Sustainable Resource Management: The End of Nickel Mining?

Abstract

As a versatile metal, nickel will experience increased demand in the coming years, with a specific focus on its importance in the battery industry and its role in achieving net-zero emissions. Recognizing the need to ensure sustainable resource management, this study analyses the flow dynamics of nickel’s supply and demand by employing a modelling approach. This is done with a focus on understanding how recycling can contribute to meeting the growing nickel demand. By considering the interaction between mining production, product applications, and recycling rates, this study contributes to a better understanding of the long-term prospects for meeting the nickel demand. It can assist policymakers, industry stakeholders, and investors in making informed decisions regarding resource management and developing sustainable practices in the nickel industry. The results revealed that mining would still play an important role in the supply of nickel for at least the next 40 years. Nickel mining and recycling practices are sufficient to meet future nickel demand if sufficient recycling practices are (rapidly) implemented. Modelling results show that nickel recycling will account for 90% of the total demand (primary nickel mining accounts for the remaining 10%) between the years 2062 and 2096.

1. Introduction

1.1. Background

The transition towards a low-emissions economy is necessary to reduce climate change impacts. Through the Paris Agreement, world nations have committed to a net-zero ambition, which requires the development of cleaner technologies [1,2,3,4]. But, the progress of cleaner technologies depends on numerous minerals, which are rare and difficult to extract [5]. Thus, comprehending these minerals’ extraction and supply is crucial to support the efforts towards clean technologies development.

Nickel is a key metal for our society and crucial for achieving a low-emissions future. Its versatility is evident in its wide-ranging applications, including supporting emerging clean energy technologies such as lithium-ion batteries and its utilisation in traditional applications, such as stainless steel and nickel-based alloys [6,7,8,9]. Currently, over 65% of the nickel produced is used in the manufacturing of steel, while nickel-containing grades make up around 75% of the total stainless-steel production. In superalloys, nickel plays a key role in the production of turbines, which are crucial for renewable energy, aerospace, and military applications [10,11].

An increasing proportion of nickel is employed in electric vehicle batteries, currently making up 15% of global primary nickel consumption for batteries [12]. The shift toward vehicle electrification is anticipated to further boost nickel demand, especially in battery applications [10]. At present, the lithium nickel manganese cobalt battery, known as NMC, is the main battery type used in electric vehicles [10]. The share of nickel in lithium-ion batteries is expected to increase to 58% by 2025 [13]. While it is evident that electric vehicles will play a major role in future transportation, relying solely on current raw material consumption as a basis for future projections is speculative.

Research is being conducted on high-performance batteries, and there may be changes in the composition of electric vehicle (EV) batteries. Nickel consumption for battery usage continues to increase for EVs, which is evident from the recent 8% increase over a 12-month period(Adamas. Battery nickel use increasing for all EV types [14]. Due to such rapid growth, nickel demand in electric vehicles is estimated to reach one million tonnes by 2030, accounting for more than 50% of the world’s total nickel production, which reached 3.6 million tonnes in 2023 [10,14,15,16].

Consequently, the demand for nickel is growing to develop clean technology solutions and to meet the net-zero targets. This growing demand for nickel is expected to persist, potentially leading to a shortage of nickel resources. Currently, the estimated amount of nickel resources worldwide is 350 Mt onshore and 300 Mt offshore (British Stainless Steel Association, 2024; Nickel Institute, 2024). Recognizing its strategic importance, many countries have designated nickel as one of their strategic metals [17]. In this context, the critical role of nickel in shaping a sustainable, low-carbon future becomes increasingly evident.

1.2. Previous Studies

Various studies have examined the global availability of critical metals in different ways. Pioneering work conducted by Meadows [18] and more recent investigations by Bardi [19], and Sverdrup, Ragnarsdottir and Koca [20], have provided diverse assessments of metal supply while expressing concerns about potential shortages or future peaks in metal production. Research studies by Reck and Gordon [21] and Reck, et al. [22] indicate that in the year 2000, the nickel recovery rate during production was 82%, the recycling rate at the end of a product’s life was 57%, and there was a 59% increase in the nickel in-use stock compared to annual nickel consumption. From an environmental perspective, nickel tends to have minimal environmental losses during use due to its non-dissipative nature in applications such as steel, alloys, and batteries [22]. Earlier studies employed different methods to perform metal sustainability assessment; e.g., to assess nickel supply, various studies used material flow analysis, input–output analysis, and life cycle assessment, as demonstrated in studies by Nakajima, et al. [23], Reck and Gordon [21], Turner, Williams and Kemp [24].

