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Scenario results
The high electricity consumption for primary aluminium production results in a strong influence of the
electricity generation on the CO2 emissions, as shown by figure 6. Thanks to the almost complete absence of
process CO2 emissions, the bipolar electrode cell benefits more from a low electricity emission factor than Hall-
HJroult does. The difference between primary and secondary routes is much smaller in case of a low electricity
emission factor.
A shift from the current
Hall-HJroult cell to the Bipolar
cell, accompanied by a zero
electricity emissions factor,
would mean an eight-fold reduction
within primary production.
In the same circumstances,
a shift to secondary production
means a thirty-fold reduction of
CO2 emissions.
Reduction Potential of the Sector
The intermediate factor two reduction
goal is attainable for
steel, even with unfavourable
external conditions. The
CO2/t
8
6
4
2
0
Aluminium production
CO2 emissions
hall_heroult bipolar secondary
Production route
0 t CO2/GJe
0.1 t CO2/GJe
MIDREX based production route nearly realises 50 % reduction relative to the standard BF150 route, with a
high electricity emissions factor and low scrap addition; high scrap addition further lowers emissions, beneath
the 50 % goal. A factor 2 reduction in aluminium production is only attainable with a low electricity emissions
factor.
On the long term, steel production can meet the factor 10 reduction goal, if external parameters are favourable.
CO2 removal is essential to attain the factor 10 reduction without changing the ratio between primary and scrap
based production routes. The electricity emission factor and the scrap addition rate may be helpful for further
reduction of emissions, but their influence is mainly to change the relative order of the production routes. On
the long term the required changes of the infrastructure to enable CO2 storage are very probably attainable,
though a social acceptation of the storage in aquifers and empty natural gas fields may raise difficulties.
Compared with steel, aluminium lags somewhat behind; within the primary production routes a factor 8 is attainable
with a low electricity emissions factor. Further reductions of emissions require a shift to scrap based
production. If this is not attainable, extra reductions in steel production may compensate the deficiency in aluminium.
Besides external factors, internal factors are likely to influence the choice of a production route. Of the production
routes with considerable reduction potentials, COREX and CCF based routes present a logical step for
primary steel producers, while DRI based routes are entirely different from the current primary production
structure. On the other hand, DRI based routes might be a logical step for the current scrap based producers.
MIDREX, Circofer and CCF could be regarded as Asafe bets@ as they always result in emission reductions,
regardless of external parameters, while COREX requires CO2 removal to realise reductions at all. The CCF
route has the advantage of its low costs, even in the removal scenarios.