Ice Storage Air Conditioning

Ice storage air conditioning is a form of thermal energy storage that freezes water into ice when cooling demand or electricity prices are low, then melts that ice to supply cooling when demand peaks, shifting the electrical load a building chiller would otherwise draw during the day. It works because water carries a large latent heat of fusion, about 334 kilojoules per kilogram, so freezing or melting one metric tonne of it stores or releases roughly 334 megajoules, about 93 kilowatt hours, of cooling capacity. Full storage systems keep enough ice on hand to meet peak cooling needs entirely from storage, letting the chiller shut down during the peak period, while partial storage systems run the chiller and the ice storage together to reduce the chiller capacity a building needs, an approach especially valuable where electricity tariffs charge steep demand charges or a large gap between peak and off peak rates; experimental systems now pair the technology with photovoltaic panels, using solar electricity to make ice for later cooling instead of relying on batteries.