Abstract
Urgently reducing global greenhouse gas emissions (GHG)
could be achieved by carbon sinks or negative emissions,
i.e. removing CO2 from the atmosphere and offsetting
historical CO2 emissions. Negative emissions can be
achieved when CO2 is captured from processes based on
biomass feedstock (bio-CCS). Biomass withdraws
atmospheric CO2 through natural processes such as the
photosynthesis. Capturing and permanently storing this
CO2 away from the natural carbon cycle enables a
withdrawal of CO2 from the atmosphere. Sustainable growth
and harvest of biomass resources is critical to achieve
carbon negativity and to allow for sound biomass
regrowth. As a result, bio-CCS provides a potential
mitigation tool to reduce the CO2 concentration in the
atmosphere. The pulp and paper industry is one of the
potential candidates for large scale demonstration of
bio-CCS and industrial CCS application. In Europe, the
pulp and paper industry is the largest user and producer
of biomass energy, contributing to around 60% of the
biomass based electricity and heat production. There are
three main sources of CO2 emissions in the pulp and paper
production (via Kraft pulping process): (1.) the Kraft
recovery boiler, (2.) the lime kiln and (3.) the
multi-fuel boiler (bark boiler). Typically, over 90% of
CO2 emissions from a pulp mill are of biogenic origin as
fossil fuel is used only for firing the lime kiln. The
main function of the recovery boiler is to recover the
spent cooking chemicals from the black liquor for reuse
in wood chips cooking and the combustion of the organic
matter in the black liquor to produce heat for steam and
electricity generation. The lime kiln is part of the
chemical recycle loop and this includes the calcination
of the lime mud (mainly calcium carbonate) to produce CaO
that is used in the recovery of the cooking chemicals
(i.e. processing of the green liquor). As a result, the
lime kiln produces a flue gas with high concentration of
CO2. The multi-fuel boiler is typically used to burn any
wood waste and residue biomass (i.e. bark and bio-sludge)
from the pulp production to produce steam used in the
process and for power production. This study addresses
the operational costs, capital investment costs and
technical aspects of retrofitting a modern Kraft market
pulp mill with a split flow post-combustion CO2 capture
based on amine absorption. The pulp production units and
the CO2 capture units are presented with detailed mass
and energy balances. Two types of mills were evaluated;
i) Stand-alone pulp mill producing 800 000 adt of
softwood pulp annually and ii) Integrated pulp and board
mill producing 740 000 adt of softwood pulp and 400 000
3-ply folding boxboard annually. Annual CO2 emissions are
2.1 Mt CO2/a. Six different cases were studied for each
mill type; CO2 capture from the three individual point
sources and three combinations of these. The
implementation of a post-combustion CO2 capture process
requires additional steam for the amine reboiler and
additional power input for pumps and compressors. In some
cases the excess power production at the pulp mill may be
sufficient to support the integration of a CO2 capture
plant. In other cases an additional auxiliary boiler is
required. The split flow MEA-based capture process
enables a reduction in the heat duty for the CO2 stripper
reboiler. The average reboiler duty was calculated to
around 2.7 - 2.8 MJ/kg captured CO2. Steam is provided
from the steam turbine island. A major focal point of the
study was to investigate the optimal extraction of steam
and condensate return. Most pulp and paper mills are
self-sufficient with electricity and produce excess
electricity that is exported to the local/national grid.
90% CO2 capture was assumed for all cases, but in future
evaluations partial CO2 capture might prove more viable,
depending on the amount of excess steam or electricity
available at the mill. This is also affected by the price
of electricity, price of emission allowances and any
renewable energy subsidies/incentives. Capturing biogenic
CO2 could potentially create additional revenues for the
mill operator, depending on whether the emission of
biogenic CO2 would be accounted for as negative CO2
emissions in emission allowance trading schemes. As a
result, accounting for negative CO2 emissions could
potentially be a low-hanging fruit and lead to
demonstration or large scale industrial business cases
for the implementation of CCS in the near future.
Original language | English |
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Title of host publication | CO2 Summit II |
Subtitle of host publication | Technologies and Opportunities |
Editors | Holly Krutka, Atorod Azizinamini, Frank Zu |
Publisher | Engineering Conferences International (ECI) |
ISBN (Print) | 978-1-5108-2441-6 |
Publication status | Published - 2016 |
MoE publication type | Not Eligible |
Event | CO2 Summit II: Technologies and Opportunities, - Santa Ana Pueblo, United States Duration: 10 Apr 2016 → 14 Apr 2016 |
Conference
Conference | CO2 Summit II: Technologies and Opportunities, |
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Country/Territory | United States |
City | Santa Ana Pueblo |
Period | 10/04/16 → 14/04/16 |
Keywords
- Bio-CCS
- concept evaluation
- climate change
- CCS
- CO2