157 WATER RESEARCH at the University of Oulu Water vs. energy – Finding hidden energy potential to provide clean water Eva Pongrácz*, Lauri Mikkonen, Noora Miilumäki and Niko Hänninen University of Oulu, Thule Institute, Centre of Northern Environmental Technology FI-90014 University of Oulu, P .O.Box 7300 1 Introduction Water and energy are two of the most fundamental resources driving civilization; both human development and industrial growth. They are also intrinsically interlinked. Energy is consumed at every stage of the water supply chain (Plappaly and Lienhard 2012) and water is a key re- source in energy generation (Rio Carrio and Frei, 2009). Both resources are limiting the other, and both are running short (Webber 2008). The suggestion is that the scarcity issues need to be solved in concert. 2 Objectives of the research The objective of the Water Asset Renewable Energy Solutions (WARES) project, which this research is part of, is to map hidden, renewable energy potential in water utilities across the Northern Periphery. The nine pilot sites participating in the project explore opportunities for micro-hydro, small and medium-scale wind energy solutions as well as for the utilisation of solar power, energy from biosolids and waste heat from wastewater. The project intends to provide practical solutions to utilise these assets in order to reduce the carbon footprint of water. 3 Results Electricity is a critical input for delivering municipal water and wastewater services and electric- ity costs can contribute up to 30 % of the operating costs of water and wastewater utilities. The largest energy consumer in providing drinking water is the pumping of water to custom- ers, which consume up to 70 – 80 % of the overall electricity usage of water utilities. Also in wastewater management, a considerable amount of electricity is needed for pumping the wastewater from households and industries back to the wastewater treatment plant (Liu et al., 2012). In wastewater treatment, sludge aeration process is the largest energy consumer, but also ultraviolet disinfection and membrane processes add substantially to electricty consump- tion costs (Tchobanoglous, et al., 2004). Although heating costs in Tchobanoglous are cited to contribute to only some 7% of wastewater tretament plan energy needs, in Northern Finland, heating costs were reported to be up 35% of total energy costs (Mikkonen). 3.1 Providing energy services in the Northern Periphery The Northern Periphery is an area deined by the Northern Periphery Programme (NPP). The programme covers parts of Sweden, Finland, Norway, Scotland, Northern Ireland and the Republic of Ireland, as well as all of the Faroes, Iceland, and Greenland. Much of the area is situated north of the Arctic Circle, and includes some of the world's northernmost com- munities (Figure 1). *Corresponding author, E-mail: eva.pongracz@oulu.i