An integrated food-energy system (IFES) is defined as a farming or food production system that builds on the principles of sustainable agriculture and ecological design/industrial symbiosis by co-locating food and energy production, or linking them to reduce inputs and improve overall system efficiency. The concept of IFES combines the sustainable production of food and energy across different ecological, spatial, and temporal scales, through multiple-cropping systems, or through systems that mix annual and perennial crop species, i.e. agroforestry systems. Either system can be combined with livestock and/or fish production (Bogdanski 2013).
In smallholder farming systems around the world, IFES can include the diversification of crop and livestock species leading to a sustainable production of both food and energy feedstock, as long as practices are locally devised and adapted. Simple systems provide woody biomass for cooking and heating. In more complex systems, livestock manure is used to produce biogas for on-farm use.