Wind power: accessible yet frustrating
Posted by Matthew Rhodes on 8 January 2009 at 1:57 pm
Wind power is one of the most accessible and yet frustrating renewable technologies.
It is accessible because it’s relatively easy to install, cheaper than many other renewables at small scale; you can buy it at any size from laptop to leviathan; it produces electricity – which is a very flexible power source than can be used for most things (or sold) and in the UK we live in one of the windiest places on earth, so there is plenty of free resource.
I haven’t yet met anyone in the UK who doesn’t believe they live in a windy location, so most people believe that if only they could afford it wind power might work for them. Unfortunately, like all renewables, there is no one-solution-fits-all answer for wind. This can make it frustrating for the uninitiated. Despite perceptions and wishful thinking, many places in the UK are not windy enough to make wind turbines economic, while others are so good you can get your money back within a few months if you can afford a large enough system.
Common sense can help a lot with wind turbines. They do not work very well near buildings or trees, which tend to obstruct the wind and absorb a lot of the energy that might otherwise be used for power generation. So installing a turbine on a house or lower than a tree line or other buildings within 100m or so is normally pretty pointless.
On the other hand, locating turbines on hilltops or well-away from obstacles on flat terrain is normally effective, and on high rise buildings or near the coast even building mounted systems can deliver tangible amounts of energy. For well-sited turbines at domestic scale (2-6kW) you can expect paybacks of 8-15 years in good locations. If you can afford larger machines the economics and carbon savings only improve.
The other very important point for beginners with wind to appreciate is not to get bogged down with power ratings (kW). The power delivered by a turbine varies with wind speed, which changes from one moment to the next. The critical parameter to worry about when selecting a turbine for your situation is not instantaneous power, but total energy generated by the system in a full year (kWh). This is also what you pay your electricity supplier for.
Average wind speed is much more predictable over a year than it is at any instant, so with a bit of maths and physics you can calculate how much energy a given turbine will deliver in your location and try to match this to your annual electricity requirement. You don’t need to worry about matching local supply and demand at a given moment, because you can use the national grid or a battery system to even out the imbalances.
This maths isn’t complicated, but to help everyone, we have developed some free Windpower calculators on our website. Just enter your postcode and you can play with different makes and models of turbine to see what they will do for you. Get out you electricity bills and see how these estimates compare with what you actually use – you’ll find you can quickly narrow down which systems and manufacturers you should be looking at more closely.
Photo by footloosiety
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