NEGATIVE CARBON-DIOXIDE EMISSIONS FROMEUCALYPTUS PULP MILL INCLUDINGBIOSLUDGE HTC TREATMENT
O PAPEL vol. 83, N.o 6, pp. 83 – 89 – JUNE 2022
Authors: Clara Mendoza-Martinez1,2, Katja Kuparinen2, Mateus Martins1, Marcelo Cardoso1, Esa Vakkilainen2, Jussi Saari21Federal University of Minas Gerais. Belo Horizonte – MG, Brazil.2Lappeenranta University of Technology – LUT Energy, Lappeenranta, Finland
ABSTRACTKraft pulp mills produce CO2 for the most part in combustionprocesses. The recovery boiler, the biomass boiler, and the limekiln are the largest sources of CO2. As these CO2 emissionsoriginate almost entirely from burning biomass (bioenergy),the pulp mill can be considered already nearly carbon neutral aslong as the wood feedstock is obtained from sustainable sources.By applying to this bioenergy use carbon capture and storage(BECCS) or use (BECCU) to permanently remove some of thecarbon from circulation, pulp mills can, therefore, provide someof the negative emissions needed for climate-change mitigation.An alternative way of creating negative emissions in a pulp millis converting process residues that are currently disposed ofby landfilling or incineration into material that can serve as astable permanent carbon storage; ideally the residues could alsobe converted into additional products resulting in additionalrevenue for the plant. In BECCS technology, the CO2 iscaptured, transported, and permanently stored in an appropriategeological formation, resulting in negative net carbon dioxideemissions. In BECCU, the captured biogenic CO2 can be usedas a raw material for bioproducts. Potential processes for CO2utilization in pulp mills include tall oil manufacturing, ligninextraction, and production of precipitated calcium carbonate(PCC), depending on mill specificities and local conditions.CO2 can be captured from a stream of flue gases by absorptionin an aqueous solvent. Chemical absorption by alkanolamines(amine scrubbing) appears to offer an attractive alternative forCO2 separation from combustion flue gases at pulp mills. Inaddition to BECCS/BECCU technologies, carbon can also bepermanently removed from circulation by applying conversiontechnologies other than combustion on some of the biomassstreams containing carbon. In the case of lignin extraction,by removing lignin from the black liquor before combustionin the recovery boiler, some of the CO2 emissions can also beavoided altogether. Hydrothermal carbonization of the biosludge generated during primary (chemical) and secondary(biological) wastewater treatment processes is another possibility of removing carbon in a pulp mill. The hydrocharproduced is an inert substance and resistant to biologicaldegradation. It has potential use, for example, as adsorbents forenvironmental applications. When mixed in soil, it can improveits carbon organic matter, reduce N2O emissions, as well asform a permanent carbon storage. In this paper the potentialof the above-mentioned technologies – post-combustion aminescrubbing for BECCU, and hydrothermal carbonization of biosludge – are evaluated.Keywords: Bioenergy with carbon capture and storageBECCS; Bioenergy with carbon capture and utilizationBECCU; Kraft pulp mill; Climate change mitigation; NegativeCO2; Hydrothermal carbonization
