We create renewable energy at 22 of our sewage treatment works, which we then use on site. At most of these, we use a process called 'combined heat and power' (CHP), which captures the methane produced during sewage treatment and uses it to drive a generator.
We consumed 1,264 GWh of energy (excluding heat) over the year, 15 per cent of which we generated on our own sites using renewable sources. When heat energy is factored in, our energy consumption increased to 1,355 GWh, of which 20 per cent was from renewable sources. This reduces our use of fossil fuels and our overall greenhouse gas emissions.
Our total electricity generation in the same period was 203 GWh, with renewable electricity generation increasing from 182 GWh to 187 GWh – the most we have ever produced in a single year. In addition, we produced 85 GWh of renewable heat energy.
By 2015, we aim to install a further 3 GWh of renewable energy generation capacity. During 2010/11, we have commissioned an innovative biogas injection plant at Didcot Sewage Treatment Works. This will enable us to supply renewable sewage gas to the gas grid, which will contribute towards the UK reducing its greenhouse gas emissions and meeting its renewable energy obligations.
All purchased electricity during the year was classed as coming from 'Good Quality' CHP sources, which have lower greenhouse gas emissions associated with them than grid electricity. In line with government reporting guidance, we have not claimed any carbon reduction benefit. However, this benefit will still be accrued by the UK at no additional cost to our customers.
| 2005/06 | 2006/07 | 2007/08 | 2008/09 | 2009/10 | |
|---|---|---|---|---|---|
| GWh (Gigawatt hours) | 154 | 157 | 169 | 182 | 187 |
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