The technology that powers spacecraft destined for deep space, where solar energy is not available, has been used to develop a self-contained power plant that can be mounted right inside a residential boiler. This device will prove to be quite useful in cold areas where power is expensive, sporadic or unavailable. Known as a thermoelectric power generation system, the device uses waste heat to produce enough electricity to power the burner, fans and pumps required in a domestic heating system. The only external power is a small battery to turn the device on. Developed by Hi-Z Technology of San Diego, USA, the device will add US $400 to the price of a residential boiler. It is expected to hit the market within two years ( Popular Science , Vol 254, No 2).