The challenge of Global Warming to the Steel Industry,

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4 The challenge of Global Warming to the Steel Industry, a European viewpoint Jean-Pierre Birat, Arcelor Innovation, IRSID, Maizières-lès-Metz, France The relationship of mankind with the environment has changed. Population growth, urbanization and the growth of the world GNP have put anthropogenic activities in the position of affecting some of the basic equilibria of the biosphere. From local, environmental issues have become global in ways that challenge our deep and detailed understanding of the complex Earth-System and forecast changes, which might be much larger and more encompassing than anything that mankind has been directly responsible for in the past, except maybe war. Change is not new to the biosphere, but the rate of change, which is now envisioned, is much larger than that of the natural kinetics of the system. Two of the most serious issues concern Biodiversity and Global Warming. These are indeed the two issues to which the United Nations have directed their attention in the formal way of publishing specific Conventions and Protocols [i, ii1. Moreover, since the Brundtland report [iii], the idea that growth should be carried out with a real concern of keeping sufficient resources available for the long-term future has become popular and society, as well as private companies, have adopted the concept of sustainability as a goal and an ethic criterion for conducting business. We shall concentrate here on the issue of Global Warming, which is closer to Physics and therefore simpler and better understood. The causes of Global Warming, anthropogenic Greenhouse Gas (GHG) emissions beyond the level that can be accommodated by the biophysical thermodynamic Earth- System, are easy to relate to specific human activities. The use of carbon from fossil deposits accumulated over a geological time scale and dissipated over a historical time scale is its main direct cause. Any large user of carbon is at the root of the problem and, whether this is defined in terms of responsibility or not, its future will be closely related to its ability to accommodate this fact and address it as squarely as possible. Moreover, when the time comes for political bodies to act on the matter in a decisive way, the dialectic of Equity versus Efficiency will be central and it is most likely that large emitters will be pointed out first for efficiency's sake and in order to show rapid results. The Steel Industry is precisely in this position of being a large user of carbon, as it accounts for 5 or 6% of anthropogenic emissions in the world. This is much less than the emissions of transportation or of housing and commercial buildings, but the Steel Industry exhibits a limited number of sources, the Integrated Mills, which have become fewer and fewer as the Industry has been increasing its efficiency, both business and environment-wise. In the post-kyoto Protocol future, this will be an uncomfortable position to hold. On the other hand, our modern world is largely based on Steel, for its infrastructures, for the basic tools of its industries and for its most common consumer items. Steel has become one the most used basic functional material in the world, second after wood or maybe first, depending on the exact definition one gives to this expression. This is due to its broad spectrum of properties, to its low price that stems from the wide availability of element iron and to the accumulation of knowledge on steel production, which has been transformed into a lean and efficient technology. This is also due to the fact that Steel is changing continuously and redefining itself into new materials although the name of Steel stays unchanged. It is unlikely that the improvement of the wellbeing of the world population, which is everyone's wish, can be based on an alternative material in any foreseeable future. Mankind needs Steel to access more widely over the world to a higher level of Standard of Living. If Steel is to meet this long-term challenge, it will most particularly need to meet the Global Warming challenge. 3

5 This is in itself a formidable endeavor, as the Industry is locked in an apparent contradiction. On the one hand, its manufacturing processes have reached a very high level of efficiency and are close to physical limits in their use of carbon. This leaves very little leeway for drastic improvement in the short or even the middle term. On the other hand, it is possible to imagine other routes for making steel that disengage themselves from carbon, but if the concepts can be clearly spelled out now, they have not been translated into an industrial technology yet. The time scale for drastically changing the technological paradigms of a heavy industry such as the Steel industry is long, 10 to 20 years at least to demonstrate that a viable and sustainable alternative is possible. We shall discuss both the short term and the long term issues, successively. 1. The Steel Industry has been working on sustainability for half a century The concept of sustainability was first introduced by Ms Brundtland, in her famous 1987 report [ III ], but Industries - and the Steel Industry more particularly - have been practicing the concept, nolens volens, since the 1960's at least. Indeed, under the drivers of mass production, quality control and cost reduction, technical progress has led to large energy savings and to the systematic use of lean and clean processes. The time series of energy consumption and CO2 generation of the French Steel Industry, over the past 40 years, bears witness to that tendency (figure 1). They have indeed decreased respectively by 50 and 60% over that period of time. And this does not reflect a recession of the sector, as the trend is visible on global as well as on specific values. There is a strong correlation between energy and CO2 emissions, which are the two faces of one single reality. The two are not completely identical though, in as far as some energy substitution is carried out by replacing coal by electricity, which has a very low carbon intensity in France, because of the large share of nuclear power in electricity generation. Moreover, behind those seemingly simple figures is shadowed a complex set of circumstances, where change and modernization have been carried out in a number of different ways, including the switchover from Integrated Mills to Electric Arc Furnace (EAF) Mills for long product manufacturing. It should be noticed that the trend was initiated before the first oil shock during the 30 Glorious Years, as the post-world War II high growth period was called by Jean Fourastié, which means that deep change was in progress long before the energy crises added their own drivers to it. However, a saturation on the kinetics of change has been observed since the beginning of the 1990s: this does not mean that the Steel Industry has dropped its target of continuously improving energy efficiency, but rather that the steelmaking processes have become close to physical limits, thermodynamic in nature. kg/t liquid steel % in 40 years 1,0 0,8 Boundaries French Steel Industry Energy consumption 10 6 TPE/ year CO 2 emissions 0,6 0,4 0,2-48 % in 40 years 0, Figure 1 Evolution of GHG emissions and energy consumption in the French Steel Industry