Recently, system dynamics modelling has been gaining attention because it allows the use of historical stocks and flow data to gain valuable insights into resource conservation. Multiple studies have used system dynamics (SD) modelling approaches to evaluate stocks and flows of different materials [25,26]. For instance, Golroudbary, Calisaya-Azpilcueta and Kraslawski [27] utilised system dynamics modelling to analyse lithium-ion batteries, while Van der Linden (2020) created a system dynamics model for cobalt, which also incorporated nickel, and investigated its application in electric vehicles and battery storage. Furthermore, Schmidt, Buchert and Schebek [28] performed a static material flow analysis to examine the use of nickel and cobalt in lithium-ion batteries, while Elshkaki, Reck and Graedel [29] created scenarios that explore future global nickel supply and demand, along with associated energy and water usage.

Giljum and Hubacek [30] discussed traditional mass flow models which lack a feedback mechanism such as considering the dynamic factors influencing the material flow. Most of these earlier resource scarcity assessment studies lack feedback and dynamic mechanisms for future policy development. Since then, there have been limited studies that use a system dynamic approach to assess the dynamics between nickel demand and supply, while considering how recycling can meet future nickel needs.

Thus, the purpose of this study is to address this research gap by examining the dynamics between global nickel stock and flow and assess how recycling can influence future nickel mining demand.

1.3. Scope and Objectives

The scope of this study is to utilise a system dynamics approach to model nickel stocks and flows and assess the sustainability of the long-term nickel supply. The paper will provide insights into the future development of the global nickel flow and how recycling may influence the future supply of nickel, and answer the following questions:

• Will nickel mining and recycling be sufficient to meet the nickel demand by 2100?
• At what date will nickel recycling make up 90% of the total supply (where primary nickel mining will be responsible for the remaining 10%)? (The choice of a 90% recycling and 10% primary nickel mining split is based on practical considerations of material flows and industry needs. Even in scenarios of zero or negative growth in nickel demand, 100% reliance on recycling is unrealistic due to inevitable losses in material quality, efficiency, and availability during the recycling process. Additionally, certain high-purity applications may continue to require primary nickel, which is more readily tailored to specific industrial needs. The 10% allowance for primary nickel ensures that these needs can be met while reflecting a significant shift towards a circular economy. This target is ambitious yet feasible, acknowledging both the limitations of current recycling technologies and the ongoing necessity of some primary nickel production).

To achieve these objectives, different recycling scenarios for nickel use cases were created using STELLA Architect^® system dynamics modelling software, Version 2.0., to model the impact of global nickel flow and recycling.

2. Scenarios

Three scenarios were selected to evaluate the effect of varying future nickel demands and to assess how recycling may influence the future primary supply of nickel. A brief description of each scenario is provided. For simplification purposes, the same parameters and specifications are used in each of the scenarios, with the exception of the forecasted nickel demand.

2.1. Base Case Scenario (“STEPS”)

The base case scenario assumes that minimal change will occur over the next 30 years in terms of EV uptake and general clean energy advancements and that the demand for nickel will only increase slightly. This scenario is based on the International Energy Agency’s (IEA) Stated Policies Scenario (STEPS) [31], which gives an indication of the potential trajectory based on current policies and measures. It is important to note that the outcomes projected by this scenario fall short of the world’s sustainability objectives. From here onwards, this scenario will be referred to as “STEPS”.

• For the STEPS scenario, the forecast nickel demand in 2040 will be 4052 kt [31].

(Note: Recent production and consumption figures show that the total nickel assumed in the STEPS scenario has already been exceeded. It has been retained as a scenario for comparison with the multiple other studies that refer to it [16].)

2.2. Medium Change Case Scenario (“SDS”)

The medium change case scenario assumes that some change will occur over the next 30 years in terms of EV uptake and general clean energy advancements and that the demand for nickel will increase somewhat. This scenario is based on the IEA’s Sustainable Development Scenario (SDS) [31], which outlines a trajectory that aligns with the global objectives aimed at addressing climate change, as stipulated in the Paris Agreement. The SDS assumes countries will attain their net-zero emissions targets, primarily by 2050, which will be achieved mainly by adopting various clean energy technologies [31]. From here onwards, this scenario will be referred to as “SDS”.

