How to reduce carbon footprint from steel industry?
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Strategies to control CO2 emissions from the Steel sector
A state-of-the-art Steel Mill is a much optimized system in terms of consumption of fuels and reducing agents. The Blast Furnace itself operates 5% away from thermodynamics and the whole mill has a potential of energy savings of roughly 10% only. This is due to several decades of cost management, as high energy prices have driven the industry to optimize its processes as close as possible to physical limits. The Industry rightfully claims energy savings and, correspondingly, CO2 cuts which range between 50 and 60% over the last 40 years, depending on the local conditions: this is the highest level of energy conservation achieved by any industrial sector.
Cutting CO2 emissions further, to the level that post-Kyoto policies require, raises therefore specific challenges: it is indeed necessary to uncouple energy savings and CO2 reduction in the Steel sector – an original feature compared to other sectors.
First, a more or less obvious fact that ought to be stated, anyway, is that the usage of steel scrap should be kept at the high level that it has reached today. It is estimated that the collecting rate of obsolete scrap is around 85% today, which forms the basis of a strong recycling economy, complete with scrap dealerships and a specific steel production route based on the EAF. In simple words, value is created by the recycling of virtually all available scrap. In the long term, this situation will continue.
It should also be pointed out that the indirect emissions related to electricity production will evolve with time. For example, ULCOS has shown that, under a strong carbon constraint, the carbon intensity of the European electricity grid will drop form 370 gCO2/kWh in 2006, to 144 g in 2050, a specific drop of 55%, which will be translated at the same level in indirect emissions [58].
The major source of CO2 emissions from steel mills still remains the ore-based route, which will retain an important role in the long term, at least until a recycling society can replace the 20th and 21st century economy of production growth that is mainly driven by population growth – probably some time in the next century or at the very end of the present one [59].
Solutions to curtail emissions from the ore-based route have to be exhibited and it is clear from the previous sections that there is no simple process, available from the shelf, that can accomplish this. Deep paradigm shifts in the way steel is produced have to be imagined and the corresponding breakthrough technologies designed and developed, by strong R&D programs.
The largest such program called ULCOS, for Ultra Low CO2 Steelmaking, has been running in the EU since 2004 to progress in this direction [55 ,60, 61,59].
The analysis that ULCOS has proposed in terms of Breakthrough Technologies is shown in Figure 24, which explains how reducing agents and fuels have to be selected from three possibilities, carbon, hydrogen and electrons, mostly in the form of electricity13. The mock ternary diagram of the figure is meant for didactic clarity: all existing energy sources can be represented on the triangle sides (e.g. coal is close to carbon on the carbon-hydrogen line, natural gas is closer to hydrogen, hydrogen from water electrolysis is on the hydrogen-electricity line, etc.).
The present steel production technology is based on coal, i.e. mostly on carbon, on natural gas, a mix of carbon and hydrogen and on electric arc furnaces. They are shown in red boxes in the figure.
To identify CO2-lean process routes, 3 major solution paths stand out and three only: either a shift away from coal, called decarbonizing, whereby carbon would be replaced by hydrogen or electricity, in processes such as hydrogen reduction or electrolysis of iron ore, or the introduction of CCS technology, or the use of sustainable biomass. They are shown in yellow boxes in the diagram.
ULCOS has investigated about 80 different variants of these concept routes in the initial phase of its research program, using modeling and laboratory approaches to evaluate their potential, in terms of CO2emissions, energy consumption, operating cost of making steel and sustainabilit
A state-of-the-art Steel Mill is a much optimized system in terms of consumption of fuels and reducing agents. The Blast Furnace itself operates 5% away from thermodynamics and the whole mill has a potential of energy savings of roughly 10% only. This is due to several decades of cost management, as high energy prices have driven the industry to optimize its processes as close as possible to physical limits. The Industry rightfully claims energy savings and, correspondingly, CO2 cuts which range between 50 and 60% over the last 40 years, depending on the local conditions: this is the highest level of energy conservation achieved by any industrial sector.
Cutting CO2 emissions further, to the level that post-Kyoto policies require, raises therefore specific challenges: it is indeed necessary to uncouple energy savings and CO2 reduction in the Steel sector – an original feature compared to other sectors.
First, a more or less obvious fact that ought to be stated, anyway, is that the usage of steel scrap should be kept at the high level that it has reached today. It is estimated that the collecting rate of obsolete scrap is around 85% today, which forms the basis of a strong recycling economy, complete with scrap dealerships and a specific steel production route based on the EAF. In simple words, value is created by the recycling of virtually all available scrap. In the long term, this situation will continue.
It should also be pointed out that the indirect emissions related to electricity production will evolve with time. For example, ULCOS has shown that, under a strong carbon constraint, the carbon intensity of the European electricity grid will drop form 370 gCO2/kWh in 2006, to 144 g in 2050, a specific drop of 55%, which will be translated at the same level in indirect emissions [58].
The major source of CO2 emissions from steel mills still remains the ore-based route, which will retain an important role in the long term, at least until a recycling society can replace the 20th and 21st century economy of production growth that is mainly driven by population growth – probably some time in the next century or at the very end of the present one [59].
Solutions to curtail emissions from the ore-based route have to be exhibited and it is clear from the previous sections that there is no simple process, available from the shelf, that can accomplish this. Deep paradigm shifts in the way steel is produced have to be imagined and the corresponding breakthrough technologies designed and developed, by strong R&D programs.
The largest such program called ULCOS, for Ultra Low CO2 Steelmaking, has been running in the EU since 2004 to progress in this direction [55 ,60, 61,59].
The analysis that ULCOS has proposed in terms of Breakthrough Technologies is shown in Figure 24, which explains how reducing agents and fuels have to be selected from three possibilities, carbon, hydrogen and electrons, mostly in the form of electricity13. The mock ternary diagram of the figure is meant for didactic clarity: all existing energy sources can be represented on the triangle sides (e.g. coal is close to carbon on the carbon-hydrogen line, natural gas is closer to hydrogen, hydrogen from water electrolysis is on the hydrogen-electricity line, etc.).
The present steel production technology is based on coal, i.e. mostly on carbon, on natural gas, a mix of carbon and hydrogen and on electric arc furnaces. They are shown in red boxes in the figure.
To identify CO2-lean process routes, 3 major solution paths stand out and three only: either a shift away from coal, called decarbonizing, whereby carbon would be replaced by hydrogen or electricity, in processes such as hydrogen reduction or electrolysis of iron ore, or the introduction of CCS technology, or the use of sustainable biomass. They are shown in yellow boxes in the diagram.
ULCOS has investigated about 80 different variants of these concept routes in the initial phase of its research program, using modeling and laboratory approaches to evaluate their potential, in terms of CO2emissions, energy consumption, operating cost of making steel and sustainabilit
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