6 Indeed, Steel is produced today in very modern Steel Mills, which use a set of unique technologies first introduced for most of them during the 1950s and scaled up to their present size over the 10 to 20 years that followed. The reactors used to generated about 700 million tons of steel every year are less than 15 years old in their present avatar and more processes are being developed, which will only be introduction into commercial plants in the future. Change is tightly woven in the Industry's culture. There are two major routes for producing steel, the Integrated Route and the EAF Route. The first one makes use of virgin iron that needs to be reduced from iron ore oxides into metallic iron, while the second one uses recycled steel. As the first one uses carbon, as a reducing agent, an energy source and an alloying element, it will release CO2 into the atmosphere directly or indirectly to the level of roughly 2 t of CO2 per t of steel. The EAF route, the thermodynamical needs of which are reduce by a factor of 3, uses electricity and therefore will release CO2 to a level directly proportional to the carbon-intensity of electricity generation. In France, where non-fossil fuel electricity production accounts for 90% of the total, this leads to a generation which is 10 times less than that of the Integrated Route. The collecting rate of steel scrap, which lies at the level of 75 to 80% in developed countries, is very high. To accommodate the demand for Steel, virgin iron is needed at the level of 57% of the iron unit inputs. It is important to emphasize the fact that Steel is rather unique among materials in as far as it has developed a production route entirely centered on recycling. This is of course due to the fact that the EAF Route is competitive with the Integrated Route and that a lot of recycled Steel, more commonly known as scrap, is available. This also means that Steel recycling has organized within the framework of the market economy to deliver a secondary raw material, which competes with virgin iron in terms of price and quality and that recycling, for the case of steel scrap, is an activity that generates value without the help of any subsidy, ecological tax or levy collected from the consumer target Consumption of reducing agents & fossil energy (mtep/t) Specific consumption of electricity (kwh/t) Specific consumption of energy (mtep/t) CO2 emisions (kg/t) Figure 2 Voluntary Agreement between the French Steel Federation and the French Government The French Steel Industry (Fédération Française de l'acier) signed a voluntary agreement with the government to restrict energy consumption and CO2 emissions over the period The targets have been met to the level of 70 to 80% (cf. figure 2). As far as specific emissions are concerned, they were reduced by 13.3% in 2000 as compared to the 1990 level. Specific carbon consumption, expressed in TPE, was reduced by 11.8%. The corresponding targets were respectively 16.3 and 15.8%. The discrepancy is due to the fact that the EAF route turned out to have developed less than had been anticipated. The results are fair, as the targets had been decided pragmatically at a time when the economic and process technology contexts were changing fast and were loaded with uncertainty. 2. Solutions for reducing CO2 emissions in the short term In order to analyze the degrees of freedom that are available to the Steel Industry, we have carried out simulation of CO2 emissions by modeling existing and future process routes, using the Fos Mill of Sollac Méditerranée as a benchmark representative of today's technology. The time horizon is both the short term and the middle term. The results are shown in figure 3. CO2 emissions are shown as a function of 5

7 the amount of pig iron or hot metal used in the Route. On the right-hand side are processes used in the Integrated Mill, while on the left-hand side are processes found in the Scrap routes. Smelting Reduction processes are located in the middle of the diagram, as the variant modeled there is the COREX process, complemented by a Midrex prereduction unit that makes use of the top gas of the shaft furnace as a reducing agent and generates prereduced iron in addition to the hot metal made by the COREX. Prereduction processes are at the left hand-side of the diagram, but they exhibit a higher level of emissions than the scrap-based EAF does kg CO 2 / t liquid steel COREX+MIDREX+EAF world average of C-intensity of electricity French scenario C-free electricity 1000 HF with top gas recycling EAF kg DRI kg of pig iron or hot metal / t liquid steel Figure 3 CO2 emissions of various steel production processes (simulations) The first explanatory factor of the CO2 emissions is the nature of the iron units used in the route, either virgin iron or scrap. This reflects the thermodynamical needs of the corresponding processes, a reduction at high temperature in the first case followed by a melting of all phases, and a simple melting in the second case. The second explanatory parameter is the carbon-intensity of the electricity used in the process. This is a second order effect for the Integrated Mill case, but it is the major one in the EAF route. There is however one solution available to drastically reduce the Integrated Mill CO2 emissions, which consists in removing CO2 emissions from the top-gas of the blast furnace, reinjecting it the residue at the bottom of the shaft or at the tuyeres and adding the extra-energy necessary to balance the heat requirements by injecting plasma [iv]. The specific emissions are thus reduced to 1350 kg. The first approach that looks promising to decrease emissions even more drastically consists in switching over from the Blast furnace route by the EAF route as much as possible. This is indeed what has been going on since the early 1990s and which explains to a large extend why the voluntary agreement of the French Steel industry could be met. The physical concept of substituting virgin iron by scrap can however be implemented in still another way, i.e. by increasing the scrap input in the oxygen converter. The effects are about the same, as far as the reductions of CO2 emissions are concerned, as by changing the process routes, but the approach can be applied to existing Integrated Mills within a reasonable time scale. This is also the solution, which exhibits the lowest substitution cost per ton of avoided CO2. Moreover, it does not require drastic revisions of steelmaking practices, as would be the case when switching high-end flat steel production from the integrated to the EAF route. Another important point, at least for the short term, is that the collecting rate of scrap is already high and therefore that the amount of extra amount of scrap that can be collected is limited, maybe to 20 to 40 Mt at world level, based on the present situation. We will argue later in the paper that this limitation might not hold true in the longer term. 6