• For the SDS scenario, the forecast nickel demand in 2040 will be 6265 kt [31].

2.3. Rapid Change Case Scenario (“1.5 °C”)

The rapid change case scenario assumes that significant change will occur over the next 30 years in terms of EV uptake and general clean energy advancements and that the demand for nickel will increase considerably. This scenario is based on the 1.5 °C scenario (as described in the BHP Climate Change Report 2020 [32]), which describes a carbon budget that restricts global warming to no more than 1.5 °C, i.e., global temperatures should not exceed preindustrial levels by more than 1.5 °C. This scenario gives the future nickel demand as a ratio between the cumulative demand of the previous 30 years and the next 30 years and suggests an increase of approximately 370% in nickel demand until 2050. Altogether, the transition to a 1.5 °C-world will require immense effort [32]. From here onwards, this scenario will be referred to as the “1.5 °C” scenario.

• For the 1.5 °C scenario, the cumulative nickel demand in the next 30 years compared to the last 30 years is ≈370% [32]. This translates into a forecast nickel demand in 2050 of 9500 kt, which is also confirmed by other forecasts [33].

Table 1. Summary of three scenarios that will be evaluated.

Scenario	Scenario Reference	Scenario Description	Ni Demand Forecast
Base case	STEPS [31]	Based on analysis of current policies	4052 kt (by 2040)
Medium change	SDS [31]	Required to meet Paris Agreement goals	6265 kt (by 2040)
Rapid change	1.5 °C [32,33]	Required to reach much below 1.5 °C	9500 kt (by 2050)

provides a summary of the three scenarios that will be evaluated in terms of their reference, description, and the nickel demand forecast for a specified year.

The International Energy Agency (IEA) has estimated the nickel demand under two scenarios (STEPS and SDS) for the year 2040, specifically [31]. This year was therefore selected as a key point in the study since forecasted data are available for this year. As for 2050, the BHP Climate Change Report has estimated the nickel demand under the scenario of achieving net zero, or the ‘1.5 °C scenario’, for the year 2050 [32]. This year was therefore used as a key point in the time period since data are available for this year.

3. Method

3.1. Modelling Overview

The model compiled within this study uses a system dynamics modelling approach to describe relationships between various parameters within the nickel industry. The model aims to determine how much recycling and mining of nickel is necessary to meet the future demand goals by 2100 under different scenarios. It also aims to determine the year in which nickel recycling will make up 90% of the total nickel supply.

The model was run from 1994 to 2100 to ensure a wide range of historical and future data were considered. All three scenarios (STEPS, SDS, and 1.5 °C) were modelled according to specific demand, and sensitivity analyses were performed to investigate the degree to which the model responds to changes in the recycling rate of EV batteries. For simplification purposes, the model assumes 2020 to be the current year since there are many references to 2020 as the year that marks the shift from past data to future predictions. Data for 2021 onwards are treated as future predictions.

3.2. Model Structure

Nickel has been mined historically and will continue to be in demand for the foreseeable future [34,35,36]. The model presents historical and projected nickel production within the light blue block shown in Figure 1. This encompasses data on nickel mining from the year 1994 to 2020, referencing historical records [37,38], and includes the expected growth rates of production from the year 2020 to 2100.

Once nickel is mined, it is distributed among three use cases: stainless steel (green block in Figure 1), EV batteries (yellow block in Figure 1), and other products such as non-ferrous alloys, alloy steels, plating, etc. (red block in Figure 1) [8], according to specific split ratios.

After a set amount of time, recycling occurs within each of the use cases and a Gaussian function models the recycling process. A recycling rate (%) and product lifetime (years) are used to determine the recycling of the specific product. The product lifetimes are assumed to stay constant, i.e., a certain product will be recycled after a fixed number of years, whereas the recycling rates are assumed to increase with time.

