Renewable Energy - Part 5 - Heat pumps

Heat pumps have been around for a long time. The principle is straight forward enough, heat is extracted from a low temperature source and dissipated via a heat exchanger, at a higher temperature. The same technology is used to operate your fridge. The heat sources we are most concerned about, with regard micro power generation for the home, are the earth, the air circulating outside, and where applicable, nearby water courses, such as rivers and streams. In each case the basic technology is the same...