Martin E Nix, an engineer from Seattle, US, who holds several patents for solar powered inventions, has devised a way of turning old refrigerators into greenhouses. The condenser, compressor and the motor are removed first; then a hole is cut at the top for a skylight and a solar-powered fan. The solar greenhouse maintains a constant temperature owing to its natural insulating properties. Nix hopes that it will be ideal for creating urban gardens in chilly weathers and cultivating plants as it keeps all the unwanted pests out effectively.