Thermally driven electrokinetic energy conversion with liquid water microjets

•Thermal expansion exploited to generate high pressures to drive liquid microjets.•Modest temperature increases result in large pressure increase (∼60PSI/°C).•Liquid water microjets convert kinetic energy directly into electricity and hydrogen gas. A goal of current energy research is to design systems and devices that can efficiently exploit waste heat and utilize solar or geothermal heat energy for electrical power generation. We demonstrate a novel technique exploiting water's large coefficient of thermal expansion, wherein modest thermal gradients produce the requisite high pressure for driving fast-flowing liquid water microjets, which can effect the direct conversion of the kinetic energy into electricity and gaseous hydrogen. Waste heat in thermoelectric generating plants and combustion engines, as well as solar and geothermal energy could be used to drive these systems.