Permanent Magnets in Sustainable Energy: Comparative Life Cycle Analysis

Abstract

This study addresses the environmental challenges associated with high-performance rare-earth magnets, particularly NdFeB, which are essential in green and digital technologies. By employing Life Cycle Assessment (LCA) with openLCA software, we evaluate the environmental impacts across the life cycles of ferrite, NdFeB, and MnAlC magnets, focusing on extraction, processing, and recycling. Various studies have explored different aspects of the LCA of NdFeB magnets, focusing on production methods, recycling processes, and the environmental impacts of different rare-earth sources. A comparative LCA highlights the significant environmental footprint of rare-earth magnets, underscoring the role of functional unit selection: when assessed per unit of energy density, the environmental impact of NdFeB magnets aligns more closely with alternatives. Methodological issues such as data quality, choice of functional units, and system complexity affect LCA accuracy, as inconsistencies in data or scope led to potential distortions in environmental assessments. This research also explores manganese-based magnets as viable alternatives to reduce reliance on rare-earth materials. Legislative initiatives, including the EU’s Ecodesign Directive and Critical Raw Materials Act, support sustainable management practices to ensure reliable material supply while promoting environmental protection. This paper highlights the importance of sustainable magnetic materials, emphasizing the need for interdisciplinary research to balance technological efficiency and environmental impact, especially as rare-earth magnet demand rises with the transition to renewable energy sources.

1. Introduction

In today’s technology-driven society, high-performance materials are crucial across various industries. Rare-earth permanent magnets (PMs), such as neodymium–iron–boron (NdFeB), have become essential in numerous modern technologies due to their exceptional magnetic properties and efficiency. They have significantly enhanced the performance and efficiency of devices and hold immense potential to drive technological advancement and innovation. The importance of rare-earth magnets is evident, as they drive technological advancement and innovation while simultaneously improving the functionality and efficiency of various devices. Despite their significant contribution to technological progress, the production and use of rare-earth magnets raise important environmental concerns. These magnets contain rare-earth elements, so their production involves the extraction, processing, and recycling of such elements, which can have substantial environmental impacts. Therefore, it is crucial to understand the life cycle of these magnets, identify the key processes involved, and evaluate their environmental impacts. Exploring potential solutions to mitigate these negative impacts is essential for sustainable development.

While playing a pivotal role in the renewable energy sector, rare-earth magnets, particularly in wind energy production, also present a complex environmental challenge. Their use in wind turbine generators is crucial for promoting sustainable energy sources and reducing global carbon emissions. However, this very application also imposes additional responsibilities. The management of these magnets’ production and waste disposal processes must be carefully handled to minimize their potential environmental impacts, highlighting their dual role and complexity in sustainability.

PMs have nearly universal applicability. They are used in industry (instrumentation, electronics, mechanical engineering, magnetic systems for various purposes, mineral processing, etc.), trade, healthcare, and everyday life. The mining and processing of these materials can be environmentally damaging and subject to supply chain issues. As a result, REEs are considered by the European Commission to be the most critical raw materials in terms of their economic importance and supply risk [1]. High-energy magnets without REEs have not been produced. To use PMs without relying on rare-earth elements (REEs), options include ferrites, alnico, and Fe-Co-C (iron–cobalt–carbon) magnets. However, these alternatives do not achieve the magnetic properties of REE-based magnets. Over the past decade, significant scientific effort has been dedicated to developing new magnetic materials that address REE issues while maintaining sufficient magnetic properties [2]. Manganese-based compounds are being explored as promising materials for various applications due to their excellent magnetic properties and potentially lower environmental impact than traditional rare-earth magnets.

LCA is a critical tool for evaluating and reducing the environmental impact of PMs. By assessing the entire life cycle—from material extraction, manufacturing, and transportation to usage, marketing, and recycling—LCA helps identify areas where improvements can be made to reduce emissions and enhance efficiency. The main principles of LCA are defined by the International Organization for Standardization (ISO) in standards ISO 14040 [3] and ISO 14044 [4].

With the EU’s commitment to reduce carbon emissions, the demand for rare-earth materials, including PMs, is expected to rise, as they are crucial in energy-efficient devices like electric motors and generators, according to the European Green Deal [5,6]. The EU plans to become the first continent with a neutral climate by 2050. Currently, energy production and consumption in the EU account for more than 75% of greenhouse gas emissions. With the EU’s drive to reduce carbon emissions, enhance renewable energy production, and increase the adoption of electric mobility, the demand for rare-earth materials is expected to rise. Electric motors and generators utilizing rare-earth PMs are currently energy-efficient devices. These magnets are crucial in various applications, including electric vehicle traction motors, wind turbines, household appliances, servo motors in robotic arms, and portable communication devices such as speakers.

