Energy use and renewable generation

In 2007/08, we used 972GWh of electricity across all of our activities, of which 707 GWh was consumed in our regulated water business, the majority of which is used to transport and treat clean water and wastewater. We are running an on-going pump and plant efficiency programme which this year secured a saving of around 10GWh.

We generated just over 93GWh of renewable electricity from our combined heat and power plants, sludge incinerator and hydropower plants, an increase of 14GWh from 2006/07. Of this, we used 98 per cent ourselves. In addition, our operations in Wales generated 1.17GWh and those in Tallinn in Estonia generated 1.16GWh. Future renewable generation in Tallinn should be helped by improvements this year to reduce the impact on biogas production of snow clearing chemicals contained within wastewater. These can cause foaming and disruption to the sludge digestion process, resulting in lower gas production. In 2007, the way that anti-foaming chemicals are dosed was successfully changed resulting in less disruption to the digestion.  Please see performance table.

Sofiyska Voda, our concession in Bulgaria, undertook an energy efficiency project in 2007 targeting sites using high levels of energy. This involved actions ranging from replacing power invertors, assessing the condition of substation transformers and repairing them and installing energy efficient light bulbs. The automated control system at the main wastewater treatment works will be extended to cover all parts of plant operation to increase efficiency.