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Anthropogenic nickel supply, demand, and associated energy and water use
Resources, Conservation & Recycling 125 (2017) 300–307
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Full length article
Anthropogenic nickel supply, demand, and associated energy and water use Ayman Elshkaki, Barbara K. Reck, T.E. Graedel
⁎
MARK
Center for Industrial Ecology, School of Forestry and Environmental Studies, Yale University, New Haven, CT 06511, USA
A R T I C L E I N F O
A B S T R A C T
Keywords: Ore grade Cumulative demand Scenarios Recycling Nickel
Concerns about the long-run availability of metals have led to speculation that resources that have traditionally been available may become increasingly scarce in the future. To investigate this possibility in the case of nickel, we have built upon the history of nickel flows into use for the period 1988 to the present to develop plausible scenarios for the potential future supply and demand of nickel for the planet, and the associated energy and water use. As in other work, these scenarios are not predictions, but rather stories of possible futures that have the purpose of providing perspective and contemplating policy options. We report herein on our results for nickel supply and demand under four scenarios. We find that calculated nickel demand increases by 140–175% by 2025 and 215–350% by 2050, depending on the scenario. The scenario with the highest prospective demand is termed Equitability World, a scenario of transition to a world of more equitable values and institutions. From the perspective of the results for the four scenarios, we conclude that nickel demands could be met until at least 2050 given known geological nickel resources. The energy and water required for nickel production are anticipated to increase to as much as 0.3% and 0.035% of projected 2050 overall global energy and water demands.
1. Introduction Metals are used in most modern technologies either as necessary constituents or to enhance technological efficiencies. Nickel is among the metals used extensively in a number of important applications, including buildings and infrastructure, transportation, industrial machinery, appliances, and metals goods. In these uses, often in the form of stainless steel or superalloys, nickel’s corrosion resistance, strength, and high-temperature stability are particularly valued. In recent years increases in global population and economic growth have been associated with an increase in the demand for metals. (Nickel production more than doubled in the past 20 years (from 1040 Gg in 1995–2280 Gg in 2015 (USGS, 1997; USGS, 2017). Concerns about the long-run availability of metals have led to speculation that nickel resources that have traditionally been available may become increasingly scarce in the future (e.g., Yang, 2009; Kerr, 2012). Economic nickel resources are found in two types of ores: sulfides and laterites. Nickel resources have traditionally been primarily produced from sulfide ores. With increasing demand, however, an increasing amount is being produced from laterite ores, leading to an increase in the energy and greenhouse gas emissions associated with nickel production due to the more complex processing required for laterites (Mudd, 2010). In addition, there is concern related to the energy and water requirements to produce metals (Norgate, 2010), and to the associated environmental impacts (UNEP, 2013). In this regard, the ⁎
Corresponding author. E-mail address: [email protected] (T.E. Graedel).
http://dx.doi.org/10.1016/j.resconrec.2017.07.002 Received 20 March 2017; Received in revised form 30 June 2017; Accepted 1 July 2017 0921-3449/ © 2017 Elsevier B.V. All rights reserved.
global energy consumption for the principal primary metals (iron, aluminum, copper, manganese, zinc, lead, and nickel) is currently (2012) about 10% of the total primary energy production (Fizaine and Court, 2015). A number of previous scenario studies have attempted to assess the future demand for metals (Binder et al., 2006; van der Voet et al., 2002; Elshkaki et al., 2005; Gerst, 2009; Hatayama et al., 2010; McLellan et al., 2016; Pauliuk et al., 2012; Liu et al., 2013; Elshkaki and Van der Voet, 2006; Stamp et al., 2014). Many of these researches have, however, been limited in their general emphasis on specific technologies rather than on more general uses. In addition, none follow from a foundational set of scenarios generated by specialists in such disciplines as demography, economics, and assessments of industrial limitations and opportunities. In this paper, in contrast, we investigate the potential future supply and demand for all principal uses of nickel and the associated energy and water use, based on the history of nickel flows into use for the period 1988 to the present. As in other work, the resulting scenarios are not predictions, but rather stories of possible futures. Their purpose is to provide perspective and contemplate policy initiatives that respond to developmental alternatives. The four scenarios are described in some detail in the Supplementary Information. In brief, however, the Market World scenario essentially posits that the newly wealthy will wish to acquire possessions similar to those of the existing wealthy, and that market forces will enable that to happen. The Toward Resilience scenario
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variables that are significant and that contribute the most to the dependent variable values. The approach further examines the separate and combined effects of significant variables. The optimal regression model, the adequacy of the model, and the significance of the variables are traditionally described by several statistical parameters: the coefficient of determination (R2), the adjusted coefficient of determination (R2adj), and the t- and F- statistics. We carried out the analysis of the historical demand from 1980 to 2010, using regression analysis with per capita GDP, the level of urbanization, and time as explanatory variables. Time is used as a proxy for such time-dependent variables as policy changes, substitution, and technological development (cf. Roberts, 1996; Guzman et al., 2005). Per capita GDP acknowledges that the rates of use of several metals have been shown to be proportional to per capita GDP (Binder et al., 2006; Rauch, 2009). The level of urbanization is used as a potential independent variable because urbanization is strongly related to housing and infrastructure, which are major uses of nickel. The form of the regression equation is
is similar except that government policies more respectful of renewable energy and the environment will be in force, with potential implications for related material demand. The Security Foremost scenario tilts toward confrontation rather than cooperation, with a consequent reduction in international commerce. Finally, the Equitability World scenario aims toward a more collaborative and inclusive world. This latter scenario is the one most closely aligned with the UN Sustainable Development Goals (United Nations, 2015).
