The US Department of Energy's National Renewable Energy Laboratory (NREL) has developed a new air-conditioning system combining membranes, evaporative coolers and desiccants into a single device with the objective to suit to all climates, especially humid climates, in a cost-effective way. The Desiccant-Enhanced eVaporative air conditioner (DEVap) cooling core uses water and liquid desiccant to draw in outside air, exhaust some of that air and return cool, dry air to the area being cooled. DEVap's integrated evaporative component and its desiccant drying process offer improved dehumidification and thus lower costs and much lower energy usage. Evaporative coolers are a lower-cost alternative to AC in dry climates that don't get too hot or humid. "In humid climates, adding water to the air creates a hot and sticky building environment. Furthermore, the air cannot absorb enough water to become cold", says E. Kozubal, co-inventor of DEVap. DEVap relies on the desiccant's capacity to create dry air using heat and evaporative coolers' capacity to take dry air and make cold air. The desiccants NREL uses are highly concentrated aqueous solutions of lithium chloride or calcium chloride. They have a high affinity for water vapour and can thus create very dry air. The thin membranes used are hydrophobic, which means water tends to bead up rather than soak through the membranes. That property keeps the water and the desiccant separated from the air stream. DEVap is claimed to use 50 to 90% less energy than today's top-of-the-line units. The refrigeration cycle is replaced with an absorption cycle that is thermally activated. It can be activated by natural gas or solar energy and uses very little electricity. www.nrel.gov/features/20100611_ac.html