For each different scenario modelled, a certain demand in total nickel mining needs to be achieved (made up of both mining and recycling). The predicted demands stated in Table 1 only extend until 2040 or 2050. Demand beyond this is assumed to be driven by world population growth and is therefore used to determine the 2100 demands for each scenario [39,40]. Figure 1 shows the structure of the model, indicating the flow of nickel mining, uses, and recycling.

3.3. Model Parameters

3.3.1. Nickel Mining

The nickel mined is represented as a stock in the model and describes the total nickel mined for a specific year. This value is determined by the input and output flows in the model (mining growth and mining decrease) and is either obtained from actual historical data (historical nickel, representing the amount of nickel that was mined per year from 1994 to 2020) or calculated by multiplying the nickel mined with the applicable production growth rate (PGR), according to Equations (1) and (2), creating an exponential function:

Nickel mined _(t) [Mt] = Nickel mined _(t–1) [Mt] × PGR _{(2021–2040)} [%] [For 2021 < t ≤ 2040]

(1)

Nickel mined _(t) [Mt] = Nickel mined _(t–1) [Mt] × PGR _{(2041–2100)} [%] [For 2041 < t ≤ 2100]

(2)

where t refers to the current year. The PGRs are calculated based on the unique demands set out in each scenario (as per Table 1) and will be discussed in Section 3.3.3.

The nickel mined is then split into the three use-case categories as described in Section 3.2. The split ratios between these three categories were taken from Wood Mackenzie (Future Facing Mined Commodities) and suggest that in 2021, 69% of nickel was used in stainless steel production, while 7% of nickel was used in batteries [41]. By 2040, these values are predicted to change to 45% and 41% for stainless steel and EV batteries, respectively [41]. Assuming a linear function, ramp functions are used to model the changes in these first split ratios according to Equations (3)–(5):

% _{stainless, t} = 69 [For t ≤ 2021]; % _{stainless, t} = 69 − 1.26·(t–2021) [For 2021 < t ≤ 2040]

(3)

% _{batteries, t} = 7 [For t ≤ 2021]; % _{batteries, t} = 7 + 1.79·(t–2021) [For 2021 < t ≤ 2040]

(4)

% _{other, t} = 100% − % _{stainless, t –} % _{batteries, t}

(5)

where % _{stainless, t}, % _{batteries, t}, and % _{other, t} refer to the percentage of nickel being used for each of the three specific products: stainless steel, EV batteries, and other products, respectively. The constant values of −1.26 and 1.79 represent the rate at which the split ratio will increase or decrease each year and were calculated using Equations (6) and (7):

$$\mathrm{SS}: \left({\displaystyle \frac{Split rati{o}_i-Split rati{o}_f}{Yea{r}_i-yea{r}_f}}\right)=\left({\displaystyle \frac{69\%-45\%}{2021-2040}}\right)=\left({\displaystyle \frac{24\%}{-19}}\right)=decrease of \mathbf{1.26}\% per year (\mathit{\text{from}} 2021 \mathit{\text{to}} 2040)$$

(6)

$$\mathrm{Batteries}: \left({\displaystyle \frac{Split rati{o}_i-Split rati{o}_f}{Yea{r}_i-yea{r}_f}}\right)=\left({\displaystyle \frac{7\%-41\%}{2021-2040}}\right)=\left({\displaystyle \frac{-34\%}{-19}}\right)=increase of \mathbf{1.79}\% per year (\mathit{\text{from}} 2021 \mathit{\text{to}} 2040)$$

(7)

where Split ratio_i refers to the initial split ratio in 2021 (which was 69% for SS and 7% for EV batteries), Split ratio_f refers to the final split ratio in 2040 (which was 45% for SS and 41% for EV batteries). Year_i and Year_f are the initial and final years corresponding to the split ratios, i.e., 2021 and 2040.

These split ratios (as calculated using Equations (3)–(5)) are illustrated in Figure 2.

The percentage of the specified use case [% _{use case}] is then multiplied by the total nickel mined (according to Equation (8)) and expressed as the metal in input at each of the three use case blocks (green, yellow, and red blocks in Figure 1).

Metal in _use-case = Nickel mined × % _{use case}

(8)

where use case can represent stainless steel, EV batteries, or other nickel products.

Figure 3 illustrates the details presented in Section 3.3.1 (which is highlighted by the red dotted line), using the stainless steel (SS) use case as an example. This image forms part of the full model shown in Figure 1.

