Those who drive into Leeds on the M1 or A63 may have seen a rather large golf ball looking object appear on the Yorkshire Water Knostrop treatment plant near Leeds.

The firm is not trying to create a mini Epcot Centre in Leeds, but building a gas bag, with its construction meaning another landmark has been reached in the £72m project.

Methane produced from sludge treatment will be stored in the bag with up to 3,700 cubic metres of gas stored at any one time. All of this gas will then be turned into electricity to help power the plant.

The facility will begin processing in August and once fully operational later this year, will contribute significantly to the recycling of 94% of Leeds’ sewage sludge by 2020.

The facility will be capable of processing up to 131 tonnes of dry sludge a day and will generate enough renewable energy, using heat and power engines, to provide 55% of Knostrop’s energy needs – enough to power 8,000 homes.

Yorkshire Water Project Manager, Lee Laherty, said: “This is the single biggest investment the company is making between 2015 and 2020.

“The installation is a huge deal because we can start creating more electricity for ourselves and do more to reduce carbon emissions and help the environment.

“It also supports Leeds council’s ambition for the Lower Aire Valley to become a hub for green energy and industry.”