The work would enable the plant to treat the solid waste left behind after the sewage treatment process and turn it into enough renewable energy to power the entire site.
The proposed upgrade will be located entirely within the existing sewage treatment works and will involve refurbishing existing digestion tanks and building new sludge thickening, de-watering and storage facilities.
When finished the power generated could power the whole treatment works.
A planning application will be submitted in May 2008 and subject to approval construction will begin in early 2009. Works are due for completion by 2010.