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From figures 4 and 5, CO2 removal evidently emerges as a key technoloy in achieving emission reductions
within primary production routes. However, the emission factors of electricity and steam are very important for
the ranking of the primary
routes.
As shown in figure 4, with
emission factors of 0.1 for electricity
and 0.06 for steam, Corex
is the outright winner, thanks to
its large excess energy production,
which in this scenario prevents
CO2 emissions by the
electricity generation. Of the
primary routes, CCF has second
lowest emissions, followed by
MIDREX and Circofer. The
blast furnace routes profit least
from the removal, due to the
large share of processes without
removal, and the small excess
energy production.
With zero emissions for electricity and steam (figure 5), the picture changes profoundly. Going from Circofer,
MIDREX, CCF to COREX, the emissions rise, the exact opposite of the previous ranking. CCF and COREX do
no longer profit from their excess energy productions. The ranking of the blast furnace routes does not change,
they have the highest emissions. Overall this scenario offers the highest possibilities for emissions reduction,
without in any way compromising the steel quality by the addition of extra scrap. With regard to the costs, CCF
is the outright winner in all included scenarios.
Tables 3 and 4 give an overview
of the emissions and costs of the
production routes in the various
scenarios, including scenarios
with high, 30%, scrap addition
in primary production routes,
not shown in the figures. When
slight decreases of steel quality
are acceptable, further reduction
of emissions results from maximum
scrap input.
tonne CO2/tonne liquid steel
ECU/tonne
2.5
2
1.5
1
0.5
0
200
180
160
140
120
100
80
60
40
CO2 emissions of steel production
0.1 t CO2/GJe, low scrap
bf 150 bf 250 corex ccf midrex circofer ac eaf dc eaf
Production route
Costs of steel production
Low scrap
bf 150 bf 250 corex ccf midrex circofer ac eaf dc eaf
Production route