The Green Park wind turbine is costing the public more money than it saves.
A Government subsidy of £130,000 was used to run the 280ft structure last year but it only generated an estimated £100,000 worth of electricity, having operated at just 15% of its capacity.
Since it began in 2005, the turbine, seen by thousands of M4 motorists everyday, has used £600,000 of public money but only runs at an annual average of 17% capacity.
South East England MEP and UKIP leader, Nigel Farage, described the turbine as “totally ineffective, vastly expensive and the greatest scam of modern times” and said it should not receive a penny more of taxpayers money.
He added: “To meet our EU energy targets Britain needs to build thousands more turbines but quite frankly, I think a reliable and cost effective energy supply is more important than laws made by people with no expertise on the subject.”
The turbine is run by Ecotricity and visited by thousands of school children every year. The figures were released by the The Renewable Energy Foundation and are based on data from regulator Ofgem.
The Coalition Government gives £48 to turbine operators for every megawatt-hours of electricity they produce, which is on top of any money earned by selling the energy.
Ministers have pledge to crack down on the amount of money given to turbines in areas where there is not enough wind to make them economically viable.
Ecotricity said the turbine achieves its aim of powering the business park and that the company and Green Park is “happy with it”.