2. Methodology 2.1. Historic nickel demand The use of nickel for industrial, commercial, and consumer purposes is widespread in the global economy, and has been so for a number of decades (Reck et al., 2008). Nickel’s major uses have significant technological momentum, and a substantial degree of substitution by other metals over the short and medium terms is unlikely (Graedel et al., 2015). In situations such as this, where the past appears to be a reasonably reliable guide to the future, regression analysis is a useful starting point. The technique is used in many scientific fields as a statistical approach to estimate and analyze the relationship between a dependent variable and a number of independent, explanatory variables. It identifies the independent variables that are significant and that contribute the most to the dependent variable. The approach further examines the separate and combined effects of significant variables. The optimal regression model, the adequacy of the model, and the significance of the variables are traditionally described by several statistical parameters: the coefficient of determination (R2), the adjusted coefficient of determination (R2adj), and the t- and F- statistics. Historical nickel flows into use are determined based on the demand for nickel in different end use sectors in different world regions (Fig. 1). We draw upon the United Nations GEO4 scenarios (UNEP, 2007; Electris et al., 2009) for demographic and economic perspectives on the future, and the International Energy Agency (2012) for energy mix and energy demand alternatives. GDP/capita is computed using GDP at purchasing power parity (constant 2005 international $) and population records from the World Data Bank (World Bank, 2015). The level of urbanization, which represents the share of inhabitants living in urban areas as a per cent of total population, is also derived from World Data Bank population records, together with urban ratios from the United Nations World Urbanization Prospects (UN Habitat, 2013; World Bank, 2015). Regression analysis is used in many scientific fields as a statistical tool to estimate and analyze the relation between a dependent variable and a number of independent explanatory variables. It identifies the
Y (t ) = α 0 +
n
∑i =1 αi Xi (t ) + ε (t )
(1)
where Y(t) is the inflow of metals into the stock-in-use at time t, n is the number of explanatory variables, Xi(t) are the explanatory variable values at time t, αi are the regression model parameters, and ε(t) is the residuals of the regression model. The historical demand for nickel, and its demand as estimated by the models obtained by regression analysis for each sector, are shown in Fig. S1 in the Supporting Information.The resultant correlations between historic nickel demand and its demand in different industrial sectors are listed in Table 1, together with the explanatory variables that are used in the four scenarios. As can be seen from the table, the historical nickel use patterns are completely explained by GDP/capita, a result consistent with that of Shigetomi et al. (2017). Our goal in this work is to examine the long-term prospects for nickel rather than to focus on monthly or yearly demand variations. As a consequence of this goal, and because there is no evidence that metal prices reflect longer-term scarcity in any way (Henckens et al., 2016), we do not employ economic or systems dynamic approaches that might be quite useful in studies with a shorter-term focus. 2.2. Historic and future nickel supply It is important to realize that the demand for nickel is met by primary and secondary (recycled) sources. The historical contribution of nickel supply from secondary sources has typically been about 30% of total nickel demand (Fig. 2). The fraction of nickel demand that can be met by the supply from secondary sources is determined by the historical nickel demand, the lifetime of nickel applications, and nickel Fig. 1. Historic global level flows into use of nickel in its principal applications. B & I = buildings and infrastructure. The data are updates from Reck & Rotter (2012).
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Table 1 Multivariate analysis results for total nickel demand at the 95% confidence level. (α1 = per capita GDP, α2 = level of urbanization, α3 = time.). Metal/End-use
α0 (t)
α1 (t)
α2 (t)
α3 (t)
r2
adj_r2
F_st
Building & Infrastructure
−308 (−10.36) −138 (−4.39) −168 (6.248) 74.1 (3.81) −155 (−2.54) −695 (−8.59)
0.0624 (16.52) 0.0452 (11.32) 0.0709 (3.721) 0.0137 (5.56) 0.0503 (6.47) 0.243 (23.58)
– – – – – – – – – – – –
– – – – – – – – – – – –
0.932
0.928
272.95
0.865
0.858
128.04
0.886
0.880
154.97
0.607
0.587
30.88
0.677
0.66
41.84
0.965
0.964
555.9
Transportation Industrial Machinery Appliances & Electronics Metal Goods Total Nickel
scenario is the amount of energy needed to satisfy nickel demand using both primary and secondary resources. It has been reported that the production of nickel from primary sources requires on average about 145 MJ/kg (Rankin, 2011); however, energy required for nickel production from secondary sources is 6.2 MJ/kg (Nuss and Eckelman, 2014), and is assumed not to change over time. Economic nickel resources are found in sulfide and laterite ores. Nickel is mainly produced from sulfide ores (about 60%) although in terms of known resources about 60% is found in laterites while 40% is contained in sulphides. This is due to the more complex processing required for laterites (Mudd 2010). Yet, laterite production is expected to overtake sulfide production by the end of the decade (Norgate and Jahanshahi, 2010).For the future energy estimates we assume that the nickel supply will be based on the shares of laterite and sulfide resources in the largest Ni sulfide and laterite projects, in which sulfide projects would account for about 53% of Ni supply and laterite projects will account for about 47% (Mudd and Jowitt, 2014). Fig. 3a shows the distribution of the average nickel ore grade in the largest Ni sulfide and laterite projects (Mudd and Jowitt, 2014.). The future energy required for primary nickel production is a function of ore grade; the relationships between ore grade (g) and embedded energy for the two main processing routes (pyrometallurgical for sulfide and part of the laterite ores and hydrometallurgical for the remaining laterite ores) as given by Eq. 2a and 2b and Fig. 3b. The two equations are based on the data review and compilation of Norgate and Jahanshahi (2010) for the conventional pyrometallurgical processing route of nickel sulfide ores and pressure acid leaching of nickel laterite ore. It has been reported that sulfide ores and 35% of the laterite ores are processed pyrometallurgically, and 65% of the laterite ores are processed hydrometallurgically (Norgate and Jahanshahi, 2010). It has been also reported that about 70% of the laterite nickel was produced by pyrometallurgical processing in 2003, although it is predicted that the proportion of nickel extracted by hydrometallurgical processing of these ores will increase (Warner et al., 2006). In this analysis, we assume that sulfide ores (accounting for 53% of the total nickel supply) and 35% of the laterite ores (accounting for 16% of the total nickel supply) are processed pyrometallurgically, and 65% of the laterite ores (accounting for 31% of the total nickel supply) are processed hydrometallurgically. Due to limited available data, we use the same
Fig. 2. The fraction of nickel demand satisfied by recycling (secondary production), 1980–2008. Data are based on Reck et al. (2008) and Reck & Rotter (2012).
