When air is compressed it gets hot. When it expands, it cools off. Add some kind of fan to circulate the hot and cold air and you have a heat pump—the technology behind refrigerators, air conditioners, home heating systems for some environments (where there is a considerable difference between the ambient temperature in two different places, e.g. the ground and the air)…. and now, washer/dryers.
Panasonic demonstrated this unit at the 2009 CES. I took a movie of it which is here, on YouTube. (sorry for all the noise… it’s CES!) Unfortunately, there are no plans to import this device to the US because the capacity is too small.