Predicting the Production and Depletion of Rare Earth Elements and Their Influence on Energy Sector Sustainability through the Utilization of Multilevel Linear Prediction Mixed-Effects Models with R Software
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3.8. Production to 2051 and Reserve to 2053
The projections conducted by LME models for various economic countries have provided noteworthy insights into production and reserve trends up to 2051 and 2053, respectively. In the initial step, a selection decision was made between the classical simple regression model and the multilevel mixed-effects model, based on multiple comparison criteria, including AIC and BIC. Upon analyzing these criteria, it was determined that the mixed model is more effective than the conventional models because it was observed that the values for mixed models were lower compared to conventional models. Therefore, the mixed model was deemed more effective. In terms of model fitting, the classical model showed a p-value greater than 0.05 for the parameter , which could potentially introduce bias to the results. Conversely, the mixed model demonstrated p-values less than 0.05 for both parameters and . Furthermore, the mixed model successfully incorporated random parameters that were absent in the initial model, enhancing its accuracy.
The study findings indicate that the ‘’ and ‘’ values have a significant impact on the timing of peak production and reserve for REE. To ensure accurate theoretical predictions, it is crucial to determine suitable values for ‘’ and ‘’. Higher ‘’ values lead to a longer product life cycle for REE and result in a higher peak value. Conversely, technical factors, advancements in the REE end-use industry, and political factors will influence the intrinsic growth rate (‘’), leading to an increase in peak production. These factors also affect the duration of resource exploitation, aligning with the scenario simulations conducted in this study. However, due to the uncertainties associated with these factors, future production and the timing of the peak may deviate from the presented predictions.
The following Figure 11a,b and Figure 12a,b present the projected estimates for diverse annual production and reserves of rare earth elements conducted using the multilevel model.
The linear mixed-effects model’s scenario simulations suggest that global production is set to increase, particularly during the period from 2024 to 2050. It is projected that peak production will occur in 2030, reaching 241,219.2665 tons. Another peak is expected in 2041, with a production mass of 247,752.76 tons. The final peak is anticipated in 2050, with a production mass of 226,231.7743 tons. This increase is justified by the demand generated by the ambitious 2050 global wind-power targets, which cannot be met without expanding REE production by 11 to 26 times according to [99]. While China is expected to retain its position as the leading global producer of REE, the results showed that, by 2024, China will know a trend of growth. Peak production is projected to occur in 2030 at 190,606.4 tons, followed by another peak in 2041, with a production mass of 195,768.5 tons. According to the mixed-effects model scenarios, China’s REE production will increase to 197,400 tons by 2022. Notably, the predicted annual data of rare earth production closely aligns with the actual data of 2022, with an average difference of less than 7%.
The United States, with a high production rate, is expected to become the second-largest producer of REEs. Its peak production is projected to occur in 2033, with a mass of 19,009.6745 tons (Figure 12b). Another peak is anticipated in 2044, with a production mass of 19,524.51 tons. Australia, securing the third position, is projected to reach its peak production in 2033, with a mass of 11,534.8478 tons. However, the lowest production is expected to be observed in 2037, with a mass of 3428.188 tons. Following this, India, Thailand, and Russia are also expected to contribute to REE production. India is projected to reach its peak production in 2023, with a mass of 5128.5758 tons. Thailand’s peak production is anticipated in 2024, with a mass of 4218.9158 tons, while Russia’s peak production is expected in 2033, with a mass of 3619.9535 tons. Another peak in production is anticipated for these countries in 2045, 2046, and 2042, respectively. During this period, India is projected to produce 5410.1315 tons, Thailand 2257.3599 tons, and Russia 3305.5146 tons.
Furthermore, Malaysia, Brazil, and South Africa are expected to have a lower volume of production compared to the leading producers. The first peak in production is anticipated in these countries in 2027, with Malaysia projected to produce 2707.2517 tons, Brazil to produce 473.6998 tons, and South Africa to produce 750.8331 tons. A second peak in production is anticipated in 2038. Notably, the timing of the last peak varies among the three countries, occurring in the periods 2047, 2050, and 2051. During these peaks, Malaysia is projected to produce 1013.0432 tons, Brazil 985.2022 tons, and South Africa 890.8896 tons.
The findings indicate that global reserves are projected to decline, particularly from 2030 to 2048 overall. The peak reserve is expected to transpire in 2026, reaching a mass of 156,926,006.93 tons. Another peak is anticipated in 2037, with a reserve mass of 158,257,305.14 tons. Conversely, a lower reserve was observed in 2030, with a mass of 77,175,546.45 tons. Another lower peak was observed in 2048, with a reserve mass of 72,866,572.14 tons. The decrease in reserves observed between 2030 and 2042 can be linked to increased demand for products during those years, showcasing a direct correlation between reserve levels and the production of rare earth elements (REEs) globally. This correlation is rooted in the significant demand for REEs across various applications, driven primarily by ambitious global wind-power objectives and the growing adoption of electric vehicles. Consequently, there is a pressing need for an 11- to 26-times expansion in REE production to meet this heightened demand, consequently affecting reserve levels.
Despite the anticipation of high rare earth element production in China, the country is still expected to maintain its position as the primary global reserve for REE, representing 39% of the total reserve. The peak reserve is projected to be reached in 2032, amounting to 50,474,342.1 tons, followed by another peak in 2043 with a reserve mass of 50,902,546.47 tons, attributed to the discovery of new mines. Notably, the years with higher production demonstrate a lower reserve. Additionally, Vietnam secures the second spot in world reserves, with a projected peak of 50,474,342.1 tons in 2028, followed by another peak in 2039 with a reserve mass of 50,902,546.47 tons. The last peak is expected in 2050. It is worth mentioning that lower reserve masses are expected in 2025 and 2043, with a further decrease to 14,236,573.64 tons in 2032.