recycling rates and efficiencies. The parameters needed for scenario construction (Table 2) are thus nickel use average life times, in use dissipation rate, recycling rate, and potential recyclability. For the future, we take the average annual nickel secondary fraction growth rates to be 0.5%, 0.5%, 0.35%, and 0.65% between 2008 and 2050 in the MW, TR, SF, EW scenarios, respectively. These percentages reflect the degree of “circular economy” commitments in the different scenarios. The supply of nickel to be provided from primary sources in the future is estimated based on the total demand for nickel in each scenario less the supply of nickel from secondary sources. Primary source nickel demand is met by nickel production in several countries. Two measures of mineable nickel that have been widely used are the “Reserves” (amounts in deposits that are currently economic to mine) and the “Reserve Base” (sub-economic amounts in deposits, plus the reserves (McKelvey, 1960; Grace, 1984; UNEP, 2011). The amount of nickel in each deposit, the shares of individual deposits in the total available resources, and the average nickel content are taken from Mudd and Jowitt (2014). In our work, we assume that the supply generated from each deposit is equal to its share in the total available resources multiplied by the total demand from primary resources. 2.3. Energy and water required for nickel production The total amount of energy required for nickel production in each Table 2 Parameters used in the scenarios construction (Reck et al., 2008; Ciacci et al., 2015). Principal use
Use fraction 2008 (%)
Average Life Time (years)
In use Dissipation (%)
Recycling rate (%)
Potentially Recyclable (%)
Industrial machinery Appliances & Electronics Buildings & Infrastructure Transportation Metal goods Total
30.5 12 17.5 17 23 100
25 15 50 22 15
0 0 0 0 0
87 29 87 74 48
100 100 100 100 100 100
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Fig. 3. (a) Current ore grades in nickel mine production, and the percentage they represent respectively of global nickel resources in 2011. The data are from Mudd and Jowitt (2014); (b) The amount of embodied energy required for primary metal mining and processing, as a function of ore grade. (left): Hydrometallurgical processing of laterite ores; (right): Pyrometallurgical processing of sulfide ores. Reprinted by permission from Norgate and Jahanshahi (2010).
world in which regional isolation and attendant income stagnation inhibit the growth in metal use. The results thus highlight the central role that global and national development policies will play in driving nickel demand from now until at least mid-century. One might expect that Fig. 4(a) should include explicit estimates of uncertainty. This is not possible with a set of fully prescribed scenarios, such as used here. (The uncertainty ranges in the IPCC scenario results (IPCC, 2013), for example, are constructed from the extreme values of results from a large number of models with different starting assumptions, an approach not feasible in the present study). However, because our four scenarios are quite disparate, the extreme values generated may be regarded as a rough estimate of the uncertainty of resourcerelated scenario results.
equation for sulfide and laterite pyrometallurgical processing.
Epyro (t ) =
169.53•g −0.607
Ehydro (t ) = 199.51•g −0.844
(2a) (2b)
The amount of water required for nickel production is set to 79 and 376.6 m3/ton for sulfide and laterite ore respectively (Rankin, 2011). 3. Results and discussion 3.1. Future nickel demand We calculate the total demand for nickel from 2010 through 2050 in the four scenarios, and nickel demand in different industrial sectors for the years 2010, 2025, and 2050 to be as shown in Figs. 4a and 4b. (Note that in the case of nickel demand, the results of the Market World and Toward Resilience scenarios are nearly the same, so they appear atop one another on the figure.) We find the total demand for nickel in 2050 compared with that in 2010 to be 260% (MW), 265% (TR), 210% (SF), and 315% (EW). The Industrial Machinery sector is the largest end use sector for nickel in the scenarios, reaching 30% of total nickel demand by 2050 (it constituted 34% in 1980), followed by Buildings & Infrastructure at 22% and 23.5% in the different scenarios (compared to 8% in 1980). The Industrial Machinery and Buildings & Infrastructure sectors employ nickel largely for products utilizing nickel-containing stainless steel, which we anticipate will be the principal form of nickel use for the next several decades. It is interesting that we find nickel demand to be highest in the EW scenario, where progress toward global equity requires significant metal increases to meet the needs of the global population. In contrast, we derive the lowest nickel demand in the SF scenario, a possible future
3.2. The secondary component of the future nickel supply The required future supply of nickel from primary sources (demand minus secondary supply) and from secondary sources in the four scenarios is shown in Fig. 5. These results assume that no limitations exist on nickel ore deposits. The secondary source contribution is about 30% in 2010. It increases over time for two reasons. First, because as more nickel enters into service over time the eventual outflow from use increases. Second, there is a change in the end use sector mix away from long lifetimes (machinery) towards shorter lifetimes (metal goods, transportation). The result is especially dramatic for the Equitability World scenario, which not only has the largest nickel flows into use but also the highest assumed recycling rates (the latter a consequence of the most rapid employment of “circular economy” approaches of any of the scenarios).
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Fig. 4. (a) Demand for nickel, 2010–2050, in the four scenarios; (b) Sectoral demand for nickel in 2010, 2025, and 2050 in the four scenarios. MW: Market World, TR: Toward Resilience, SF: Security First, EW: Equitability World.
future mines being more frequently located in water-rich equatorial and less in arid zones.
