Electrostatics have long been a high-efficiency technology for removing pollutants from the air, from residential air cleaners to the electrostatic precipitators in coal-fired power plants. A new use for this technology has been developed by an MIT spinoff that promises to capture water vapour emitted by industrial and commercial cooling towers. Captured water is pure enough to be practical for human consumption or as boiler feed water for generating plants.Battery storage of electrical power is an essential part of intermittent clean energy systems like photovoltaics and wind turbines. But batteries can have a secondary and equally important purpose: grid forming. Frequency control of large AC grids can be difficult with multiple generating sources and varying loads across a system. With advanced computer control of inverters, battery storage systems can act as a frequency regulator in large grid systems, forming an electrical equivalent of the large rotating inertial mass of a mechanical generator. Technology makes battery storage for grid purposes both more useful and cost-effective.Access all episodes of This Week in Engineering on engineering.com TV along with all of our other series.