Investment in anaerobic digestion has played a leading role in the reduction. Eighteen of the company’s major sewage treatment works now generate electricity from this renewable source.
Yorkshire Water’s sewage treatment works at Naburn in York and Blackburn Meadows in Sheffield each generate more than a third of their energy from renewables.
Yorkshire Water energy and recycling manager Erica Lack said: “To achieve a reduction of more than 4 per cent in carbon emissions within the last three years demonstrates we are serious about improving the environmental performance of the business.
“Water and wastewater treatment is a hugely energy intensive process, but thanks to advances in technology and lots of hard work from colleagues across the business, we are making major reductions in operational emissions.”
Anaerobic digestion works by converting human sludge into biogas, which is used to produce electricity.
Yorkshire Water has also invested in wind turbines and hydro-turbines to generate green power.
The company aims to generate 12 per cent of its total energy needs from renewable sources in 2016/17, which will help reduce its annual electricity costs of around £50 million.
Investing in renewables has helped Yorkshire Water reduce its carbon emissions by a total of 15 per cent since 2008.
In its financial report for the six months to September 2016, Yorkshire Water reported an increase in turnover of 2.6 per cent to £506.5 million, compared with £493.5 million the previous period. The group said this was as a result of higher trade effluent charges and a slight increase in volume used by measured customers for the six-month period.
Meanwhile, operating profit for the period reduced by 5.8 per cent to £147.8 million as operating costs increased by 6.6 per cent to £358.7 million.
In September, the firm was given the green light for its proposed £72 million new state-of the-art sludge treatment and anaerobic digestion facility at its Knostrop works in the centre of Leeds. When completed in 2019, the new facility will provide 55 per cent of the site’s energy needs, and contribute to the region’s target to recycle 94 per cent of its sludge by 2020.