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uid metal as the product; it did not include the subsequent, product-specific, less energy intensive processes for
casting, rolling and finishing, mainly important for their material efficiency.
Calculations of emissions and costs of the production routes took place by process analysis and aggregation of
the individual processes into production routes. First, individual process data were collected, including consumption
and production and data on investment and operation costs [1-9,11,12,14-18,21-23]. Stacking of the
processes into production routes allowed calculation of the consumption and production data per unit product.
Subsequent combination of these data with prices [9], carbon contents and CO2 emission factors resulted in
costs and CO2 emissions for each product.
As always in process analysis, system boundaries presented a problem. As all selected production routes use
electricity or produce excess energy, the CO2 emissions to be attributed to the production routes depended on
the technology applied outside the base metal industry. Therefore, the emissions were calculated for two CO2
emission factors of the electricity production, of 0 and 0.1 tonne CO2 per GJe. Nuclear, solar, wind and water
based power plants or fossil power plants with CO2 removal results in a (near) zero emission factor, while 0.1
tonne CO2 per GJe represents the current European average. Conversion of excess energy emerging from a production
route to electricity at an efficiency of 40% allowed subtraction of the avoided CO2 emissions in the
electricity sector from the emissions by steel production. Steam production may also have varying emissions.
There is no separate scenario: 0.06 t CO2 per GJ steam emission factor accompanies the high electricity emissions
factor; zero emissions for steam accompany the zero electricity emissions factor.
For steel, two additional, partly external parameters were used to define scenarios. For both scrap addition and
CO2 removal two additional scenario parameters were defined, resulting in a total of 8 scenarios. The steelmaker
decides on scrap addition, but the possibilities for scrap addition strongly depend on external factors.
Likewise, CO2 removal is a technique applied by the steel producer, but transport and storage require external
infrastructure, involving external decision makers.
Steel Production
The selection of steel production routes, listed in table 1, represents the four main types of liquid steel production,
namely the blast furnace, smelting-reduction, direct reduction and scrap based routes, with two of each. In
the EC, 1993, the conventional blast furnace route accounted for about 88 million tonnes crude steel, and scrap
based electric steelmaking for about 44 million tonnes [10], with application of best practice techiques resulting
in over 150 and 9 Mt CO2 emissions, respectively.
Table 1 Important characteristics of the production routes
Route Energy input Energy output Number of
processes
CO2 removal
Proces Type GJtot * GJe* Gas* Steam* Total CO2 rate ECU/t
removal** % CO2***
BF150 coal 19.6 3.1 5 1 (p) 80 32
BF250 coal 16.7 2.5 5 1 (p) 90 30
COREX coal 28.3 10.8 4 1 (p) 90 30
CCF coal 18.8 3.5 5.5 3 1 (p) 90 30
MIDREX gas, electricity 14.3 1.6 3 1 (s) 90 10
Circofer coal,
electricity
16.1 1.6 3 1 (s) 90 10
ACEAF electricity 1.7 1.4 1
DCEAF electricity, coal 1.7 0.9 1
* Values for low scrap addition, GJ per tonne steel. **(p) indicates that removal is possible, (s) that removal is part of
tion. *** total of removal, transport and storage.
normal process opera-
A thorough description of all processes in detail would be too elaborate, but it is essential to provide some
background information on the analysed production routes. Table 1 lists some characteristics of the the produc-