8 The scrap melting capacity of an oxygen converter is roughly 250 kg of scrap per ton of liquid steel, in a normal operation that does not call for reduction-melting conditions and is based on hematite. The operating data of the major European Steelshops in 2000 are given in figure 4. Clearly, most of them have much leeway to increase their scrap input. 300 scrap input (kg/t hot metal) Linz Eko Dillingen SidmarRaahe Salzgitter IJmuiden Charleroi Florange Duisburg Liège SSAB Dunkerque Taranto Fos hot metal input (kg/t steel) Figure 4 Correlation between hot metal ratio and scrap input in European Blast Furnaces There is a reasonably fair correlation between scrap input and CO2 emissions as figure 5 shows, in spite of the variety of steelmaking practices that are implemented in the various European steelshops. CO2 emission (kg/t coil) Pig iron rate (kg/t steel) Figure 5 - Correlation between hot metal ratio and GHG emissions in European Blast Furnaces Usinor took part in simulation exercises of CO2 emission trading carried out within the GETS2 program [v]. This has made it possible to design strategies for progressively reducing emissions, which take into account realistic kinetics of switchover to new technologies, and to estimate the corresponding cost, which is actually a cost of avoided CO2. The data given in figure 6 indicate only orders of magnitude, as they have been calculated within the limited context of a kind of wargame. However, they show that slowing down or shutting down existing plants (such as a sinter plant, for example) may be more costly than adding more scrap or DRI in the converter. Changing production routes, with the only rationale for reducing emissions, can be several orders of magnitude more expensive and go beyond the range of 10 to 100 /t of avoided CO2, which is considered as realistic for the time being. Another point, which the program clearly made, is that the system of emission trading adopted in the exercise ensured a smoother transition to the lower levels of emissions, which were dictated by the game leader, who was impersonating the legislator, than would have been achieved otherwise. 7

9 Change of Process Routes Increased use of scrap and DRI Shut down of production plants Slow down of plants Cost coût d'abattement of avoided CO /t 2 CO ( /t) 2 3. Bookkeeping of CO2 emissions Figure 6 Results of the GETS2 exercise (cost of avoided CO2) The estimates of CO2 emissions, which have been given until now, have been made on the basis of mass balances carried out rather "generously" within wide boundaries to account for the energy needs of steel production and to testify about the ecological footprint that they entail. We have looked at the issue from a physicist or a process engineer point of view and have not argued about the boundaries within which the CO2 bookkeeping ought to be carried out. In the context of future legislative and regulatory action, it will be necessary to look at the matter more carefully, with a bookkeeper or a lawyer's viewpoint. The best methodology available to deal with this issue is that of Life Cycle Analysis (LCA), also called ecobalance. In the case of greenhouse gas (GHG) emissions, an ecobalance is a mass balance of carbon or carbon dioxide carried out within the boundaries of a system clearly specified according to the ISO Standard series. Figure 7 present the various boundaries, which can be drawn around the Steel Mill system, depending on whether the production site itself only is taken into account (gate-togate), or the whole route from raw materials to steel products (cradle-to-gate) or the full-life of a steelbearing manufactured good (cradle -to-gate), or recycling is also introduced. Recycling is not fully taken into account in the present versions of LCAs, although the methodology allows for it, and, when it is, once-around recycling only is described, whereas materials like steel can be recycled indefinitely. Therefore, some new methodological developments will be in order to bring these concepts onboard. 8

10 Cradle to gate Gate to gate Cradle to grave Figure 7 life Cycle Analysis: definition of the various boundaries used to describe the system Raw materials + transportation = 479 kwh + steam = Gate to gate 1424 Cradle-to-gate 1827 Gate-to-BP 1889 Cradle-to-BP kg CO2 /t coated coil 42 Export of by-products BP (gases) 465 Figure 8 - specific CO2 emissions per ton of organic coated coils from an LCA of an Integrated Steel Mill To illustrate the practical meaning of these concepts, we have shown in figure 8 the Greenhouse Gas emissions, expressed as specific CO2 emissions per ton of organic coated coils, that stem out of an LCA model applied to an Integrated Steel Mill, representative of today's state-of-the-art. Each plant in the Mill is shown with its local emissions, while the overall figures are given at the top right of the figure. The larger part of the GHG leaves the smokestacks at the Coke Ovens (218 kg), at the Sinter Plant (261), at the Blast Furnace and the Oxygen Steel Shop (518 kg) and at the electrical Power Plant (465), this later one being assumed here as lying outside of the Steel Mill boundary. All of this CO2 9

