Water, meet Energy and Energy, meet Water
With water and energy interconnected, there are a vast array of opportunities available to reduce water-energy nexus pressures.
By 2050, demand for water is projected to increase by 55% mainly due to increased demand from urban populations. At the same time, demand for energy in providing water and wastewater treatment services will increase.
Water and energy interconnected
Energy and water are interlinked in two ways, first, water is used in the production of nearly all types of energy (coal, geothermal, hydro, oil and gas, nuclear), and second, energy is the dominant cost factor in the provision of water and wastewater services (extracting and conveying water, treating water, distributing water, using water and collecting and treating wastewater). In fact, energy can account for up to 30% of total operating costs of water and wastewater utilities: in some developing countries, this can be as high as 40% of the total operating cost. Meanwhile, on average 15% of the world’s total water withdrawals are used for energy production.
Wastewater heat recovery
Scottish Water Horizons — a commercial subsidiary of Scottish Water — has teamed up with SHARC Energy Systems to establish a joint venture to expand and accelerate the deployment of wastewater heat recovery systems across Scotland. Scottish Water Horizons will provide commercial funding for the projects while SHARC Energy Systems will provide the design, build, and operational expertise for the green energy installations. The Scottish Government is supporting the scheme too by providing 50% capital support through its Low Carbon Infrastructure Transition Programme.
Sludge-to-energy
Helsinki’s Viikinmäki Wastewater Treatment Plant processes wastewater from industry and 800,000 people in Helsinki and its 7 neighboring municipalities. The sludge generated in the treatment process is processed in digestion tanks, with the methane gas generated in the digestion process utilized in energy generation to produce electricity and heat. The electricity generated corresponds to 70% of the wastewater treatment plant’s electricity needs, with the aim of reaching 80% soon.
Hydropower from drinking water
Melbourne Water has hydro-electric power stations operating throughout its supply network, generating renewable energy from the flow and pressure of moving water, with the electricity being fed back into the grid. In addition to the nine existing power stations, five additional mini-hydro plants were commissioned in 2016–2017. In total, the 14 hydro-electric power stations can generate up to 69,5000-megawatt-hours of electricity per year. By operating these power stations, Melbourne Water prevents over 75,800 tons of carbon dioxide emissions each year.
Conclusion
It is up to the imagination how far we can go to reduce water-energy nexus pressures.