The total SS in the figure represents the amount of nickel currently present in stainless steel products that can be recycled once they reach the end of life.

3.3.2. Nickel Recycling

Recycling occurs when a product has reached the end of its life and can be repurposed to create a new product. For stainless steel, an average lifetime of 25 years has been used [42]. For batteries, a value of 10 years was used (assumed to have no second life), according to references [34,35,36], and an average of 15 years has been assumed for the rest of the nickel products. For each of the three use cases’ lifetime parameters, a lifetime standard deviation was assumed to account for model variability. For stainless steel, batteries, and other products, standard deviations of 3 years, 2 years, and 2 years were assumed, respectively.

The recycling rate (%) determines the percentage of nickel that will be recycled after the product’s end of life. From other studies [43], these rates consider the amount of product that is collected for recycling as well as the recovery rate (i.e., the amount that is recovered from the chemical recovery process). For simplification purposes, the recycling rates referred to in this paper represent this final value, i.e., no distinction is made between collection and recovery rates. The initial recycling rates for stainless steel and other products are 60% [44] and were assumed to increase steadily up to 90% in 2050 [43].

For the EV batteries, the initial recycling rate is much lower, since they are relatively new and there is a lack of specific pre-existing recycling infrastructure available [45]. Starting at 5%, this rate increases rapidly until 2040, whereafter it plateaus at a constant value [46]. CSIRO [45] assumed a maximum recycling rate of 98%; however, for this study, it was decided to adjust this projected battery recycling rate for 2040 within the range of 90% to 98% in order to assess the impact of varying recycling advancements. These recycling rates are illustrated in Figure 4.

A Gaussian function is used to model the recycling process. The final recycled material is determined by considering the end of life (or time to recycle) for the specific product, the amount of product available for recycling, as well as the recycling rate. This is calculated by Equation (9) and illustrated in Figure 5.

Recycled metal = DelayedMetal × GaussRecycAmount × Recycle_Rate

(9)

After the metal has gone through the recycling process, the recycled metal, together with the newly mined nickel (nickel mined), forms the final nickel production (e.g., Total SS final). This value, together with those from EV batteries and other products, will be used to calculate the required PGRs according to the set demand targets, which will be discussed in Section 3.3.3. The model (starting in 1994) assumes that all metal required to produce stainless steel, EV batteries, and other products in the first year must come from mining only. This means that 1994 is considered the first year of any nickel production and that recycling will only happen once the new products reach their end of life [45]. This is assumed for model simplification purposes mainly, and since a relatively small amount of nickel units in steel production during the 1990s came from scrap metal.

3.3.3. Meeting Future Demands

After the recycling and mining of nickel has been set up to produce the final amount of nickel (total metal), the PGRs must be calculated, as highlighted in Section 3.3.1. This is achieved by considering the forecast demands specified for each scenario (Table 1). These demands are only forecast until 2040 or 2050; therefore, world population growth is used to determine the 2100 demand figure in each scenario [39,40]. A goal-seek function is then used to optimise the PGRs (which were initially guessed) to ensure that the final total metal supply aligns with the targeted demands. This part of the model is highlighted in Figure 6.

3.4. Model Assumptions and Limitations

The nickel metal flow for supply and demand was modelled according to the information provided in Section 3.3. There were, however, several assumptions that were made in the development of the model. These are as follows:

• 2020 is the current year (since there is much reference to 2020 as a starting point, this was a simple way to incorporate certain assumptions) [41].
• Pre-2021 split ratios of nickel use cases are assumed to be the same as in 2021.
• Nickel demand (between 2050 and 2100) is driven by world population [39].
• Nickel within all products can be recycled again and again (infinite recycling) [8].
• Once nickel is used in a certain product (e.g., an EV battery), it will always be used in this product, and never for another product (e.g., stainless steel) [36]; i.e., “Once a battery, always a battery”. This is because the process of extracting nickel from complex materials (like an EV battery) to revert it to a pure, raw form is energy-intensive and costly. This assumption was also made for model simplification purposes.
• Possible nickel exhaustion will only be an issue after 2100 [39]; i.e., resource exhaustion is not considered in this paper.
• All metal required to produce nickel products in the first year must come from mining only, and none is available for recycling before 1994 [44].