11 however, originates from the coal, which is used in the coke ovens or directly injected at the BF tuyeres to act as a reducing agent that the Blast Furnace needs, and is progressively oxidized fully into CO2 at various steps along the production route. LCAs are thus seemingly more interested in chemical (oxidation) than physical processes! The figures that we have been manipulating in the previous sections are gate-to-gate estimates, which assume that the Steel Mill boundaries include the electricity, lime and oxygen plants needed for supplying the needs of the Works and running on electricity with a carbon-intensity representative of the country average, as well as the power plant, which burns the off-gases. Moreover, the reference was to liquid steel and not to coated coils, which introduces a difference due to the CO2 emissions of the rolling and coating lines and to the material yield of these plants. The difference between the various estimates is of the order of 1 tco2 / tsteel, i.e. 70 % of the simplest gate-to-gate value. The choice of the system boundary will therefore will be paramount, whenever a monetary value becomes attached to the emissions, either through a carbon tax or an emission trading system. The trend is to favor a true gate-to-gate system, which will exhibit a lower GHG emission level than the process engineering approach does, but it is likely that the emissions taking place outside of the chosen boundaries, upstream or downstream, will weight on the prices of the raw material and of steel, which will incorporate as much of the value of CO2, as the market will allow. A sharp competition is to be expected, which will in particular increase the intermaterial competition of today. One should, however, move still further into the discussion. A Steel Mill generates an array of products and by-products. Blast furnace (BF) slag for example, which is an excellent material for cement production, can favorably replace clinker and thus bypass the cement kiln and avoid its high energy consumption and the associated GHG emissions. It makes sense, therefore, to associate the generation of GHG of the Integrated Steel Mill to both Steel and Slag. An analysis was carried out in the case of BF slag (vi) and showed that 1250 kg of CO2 ought to be tagged or allocated to 1 t of slag sold to the cement industry (250 kg of slag per t of hot metal). This decreases the GHG generation traditionally associated to BF and BOF steel production by about 15 %. Steelmaking slag is not as thoroughly used as BF slag outside of the Steel Mill but it could eventually be analyzed along the same lines. The off-gases, if generated in excess of the Steel Mill s own needs, ought also to be taken into account in the same manner. The Ecotech option of the IISI analysis of the energy efficiency of the Steel Mill [vii] thus predicts an excess of 2.4 GJ/tls, i.e. a credit of 230 kg of CO2. SR processes would bring in even more credit (8.5 MJ for Corex, 4.7 for DIOS and 2.8 for the CCF). One should be aware of the fact that this approach is deviating slightly from what has been the Standard adopted until today by IISI, where the Steel Mill is supposed to manufacture only one product, steel, and an array of by-products and waste. The present analysis consists in fact in assuming that the Mill produces several products, steel, ironmaking slag, etc. and that each one of them is allocated its "true" share of the CO2 emissions, rather than a figure obtained by comparing the by-product to the material it replaces. There is probably no best approach today and the one that ought to be preferred should be selected on the basis of its merits, which will become gradually and pragmatically apparent, as the economy adapts to the Kyoto instruments. Another issue that needs revisiting is that of steel recycling. The advantages of recycling in general and of recycling steel in particular have already been pointed out on the basis of the reduced energy needs of melting vs smelting reduction, but the consequences should also be drawn in terms of LCA, which has been weak in introducing the idea into its methodology. In particular, materials like steel, which can rightly claim that they can be recycled indefinitely, are not properly pictured in the LCA language. As has already been pointed out, recycling reduces GHG emissions: the EAF route, for example, avoids producing 1665 kg of CO2, if the steel replaces BOF material. Moreover, the effect is compounded if recycling is carried out several times. This positive effect of indefinite or sustainable recycling, a feature that steel exhibits contrary to most materials [viii], is analyzed in figure 9. The amount of avoided CO2 emissions per ton of BOF steel is plotted against the number of recycling steps, with the recycling ratio as a parameter. If the recycling ratio is 100%, each step avoids the generation of 1665 kg of CO2. However, the recycling ratio is usually less than 1, and an asymptotic value is reached after a number of cycles 10

12 that depends on the level of the recycling rate. Because the average recycling life of steel is of the order of 10/15 years, it is ludicrous to consider more than 6 steps of recycling (cf. figure 10), so that the asymptote is reached only when the recycling rate is less than 50% (figure 9). A material, which is sustainably recyclable, is therefore more environmentally friendly in terms of GHG emissions than another, which would be recycled only once. CO2 emissions avoided (kg CO2/tls) Recycling rate 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% number of recycling steps Figure 9 CO2 emissions avoided by the continuous recycling of steel [IX] CO2 emissions avoided after 6 recycling steps (kg CO2/tls) ,2 0,4 0,6 0,8 1 recycling rate Figure 10 CO2 emissions avoided after 6 steps of steel recycling vs. Recycling rate steel [ix] There are no provisions today, either in conventional LCA analysis or in the emission right rationale, to give credit to this particular behavior. One solution would consist in giving a credit to steel production in the Integrated Route, as it is in effect generating future scrap that will serve as the stock for EAF steelmaking. This would seem all the more reasonable as companies that produce steel from virgin iron units usually do not make any steel from scrap and therefore cannot claim the benefit of scrap usage in their own mills. Figure 10, where the total compounded amount of avoided GHG emissions is plotted after 6 recycling steps, shows that as soon as the recycling rate is higher than 50% the credit would become larger than the initial generation of GHG due to BOF steelmaking. One could therefore argue that recycling, when conducted in such a virtuous way, should erase any liability or debit due to the initial emissions. Of course, this approach is new and needs some further discussion. Exploring this concept further, one sees that the reason why emissions are avoided is that the recycling rate is high and that recycling is allowed to be carried out in a steady-state kind of way. This points out to the difference between recyclability and actual recycling level. Steel scrap, for example, has been traded for so long, that the recycling rate in developed countries has already reached very high levels, 11