The growing geopolitical emphasis on resilience and security in the net-zero industry has strengthened the EU’s supply chain for clean technologies, including critical materials like PMs, vital for sustainable energy advancements, through legislation and strategic partnerships [7]. The EU focuses on building resilience and achieving strategic autonomy in the rare-earth and magnet supply chains to ensure a stable supply and reduce dependence on external sources. This effort aims to strengthen Europe’s capacity to produce, process, and recycle these critical materials, enhancing its industrial ecosystem’s sustainability and security.

The Ecodesign Directive primarily addresses the EU legislation on rare-earth magnets [8] and the more recent Ecodesign for Sustainable Products Regulation (ESPR) [9], as well as specific initiatives and acts like the Critical Raw Materials Act. The Ecodesign Directive (2009/125/EC) focuses on improving the environmental performance of energy-related products, including rare-earth magnets used in various applications, like electric motors and wind turbines. The Ecodesign for Sustainable Products Regulation (ESPR) expands the scope of the Ecodesign Directive by establishing a comprehensive framework for ecodesign requirements for almost all physical goods. It emphasizes the importance of increasing product durability, reusability, repairability, and recyclability, enhancing the sustainability of products containing rare-earth elements. The Critical Raw Materials Act ensures the EU has a reliable and sustainable supply of critical raw materials, including rare-earth elements. The act focuses on diversifying the supply of these critical materials to reduce dependence on a single external supplier, such as China. Currently, 98% of the EU’s demand for rare-earth magnets is met by imports from China.

This study examines the life cycle of rare-earth magnets and their alternatives, evaluates the environmental impact at all stages of their production, and proposes sustainable solutions to mitigate negative environmental effects. This will enable developers and manufacturers to choose eco-friendly materials, fostering the advancement of green technologies and reducing dependence on rare-earth elements. These research findings will be valuable to policymakers, manufacturers, and researchers by helping them select sustainable materials and support eco-friendly policies in magnet production and renewable energy sectors. Developers of machines and devices with permanent magnets can use these data to choose materials with a lower environmental impact, which is especially crucial given the growing demand for green technologies.

2. Materials and Methods

The global PM market was valued at USD 35.0 billion in 2022 and is projected to reach USD 78.9 billion by 2032, growing at a compound annual growth rate (CAGR) of 8.7% [10]. This growth is largely attributed to the increasing applications of magnets in the automotive and electronics industries and heightened investments in renewable energy projects. In the global PM market, NdFeB magnets are projected to hold a significant share, estimated at approximately 45% by 2030 [11]. Projections indicate that electric vehicles will account for 32% of total NdFeB magnet consumption by 2032. Figure 1 illustrates the projected demand for permanent magnets across various application fields. The demand is categorized into several key sectors: hybrid electric vehicles, plug-in hybrid electric vehicles, and electric vehicles; traditional combustion-engine vehicles; smartphones, laptops, and household appliances; wind turbines; air conditioning; electrical and mechanical components; and other applications. The 2030 demand forecast for Nd-Fe-B raises concerns about raw material availability and processing capabilities. Diversified global supply chains are essential to manage risks, including extraction, processing, and support for alternative sources in other countries, while adhering to environmental standards. Developing alternative materials and technologies is also critical for flexibility. Recycling, reuse, and efficient resource use could significantly reduce demand for newly extracted materials. Research and policy will help make recycling economically viable.

The extent of China’s worldwide dependency on rare-earth elements became evident in late 2010, when China threatened to limit supplies. At that time, rare-earth elements’ prices skyrocketed, e.g., Nd and Dy prices rose about 25 times [13]. From 2012 onward, the prices of most of the elements have fallen substantially, but the issue of the availability and price of rare-earth magnets in the future remains unclear. Many experts foresee a shortfall in the supply of some rare-earth elements, as demand is expected to exceed the industry’s potential.

PMs have been crucial in developing technology and industry by providing consistent and reliable magnetic fields without needing an external power source. Due to their intrinsic properties, these magnets generate a persistent magnetic field, making them essential in various applications, from household items to advanced industrial equipment. Figure 2 illustrates the magnetic parameters of various PMs, highlighting key properties such as magnetization coercivity H_c,(kA/m), remanence Br(T), and maximum energy product BH_max(kJ/m³)_.