3.3. Energy and water required for nickel production The energy required for nickel production from primary sources, based on the nickel production from sulfide and laterite ores in the four scenarios (Fig. 5), the distribution of ore grade in available resources (Fig. 3(a)), and the energy required to produce one kg of nickel by the pyrometallurgical and hydrometallurgical process routes (Fig. 3(b)), is shown in Fig. 6. These quantities of energy constitute 0.15% (MW), 0.22% (TR), 0.14% (SF), and 0.31% (EW) of the total final energy demand for all societal uses anticipated by 2050 (UNEP, 2007). The highest amount of energy required is found to be in the EW scenario due to the associated high demand for nickel. This demand is ameliorated somewhat by the lower overall total global energy demand compared to the other scenarios. However, the EW nickel demand does not lead to the highest emissions of CO2 because the EW scenario has the highest share of renewable technologies, with lower CO2 emissions per unit of energy. The total water required to produce the nickel demanded in the four scenarios is shown in Fig. 7. It amounts to 0.016% (MW), 0.028% (TR), 0.013% (SF), and 0.034% (EW) of the total water demand anticipated by 2050 (UNEP, 2007). The greatest amount of water required is in the EW scenario due to the associated high demand for nickel compared to the other scenarios. Results from Northey et al. (2017) suggest that the nickel industry will more easily meet its future water requirements than the copper, lead, and zinc industries, a result of nickel’s current and
3.4. Nickel supply limitations Short term limitations on supplies of metals have always existed, a result of fluctuating economic factors, regulatory changes, geopolitics, and other circumstances. For the longer term, the factor of principal interest so far as supply limitations is concerned is the total quantity of a given metal that could be made available over time in sufficient amounts and at affordable prices. However, such factors as the yet undiscovered and/or buried ore deposits, rapidly evolving mining technology, and increasing remote sensing capabilities render such estimates extremely challenging (e.g., Meinert et al., 2016; Ali et al., 2017). One could also imagine supply fluctuations resulting from the dynamics of a metal being mined as principal metal as opposed to as coproduct or by-product metal. This is a supply risk that we consider to be minimal for nickel. Nickel’s current by-production is very low (2%, Nassar et al., 2015) and is unlikely to substantially change in the future. Nickel is most frequently processed from ores that may also contain copper, cobalt, gold, silver, and platinum group metals (PGMs). In the case of co-production (mines where more than one metal contribute significantly to the potential overall returns), Mudd and Jowitt (2014) state that nickel is most frequently co-produced with PGMs, with either one of them having the higher potential value. Fig. 5. Secondary supply of nickel in the four scenarios (dashed lines) and the primary supply thus required to meet demand (solid and dotted lines). MW: Market World, TR: Toward Resilience, SF: Security First, EW: Equitability World.
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Fig. 6. Total energy demand for the production of nickel in the four scenarios. MW: Market World, TR: Toward Resilience, SF: Security First, EW: Equitability World.
the U.S. Geological Survey reported the “Reserve Base” for metals, defined as “that part of an identified resource that meets specific minimum physical and chemical criteria related to current mining and production practices”. The latest estimate (USGS, 2009) of the Reserve Base for nickel is 150 Tg (150 million metric tons). While recognizing that a high level of uncertainty exists in this estimate, we use it as a starting point in our discussions of long-term supply limitations. The US Geological Survey also defines a much more reliable metric termed the “Reserves”, which is defined as “that part of the Reserve Base that could be economically extracted or produced at the time of determination”. Because this measure is based on well-characterized and (often) currently active mining operations, it is a reasonably good estimate of nickel supply prospects for perhaps the next decade or two. For year 2010 (the starting year for our scenarios), global nickel Reserves are estimated to be 76 Tg (USGS, 2010). In Fig. 8, we compare the cumulative global nickel production as derived from our scenarios with the nickel Reserves and Reserve Base determinations for the 2009–2010 epoch. The integrated nickel production can be seen to exceed the Reserves in about 2038–2042 (depending on the scenario), but does not approach the limit of the (rather uncertain) Reserve Base in any of the scenario results. Additionally, as shown in Fig. 5 30% or more of the demand is anticipated to be met by
Nickel is the main product in 14 of the largest 25 nickel resources (Mudd and Jowitt, 2014). In 10 of these resources, nickel has a value of more than 50% of the total project value, and in 4 of the projects it has a value between 40% and 50%. Nickel resources total about 75 Tg in these 14 resources. PGMs are the main product in the remaining largest nickel resources, with about 15 Tg of nickel available in these deposits (Mudd, 2012). Cobalt is also co-extracted with nickel, with about 20% of cobalt resources in current cobalt-producing mines occuring together with nickel (Mudd et al., 2013). Cobalt has a value between 2% and 19% in 9 of the largest nickel resources (Mudd and Jowitt, 2014). In all 9 projects, nickel accounts for more than 48% of the economic value of the respective mine. Cumulative nickel demand from primary sources is about 75 Tg around 2040 depending on the scenario, which means that nickel demand could be met by the supply from nickel deposits where nickel is the principal metal. After 2040, nickel demand will be met by the supply from deposits in which nickel is not the principal product (i.e. the supply of nickel will be dependent on companion metals, mainly PGMs), making nickel supply somewhat vulnerable to the demand situation for PGMs. In general, there remains uncertainty when it comes to estimating the long-term potentially mineable assets in nickel deposits. Until 2009,
Fig. 7. Total water demand for the production of nickel in the four scenarios. MW: Market World, TR: Toward Resilience, SF: Security First, EW: Equitability World.
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Fig. 8. Cumulative demand for nickel as a function of the fraction of the nickel Reserve Base. The vertical lines indicate the dates when demand exceeds the 2010 USGS estimate of Reserves.
Appendix A. Supplementary data
recycled nickel. We conclude, therefore, that there is likely to be no significant limit to nickel supplies from primary stocks, by 2050 at least.
Supplementary data associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/j.resconrec.2017.07.002.
4. Conclusions
References
This study has developed and utilized four scenarios for the demand and supply of nickel and the associated energy and water required for nickel production. The most significant conclusions of the analysis are · The demand for nickel is anticipated to increase by between 140 and 175% by 2025 and between 215 and 350% by 2050, depending on the scenario. · The demand for nickel is found to be highest in the Equitability World scenario (a world of increased affluence, collaboration, and inclusivity) and lowest in the Security Foremost scenario (a world of confrontation and significant disparities among peoples). · The energy required to produce nickel in these scenarios constitutes 0.14- 0.3% of the total global energy demand by 2050 for all sectors of society, and the water required to produce nickel constitutes 0.013- 0.034% of the total global water demand by 2050. · The cumulative demand for nickel in the four scenarios is expected to exceed nickel Reserves but not the nickel Reserve Base by mid-century. Thus, there is likely to be no significant limit to nickel supplies over that period. Finally, it is important to note that scenarios are not predictions of the future. Rather, they are plausible stories of how conditions might evolve over time. Their value is to help envision possible responses to those stories, i.e., “If the world appears to be following the pattern of Scenario X, what would be the consequences for my/our area of interest, and how might I/my organization best respond?” The scenario results presented here are thus of interest to a wide variety of the segments of society: the nickel industry, nickel supply and demand chain participants, economic planners, and doubtless others. If fully embraced, the nickel scenario results promise the same sort of useful perspectives that scenario approaches have provided to such diverse audiences as the oil industry (Wack, 1985), ecosystems scientists (Pereira et al., 2010), and the military (Herman et al., 2009).