13 especially as far as automobiles are concerned. This is also true of some non-ferrous metals, but probably not yet of aluminum in cars and not at all of plastics. The claim for sustainable recycling is also a strong condition that only experience with long term recycling can substantiate. The previous analyses have explored various methods for assessing GHG emissions and for giving credit for avoided GHG generation. However, the focus has been on the process metallurgy of making steel. Steel itself is being continuously developed into new products that offer more service performance. This also has a strong impact on GHG emissions. A completely general discussion of this issue would lack depth and relevance. It seems more meaningful to choose a particular application and to conduct the analysis on this special case. An emblematic example is that of the automotive industry and the ULSAB1 projections can serve to illustrate the point (x). Table I- Projections for weight and CO2 emissions in concept cars of the ULSAB family. reference car ULSAB + ULSAC + ULSAS Avoided emissions for 10 5 km hyp. 1 Avoided emissions for 10 5 km hyp. 2 Avoided emissions in Steel Mill hyp. 3 Avoided emissions in Steel Mill hyp. 4 Avoided emissions total minimum Avoided emissions total maximum kg kg kg CO2 kg CO2 kg CO2 kg CO2 kg CO2 kg CO2 body closures suspensions total steel total car The discussion is presented in table I [IX]. It uses figures on car weight for a reference European car and for a car that would incorporate the weight reductions brought about by the three ULSAB-related projects (ULSAB for Body, ULSAC for Closures and ULAS for Suspensions). The model assumes that a consumption of 1 l of gasoline leads to the emission of 24 g of CO2 and that a car runs for km during its life. Reductions in CO2 emissions are calculated for car utilization (with two ratios of 0.3 (hypothesis 1) and 0.7 l (hyp. 2) reduction in gasoline consumption per 100 km caused by a weight reduction of 100 kg) and for the avoided steel production (with the CO2 ratios of 2.0 (hyp.3) and 1.55 t/tls (hyp.4) and a home and prompt scrap generation of 25%). The last 2 columns add up the minimum and maximum values of CO2 reduction. This is typically an LCA-type of estimation. The avoided emissions due to the utilization of the car are systematically larger than those due to the reduced amount of material necessary to build a lighter car, by a factor of 3 to 6, depending on the assumptions. The total amount of emissions saved accounts for 6 to 13 % of the total emissions attributable to the car. This illustrates both the potential and the limits of vehicle weight reduction on GHG emissions. This example could be duplicated in a variety of different situations, where improved material performance is translated into lighter weight or longer life. A more subtle rationale is being investigated within the ULSAB-AVC (for Advanced Vehicle Concept) Project, where improved properties are being used to increase the safety of the car, as weight reduction should not result in reduced safety. Although safety is not directly taken into account in CO2 emission bookkeeping or in conventional LCA, it is an essential point in making manufactured goods more friendly both to the environment and to users, i.e. to mankind. Improved material performance thus generates savings in CO2 emissions, which are larger than the emissions caused by the making of the material. To keep up the rate of innovation in material develop- 1 Ultra-Light Steel Automotive Body, a project carried out by the Steel Industry within the IISI organization. 12

14 ment, it will be important to maintain this substitution rate in a sustainable way. This ability for a material to remain creative should also probably be a criterion for material choice in an improved DFE (Design for the Environment) approach. To emphasize the previous points, we have added all the debits and credits in GHG emissions, which we have been discussing until now, in Figure 11. It should certainly be viewed as a riddle and a mindtwister, but also as food for thought, at a time when Global Warming has come to be accepted by society as part of our future and governments will feel compelled to design action plans to counter it CO2 emissions (t CO2/tls) carbon input reduction by 250 kg scrap reduction by yield improvement reduction by energy savings Ecotech process CO2 reduction due to slag CO2 reduction due to off-gas CO2 Inside-the-Mill CO2 reduction due to sequestration CO2 after sequestration S1 S4 CO emissions (t CO /t ) carbon input process CO2 Inside-the-Mill CO2 CO2 sequestration CO2 with bonuses Figure 11 CO2 emission balance in an Integrated Mill adding up the various debits and credits described in this paper The conclusion of this section is that the internalization of GHG emissions in the monetary economy, through market forces and legislative regulations, is a very complex issue that cannot be decided simply on the basis of present LCA methodology for example. The Steel Industry is embedded in a wider system, with which it interacts and its impact should be analyzed from this broader and more holistic viewpoint. The main point is to base the future on materials, which exhibit a strong potential for change, as far as sustainability is concerned. This will change the competition among materials and among consumer goods, in terms of ecodesign, durability and environmental friendliness. Needless to say, Steel has a strong claim to belonging to the class of the better performing materials. Finally, the danger of implementing policies that distort the competition in arbitrary ways should be avoided. It would probably be worth it to pursue the analysis further and to investigate how the societal value of a material like steel can be evaluated: what would be a world without steel, in terms of the wellbeing of the people and of day-to-day life, where the ubiquitous properties of steel are taken for granted? 2 2 British Steel produced a short didactic movie in the 1990s, where high-rise buildings made without steel would sway in the wind and surgeons would operate on patient with ceramic scalpels 13

