Two hundred years ago, wind power played an important role in the lives of ordinary people. The milling of grain was central to rural life and every community had a flour mill, often powered by wind. In fact, wind-powered flour mills have existed for more than a thousand years. They were well designed, with sails that could be adjusted according to the prevailing wind direction. Windmills also provided power for processes such as timber milling; but during the industrial revolution, wind power lost favour.
Steam, produced by huge furnaces consuming vast quantities of fossil fuels, was found to be a more effective way of driving heavy machinery. But we now recognise that our reliance on fossil fuels is not sustainable, and we are once again turning to renewable energy sources – such as wind power.
Wind Power into the 21st Century
One problem with depending on wind to drive mechanical processes is that it does not blow at a constant rate. When there is no wind, the machinery stops. If, instead, wind power is used to generate electricity, this is no longer such a problem. Electricity will be generated for as long as the wind speed is sufficient, and electricity that is not used can be stored, for use when the wind drops.
The UK’s first wind farm was built in 1991. By March 2004, 84 wind farms with a total of just over one thousand wind turbines were in operation, and by August 2008, according to the British Wind Energy Association, there were 176 wind farms supplying electricity into the national grid from a total of more than two thousand wind turbines.
How Wind is Turned into Electricity
Mechanical energy can be converted, via a generator, into an electrical current. The common process in most types of power station is to produce mechanical energy from a turbine, and the same process is used to turn wind into electricity. Most wind turbines have three blades. The wind causes the blades to rotate, thereby turning a shaft inside the turbine. A generator connected to the shaft converts this rotational energy into electricity.
This can be done on any scale; the principle is the same for large commercial wind farms and for micro installations used, for instance, to charge the battery on a boat or to provide energy for a parking meter. A small domestic turbine is likely to produce between one and six kilowatts, while large commercial wind turbines generate between two and three megawatts. Large wind farms are connected to the national electricity grid. Domestic installations either have an independent means of storing the electricity they produce, or they too can be linked to the national grid.
As Free as the Wind – Or is There a Cost?
In environmental terms, wind power is in many ways an exemplary source of renewable energy. It does not involve combustion so it produces no emissions to upset the balance of the atmosphere or pollute the environment. Wind farms are not incompatible with agricultural land use and cause minimal disruption to the sites where they are installed. However, they do visually alter the landscape, and this might be classed as visual pollution.
Another criticism that was initially levelled against wind farms was that they posed a danger to birds, but it is generally accepted that this risk is small; in the UK, it is believed that on average one bird is killed per turbine per year. Wind farms create a small amount of noise pollution, but again this is not a widespread problem since large wind farms tend not to be sited in residential areas. They can cause slight interference with television reception; again, this is considered negligible.
In economic terms, the only costs are the initial installation and ongoing maintenance.
A Global View of Wind Power
Although the UK’s weather provides plenty of wind, other countries generate a far higher proportion of their electricity by wind power. Less than two per cent of the UK’s electricity is wind-generated, whereas in Denmark, for instance, the figure is nearer 20 per cent. Germany generates around 6 per cent of its electricity from wind power and has over 22,000 turbines, producing over 20 gigawatts; the UK has less than one-tenth of this capacity. However, the government must find ways of reducing carbon emissions, and wind is an accessible and non-polluting energy source; so we may see a significant increase in our use of wind farms to generate electricity in the coming years.