4. Results

The model was run for all three scenarios, with varying EV battery recycling rates (90%, 94%, and 98%) as inputs, from 2020 to 2100. The model outputs of these simulations are predictions of the supply and demand dynamics within the nickel industry.

4.1. Meeting Future Demands

Future nickel production will combine mining and recycling to meet demand targets determined by future applications. These future demand targets of nickel production are specified for each of the three scenarios in

Table 2. Future nickel demand targets for different scenarios.

Scenario	Ni Demand Forecast (2040, unless Stated Otherwise)	Ni Demand Forecast (2100) b
STEPS	4052 kt	4564 kt
SDS	6265 kt	7057 kt
1.5 °C	9500 kt (2050) a	11,550 kt

^a This value also adheres to the 370% cumulative demand forecast, as per the BHP Climate Change Report [32]. ^b Demands for 2100 were calculated using world population growth forecasts from 2040 to 2100 [39].

(derived from Table 1).

When running the model, the PGRs are adjusted such that the final total nickel production can meet these demand targets. Figure 7 shows the final total nickel production (mining and recycling) from 2000 to 2100, with Figure 7a–c representing the modelling outcomes for the STEPS, SDS, and 1.5 °C scenarios, respectively. The graphs shown here only represent the 90%-EV battery recycling rate models, since the visual difference between the varying rates is negligible. These graphs distinguish between the different nickel products, and it is seen that EV batteries, specifically (yellow area), are increasing over time. The demand targets are also indicated (in black) to illustrate the demands being met.

The final total nickel production (as shown in Figure 7) is a combination of mining and recycling. Figure 8 shows the contribution of the mining component to the total nickel production, as a percentage, from 2000 to 2100, with Figure 8a–c representing the STEPS, SDS, and 1.5 °C scenarios, respectively. Additionally, the specific year in which nickel recycling will make up 90% of the total supply (and nickel mining the remaining 10%) is also indicated on the graphs. The latest (2021) data point was also added to the graph (★) to see how we are tracking in terms of production via mining vs. recycling. This data point suggests that recycling of nickel is not occurring as frequently as the model assumed. Based on the scenarios, recycling would have been at around 20% (80% mining), but is currently at only 5% (95% mining) of the total nickel supply.)

An alternative way of representing the graphs from Figure 8 is to display an area graph to show the fraction of the nickel that is supplied by mining as opposed to recycling. One can observe the area of mined units decreasing, while the area of recycled units increases over the duration of the modelling period. The 1.5 °C scenario for 90% recycling is shown in Figure 9 as an example.

The specific year in which nickel recycling will make up 90% of the total supply (and nickel mining the remaining 10%) is summarised in

Table 3. Year where nickel supply will consist of only 10% mining to meet future nickel demands.

Scenario	EV Batteries Recycle Rate
	90%	94%	98%
STEPS	2073	2068	2062
SDS	2074	2068	2063
1.5 °C	2096	2086	2078

, according to the three scenarios and the varying battery recycle rates.

4.2. Nickel Mining

The future nickel mined is determined by the applicable production growth rates (PGRs), which are computed based on the demand target set out in each scenario. Figure 10 shows the primary supply (mining) of nickel from 2000 to 2100 for the three different EV battery recycling rates (90%, 94%, and 98%). Figure 10a,b show the results for STEPS and SDS, while Figure 10c represents the 1.5 °C scenario results.

There is a distinct change in the graph at 2020, 2040, and 2100, due to the periods around these dates being pre-defined: all data until 2020 are historical data, while the periods 2021–2040 and 2040–2100 are each defined by a unique production growth rate (PGR). These three periods are indicated by the grey and orange blocks in Figure 10a–c. The PGRs determining these mining forecasts are shown in

Table 4. Mined production growth rates (MPGR) per period for varying EV battery recycle rates.

Scenario	EV Batteries Recycle Rate
	90%		94%		98%
	MPGR: 2020–2040	MPGR: 2040–2100	MPGR: 2020–2040	MPGR: 2040–2100	MPGR: 2020–2040	MPGR: 2040–2100
STEPS	−1.98	−3.52	−2.07	−4.33	−2.16	−5.62
SDS	1.79	−4.39	1.73	−5.34	1.66	−6.84
1.5 °C	2.9	−2.41	2.77	−2.87	2.65	−3.52

. Recent production and consumption figures show that the total nickel assumed in the STEPS scenario has already been exceeded. However, it has been retained as a scenario for comparison with the multiple other studies that refer to it [16].

