Insight on Biomass Supply and Feedstock Definition for Fischer-Tropsch Based BTL Processes

Process chains of thermo chemical conversion of lignocellulosic biomass through gasification and Fischer-Tropsch synthesis (known as BTL) represent promising alternatives for biofuels production. Since biomass is heterogeneous and not homogeneously spread over territories, one of the major technological stakes of the project is to develop a flexible industrial chain capable of co-treating the widest possible range of biomass and fossil fuel feedstock. The present study aims at characterizing biomass diversity (availability and potentials by area, cost and mineral composition) by carrying out a state of the art, as a preliminary step in order to define a series of biomasses to be tested in the demonstration plant and therefore define specifications for the process. Fifty different biomasses were considered for their bioenergy application potential and were finally classified into four categories: agricultural by-products, dedicated energy crops, (Very) Short Rotation Coppice ((V)SRC) and forestry biomasses. Biomass availability and potentials were investigated by the mean of a literature review of past and current projects (e.g. RENEW project, Biomass Energy Europe Project, etc.) and scientific articles. Most collected data are technical potentials, meaning that they take into account biophysical limits of crops and forests, technological possibilities, competition with other land uses and ecological constraints (e.g. natural reserves). Results show various emerging markets: North and South America have considerable amounts of agricultural by-products, forest residues, and large land areas which could be dedicated to energy crops; Africa shows relevant possibilities to grow Short Rotation Forestry (SRF) and energy crops; Russia has large available quantities of agricultural by-products and forest residues, as well as little valuable land where energy crops and SRC could be grown, and Asia shows relevant amounts of forest residues and possibilities of growing SRC, as well as relevant quantities of agricultural residues (notably from palm oil cropping systems). To a lesser extent, Europe also presents significant amounts of agricultural co-products and forestry residues which could be available for bio-energy. Nevertheless an improvement of biomass supply structure is necessary to be in the position to answer the demand for BtL (Biomass to Liquid) industry. Mineral composition is also a relevant parameter to be considered for the thermochemical conversion process, since the Fischer-Tropsch catalysis — last step of the conversion process — is very sensitive to mineral elements of biomass. Concerning mineral composition of biomasses, five public databases were analysed to collect relevant characteristics and the information was aggregated in one large database dedicated to the project. Nitrogen, chlorine, phosphorus, sulphur, ash and energy contents are the major parameters collected. By analysing these data, we observe that fast-growing plants (typically agricultural co products) contain much more minerals than low-growing crops (typically forest residues) . This is mostly due to the fertilizers spread in the fields for the growth of agricultural crops. Consequently, agricultural by-products appear as the most constraining biomasses in terms of mineral contents. Regarding costs, a literature review was also carried out, with a special focus on the French case. Most data come from REGIX Programme and French organisms (FCBA, Association AILE, etc.). This allowed us to observe that agricultural by-products are the cheapest biomasses (10 to 15 € IMWh, equivalent to 50 to 75 € /TDM), as they are still considered as sub products of grains. Their price is only driven by conditioning and transport costs. (Very) short rotation forestry biomasses are slightly more expensive (13 to 17€ IMWh, equivalent to 70 to 90 € / TDM), due to harvest costs, but they remain cheaper than energy crops (20 to 22 € /MWh, equivalent to 95 to 110 € /TDM), whose crop management practices (basically phytosanitary treatments and fertilization) increase costs. Finally, forestry wood chips show very variable prices (11 to 25 € /MWh, equivalent to 60 to 130 € 1TDM), depending on the costs attributed to wood material, technology used, access to the plots, and the use of storage platform or not