Ex-ante Life Cycle Assessment of carbonating Green Liquor Dregs for CCUS An early assessment on the prospects of using direct aqueous carbonation on green liquor dregs from the pulp industry for carbon capture, utilization and storage
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Typ
Examensarbete för masterexamen
Master's Thesis
Master's Thesis
Program
Industrial ecology (MPTSE), MSc
Publicerad
2024
Författare
Olivegren, Harald
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
Since pre-industrial time, the temperature on earth has risen with over 1°C due to
human activities. To limit the temperature rise to less than 2°C there is a need of
Carbon Capture, Utilization and Storage, CCUS, technologies that collect and store
or use CO2 from the atmosphere. However, the existing CCUS technologies are either
expensive or ineffective, therefore there is a need to develop new CCUS technologies.
This thesis aims to show the possible prospects for CCUS by direct aqueous carbonation
of green liquor dregs, GLD, using flue gas from pulp mills. With data from lab
experiments and from Smurfit Kappa mill in Pite˚a, a scaled-up model was built to
evaluate the maximum yield of sequestered CO2, electrical energy needed to run the
carbonation process and the possible avoided emissions from product replacement
using the carbonated GLD, cGLD. The results was then scaled up to the total GLD
production in Sweden in 2022.
Three scenarios were studied, 1.The cGLD was only filtered and assumed to be
land-filled, 2.The cGLD was dried and used to substitute clinker and 3.The cGLD
was dried and used to substitute gravel. The results show that scenario 2 has the
highest negative emissions of -0.756 ton CO2 per ton of input GLD, compared with
roughly -0.176 ton CO2 per ton input GLD for both scenario 1 and 3, using Swedish
electricity mix for the emissions from electricity generation. The most energy intensive
process step was drying, which in case 2 and 3 stood for 96% of the electricity
use. When scaled up to incorporate carbonating all GLD produced in Sweden in
2022, the maximum negative emissions for the 2nd scenario summed up to 0.31%
of all emissions from Sweden and 24% of the emissions from the total Swedish pulp
and paper industry. A sensitivity analysis was performed by changing the electricity
generation to be from general EU-mix. The impact on scenario 1 was minimal but
for scenarios 2 and 3, the electricity mix had significant impact with total negative
emissions of -0.627 and -0.005 ton CO2 per ton input GLD respectively, due to the
high energy use in the drying step.
Since this is a novel technology, no earlier studies regarding carbonation of GLD has
been published. This report should therefore only be viewed as an indication that
there could be noteworthy benefits of carbonating GLD for CCUS, with significant
negative emissions of 0.31% of Sweden’s total emissions.
Beskrivning
Ämne/nyckelord
Green liquor dregs , carbonation , direct aqueous carbonation , carbon capture and storage , ex-ante life cycle assessment , pulp , material flow analysis