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Acknowledgements We thank the Nickel Institute and the United Nations Environment Programme for helpful discussions and for financial support for this study. We also thank two anonymous reviewers for their helpful comments. 306
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Full length article
Anthropogenic nickel supply, demand, and associated energy and water use Ayman Elshkaki, Barbara K. Reck, T.E. Graedel
⁎
MARK
Center for Industrial Ecology, School of Forestry and Environmental Studies, Yale University, New Haven, CT 06511, USA
A R T I C L E I N F O
A B S T R A C T
Keywords: Ore grade Cumulative demand Scenarios Recycling Nickel
Concerns about the long-run availability of metals have led to speculation that resources that have traditionally been available may become increasingly scarce in the future. To investigate this possibility in the case of nickel, we have built upon the history of nickel flows into use for the period 1988 to the present to develop plausible scenarios for the potential future supply and demand of nickel for the planet, and the associated energy and water use. As in other work, these scenarios are not predictions, but rather stories of possible futures that have the purpose of providing perspective and contemplating policy options. We report herein on our results for nickel supply and demand under four scenarios. We find that calculated nickel demand increases by 140–175% by 2025 and 215–350% by 2050, depending on the scenario. The scenario with the highest prospective demand is termed Equitability World, a scenario of transition to a world of more equitable values and institutions. From the perspective of the results for the four scenarios, we conclude that nickel demands could be met until at least 2050 given known geological nickel resources. The energy and water required for nickel production are anticipated to increase to as much as 0.3% and 0.035% of projected 2050 overall global energy and water demands.
1. Introduction Metals are used in most modern technologies either as necessary constituents or to enhance technological efficiencies. Nickel is among the metals used extensively in a number of important applications, including buildings and infrastructure, transportation, industrial machinery, appliances, and metals goods. In these uses, often in the form of stainless steel or superalloys, nickel’s corrosion resistance, strength, and high-temperature stability are particularly valued. In recent years increases in global population and economic growth have been associated with an increase in the demand for metals. (Nickel production more than doubled in the past 20 years (from 1040 Gg in 1995–2280 Gg in 2015 (USGS, 1997; USGS, 2017). Concerns about the long-run availability of metals have led to speculation that nickel resources that have traditionally been available may become increasingly scarce in the future (e.g., Yang, 2009; Kerr, 2012). Economic nickel resources are found in two types of ores: sulfides and laterites. Nickel resources have traditionally been primarily produced from sulfide ores. With increasing demand, however, an increasing amount is being produced from laterite ores, leading to an increase in the energy and greenhouse gas emissions associated with nickel production due to the more complex processing required for laterites (Mudd, 2010). In addition, there is concern related to the energy and water requirements to produce metals (Norgate, 2010), and to the associated environmental impacts (UNEP, 2013). In this regard, the ⁎
Corresponding author. E-mail address: [email protected] (T.E. Graedel).
http://dx.doi.org/10.1016/j.resconrec.2017.07.002 Received 20 March 2017; Received in revised form 30 June 2017; Accepted 1 July 2017 0921-3449/ © 2017 Elsevier B.V. All rights reserved.
global energy consumption for the principal primary metals (iron, aluminum, copper, manganese, zinc, lead, and nickel) is currently (2012) about 10% of the total primary energy production (Fizaine and Court, 2015). A number of previous scenario studies have attempted to assess the future demand for metals (Binder et al., 2006; van der Voet et al., 2002; Elshkaki et al., 2005; Gerst, 2009; Hatayama et al., 2010; McLellan et al., 2016; Pauliuk et al., 2012; Liu et al., 2013; Elshkaki and Van der Voet, 2006; Stamp et al., 2014). Many of these researches have, however, been limited in their general emphasis on specific technologies rather than on more general uses. In addition, none follow from a foundational set of scenarios generated by specialists in such disciplines as demography, economics, and assessments of industrial limitations and opportunities. In this paper, in contrast, we investigate the potential future supply and demand for all principal uses of nickel and the associated energy and water use, based on the history of nickel flows into use for the period 1988 to the present. As in other work, the resulting scenarios are not predictions, but rather stories of possible futures. Their purpose is to provide perspective and contemplate policy initiatives that respond to developmental alternatives. The four scenarios are described in some detail in the Supplementary Information. In brief, however, the Market World scenario essentially posits that the newly wealthy will wish to acquire possessions similar to those of the existing wealthy, and that market forces will enable that to happen. The Toward Resilience scenario
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variables that are significant and that contribute the most to the dependent variable values. The approach further examines the separate and combined effects of significant variables. The optimal regression model, the adequacy of the model, and the significance of the variables are traditionally described by several statistical parameters: the coefficient of determination (R2), the adjusted coefficient of determination (R2adj), and the t- and F- statistics. We carried out the analysis of the historical demand from 1980 to 2010, using regression analysis with per capita GDP, the level of urbanization, and time as explanatory variables. Time is used as a proxy for such time-dependent variables as policy changes, substitution, and technological development (cf. Roberts, 1996; Guzman et al., 2005). Per capita GDP acknowledges that the rates of use of several metals have been shown to be proportional to per capita GDP (Binder et al., 2006; Rauch, 2009). The level of urbanization is used as a potential independent variable because urbanization is strongly related to housing and infrastructure, which are major uses of nickel. The form of the regression equation is
is similar except that government policies more respectful of renewable energy and the environment will be in force, with potential implications for related material demand. The Security Foremost scenario tilts toward confrontation rather than cooperation, with a consequent reduction in international commerce. Finally, the Equitability World scenario aims toward a more collaborative and inclusive world. This latter scenario is the one most closely aligned with the UN Sustainable Development Goals (United Nations, 2015).
