Two innovative Swedish companies are now developing wind energy conversion systems for heating. In Sweden the winters are long and cold and replacement of heating oil or wood with wind would result in huge environmental gains, eliminating quantities of polluting smoke. A wind-heater feeds electricity to an electric heater in a water filled storage tank. If the tank is big enough, it can store heat for a week. Many such homemade systems have worked well for years in Sweden, but now two companies are separately ready to manufacture their first so called zero-series of wind heaters. Nordex Energi in Åmål has constructed a 15 kW turbine, with a three-bladed off-wind rotor on a 16 m tower. The technology can be kept extremely simple because the power does not have to be of grid quality. Nordex Energi is also working on a 35 kW model. A second newly established company, Windbuster, in Helsingborg, uses a different concept. The turbine is a giromill with five vertical blades, although it still heats water in tank just like the Nordex system. The first Windbuster wind heater is a small model made mainly for use in holiday homes and cabins. It has an 8 kW generator and four metre diameter rotor. Three larger models will be manufactured later.