15 4. Facing the longer term A first question to address, when facing the long term, is to inquire about how much of the potential for reducing GHG emissions due to the substitution by scrap of virgin iron can be captured by the Steel Industry? This is a complex issue that requires a projection further into the future than is commonly the habit in Technological Forecasting studies. We have chosen to do it within a time frame that is consistent with the Global Warming time scale, i.e. 100 years. This means that the assumptions are strong and probably were debatable. But they are only meant to start a discussion. We assume that population will grow from 6 billions in 2000, to 9 billions in 2050 and 12 billions in Steel, which is at the basis of the infrastructure of the economy that has provided a high standard of living in developed countries, is supposed to be needed at an increasing rate in order to help the rest of the world catch up with the richest nations. Steel consumption per capita would thus grow from 125 kg in 2000 to 263 kg in 2050, and from then on remain at that level. Steel output would thus jump from 750 Mtpy today to Mtpy in 2100, i.e. a 3.2 fold increase, which is modest compared to the achievement of the 20 th century. This means that steel production would grow faster than population in order to help improve the standard of living in the world (figure 12) (inhabitants or tons) rate of increase World population Steel output Figure year forecasting model. Population and steel output evolution (left) and respective relative growth rates (right) Scrap is supposed to be collected at a rate of 75% with an average life of 15 years. Moreover, we assume full sustainability of scrap Recycling, i.e. that the same qualities of steel can be produced either from virgin iron units or from scrap. Figure 13 shows the evolution of scrap generation and its impact on steel production. From 43% today, it would increase to 70% in 2100, as a mechanical consequence of the increased production and of a high collecting rate over most of the world (figure 13). Scrap generation (M tpy) Scrap intensity in Steel output (%) Figure year forecasting model. Scrap generation. The consequences in terms of the CO2 emissions of the world Steel Industry are shown in figure 14. The CO2-intensity per ton of steel would decrease from 1.67 t today to 1.22 t in 2100, due to the higher pro- 14

16 portion of EAF route. Increasing the use of scrap is thus a fairly effective way of reducing GHG emissions from the Steel Industry. CO 2 intensity (t) per ton of steel Figure year forecasting model. CO2 emissions. This paints a different future for the potential of recycling than the short term projections of section 2 would have let anticipate. This future should be seen as a contrasted scenario, to adopt the vocabulary of Technological Forecasting and more precisely of Prospective. There is of course no way of ascertaining its truth. It just shows that one should not remain trapped in short term thinking, where today's conditions are often extrapolated without taking a broad enough perspective. 5. Breakthrough and sustainable technologies for iron and steelmaking To break away from the high level of GHG emissions, which is inherent to material production - and to steel production in particular, and which is dictated mainly by thermodynamics, one should look at carbon-free sources of energy and reducing agents. This a an old quest, playing on the concepts of renewable energy and of renewable raw materials like recycling does, and bordering on the myth of free energy, although it has realistic overtones. Breakthrough and sustainable technologies for iron and steelmaking The French language has poetic words to talk about renewable energies: houille blanche, houille rouge, houille bleue, houille d or. Except for hydroelectric power, which is close to saturation, all of these, complemented by wind and biomass power, are developing at their own pace, but are still far from replacing fossil fuel or nuclear energy at a significant level. Cost remains a major limiting factor: wind power has been brought down to 4-6 US /kwh, but solar energy is still 17 /kwh for photovoltaic and 8-13 /kwh for thermal solutions, with biomass electricity at 6 /kwh (classical electricity cost varies from 1.5 to 4 /kwh). The issue of the storage of nuclear waste has brought fission nuclear power to a standstill. Fusion power is locked in a permanent 50-year future and the recent uncertainties about the ITER project do not augur well of its future. Orbital solar power plants that would beam down energy in microwave form still belong to science fiction-like technology, almost at the same level as Dyson spheres! A public and worldwide debate on renewable and nuclear energies has still to be conducted before any clear picture of their future can be outlined and policies for energy intensive industries derived from it. Carbon-free reducing agents Natural gas is the only alternative to carbon as a reducing agent that has any realistic existence today. It is being used in the most common prereduction processes. Hydrogen would have interesting advantages, but it is not available as a raw material today. It can be produced from natural gas (NG), for example by reforming, but as such it is not different from NG, as it is hidden in the process of the user. Hydrogen can also be produced by electrolysis of seawater, and 15

