines are often met with opposition and hostility. For every fan firmly committed to the cause of wind power, there seems to be someone else determined to try to stop the march of aero-generators spoiling yet another beauty spot.

So who’s right? Well the truth is, they both are – well sort of, at least. As Obi-Wan Kenobi (fictitiously) put it, many of the truths we cling to depend greatly on our own point of view, although the old Jedi master was, of course, referring to an entirely different kind of ‘Force’ at the time!

Not everything is quite so clear cut as perhaps we’d like it to be, so let us present some of the relevant facts about wind power – and leave you to make your own mind up about where you stand on things.

The Pro's

Small wind turbines can make a contribution to household energy demand, as well as being a very public statement about your stance on environmental matters – something that more than a few politicians have used to shine up their green credentials!

A small 1.5kW turbine can produce nearly 4,000 kilowatt hours (kWh) of electricity per year – the equivalent of almost all of the annual 4,700 kWh used by an average household. Opt for a larger one – 5kW turbines or even larger – and the prospect of making some real cash by selling your surplus begins to look attractive.

The question of noise is something that often gets brought up, but the latest generation of small wind turbines are quiet by design – far quieter than the wind itself. In most cases, stand 40 or 50 metres away and you’ll hear nothing at all.

Even standing within a few hundred metres of a large commercial wind farm, you’ll be subjected to less noise than you would in a busy office environment. According to government figures, the wind farm will have a typical indicative noise level of around 35-45 decibels, while the office will be around 60 decibels; to put that even more in context a ‘quiet’ bedroom is about 35 decibels.

Another key ‘pro’ of wind farms is the relative cheapness of the power they produce. Wind generation is broadly competitive with electricity from new clean coal-fired power stations and works out significantly cheaper than power from new nuclear facilities.

The Con's

On the down side, however, there’s really no getting around the fact that building a wind farm has a major environmental impact – and not simply in terms of the effect on the view or the possible harm caused to migrating birds. Each turbine needs a significant slab of reinforced concrete to anchor it into the ground – a foundation of around 1000 tonnes being required for a fairly typical turbine of 375ft in height. Add to this the need to build access-ways and service roads, the energy used to manufacture the turbine in the first place, and the fuel consumed to transport it to its final destination and you have a pretty major embedded carbon debt to work-off, before those blades ever turn.

Another point which is often made by opponents of wind energy is that the basic power supply – wind – is very variable. Even though a modern wind turbine will produce electricity for perhaps 80% of the time, the actual output it achieves depends on how fast the wind is blowing; as a result, over the course of a year it will only generate a third of what it theoretically could. In the power industry, this is termed the ‘load factor’ – and the load factor for a conventional power station is notably better, at 50%.

Wind speed limits turbines in other ways too. Electricity can be generated when the wind reaches a gentle breeze, blowing at 10-12 mph (4-5 metres per second) – but in severe gale conditions, turbines have to be shut down for safety reasons. While Britain may be the windiest country in Europe, clearly not all of that resource can be exploited.

One thing is for certain, by its very nature wind power could never provide all of our electricity needs – there are just too many still days, even in the windiest reaches of this island, for that to happen. Never the less, it is hard to imagine even the most die-hard opponent of wind farms seriously suggesting that it doesn’t have some part to play in Britain’s overall energy strategy.

The trick would seem to lie in getting the balance right.

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