2. Methodology 2.1. Historic nickel demand The use of nickel for industrial, commercial, and consumer purposes is widespread in the global economy, and has been so for a number of decades (Reck et al., 2008). Nickel’s major uses have significant technological momentum, and a substantial degree of substitution by other metals over the short and medium terms is unlikely (Graedel et al., 2015). In situations such as this, where the past appears to be a reasonably reliable guide to the future, regression analysis is a useful starting point. The technique is used in many scientific fields as a statistical approach to estimate and analyze the relationship between a dependent variable and a number of independent, explanatory variables. It identifies the independent variables that are significant and that contribute the most to the dependent variable. The approach further examines the separate and combined effects of significant variables. The optimal regression model, the adequacy of the model, and the significance of the variables are traditionally described by several statistical parameters: the coefficient of determination (R2), the adjusted coefficient of determination (R2adj), and the t- and F- statistics. Historical nickel flows into use are determined based on the demand for nickel in different end use sectors in different world regions (Fig. 1). We draw upon the United Nations GEO4 scenarios (UNEP, 2007; Electris et al., 2009) for demographic and economic perspectives on the future, and the International Energy Agency (2012) for energy mix and energy demand alternatives. GDP/capita is computed using GDP at purchasing power parity (constant 2005 international $) and population records from the World Data Bank (World Bank, 2015). The level of urbanization, which represents the share of inhabitants living in urban areas as a per cent of total population, is also derived from World Data Bank population records, together with urban ratios from the United Nations World Urbanization Prospects (UN Habitat, 2013; World Bank, 2015). Regression analysis is used in many scientific fields as a statistical tool to estimate and analyze the relation between a dependent variable and a number of independent explanatory variables. It identifies the
Y (t ) = α 0 +
n
∑i =1 αi Xi (t ) + ε (t )
(1)
where Y(t) is the inflow of metals into the stock-in-use at time t, n is the number of explanatory variables, Xi(t) are the explanatory variable values at time t, αi are the regression model parameters, and ε(t) is the residuals of the regression model. The historical demand for nickel, and its demand as estimated by the models obtained by regression analysis for each sector, are shown in Fig. S1 in the Supporting Information.The resultant correlations between historic nickel demand and its demand in different industrial sectors are listed in Table 1, together with the explanatory variables that are used in the four scenarios. As can be seen from the table, the historical nickel use patterns are completely explained by GDP/capita, a result consistent with that of Shigetomi et al. (2017). Our goal in this work is to examine the long-term prospects for nickel rather than to focus on monthly or yearly demand variations. As a consequence of this goal, and because there is no evidence that metal prices reflect longer-term scarcity in any way (Henckens et al., 2016), we do not employ economic or systems dynamic approaches that might be quite useful in studies with a shorter-term focus. 2.2. Historic and future nickel supply It is important to realize that the demand for nickel is met by primary and secondary (recycled) sources. The historical contribution of nickel supply from secondary sources has typically been about 30% of total nickel demand (Fig. 2). The fraction of nickel demand that can be met by the supply from secondary sources is determined by the historical nickel demand, the lifetime of nickel applications, and nickel Fig. 1. Historic global level flows into use of nickel in its principal applications. B & I = buildings and infrastructure. The data are updates from Reck & Rotter (2012).
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Table 1 Multivariate analysis results for total nickel demand at the 95% confidence level. (α1 = per capita GDP, α2 = level of urbanization, α3 = time.). Metal/End-use
α0 (t)
α1 (t)
α2 (t)
α3 (t)
r2
adj_r2
F_st
Building & Infrastructure
−308 (−10.36) −138 (−4.39) −168 (6.248) 74.1 (3.81) −155 (−2.54) −695 (−8.59)
0.0624 (16.52) 0.0452 (11.32) 0.0709 (3.721) 0.0137 (5.56) 0.0503 (6.47) 0.243 (23.58)
– – – – – – – – – – – –
– – – – – – – – – – – –
0.932
0.928
272.95
0.865
0.858
128.04
0.886
0.880
154.97
0.607
0.587
30.88
0.677
0.66
41.84
0.965
0.964
555.9
Transportation Industrial Machinery Appliances & Electronics Metal Goods Total Nickel
scenario is the amount of energy needed to satisfy nickel demand using both primary and secondary resources. It has been reported that the production of nickel from primary sources requires on average about 145 MJ/kg (Rankin, 2011); however, energy required for nickel production from secondary sources is 6.2 MJ/kg (Nuss and Eckelman, 2014), and is assumed not to change over time. Economic nickel resources are found in sulfide and laterite ores. Nickel is mainly produced from sulfide ores (about 60%) although in terms of known resources about 60% is found in laterites while 40% is contained in sulphides. This is due to the more complex processing required for laterites (Mudd 2010). Yet, laterite production is expected to overtake sulfide production by the end of the decade (Norgate and Jahanshahi, 2010).For the future energy estimates we assume that the nickel supply will be based on the shares of laterite and sulfide resources in the largest Ni sulfide and laterite projects, in which sulfide projects would account for about 53% of Ni supply and laterite projects will account for about 47% (Mudd and Jowitt, 2014). Fig. 3a shows the distribution of the average nickel ore grade in the largest Ni sulfide and laterite projects (Mudd and Jowitt, 2014.). The future energy required for primary nickel production is a function of ore grade; the relationships between ore grade (g) and embedded energy for the two main processing routes (pyrometallurgical for sulfide and part of the laterite ores and hydrometallurgical for the remaining laterite ores) as given by Eq. 2a and 2b and Fig. 3b. The two equations are based on the data review and compilation of Norgate and Jahanshahi (2010) for the conventional pyrometallurgical processing route of nickel sulfide ores and pressure acid leaching of nickel laterite ore. It has been reported that sulfide ores and 35% of the laterite ores are processed pyrometallurgically, and 65% of the laterite ores are processed hydrometallurgically (Norgate and Jahanshahi, 2010). It has been also reported that about 70% of the laterite nickel was produced by pyrometallurgical processing in 2003, although it is predicted that the proportion of nickel extracted by hydrometallurgical processing of these ores will increase (Warner et al., 2006). In this analysis, we assume that sulfide ores (accounting for 53% of the total nickel supply) and 35% of the laterite ores (accounting for 16% of the total nickel supply) are processed pyrometallurgically, and 65% of the laterite ores (accounting for 31% of the total nickel supply) are processed hydrometallurgically. Due to limited available data, we use the same
Fig. 2. The fraction of nickel demand satisfied by recycling (secondary production), 1980–2008. Data are based on Reck et al. (2008) and Reck & Rotter (2012).