17 as such is actually an energy vector substituting for nuclear power or renewable energies, which cannot be stored as electricity. Its future is entirely linked to that of these new energies. One may recall that hydrogen-based prereduction was developed [xi] 40 years ago at the scale of a credible pilot plant that carried out the reduction of fine ores in a fluidized bed. The H-Iron process never became commercial due to the absence of large quantities of cheap hydrogen on the market. Today, the Circored process is based on hydrogen prereduction [xii], as was also the now-abandoned Iron Carbide Process. Some of the snags of the technology have therefore being debugged. Electrolysis is widely used in the metal industry to produce aluminum, copper or zinc and probably titanium in the near future. It is in effect using electrons to reduce metal cations into the zero valence element. Although it is not implemented in the Steel Industry, electrolysis could in principle be applied in different ways to Steel production: aqueous solutions of Fe +++ ions obtained by leaching iron ores or scrap by HCl can be electrolyzed directly into a foil, 10 to 150 µm in thickness. A pilot plant based on this concept was experimented at CRM under the name of Electrofoil process, with an output of 4.5 t/h and a drawing speed of 31 m/min for the 0.15 mm thickness [xiii]. The solution was either replenished with scrap or with sulfide ore. a soda solution, where iron ore pulp was dispersed, was also experimented upon at IRSID [ xiv]. Electrolysis was assumed to dissociate water into OH-ions and free hydrogen, which would then reduce Fe2O3 and regenerate water. The iron deposit had to be melted, cast, rolled and finished. iron ore can also be dissolved into liquid salts (e.g. Na2CO3+B2O3) at high temperature and the electrolysis carried out in the salt. Depending on the temperature, solid iron can deposit on the cathode, or liquid iron can flow down to the bottom of the cell, thus mimicking aluminum production. These routes are being studied at MIT [xv, xvi]. The energy requirements for the first process was kwh/t or 23 GJ/t (electrolysis + annealing), while the second one used up 3800 kwh/t or 13.7 GJ/t., for the electrolysis and 1300 kwh/t or 4.7 GJ/t for the subsequent production. Electrolysis, which leads directly to final products, is to be compared to a whole conventional mill, which has an energy consumption of 15 to 20 GJ/tls, a similar order of magnitude. The technology might be attractive in terms of CO2 emissions, if the carbon content of electricity is sufficiently low. Electrolysis, however, needs to be better understood, before its significance for the future can be assessed. Biological treatment of ores by bacteria is practiced in the precious metals industries, but not in the Steel Industry. Siderophile bacteria that transform Fe +++ into Fe ++ have been identified [xvii], but none are known today that would completely reduce Fe cations into metallic Fe. Carbon dioxide sequestration A potentially attractive solution for carbon-intensive activities is CO2 sequestration. It can be carried out, in principle, in a variety of ways, although all remain speculative, as no experience acquired at a sufficiently large scale is available yet, although this is changing very fast. Chemical, physical or biological sequestration has been proposed [xviii]. Chemical sequestration consists in storing CO2 as a chemical compound. This can be done, for example, by adding a -C-O-O- chain in an amine molecule (MEA, MDEA or AMP). Industrial systems exist at the scale of several hundreds of tons of CO2 per day, which is an order of magnitude less than what would be needed for treating the emission of one blast furnace. The cost is estimated at 40 US$/t of CO2. Physical sequestration means either trapping CO2 in underground reservoirs, such as aquifers or empty gas or oil deposits, or injecting it to the bottom of oceans, where the pressure beyond a depth of 500 m liquefies CO2. The underground storage capacity available worldwide is estimated at 63 Gt of CO2, or roughly 10 % of the anthropogenic emissions per year. A technology for injecting CO2 into oil reservoir already exists, as it is being used by the oil industry to improve the recovery of oil. Sea sequestration has in principle a potential several orders of magnitude larger than underground reservoirs and is expected 16

18 to be effective for at least one century. The Norwegian power industry has shown that one third of the power of a fossil fuel power plant would be used up by the injection [xix]. Biological sequestration means that C or CO2 are accumulated in living organisms, the energy necessary for the process being derived from solar energy by natural photosynthesis or enzyme catalyzed biological reactions. It is interesting to recall that the reduction in CO2 levels of the primordial atmosphere of the Cambrian and Carboniferous eras was carried out by blue algae and gigantic trees by applying just these methods and that this had led to the thriving of life as we know it today The compensation of emissions by planting trees has been put forward as a realistic solution for carrying out biological sequestration [xx]. This requires that the wood itself be sequestered after the death of the tree. Furthermore, the area necessary to absorb the emission of one blast furnace has the size of a French département. Car companies such as Toyota [xxi] or Peugeot [xxii] have started actually planting trees, probably as a token of their concern over the issue, since 10 million trees fall far short of what would be necessary to absorb the emissions of the cars they manufacture. The concept of using the wood to make iron in a charcoal blast furnace is presently being applied in Brazil, with the provision of husbanding fast growing species to provide the necessary wood in a self sustaining manner [xxiii]. Microalgae bred in biological reactors exhibit a more efficient photosynthesis than trees and experiments have been carried out in France and in Japan to produce rare pharmaceutical molecules [xxiv]. The size of the reactor that could serve one blast furnace is however prohibitive. Sequestration of CO2 by living animals such as corals, which would produce carbonates from solar power, is another possibility, put forward by utopist architects and biologists [xxv]. They would use the material as building blocks for artificial islands. An experiment is in progress. All of these concepts are studied in details by the power industry and can also provide a solution for the production of Steel from virgin iron. This would be a long term endeavor, as a complex technology would have to be designed to concentrate CO2 on the basis of membrane solutions or on special thermodynamic cycles, which would avoid the dilution of CO2 by nitrogen from the air and thus make separation easier (IGCC ). Anyway, the solutions outlined here need to be explored further by the Steel Industry. Figure 15 summarizes the previous discussion in an Ishikawa diagram where all the available approaches to CO2 mitigation are presented. Reduce & Replace carbon as reducing agent Reduce & Replace carbon as fuel Favor Steel Solurions with low C-intensity Face up to Global Warming Capture & sequester CO 2 Use CO 2 as a product Climate Engineering Move populations Regulations Adapt to Global Warming Build dams, save water Figure 15 Ishikawa diagram showing the various strategies available to mitigate the GHG emissions of the Steel Industry 17

