Classifying IFES Systems
In order to maximize synergies between food crops, livestock, fish production, and sources of renewable energy, agro-industrial technology such as gasification or anaerobic digestion may be added to the system. Such a combination maximizes the utilization of all by-products, and encourages the recycling and economic use of residues. In many situations, the production of renewable energy can feasibly surpass bioenergy alone. Other locally available (non-biological) renewables may be incorporated, such as solar thermal, PV, geothermal, wind, and water power. Additionally, end-use devices, such as improved cooking stoves or efficient irrigation devices, increase the energy-use efficiency of IFES (Bogdanski 2013). IFES examples include fuelwood grown on farmland in conjunction with food crops (agroforestry systems) for fueling cooking stoves, biogas derived from manure in integrated crop-livestock systems, or bioethanol from intercropped food and energy crops. Many case studies have shown that food and energy for fuel, heat, and electricity may be sustainably produced in such integrated food-energy systems (2013).
Type 1 and Type 2 Systems:
In Gerst et al. 2015 (A Taxonomic Framework for Assessing Governance Challenges and Environmental Effects of Integrated Food-Energy Systems), the authors divide IFES into two categories: Type 1 systems involve cropping patterns that produce food and energy feedstock, such as agroforestry, while Type 2 systems contain more technological complexity that maximizes the use of byproducts, such as the sequestration of methane from cow manure via anaerobic digestion.
From there, the authors further break down digester categories using their taxonomic framework. They divide IFES into plant, animal, or energy “subsystems” based on the products produced. The many dairy farm case studies on this site are therefore animal systems, because dairy cows represent the crucial component to which, and from which, the inputs and outputs on the IFES flow. Plant and animal subsystems may be combined as “multifunctional systems” if they produce both food and feed, or fuel and energy (Gerst et al. 2015).