Techno-Economic and Environmental Analysis of Oil Crop and Forestry Residues based Biorefineries for Biojet Fuel production in Brazil

Abstract

The well-known volatility of petroleum price and, subsequently, of its derived products has long time urged the attention for the discovery of alternatives to fossil oil. More recently, the dichotomy food-fuel, has redirected the research towards second generation feedstocks, in which biomass residues are included. In line with this, a consortium of Dutch and Brazilian companies and Universities – HIP – joined forces to evaluate the potential of biojet fuel production in the Brazilian supply chain for which this study contributes. This project aims to identify the most promising combinations of location/feedstock/technology/ by-products for a biojet fuel biorefinery in the Brazilian context. For this, different feedstock that are significantly available in Brazil are considered, namely wood residues (Eucalyptus, Pine), agro residues (Coffee and Rice) and oil crops (Macauba). Then, 208.5 kton of biojet per year is taken as base capacity which supplies in 10% the project demand for 2020 of both São Paulo and Rio de Janeiro airports. Furthermore, this value also corresponds to a “drop-in” fuel at 50/50 blend of biojet and conventional jet. To achieve the established goal, around 120 scenarios were generated focusing on the comparison of lignocellulosic and/or lignin valorisation processes, the latter coupled with sugar production to be used in fermentation. Therefore, three pre-treatment processes are considered (steam explosion, dilute acid and organosolv), followed by enzymatic hydrolysis; and two possible thermo-chemical processes are included for lignin upgrade to biojet fuel (fast pyrolysis and gasification Fischer-Tropsch). Regarding lignocellulosic material, its valorisation is also achieved by thermo-chemical processes; being fast pyrolysis, gasification Fischer-Tropsch and hydrothermal liquefaction the alternatives studied. Additionally, the conversion of the extracted oils into biojet is obtained via hydro-processing of esters and fatty acids which step is common to all oil crop scenarios. In general, literature data was used to support most technology related decisions. Then, the number of scenarios is refined according to feedstock availability, gross profit estimation and minimum sales price, for which a price of 605 US$/ton is assumed for the biojet produced. After this preliminary analysis, the six most promising scenarios are simulated: fast pyrolysis and hydrothermal liquefaction for Pinus, Eucalyptus and Macauba, while aiming for the introduction of more detail in the techno-economic evaluation of these scenarios. Consequently, the biojet minimum sales price for the simulated scenarios ranged from 834-1188 US$/ton, being a biorefinery in Rio Grande do Sul for the conversion of Pinus via hydrothermal liquefaction the best performing scenario. Furthermore, it is also confirmed that overall these scenarios have a lower climate change impact, 1-19 kg CO2/GJ biojet, and require less primary energy, 16-395 MJ/GJ biojet, for biojet production in comparison to its homologous from crude oil, 87.5 kg CO2/GJ jet and 1210 MJ/GJ jet, respectively.