1. Introduction - Firenze University Press

4 the CO2 emissions effect for BLGMF is further improved due to the occurrence of CCS on
the margin in the power sector. If CCS is available, BLGCC gives almost as large CO2
emission reductions as RBU:CCS, however, due to a higher capital intensity it always shows
a poorer economic performance.
5.5. Comparison with results for unchanged production capacity
Here, the results of this paper are compared with the results from a previous study of the same
mill where the production capacity remained unchanged (presented in [18]). Comparing the
results from this paper with those previous results it becomes clear that the BLG cases,
BLGMF and BLGCC (both with and without CCS), benefit from economy of scale. Thus,
they have a better economic performance when increasing the production capacity than when
the production capacity remains unchanged. For the BLGMF case, this means that if the
production capacity is increased, BLGMF becomes more profitable than Lignin:Oil for some
of the scenarios where lignin prices as oil were more profitable in case of unchanged
production. For the RBU:Electricity and RBU:CCS cases, the production capacity increase
affects the economic performance in a negative way. This is due to the fact that an additional
investment in an upgrading of the recovery boiler has to be made. Thus, a production capacity
increase benefits lignin extraction and BLG since these technologies unload the existing
recovery boiler and thereby an investment in an upgrade of the recovery boiler can be
avoided.
6. Conclusions
This paper compares different technologies for utilisation of a potential steam surplus and
debottlenecking the recovery boiler of a typical Scandinavian kraft pulp mill assuming a pulp
production increase of 25%. The technologies are compared with respect to annual net profit
and global CO2 emissions for four different energy market scenarios using two time frames,
2020 (where CCS is not available, neither for the mill nor in the surrounding power system)
and 2030. Based on the results and discussion the following main conclusions can be drawn:
For all energy market scenarios, both year 2020 and 2030, BLGMF and lignin
extraction where the lignin is priced as oil have a better economic performance than
upgrading the recovery boiler (and existing steam turbines).
The BLGMF case generally has the best economic performance, but is contrary to
lignin extraction very sensitive to changes of several parameters, especially the level
of support for biofuels and the investment cost.
Extraction of lignin that can be priced as oil has a very good economic performance
and it is not highly influenced by any of the parameters studied outside the scenarios
and can therefore be said to be a fairly robust investment. The CO2 emissions
reduction from lignin extraction is also fairly stable between the scenarios.
For the year 2020, where there are assumed to be no possibilities for CCS, BLGCC
generally gives the highest CO2reduction potential. For the year 2030, where there is
assumed to be an established infrastructure for CCS, upgrading the recovery boiler and
investing in CCS coupled to the boiler flue gases render the highest CO2 reduction
potential, followed by BLGCC and BLGMF, where CCS also can be included.
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