More than 80 percent of the world still uses a furnace fueled by firewood for cooking. Fumes and soot can cause health and environmental problems; time is wasted and forests are drained in search of the firewood. The Biofuel Clean Cookstove applies a new, combustion technology to previously used cooking oil, or oil extracted from plants. It is easy to ignite; the heat is adjustable; and the risk of fire danger is low because it is extinguished automatically when more than the appropriate amount of fire is used, and has a protective cap around the burner.