recycling rates and efficiencies. The parameters needed for scenario construction (Table 2) are thus nickel use average life times, in use dissipation rate, recycling rate, and potential recyclability. For the future, we take the average annual nickel secondary fraction growth rates to be 0.5%, 0.5%, 0.35%, and 0.65% between 2008 and 2050 in the MW, TR, SF, EW scenarios, respectively. These percentages reflect the degree of “circular economy” commitments in the different scenarios. The supply of nickel to be provided from primary sources in the future is estimated based on the total demand for nickel in each scenario less the supply of nickel from secondary sources. Primary source nickel demand is met by nickel production in several countries. Two measures of mineable nickel that have been widely used are the “Reserves” (amounts in deposits that are currently economic to mine) and the “Reserve Base” (sub-economic amounts in deposits, plus the reserves (McKelvey, 1960; Grace, 1984; UNEP, 2011). The amount of nickel in each deposit, the shares of individual deposits in the total available resources, and the average nickel content are taken from Mudd and Jowitt (2014). In our work, we assume that the supply generated from each deposit is equal to its share in the total available resources multiplied by the total demand from primary resources. 2.3. Energy and water required for nickel production The total amount of energy required for nickel production in each Table 2 Parameters used in the scenarios construction (Reck et al., 2008; Ciacci et al., 2015). Principal use
Use fraction 2008 (%)
Average Life Time (years)
In use Dissipation (%)
Recycling rate (%)
Potentially Recyclable (%)
Industrial machinery Appliances & Electronics Buildings & Infrastructure Transportation Metal goods Total
30.5 12 17.5 17 23 100
25 15 50 22 15
0 0 0 0 0
87 29 87 74 48
100 100 100 100 100 100
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Fig. 3. (a) Current ore grades in nickel mine production, and the percentage they represent respectively of global nickel resources in 2011. The data are from Mudd and Jowitt (2014); (b) The amount of embodied energy required for primary metal mining and processing, as a function of ore grade. (left): Hydrometallurgical processing of laterite ores; (right): Pyrometallurgical processing of sulfide ores. Reprinted by permission from Norgate and Jahanshahi (2010).
world in which regional isolation and attendant income stagnation inhibit the growth in metal use. The results thus highlight the central role that global and national development policies will play in driving nickel demand from now until at least mid-century. One might expect that Fig. 4(a) should include explicit estimates of uncertainty. This is not possible with a set of fully prescribed scenarios, such as used here. (The uncertainty ranges in the IPCC scenario results (IPCC, 2013), for example, are constructed from the extreme values of results from a large number of models with different starting assumptions, an approach not feasible in the present study). However, because our four scenarios are quite disparate, the extreme values generated may be regarded as a rough estimate of the uncertainty of resourcerelated scenario results.
equation for sulfide and laterite pyrometallurgical processing.
Epyro (t ) =
169.53•g −0.607
Ehydro (t ) = 199.51•g −0.844
(2a) (2b)
The amount of water required for nickel production is set to 79 and 376.6 m3/ton for sulfide and laterite ore respectively (Rankin, 2011). 3. Results and discussion 3.1. Future nickel demand We calculate the total demand for nickel from 2010 through 2050 in the four scenarios, and nickel demand in different industrial sectors for the years 2010, 2025, and 2050 to be as shown in Figs. 4a and 4b. (Note that in the case of nickel demand, the results of the Market World and Toward Resilience scenarios are nearly the same, so they appear atop one another on the figure.) We find the total demand for nickel in 2050 compared with that in 2010 to be 260% (MW), 265% (TR), 210% (SF), and 315% (EW). The Industrial Machinery sector is the largest end use sector for nickel in the scenarios, reaching 30% of total nickel demand by 2050 (it constituted 34% in 1980), followed by Buildings & Infrastructure at 22% and 23.5% in the different scenarios (compared to 8% in 1980). The Industrial Machinery and Buildings & Infrastructure sectors employ nickel largely for products utilizing nickel-containing stainless steel, which we anticipate will be the principal form of nickel use for the next several decades. It is interesting that we find nickel demand to be highest in the EW scenario, where progress toward global equity requires significant metal increases to meet the needs of the global population. In contrast, we derive the lowest nickel demand in the SF scenario, a possible future
3.2. The secondary component of the future nickel supply The required future supply of nickel from primary sources (demand minus secondary supply) and from secondary sources in the four scenarios is shown in Fig. 5. These results assume that no limitations exist on nickel ore deposits. The secondary source contribution is about 30% in 2010. It increases over time for two reasons. First, because as more nickel enters into service over time the eventual outflow from use increases. Second, there is a change in the end use sector mix away from long lifetimes (machinery) towards shorter lifetimes (metal goods, transportation). The result is especially dramatic for the Equitability World scenario, which not only has the largest nickel flows into use but also the highest assumed recycling rates (the latter a consequence of the most rapid employment of “circular economy” approaches of any of the scenarios).
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Fig. 4. (a) Demand for nickel, 2010–2050, in the four scenarios; (b) Sectoral demand for nickel in 2010, 2025, and 2050 in the four scenarios. MW: Market World, TR: Toward Resilience, SF: Security First, EW: Equitability World.
future mines being more frequently located in water-rich equatorial and less in arid zones.