19 Breakthrough Routes In summary, it is possible to imagine drastically lower CO2 emissions associated with steel production. This, however, calls for a complete paradigm shift steering steelmaking process technology away from today's mainstream practices. And, beyond doing a Technological Forecasting exercise on paper, there would the need for a very large R&D program, probably carried out at a world scale, to sort out what will be indeed feasible under the economic conditions that will prevail 10 or 20 years in the future. There are three paths to tread in this longer-term vision (figure 16): the first one consists in separating energy needs from GHG emissions, by moving away as much as possible from using carbon. This means resorting to renewable or fossil-fuel-free energy and switching to non-carbon reducing agents, i.e. hydrogen, electrons, heat, bacteria, etc. the second one consists in sticking to the carbon-based steel production route but in preventing CO2 emissions by capturing the gas and sequestering it. the third one consists in integrating steel production within the natural carbon cycle by using raw materials grown for atmospheric CO2 by biological processes, i.e. plants or animals. Anything else falls short of an objective of drastic reduction of emissions of, for example, 50%, as compared to the benchmark Blast Furnace route of today. Carbon Coke Blast Furnace Syngas Coal Redsmelt Smelting Reduction from coal Blast Furnace + plasma Natural Gas Smelting Reduction from NG H 2 prereduction EAF H 2 H 2 by electrolysis of H 2 O Electrolysis Hydrogen Electrons Other reducing agents: Al dross, etc. Figure 16 Conceptual representation of the various "breakthrough" steel production routes More practically, this would mean resorting to: smelting reduction routes, based on the Blast Furnace with top gas recycling and CO2 sequestration, or on refurbished Smelting Reduction Technologies and also recycling the top gas and sequestering CO2. hydrogen prereduction, whereby hydrogen would either be produced by water electrolysis with low-carbon intensity electricity or by coal gasification with carbon sequestration, using, for example, the IGCC technology that makes it easier to sequester carbon. biomass-based routes, using either natural biomass, such as charcoal derived from "steadystate" grown forests, or,alternatively, biomass or biogas derived from waste. 18

20 electrolysis of iron ore. Representative examples of these routes are shown in figure 17, shown in the case where the carbon intensity of electricity is only 90g/kWh. Very low emissions levels can indeed be achieved kg CO 2 /tls kg CO2//tls GJ net energy 90 g CO2/kWh electricity % Benchmark BF % Benchmark BF Benchmark BF BFbis : mini seques BFter : maxi seques BF gas recycling & O2 injection BF gas recycling & O2 mini seq BF gas recycling & O2 maxi seq BF gas recycling & plasma BF gas recyc. & plasma mini seq BF gas recyc. & plasma maxi seq BF & nat gas DRI BF & COG DRI to BF Corex Benchmark BF & COG DRI to EAF Corex & Midrex & Conarc Corex & top gaz recycling CCF_Corus CCF_Corus sequestration Hismelt Pilot Hismelt sequestration Hismelt Industrial Hismelt Industrial + Preheat Tecnored optimised Tecnored Pilot Tecnored Pilot sequestration Redsmelt Redsmelt sequestration Jupiter coal Jupiter plasma Benchmark EAF EAF nat gas DRI EAF H2 DRI (electrical heating) EAF H2 DRI (natural gas heating) Ore slurry electrolysis & EAF Electrofoil Molten bath electrolysis Biomass 0 Figure 17 Comparison of simulations of CO2 emissions for various steelmaking process routes (per t of liquid steel process engineering boundaries) 6. Scenarios and Futures From what has been presented so far, a complete and exhaustive Futures Analysis can in principle be build in terms of a set of scenarios. It is however an extensive exercise that goes beyond the scope of the present paper and we shall restrict ourselves here to one basic scenario, which, we trust, is a longterm trend scenario for the middle of the century. In 2050, the world has a population of 9 billions, Steel production may by then have reached Mt/year from today's 700 Mt, if steel is to play its role and accompany the improvement of the standard of living in China, the Indian subcontinent, Indonesia, Russia and South America [xxvi]. The exact figure is however not central to developing the scenario, as we are mostly interested in the market share of the various processes. The scenario has been built from a list of technologies, which are felt to be important for the long term in the fields of converting Iron Units into liquid metal and of shaping it through solidification and rolling. This means that we believe that liquid-metal, high-temperature metallurgy will continue to be central for an enduring period of time in Steel metallurgy and therefore that solidification will also be a necessary step in the Steel Manufacturing Route. Solidification will involve some form of Continuous Casting a robust technology still for a long time to come [xxvii]. 19