BECCS Opportunities in Brazil: Pre and Post-Combustion Comparison in a Typical Sugarcane Mill

Abstract

In order to make feasible the efforts that would limit the rise of Earth's temperature to no more than 2°C, profound changes are required in the energy systems. In this sense, BECCS (sustainable bioenergy systems, combined with carbon capture and storage) are considered instrumental to attain possible negative emissions. This brings the attention to the sugarcane industry in Brazil, in which it is possible to produce fuel ethanol at a relative low cost and a large amount of relatively cheap biomass is available. The already good results related to the avoided emissions could be further improved with the storage of the CO2 produced during fermentation. In addition, with not yet commercial BIG-CC systems (biomass-integrated gasification to combined cycle), it would be possible to at least double the generation of electricity at a sugarcane plant, compared to the results of conventional cogeneration systems. In this case, as biomass gasification is required, it would be possible to use pre-combustion capture technologies, reducing energy penalties. This article is part of a research that aims to study the combined production of liquid fuels and electricity, using sustainable sources of biomass and maximizing carbon capture. In both cases evaluated, the capture is based on amine technology: pre-combustion capture of CO2 from the fuel gas derived from biomass gasification, and post-combustion capture from gas turbine exhaust gases. Modelling is based on literature information for all systems, as well as for estimating energy penalties associated with CO2 capture, transport and storage. The results indicate technical feasibility for both technologies, but difficulties in setting the full integration of the BIG-CC unit with the sugarcane mill and the CCUS system, due to the high demand for thermal energy as low pressure steam. The estimated CO2 abatement cost is in the range 66–77 €/tCO2 for pre-combustion capture, and 58–68 €/tCO2 in the case of post-combustion. Feasibility results are impacted by the scale of CO2 capture from the combustion gases (0.54–1.11 MtCO2/year), mainly in the pre-combustion case, and by the relatively high cost of electricity generation (46 €/MWh).