Thermal Hydrolysis Plant in Bradford generates record amount of electricity

Yorkshire Water says it has generated enough electricity in one week from its flagship Thermal Hydrolysis Plant (THP) at Esholt WWTW’s in Bradford to power 3,600 homes, in a 5 October announcement.

The firm’s £34m Thermal Hydrolysis Plant (THP) opened in 2014 with the sole intention of creating energy from sludge to power the site and supply any excess electricity to the National Grid. The secret to the THP process is heating up sludge to 165ºC to kill off any pathogens. This then enables the bio-digestion process to generate more methane gas per unit of sludge, which is used to power Combined Heat and Power systems to generate electricity.

It’s record performing week in September generated 490 MWh and as well as powering the sewage works supplied enough electricity to the Grid to power 3,600 homes. This also adds towards a wider commitment the firm has made to create up to 12 per cent of its own electricity from renewable sources.

Gavin Stowell, plant engineer at Yorkshire Water said: “Technology such as Thermal Hydrolysis and anaerobic digestion that is able to generate electricity from sludge is crucial to help power our energy intensive waste water treatment processes. As a business, we have an annual electricity bill of around £50m but by embracing the highly efficient THP process, this helps us keep costs down with the added benefit of supplying electricity to the National Grid.”

Currently, Yorkshire Water has just one Thermal Hydrolysis plant, but says in the future it would be able to bolt this technology onto its new waste water treatment works if required. A similar technology, anaerobic digestion, is currently used at 18 of the firm’s sewage sites.

The by-product of the digestion process can be used as a rich land fertiliser by the agricultural sector, avoiding any waste having to go to landfill.