3.3. Energy and water required for nickel production The energy required for nickel production from primary sources, based on the nickel production from sulfide and laterite ores in the four scenarios (Fig. 5), the distribution of ore grade in available resources (Fig. 3(a)), and the energy required to produce one kg of nickel by the pyrometallurgical and hydrometallurgical process routes (Fig. 3(b)), is shown in Fig. 6. These quantities of energy constitute 0.15% (MW), 0.22% (TR), 0.14% (SF), and 0.31% (EW) of the total final energy demand for all societal uses anticipated by 2050 (UNEP, 2007). The highest amount of energy required is found to be in the EW scenario due to the associated high demand for nickel. This demand is ameliorated somewhat by the lower overall total global energy demand compared to the other scenarios. However, the EW nickel demand does not lead to the highest emissions of CO2 because the EW scenario has the highest share of renewable technologies, with lower CO2 emissions per unit of energy. The total water required to produce the nickel demanded in the four scenarios is shown in Fig. 7. It amounts to 0.016% (MW), 0.028% (TR), 0.013% (SF), and 0.034% (EW) of the total water demand anticipated by 2050 (UNEP, 2007). The greatest amount of water required is in the EW scenario due to the associated high demand for nickel compared to the other scenarios. Results from Northey et al. (2017) suggest that the nickel industry will more easily meet its future water requirements than the copper, lead, and zinc industries, a result of nickel’s current and
3.4. Nickel supply limitations Short term limitations on supplies of metals have always existed, a result of fluctuating economic factors, regulatory changes, geopolitics, and other circumstances. For the longer term, the factor of principal interest so far as supply limitations is concerned is the total quantity of a given metal that could be made available over time in sufficient amounts and at affordable prices. However, such factors as the yet undiscovered and/or buried ore deposits, rapidly evolving mining technology, and increasing remote sensing capabilities render such estimates extremely challenging (e.g., Meinert et al., 2016; Ali et al., 2017). One could also imagine supply fluctuations resulting from the dynamics of a metal being mined as principal metal as opposed to as coproduct or by-product metal. This is a supply risk that we consider to be minimal for nickel. Nickel’s current by-production is very low (2%, Nassar et al., 2015) and is unlikely to substantially change in the future. Nickel is most frequently processed from ores that may also contain copper, cobalt, gold, silver, and platinum group metals (PGMs). In the case of co-production (mines where more than one metal contribute significantly to the potential overall returns), Mudd and Jowitt (2014) state that nickel is most frequently co-produced with PGMs, with either one of them having the higher potential value. Fig. 5. Secondary supply of nickel in the four scenarios (dashed lines) and the primary supply thus required to meet demand (solid and dotted lines). MW: Market World, TR: Toward Resilience, SF: Security First, EW: Equitability World.
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Fig. 6. Total energy demand for the production of nickel in the four scenarios. MW: Market World, TR: Toward Resilience, SF: Security First, EW: Equitability World.
the U.S. Geological Survey reported the “Reserve Base” for metals, defined as “that part of an identified resource that meets specific minimum physical and chemical criteria related to current mining and production practices”. The latest estimate (USGS, 2009) of the Reserve Base for nickel is 150 Tg (150 million metric tons). While recognizing that a high level of uncertainty exists in this estimate, we use it as a starting point in our discussions of long-term supply limitations. The US Geological Survey also defines a much more reliable metric termed the “Reserves”, which is defined as “that part of the Reserve Base that could be economically extracted or produced at the time of determination”. Because this measure is based on well-characterized and (often) currently active mining operations, it is a reasonably good estimate of nickel supply prospects for perhaps the next decade or two. For year 2010 (the starting year for our scenarios), global nickel Reserves are estimated to be 76 Tg (USGS, 2010). In Fig. 8, we compare the cumulative global nickel production as derived from our scenarios with the nickel Reserves and Reserve Base determinations for the 2009–2010 epoch. The integrated nickel production can be seen to exceed the Reserves in about 2038–2042 (depending on the scenario), but does not approach the limit of the (rather uncertain) Reserve Base in any of the scenario results. Additionally, as shown in Fig. 5 30% or more of the demand is anticipated to be met by
Nickel is the main product in 14 of the largest 25 nickel resources (Mudd and Jowitt, 2014). In 10 of these resources, nickel has a value of more than 50% of the total project value, and in 4 of the projects it has a value between 40% and 50%. Nickel resources total about 75 Tg in these 14 resources. PGMs are the main product in the remaining largest nickel resources, with about 15 Tg of nickel available in these deposits (Mudd, 2012). Cobalt is also co-extracted with nickel, with about 20% of cobalt resources in current cobalt-producing mines occuring together with nickel (Mudd et al., 2013). Cobalt has a value between 2% and 19% in 9 of the largest nickel resources (Mudd and Jowitt, 2014). In all 9 projects, nickel accounts for more than 48% of the economic value of the respective mine. Cumulative nickel demand from primary sources is about 75 Tg around 2040 depending on the scenario, which means that nickel demand could be met by the supply from nickel deposits where nickel is the principal metal. After 2040, nickel demand will be met by the supply from deposits in which nickel is not the principal product (i.e. the supply of nickel will be dependent on companion metals, mainly PGMs), making nickel supply somewhat vulnerable to the demand situation for PGMs. In general, there remains uncertainty when it comes to estimating the long-term potentially mineable assets in nickel deposits. Until 2009,
Fig. 7. Total water demand for the production of nickel in the four scenarios. MW: Market World, TR: Toward Resilience, SF: Security First, EW: Equitability World.
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Fig. 8. Cumulative demand for nickel as a function of the fraction of the nickel Reserve Base. The vertical lines indicate the dates when demand exceeds the 2010 USGS estimate of Reserves.
Appendix A. Supplementary data
recycled nickel. We conclude, therefore, that there is likely to be no significant limit to nickel supplies from primary stocks, by 2050 at least.
Supplementary data associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/j.resconrec.2017.07.002.
4. Conclusions
References
This study has developed and utilized four scenarios for the demand and supply of nickel and the associated energy and water required for nickel production. The most significant conclusions of the analysis are · The demand for nickel is anticipated to increase by between 140 and 175% by 2025 and between 215 and 350% by 2050, depending on the scenario. · The demand for nickel is found to be highest in the Equitability World scenario (a world of increased affluence, collaboration, and inclusivity) and lowest in the Security Foremost scenario (a world of confrontation and significant disparities among peoples). · The energy required to produce nickel in these scenarios constitutes 0.14- 0.3% of the total global energy demand by 2050 for all sectors of society, and the water required to produce nickel constitutes 0.013- 0.034% of the total global water demand by 2050. · The cumulative demand for nickel in the four scenarios is expected to exceed nickel Reserves but not the nickel Reserve Base by mid-century. Thus, there is likely to be no significant limit to nickel supplies over that period. Finally, it is important to note that scenarios are not predictions of the future. Rather, they are plausible stories of how conditions might evolve over time. Their value is to help envision possible responses to those stories, i.e., “If the world appears to be following the pattern of Scenario X, what would be the consequences for my/our area of interest, and how might I/my organization best respond?” The scenario results presented here are thus of interest to a wide variety of the segments of society: the nickel industry, nickel supply and demand chain participants, economic planners, and doubtless others. If fully embraced, the nickel scenario results promise the same sort of useful perspectives that scenario approaches have provided to such diverse audiences as the oil industry (Wack, 1985), ecosystems scientists (Pereira et al., 2010), and the military (Herman et al., 2009).
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