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@PHDTHESIS{Suer:963309,
author = {Suer, Julian},
othercontributors = {Traverso, Marzia and Deike, Rüdiger},
title = {{G}reen steel - life cycle modeling of an integrated steel
site : carbon footprint and energy transformation analysis
of decarbonized steel production},
school = {Rheinisch-Westfälische Technische Hochschule Aachen},
type = {Dissertation},
address = {Aachen},
publisher = {RWTH Aachen University},
reportid = {RWTH-2023-07732},
pages = {1 Online-Ressource : Illustrationen, Diagramme},
year = {2023},
note = {Veröffentlicht auf dem Publikationsserver der RWTH Aachen
University; Dissertation, Rheinisch-Westfälische Technische
Hochschule Aachen, 2023, Kumulative Dissertation},
abstract = {The steel industry is focused on reducing its environmental
impact. Steel is typically produced primarily from iron ores
in integrated sites and secondarily from scrap recycling in
electric arc furnaces (EAF). Traditional integrated sites
include hot metal generation via the blast furnace route,
basic oxygen steelmaking (BOF), continuous casting, and
subsequent hot-rolling. For the evaluation of environmental
impacts generated by the product, the life cycle assessment
(LCA) methodology according to ISO 14040/44 has been used.
The LCA is internationally recognized and standardized.
Using the LCA methodology, the impacts of primary steel
production via the blast furnace route and the secondary
scrap-based steel production via the EAF route are assessed.
These production routes represent the state-of-the art.
Subsequently, decarbonization strategies are analysed using
the product carbon footprint (PCF) methodology according to
ISO 14067. In a blast furnace coal and coke are used for the
reduction and melting of iron ores. The decarbonization of
the steel industry requires a shift from a coal-based
metallurgy towards a hydrogen and electricity-based steel
production, or purely electric, if the utilized hydrogen
stems from electrolysis. The blast furnace can be
substituted by direct reduction (DR) plants with subsequent
electrical melting. In DR plants, iron oxides can be reduced
by natural gas as well as pure hydrogen. DR plants have
reached capacities, which allow replacing blast furnaces on
a direct basis. While the majority of European steel
producers have pointed to direct reduced iron (DRI)
production as a key part of their decarbonization targets,
the next steps are highly discussed. Two main routes stand
out: (1) Melting and processing the DRI in an EAF directly
to crude steel; (2) Melting and carburizing the DRI in an
electric melting unit to hot metal. The hot metal is then
further refined in a BOF to crude steel. Whereas the first
route seems to be more straightforward, some metallurgical
points require discussion. On the basis of the carbon
footprint methodology different scenarios of a stepwise
transition are evaluated and values of possible
CO2equivalent (CO2eq) reduction are coupled with the demand
of hydrogen, electricity, natural gas, and coal. For
example, while the traditional blast furnace - BOF route
delivers a surplus of electricity in the range of 0.7 MJ/kg
hot-rolled coil; this surplus turns into a deficit of about
17 MJ/kg hot-rolled coil for a hydrogen-based steel
production route. On the other hand, while the product
carbon footprint of the blast furnace-related production
route is 2.1 kg CO2eq/kg hot-rolled coil; this footprint can
be reduced to 0.75 kg CO2eq/kg hot-rolled coil for the
hydrogen-related route, obtained with electricity input
generated by renewable sources. Thereby the direct impact of
the processes of the integrated site can even be reduced to
0.15 kg CO2eq/kg hotrolled coil. The remaining carbon
footprint is caused by upstream processes for which no
improvements are considered. However, if the electricity
input has a carbon footprint related to the German or
European electricity grid mix, the respective carbon
footprint of hot-rolled coil increases up to 3.0 kg CO2eq/kg
hot-rolled coil. A natural gas-based DR production route
leads to a carbon footprint of 1.4 - 1.7 kg CO2eq/kg
hot-rolled coil, depending on the electricity mix used for
the steel production processes. A detailed break-even
analysis is given, comparing the use of natural gas and
hydrogen using different electricity mixes. Intermediate
scenarios can enable a stepwise transition of changed plant
configurations and material and energy related feedstocks.
Simultaneously, the intermediate scenarios lead to PCF
reductions in time. In this dissertation the scenarios
hydrogen and natural gas injection into a blast furnace and
the use of hot briquetted iron (HBI) in a blast furnace are
analyzed.},
cin = {316710},
ddc = {624},
cid = {$I:(DE-82)316710_20180607$},
typ = {PUB:(DE-HGF)11},
doi = {10.18154/RWTH-2023-07732},
url = {https://publications.rwth-aachen.de/record/963309},
}
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