Transforming the chemical pulp industry : From an emitter to a source of negative CO2 emissions
Kuparinen, Katja (2019-10-18)
Väitöskirja
Kuparinen, Katja
18.10.2019
Lappeenranta-Lahti University of Technology LUT
Acta Universitatis Lappeenrantaensis
School of Energy Systems
School of Energy Systems, Energiatekniikka
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Julkaisun pysyvä osoite on
https://urn.fi/URN:ISBN:978-952-335-423-4
https://urn.fi/URN:ISBN:978-952-335-423-4
Tiivistelmä
The chemical pulp industry is an energy-intensive industrial sector. Modern kraft pulp mills are typically energy-independent, and fossil fuels are used mainly in lime kilns. Following the Paris Agreement, the pulp industry along with other industrial sectors is urged to take action to combat climate change. This requires the reduction of fossil fuel use and CO2 emissions. The kraft pulp mill process offers several possibilities to achieve the desired environmental targets. This thesis evaluates the significance and possible routes of the chemical pulp industry in fulfilling the recently presented climate targets. The replacement of fossil fuels in lime kilns with renewable biomass or synthetic fuel and implementing CO2 capture technologies offer pulp mills the possibility to operate nearly fossil fuel-free or even to become sources of negative CO2 emissions.
Various biomass processes to convert solid biomass to biofuels are tested and used, but only a few of them in large scale. Kraft pulp mills have a globally significant role in converting biomass to energy due to recovery boilers, but not yet in biofuel production. New biomass conversion technologies, power-to-gas, and carbon capture are options to reduce fossil fuel use and fossil-based CO2 emissions in kraft pulp mills. Renewable biomass-based fuels can, in many cases, fully substitute fossils in lime kilns in a feasible way. Kraft pulp mills have a significant potential to utilize biomass conversion for fossil fuel replacement. Hydrogen from an integrated electrolyser can replace part of the fossil fuels used in a lime kiln and simultaneously make separate oxygen production unnecessary. Electrolysis is most feasible in stand-alone mills when the electricity price is low. Carbon capture methods are still developing technologies. In kraft pulp mills, even a small capture can make the mill a negative CO2 emitter, when wood raw material is from a sustainable origin. A part of the captured CO2 can be utilized in existing processes. All of these technologies were found to be technically feasible. Economic feasibility depends on mill-specific details, technology development, and political decision-making, such as carbon taxes and possible incentives for carbon-neutral/-negative technologies.
Various biomass processes to convert solid biomass to biofuels are tested and used, but only a few of them in large scale. Kraft pulp mills have a globally significant role in converting biomass to energy due to recovery boilers, but not yet in biofuel production. New biomass conversion technologies, power-to-gas, and carbon capture are options to reduce fossil fuel use and fossil-based CO2 emissions in kraft pulp mills. Renewable biomass-based fuels can, in many cases, fully substitute fossils in lime kilns in a feasible way. Kraft pulp mills have a significant potential to utilize biomass conversion for fossil fuel replacement. Hydrogen from an integrated electrolyser can replace part of the fossil fuels used in a lime kiln and simultaneously make separate oxygen production unnecessary. Electrolysis is most feasible in stand-alone mills when the electricity price is low. Carbon capture methods are still developing technologies. In kraft pulp mills, even a small capture can make the mill a negative CO2 emitter, when wood raw material is from a sustainable origin. A part of the captured CO2 can be utilized in existing processes. All of these technologies were found to be technically feasible. Economic feasibility depends on mill-specific details, technology development, and political decision-making, such as carbon taxes and possible incentives for carbon-neutral/-negative technologies.
Kokoelmat
- Väitöskirjat [1099]