Yorkshire Water is taking further steps to ensure that the wastewater treatment works at its Esholt site will be completely energy self- sufficient.

The company has already installed two combined heat and power generators at a cost of £1m each. These can create around one third of the energy required to power the plant each day by turning methane into heat and power.

The utility has also built the first hydro screw electricity generator ever to feature in a UK sewage works. This consists of two 12 metre-long Archimedes screws which harness the energy created by the waste water as it flows into the plant, fuelling 10 per cent of the site's daily energy consumption.

More schemes are in the pipeline to ensure the site becomes fully sustainable - work recently started on a £30m project which will make improvements to the way sludge is treated. The addition of a fourth digester will make the site more environmentally friendly as well as becoming more energy self-sufficient.

The scheme will also include the construction of new facilities enabling increased biogas production for renewable energy generation via the provision of two new high efficiency Combined Heat and Power units.