Energy sustainability and the water sector: systems modelling approaches for decision-making

Water managers face enormous challenges in securing future supplies of water under the uncertainty of climate change and population growth. Energy sustainability is an increasingly important factor in the planning and management of water resources. Electricity use in the water and wastewater sectors has been growing at unprecedented rates. Left unchecked, this could compromise both the affordability and sustainability of the sector. At the same time, a number of promising options exist to the industry to enhance its energy efficiency and also reduce its reliance on the energy grid, though there are few analyses of the costs and risks associated with these opportunities at the moment. Water managers need reliable decision-making frameworks and tools to understand the complex interactions between water and energy systems. Such methodological advances will be important for the sustainable planning and development of the water industry. The aim of this thesis is to introduce novel modelling techniques and frameworks that can capture the linkages between water and energy systems, for the purpose of facilitating transitions toward a more reliable, resilient, and energy sustainable water industry. Specifically, this thesis presents analytical approaches to: (1) understand the temporal evolution and drivers of electricity consumption in water-related systems; (2) model integrated water, wastewater, and energy networks; (3) model and study the costs, risks, and benefits of operational changes at high temporal resolution; and (4) map pathways to energy sustainability in the water sector under deeply uncertain futures. The tools and frameworks developed in this thesis are applied to study the water system in the Thames basin, a region considered to be `seriously water stressed' and encompassing the mega-city of London. Results from the case-study demonstrate that water-related energy use has been rising sharply in the region (10.8% per year) and this is driven by expansions in operational capacity for larger populations, as well as local climate mitigation efforts. Yet, a number of opportunities to curtail rising energy costs are also available to the local utility. Results from this thesis demonstrate that participation in energy demand-response programmes has the potential to substantially lower energy costs by up to £5.2 million per year. Further, the utility can also expand on its energy self-generation capacity using a combination of biogas, solar, and wind generation, to decrease their reliance on the local energy system and realise net-zero carbon targets.