4.3. Nickel Recycling

The recycling of nickel metal is determined by the amount of nickel products available for recycling, the lifetime of these products, and the recycling rates associated with them. Nickel products are recycled after their lifetime, which, for the purposes of this model, started no earlier than 1994. As discussed in Section 3.3.2, the recycling rates for stainless steel and other products were modelled to start at 60% and reach 90% by 2050. The initial recycling rate used for EV batteries was 5%, increasing rapidly until 2040 and then stabilising (ranging from 90% to 98%, to gauge the effects of different recycling advancements).

Figure 11 shows the total recycled nickel from 2000 to 2100 for the three different EV battery recycling rates (90%, 94%, and 98%). Figure 11a–c represent the modelling outcomes for the STEPS, SDS, and 1.5 °C scenarios.

Recycling starts at zero in 2000, whereafter a steep incline in recycled metal is seen within the “fast growth” section. After this, the curves begin to flatten as the recycling rates stay constant across the different products and no longer increase with time, as seen in the “stable recycling” sections. The decrease in recycled metal is also due to the assumed population decrease. As stated in Section 3.3.3, nickel demand is assumed to be driven by the world’s population, which will start decreasing around the 2080s [39,40].

The blue, red, and pink lines in each graph represent the varying recycling rates of EV batteries: 90%, 94%, and 98%, respectively. By 2100, the difference in recycled metal between the 90% and 98% rates (blue vs. pink lines in Figure 11) was 3.2%, 2.9%, and 5.1% for the STEPS, SDS, and 1.5 °C scenarios, respectively.

5. Discussion

5.1. Nickel Mining Trends

The model (Figure 10) displayed a significant shift in nickel mining activity across the three distinct periods: pre-2020, 2020–2040, and 2040–2100. The results suggest that mining of nickel will start to decline soon, if the STEPS scenario is assumed. However, if countries are determined to achieve their net-zero goals and start adopting various clean energy technologies (i.e., following an SDS or 1.5 °C scenario), then nickel mining will continue to increase until 2040 to meet future demands (especially for certain net zero targets to be met), whereafter it may start to decrease.

The limited constraints in the model resulted in sharp inflection points during 2020 and/or 2040, which may not necessarily reflect the realistic dynamics of the nickel market. This can be mitigated by setting more regular targets, e.g., every 10 years. This may ‘smooth out’ the model to represent a more realistic future mining trend.

However, the ultimate goal of this model was to evaluate the amount of mining necessary to reach certain demand targets. The results are therefore valuable in highlighting that irrespective of assuming an SDS or 1.5 °C scenario, the mining of nickel will have to increase significantly for the world to attempt to reach its net-zero goals. Substantial investment is necessary to support this drive and facilitate the primary supply of nickel. The mining of nickel remains a crucial industry and is expected to continue as such until, at least, the 2060s, whereafter recycling is projected to dominate the supply of nickel.

5.2. Recycling and Recycle Rates

The model results, referring specifically to Figure 11, showed the total recycled nickel from 2000 to 2100 for the three different EV battery recycling rates. The recycling rates started at 5% and gradually increased to 90%, 94%, or 98% over a period of 20 years. One could expect different outcomes by varying the rates; however, this seemed to have had minimal effect on the amount of final recycled metal. By 2100, the difference in recycled metal between the 90% and 98% rates was 3.2%, 2.9%, and 5.1% for the three different scenarios, which can be considered negligible. These rates may be adjusted in a future study to cover a wider range.

Some authors have questioned the assumption of a current 5% recycling rate [47] and suggested that recycling rates of lithium-ion batteries in 2019 were closer to 59%. Incorporating an initial rate of 60% recycling instead of the assumed initial 5% resulted in negligible differences in recycled metal by 2100 and a movement of only two years in the attainment of the 90% threshold for the most favourable recycling scenario.

5.3. Implications

The model highlights the importance of recycling in meeting future demands, but also simultaneously confirms the fundamental role of mining. The results strongly suggest that mining remains a critical component, even as recycling becomes increasingly prominent in ensuring a sustainable future.

