Bio-methanol with negative CO2 emissions from residual forestry biomass gasification: Modelling and techno-economic assessment of different process configurations
Giorgia Lombardelli, Roberto Scaccabarozzi, Antonio Conversano, Manuele Gatti
Abstract
The paper presents a techno-economic comparison among five alternative process configurations for bio-methanol production from the gasification of residual forestry biomass. Process design and simulations are performed in Aspen Plus for mass and energy balance calculation, followed by preliminary sizing and economic analysis. Process schemes include a gasification island (state-of-the-art low-pressure gasification compared against a high-pressure gasifier) with syngas conditioning and compression, heat recovery, syngas composition adjustment (by CO 2 capture or addition of hydrogen produced by electrolysis), methanol synthesis and purification and a heat recovery cycle for power generation. CO 2 capture is performed with conventional chemical absorption in the benchmark cases, while low-temperature partial condensation of CO 2 is modeled in the advanced scenario. Methanol output is 14–15 kt/y in the CO 2 capture cases and 36 kt/y in the H 2 addition option. Configurations with a pressurized gasifier and phase-change-based CO 2 separation are the most efficient ones, with a primary energy efficiency of 50 % and a Levelized Cost of Methanol (LCOM) of 700 €/t MeOH . In comparison, LCOM increases to 730 €/t MeOH in the case with conventional capture or between 792 €/t MeOH and 831 €/t MeOH (depending on the CCS technology) if the gasification pressure is conservatively reduced to 2.5 bar. In the H 2 addition scenario, LCOM increases to 821 €/t MeOH due to the significant impact of the electricity consumption for H 2 production, (only partly compensated by the increased methanol production). Scenarios with CO 2 capture feature negative CO 2 emissions, in the range −1.64 to −1.84 t CO2eq /t MeOH , as a result of the capture and storage of biogenic CO 2 (BECCS approach). • Study of 5 bio-methanol configurations with CO 2 Capture and Storage or H 2 addition. • Process design and simulation of high- and low-P biomass gasification to methanol. • Partial liquefaction CO 2 capture and benchmarking against chemical absorption. • Minimum Levelized Cost of MeOH (700 €/t) for high-P gasifier and low-T CO 2 removal. • Negative net fossil CO 2 emissions of biomass-to-MeOH process due to BECCS.