Solar powered device harvests water from air

(Credit: MIT/Hyunho Kim)

The harvester, described in the journal Science, uses a material known as a metal organic framework (MOF) to first extract the water from the air. MOFs combine metals with organic molecules to form porous structures that are excellent for storing gases and liquids. Different compositions of MOFs can be used to capture and store various substances, such as hydrogen, carbon dioxide or natural gas.

Using an MOF derived from zirconium metal and adipic acid, the new device is able to harvest water vapour from the atmosphere. Sunlight then heats the MOF and drives the water towards a condenser, which is at the same temperature as the outside air. The vapour condenses into liquid form and drips into a collector. On the roof of an MIT building, a prototype containing 1kg of the MOF material was able to collect 2.8 litres of water over a 12-hour period, under conditions of 20-30 per cent humidity.