Evaluating sustainable energy strategies for a water utility

Research suggests that political will to deliver improvements in the quality of surface water in the UK and across the EU, alongside measures to place tighter controls on the quality of biosolids applied to agricultural land, will augment the levels of energy used in sewage and sludge treatment. This coincides with increasing concerns over the use of fossil fuel derived energy sources and their potential to enhance the Earth's greenhouse effect and promote global climate change, creating a serious paradox for these responsible for managing the aquatic environment. However, previous research also suggests that novel technologies and practices could potentially mitigate the problem in hand. This paper describes the development of a model for estimating future energy use and CO2 emissions in the wastewater treatment sector, and outlines the results of different projections using incumbent and novel practices. Indications are that using incumbent approaches could augment CO2 emissions by 15-30% in the medium- to long-term, while loss of the agricultural sludge route and deployment of an incineration strategy could mean increases are of the order of 50-70%. Alternatively, the construction of a greater number of sludge treatment facilities, with greater biogas recovery, could reduce this burden to around -8 to +7% over the same period, while the realisation of the full potential an anaerobic pre-treatment process could lead to reductions of up to 16%. Nevertheless, some of the options will come at a higher cost than incumbents, and the potential for making the business case for these investments is explored.