Current and future technical, economic and environmental feasibility of maize and wheat residues supply for biomass energy application: Illustrated for South Africa

At the farm gate, crop residues cost between 0.9 and 1.7 $ GJ−1. About 96% of these residues are available below 1.5 $ GJ−1. In the improved scenario, up to 85% of the biomass is below 1.3 $ GJ−1. For biomass deliveries at the conversion plant, about 36% is below 5 $ GJ−1 while in the optimised scenario, about 87% is delivered below 5$ GJ−1. Co-firing residues with coal results in lower cost of electricity compared to other renewables and significant GHG (CO2 eq) emissions reduction (up to 0.72 tons MWh−1). Establishing sustainable crop residue supply systems in South Africa could start by utilising the existing agricultural infrastructure to secure supply and develop a functional market. It would then be necessary to incentivise improvements across the value chain.