How Effective Are Wind Turbines
The UK benefits from one of the most reliable electricity supplies in the world. This is founded on a diverse mix of different electricity generating technologies, of which onshore wind is a key component, and a sophisticated National Grid which controls both the amount of power generated and the distribution of that power.
Onshore Wind Effectiveness
In 2011 onshore wind generated 10,372 GWh of electricity, enough to power 2.4 million homes. This represented about 44% of UK renewable electricity production, and just under 4% of all electricity produced. By 2020 it is estimated that onshore wind could provide 24-32TWh electricity, enough to power up to 7.7 million homes.
Variability and Efficiency
Wind energy is a variable (or intermittent) source of energy but that does not mean it is inefficient. Wind turbines tend to generate electricity for around 80-85% of the time without any significant losses. In comparison thermal generation results in significant heat losses converting heat energy in the resource used into electricity output. In 2010 thermal efficiencies for coal and combined cycle gas turbine generation were 36.1% and 47.6% respectively.
However, whilst turbines are efficient, wind speeds vary which impacts how much power is produced and what is called the 'load factor' of a technology. The load factor is the accepted measure for the percentage of a theoretical maximum output of 24 hours a day, 365 days a year that a particular generating plant or technology achieves, with no technology achieving 100%. Over a 5 year period the average onshore wind load factor was 26.2% with offshore wind at 28.2%. For comparison in 2010 coal fired power stations averaged 40.9%, biomass 53.3%, nuclear 59.4% and Combine Cycle Gas Turbine 60.6%.