Despite the rising prominence of recycling practices, mining remains an indispensable part of the equation. It is essential, therefore, to continue advancing mining activities and strategies to ensure they are as efficient, sustainable, and environmentally responsible as possible. Rather than being an outdated practice, mining remains a dynamic and essential sector in the industry. Its evolution and adaptation will be key to meeting our ongoing and future resource needs. Thus, while we embrace the era of recycling, we must also recognise and support the continuous, essential role of mining in our world.

5.4. Comparison to CSIRO Model

The model in this paper was similar to another study conducted by CSIRO, ‘Known unknowns: the devil in the details of energy metal demand’ CSIRO [45]. Both studies considered various metal scenarios to account for different future changes in battery uptake, technological changes, etc. (similar to our STEPS, SDS, and 1.5 °C scenarios). Both studies assumed similar maximum EV battery recycling rates of 98%.

The major differences between these two studies include the CSIRO study introducing the possibility that end-of-life batteries have a second life in energy storage, for some of the scenarios, thereby potentially extending the life of batteries by another 5–10 years. However, in this study, no second life was assumed for modelling simplification purposes.

They also assumed 2020 as the starting year (as opposed to our starting year of 1994), and similarly assumed zero recycled material available (i.e., recycling will only begin once the products produced in year 1 are at the end of life). This study also assumed that nickel metal can be recycled over and over again, as many other studies have stated.

Another difference between the two studies is the fact that the CSIRO study focused specifically on EVs and evaluated the supply and demand of the main battery metals (Ni, Co, Li) involved. In this study, the focus was only on nickel but it was considered among stainless steel and other use cases as well. Future studies may look at cobalt and lithium flows as well.

In this study, future demand was either based on forecast values from literature (‘near future’) or assumed to be following population growth forecasts (‘far-off future’). However, the CSIRO study considered certain EV uptake % assumptions (e.g., 2% EV uptake, 60% EV uptake, and 100% EV uptake, in different scenarios by a certain time), assuming that metal is recycled again and again. These discrepancies, amongst others, have led to a material impact on nickel demand. According to their findings, the total amount of nickel supply through ‘new products; ranges between 4 000 and 6 000 kt by 2060. In contrast, our study predicted 8 000–10 000 kt based on the SDS and 1.5 °C scenarios. Many other differences, such as modelling techniques, assumptions, time periods, data sources, and modelling software were used in the two studies, which may also explain additional discrepancies.

6. Conclusions

Nickel’s diverse applications suggest its market demand will rise in the near future, particularly due to its critical role in battery production and its contribution to achieving net-zero emissions targets.

Recognizing the need to ensure sustainable resource management, this study analysed the supply–demand dynamics of nickel through a modelling methodology, with a specific focus on evaluating how recycling can contribute to meeting the growing nickel demand. The two main objectives were addressed by using different recycling scenarios for nickel use cases to model the impact of global nickel flow and recycling.

6.1. Will the Current Ni Mining and Recycling Be Sufficient to Meet the Ni Demand by 2100?

The findings indicated that, for at least the next four decades, nickel mining will continue to be a significant contributor to nickel supply. Adequate nickel mining and recycling methods can fulfil future nickel needs, provided that robust recycling practices are swiftly put into place. Current data on available nickel resources suggest that mining will still be possible within this timeframe.

6.2. By When Will Ni Recycling Make up 90% of the Total Demand?

The outcomes of the model indicate that nickel recycling will account for 90% of the total demand (with primary nickel mining accounting for the remaining 10%) between the years 2062 and 2096. This suggests a major shift towards recycling as the predominant source of nickel supply, with mining playing a lesser, though still vital, role in meeting the global nickel requirements.

In summary, while this study underscores the increasing importance of recycling in meeting future demands, it simultaneously reaffirms the vital role of mining. The evidence clearly indicates that, despite the rising prominence of recycling practices, mining remains an indispensable part of the equation. It is essential, therefore, to continue advancing mining activities and strategies to ensure they are as efficient, sustainable, and environmentally responsible as possible. Rather than being an outdated practice, mining remains a dynamic and essential sector in the industry. Its evolution and adaptation will be key to meeting our ongoing and future resource needs. Thus, while we embrace the era of recycling, we must also recognise and support the continuous, essential role of mining in our world.