Providing energy services often becomes simpler and more efficient when water is available; for cooling, heat extraction, cleaning and potential, thermal or thermochemical energy storage. Conversely, water access and purification requires energy; for pumping, heating, cooling, filtration, treatment and purification. Providing energy and water services in tandem, rather than through separate technological processes, often leads to synergies that make each simpler, cheaper and more efficient. This can improve access to both, particularly in developing countries, where piped-water and grid-electricity are often unavailable. Furthermore, at the interface between energy and water, lie many well-known but under-exploited thermodynamic and fluid-mechanical phenomena. Exploiting these can further reduce costs and improve service life and reliability, by minimising mechanical and materials complexity. Thermofluidics' IP lies in the understanding and exploitation of these phenomena and synergies to improve people’s lives, and the impact of their lives on the natural environment.