Russia holds the third position, projected to reach a peak reserve of 22,907,990.73 tons in 2031, followed by another peak in 2051 with a reserve mass of 22,448,129.24 tons. The lower reserve masses are expected in 2042 and 2053, with amounts of 15,610,028.88 tons and 15,742,458.19 tons, respectively. On the other hand, the United States and Australia will secure the fourth and fifth positions. In the US, the peak reserve is projected to be reached in 2027 and 2042, with masses of 8,983,237.05 tons and 9,059,447.29 tons, respectively. As for Australia, the maximum reserve is expected in 2039 with a mass of 5,170,508.5 tons, followed by the second peak in 2050 with a reserve of 5,214,373.05 tons. Lower reserve volumes were observed in 2030 and 2052 in both countries.
In comparison to the leading reserve countries for rare earth elements, India, Brazil, Canada, South Africa, Thailand, and Malaysia are projected to have lower volumes of rare earth reserves, respectively. Among these countries, India, Canada, and Malaysia are expected to experience their first peak in production in 2025, with projected reserves of 2,831,677.08 tons, 1,372,631.43 tons, and 40,973.38 tons, respectively. A second peak in production is anticipated in 2036, with volumes of 2,855,699.91 tons, 1,384,276.29 tons, and 41,320.98 tons. These countries are also expected to have lower reserve mass in 2029 and 2048 (Figure 11a).
Brazil is projected to reach a peak reserve of 1,293,008.71 tons in 2031, followed by another peak in 2042 with a reserve mass of 1,303,978.08 tons. The lower reserve volumes are expected in 2033 and 2045, amounting to 906,763.11 tons. In South Africa and Thailand, higher reserves are anticipated in 2039 and 2051, with mass of 355,038.06 tons and 265,687.22 tons, respectively. The second projected peak for South Africa is 2,051,299,840.26 tons while, for Thailand, it is 344,653.24 tons. Conversely, the lower reserve in South Africa is expected in 2041, totaling 248,981.63 tons while, in Thailand, the lower peak will be observed in 2046 with a mass of 168,073.14 tons.
The increase in rare earth element (REE) reserves is attributed to the vital role these elements play in the development of nations. Following the 2010 China crisis, which highlighted the vulnerability of relying on a single source for Chinese REEs, countries have been compelled to explore and discover new sources and mines for these crucial minerals. Consequently, the model predicts a surge in reserves in major countries, characterized by three distinct phases of growth.
Based on the literature review, it is identified that there is only one study that analyzes the long-term production of rare earths worldwide using quantitative methods [17]. In addition, there are three studies that present the long-term production trajectory of China’s rare earths [41,49,77].
Furthermore, the Mineral Commodity Summaries 2018 report published by the USGS reveals that, in 2017, the total global rare earth production amounted to 133.5 thousand tons, with 78.65% of this production originating from China. This paper assumes that this proportion remains constant in the future. Therefore, the world’s rare earth production can be estimated based on the results of these three studies by dividing their production figures by 78.65%.
Our study corroborates previous research on global rare earth production using the curve-fitting model and the Richards method, as presented by Wang [17]. It suggests an upward trend in global rare earth production, particularly from 2024 to 2050. However, there are contrasting views presented by Wang [41,77], who proposes a different pattern. According to their studies, rare earth production is projected to initially experience rapid growth, reach a peak, and subsequently decline significantly by 2050, supporting the hypothesis of lower production in the long term. Regarding China’s rare earth production, our study aligns with previous research that utilized the Wang model [77]. Our results indicate a growth trend, with projected peak production in 2030 at 190,606.4 tons, followed by another peak in 2041 with a production mass of 195,768.5 tons. These findings are consistent with Wang’s study, which also suggests a steady annual growth rate of 1.72% from 2024 to 2045. However, it is important to note that the study forecasts a slight decrease in production, with an estimated annual decline of 4% by 2050. This decrease represents the smallest reduction in production compared to earlier years.
The history and present state of the REE supply chain exhibit the important role these materials already play in the world economy. Projections of a sharp increase in demand over the coming decades raise several questions about the future supply risks to this industry. A 2012 MIT study by Alonso et al. thoroughly explores this question of future supply, and projects total global demand up to 2035 under five divergent scenarios [100].
One of these scenarios uses the IEA Blue Map scenario to estimate future automotive electrification (Hub, n.d.). This model only seeks to reduce global carbon emissions by 50% by 2050.
Under this scenario, the study projects that, by 2035, global demand for REEs will reach close to 450,000 tons per year, compared to approximately 200,000 tons per year in 2021 (USGS 2021). This represents more than a doubling in the size of the industry in just 15 years. Furthermore, the rate of demand growth accelerates rapidly, as do projections of EV production up to 2050, indicating that this increase in industry demand is only the beginning of a pattern of accelerating growth that will likely last for decades [54].
The demand for REEs in EVs under the pessimistic, neutral, and optimistic scenarios will be 44 thousand tons, 89 thousand tons, and 179 thousand tons, respectively. The demands for Pr, Nd, and Dy will be higher than the demands for the other elements. The demands for these three elements in EVs will be 6–23 thousand tons for Pr, 26–108 thousand tons for Nd, and 11–47 thousand tons for Dy in China up to 2030, see for example Leal [24]. This is why it provides an encompassing understanding of the potential constraints resulting from rare earth element depletion/production and their impact on the energy sector.
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