Biogas is the gaseous product of breaking down organic matter in the absence of oxygen (see Anaerobic Digestion). It can be used to meet the energy need for cooking and baking in individual households as well as in small businesses (e.g. restaurants and bakeries) or in communal facilities. Stoves and ovens for biogas application are similar to conventional appliances that run on commercial fuels such as butane and propane. However, special modifications (particularly in the design of the burners) are required in order to ensure proper combustion and the efficient use of energy.