Scotland’s biggest sewage works heads for 100% renewable energy self-sufficiency in 2018

Workers at the Scottish Water sewage plant in Edinburgh.
Workers install renewable energy units at the Scottish Water sewage plant in Edinburgh.

The largest sewage treatment works in Scotland is nearing a state of renewable energy self-sufficiency on a permanent basis.

The Seafield waste water treatment plant, near Portobello beach in Edinburgh – has already achieved 100% self-sufficiency status on a number of one-off days during 2017 when it required no electricity from National Grid plc.

Resource management company Veolia helped Scottish Water to increase the plant’s capability to generate its own energy from 55% to around 85% by boosting the renewable energy derived from a combination anaerobic digestion of sludge and biogas fired combined heat and power (CHP) plants.

By implementing a range of innovations and increasing efficiency the target of energy self-sufficiency has been set as the practical target and will further sustainability and lower carbon emissions. The advances to date mean that the Seafiled site has also reduced its energy costs by 50% which will help meet the value-for-money consumer criteria set for the industry.

The Seafield plant treats sewage for a population equivalent of approximately 850,000 people from Edinburgh and the Lothians, which equates to 300 million litres of wastewater every day – enough to fill 121 Olympic sized swimming pools.

The Scottish Water board is the biggest single consumer of electricity in Scotland.

The water industry is the fourth most energy intensive UK industry and uses around 3% of UK generated electricity for pumping, water treatment and waste management which directly contributes around 1% of the UK’s greenhouse gas (GHG) emissions. 

More advanced technologies now mean that biogas from all the available sewage could deliver an estimated 1,697GWh – enough electricity to power over half a million homes, increasing the resilience of the National Grid and helping to control energy bills.

At Sellafield, Veolia introduced a wide range of measures to derive renewable energy using sludge as a valuable resource. Measures installed to date include a thermal hydrolysis process that has increased biogas production by around 10%, investment in an additional CHP unit to provide greater energy generation and to take advantage of the additional biogas, and a further 3% increase in the yield of biogas.

4 Jan 2018

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