MOBILISING AGRI-RESIDUES FOR MODERN BIOENERGY, ICSC/332

Agricultural and food processing residues have a role to play in the energy mix for many countries as they look towards carbon reduction and net zero emission strategies. Many of these resources are in surplus and considered a waste, low-cost feedstock for adding to fuel strategies for heat and power. However, mobilisation of this resource is a key bottleneck in many instances. Their dispersed nature, high moisture content, and poor shelf-life means that collection and densification is required close to the point of production. Since this is often in rural areas, costs and emissions from transportation to a larger pellet production facility or bioenergy facility can limit the feasibility of utilisation. Nevertheless, agri residues provide many avenues for promoting Sustainable Development Goals including through the provision of local heat and/or power, improving air and water quality (by avoiding open burning or water run-off from heaps for example), creating employment opportunities in rural areas and offering additional income streams to farmers. Assuming the resource can be mobilised, the next challenge is to convert it into a fungible supply that is attractive to users. This entails, not only optimising the pelleting process but also, considering other pretreatment options to enhance energy density further and decrease problematic components (such as ash, K, Cl) in order to deliver premium fuels. This report discusses technologies and options for achieving this goal. The four important primary residues in terms of quantity are those from the production of sugar cane, maize, rice and wheat, which are the top commodity agricultural crops globally. Similarly, some of the most abundant secondary residues are those that arise from their processing: sugar cane bagasse, dried distiller’s grains and solubles (DDGS), and rice and wheat husks. Residues from the soya bean and palm industries are also abundant. Some of these residues (such as DDGS and soya bean cake) have significant global markets, mainly in the provision of animal feed, but also animal bedding. Others are finding increasing local and regional use for energy purposes. The report evaluates the opportunities for exploiting surplus agri-residue resources, which will depend on many factors including not just what is technically feasible, but what is sustainable.