It is also through that the biomass generator will prevent the emission of around 140,000 tonnes of greenhouse gases in a move which E.ON's project manager Andy Carling called "groundbreaking".
He said: "Steven's Croft is a groundbreaking project that has been built on time and on budget.
"We've already tested the boiler and various other components, but yesterday was the first time we've run everything together as we would during full commercial operation."
The announcement about Steven's Croft has come after E.ON launched a new campaign to encourage football fans to reduce their carbon footprints when watching the FA Cup this season.
Portsmouth and England goalkeeper David James is involved in the project to offset around 45,000 tonnes of carbon emissions produced by the tournament.
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