I’ve been looking at renewable heat recently, the next priority after decarbonising our electricity supply. There are all sorts of ideas for district heating or hybrid systems out there, but the most inspiring idea I’ve come across so far is the off grid solar furnace. It’s been perfected by a renewable energy pioneer called Henry Red Cloud, who creates community energy solutions and employment opportunities on Native American reservations.
The solar heating system his team install is beautifully simple. A large glass-covered box is fitted to the south side of houses, with a heat absorbing metal plate that collects the warmth from the sun. When a thermostat detects that the air in the box is warmer than the air in the house, a fan switches on and directs it inside through a pipe. The fan is powered by a small solar PV panel on the roof, making the whole system self-contained.
This device reduces resident’s energy bills by around a quarter. Check out Lakota Solar Enterprises for more information, and Mr Red Cloud’s inspiring story.
These systems have been optimised for domestic use, but you won’t be surprised to know that the internet has plenty of advice on how to build a solar air heater for your own use – perhaps to fit to a greenhouse or a garage, or to sit on a sunny windowsill. Stacks of empty tin cans painted black seem to be popular.