A ferrite or ceramic magnet primarily consists of iron oxide (Fe₂O₃) as the main magnetic element. In addition to iron oxide, it typically contains strontium carbonate (SrCO₃) and barium carbonate (BaCO₃) as a secondary component. Combining these elements forms a hard, brittle material with magnetic properties suitable for various applications. Ferrites are corrosion-proof and are therefore used to increase the life cycle of many products. Ferrite magnets can be used in sweltering conditions (up to 300 degrees Celsius), and their manufacturing cost is low, especially in large volumes. Their classification can be further subdivided into “hard”, “semi-hard”, and “soft” ferrites depending on their magnetic properties. Since it is difficult to demagnetize hard ferrites, they have a high coercivity. They are used to make magnets for appliances and units, such as electric motors and loudspeakers.

The production of ferrite magnets involves a series of well-defined steps that ensure the creation of materials with desirable magnetic properties (Figure 3). These steps include preparing raw materials, mixing, pre-sintering, sintering, and finishing processes. Each step is crucial in determining the final quality and performance of the ferrite magnets.

The manufacturing process involves mixing iron oxide powder with the chosen carbonate material and pressing the mixture into the desired shape. The mixture is formed into small pellets. The pellets undergo an initial heating process to prepare them for further processing—additional drying and separation of the material into finer particles. The dried material is crushed into a fine powder. The material is initially broken down into coarser particles before the finer crushing stage, after which the material sinters at high temperatures (typically around 1200 °C or 2192 °F). This sintering process helps fuse the particles, creating a solid and magnetically active structure. The resulting ferrite magnet has a crystalline structure with aligned magnetic domains, contributing to its magnetic strength and stability. In some cases, machining is employed to achieve specific shapes or sizes. This step ensures precision and customization based on the intended application. The formed magnets undergo magnetization, exposing them to a strong magnetic field. This step aligns the magnetic domains within the material, enhancing its overall magnetic strength. Each batch of ferrite magnets undergoes rigorous testing to ensure they meet the required magnetic strength and other specified properties. Quality control includes a thorough inspection to check for defects, ensuring that only high-quality magnets move forward in production.

Recent advancements in sintering techniques for ferrite magnets have focused on reducing sintering time, lowering temperature, and minimizing energy consumption. Emerging methods, including microwave, flash, spark plasma, and hydrothermal sintering, offer faster and more efficient processes, often combining heating with pressure. These techniques have yielded promising results, yielding high densities and competitive magnetic properties for ferrite magnets. However, they remain largely experimental, primarily within laboratory settings [22,23].

Rare-earth magnets are made of rare-earth element alloys, which include 18 elements: scandium, yttrium, lanthanum, and lanthanides (cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, and vanadium). These elements are categorized into light rare-earth elements (LREEs) and heavy rare-earth elements (HREEs) based on their atomic numbers. Light rare-earth elements (LREEs) like lanthanum, cerium, praseodymium, Nd, samarium, and europium are primarily sourced from mineral concentrates of monazite and bastnaesite, with significant operations in countries like China, the USA, Australia, India, and Madagascar. Heavy rare-earth elements (HREEs) include gadolinium, terbium, Dy, holmium, erbium, thulium, ytterbium, and lutetium. They are mainly produced from ion-adsorption clays and xenotime mineralization, particularly in Southern China, Myanmar, and Australia [24]. There are two types of rare-earth magnets: samarium–cobalt and Nd magnets.

Samarium–cobalt magnets are made of alloys similar in composition to the intermetallic compounds SmCo₅ or Sm₂Co₁₇. SmCo₅ alloy is supplemented by copper, zirconium, gadolinium, and erbium, Sm₂Co₁₇ is not supplemented by additives. Magnets are manufactured using powder metallurgy methods, i.e., first, the powder is made by grinding the alloy, and then the obtained powder is pressed into the product with the simultaneous orientation of the particles in the magnetic field. Then, the parts get agglomerated into the product unit. The agglomerated magnets are finished using an abrasive tool to obtain the required dimensions. It is advisable to use SmCo magnets if necessary to have a minimum size and weight for the final products. This is most appropriate in spacecraft, aircraft, and computer equipment, minimum-size electric motors and magnetic couplings, and mobile devices and gadgets (watches, headphones, mobile phones, etc.).

Magnets made of rare-earth metal alloys with chemical composition Nd₂Fe₁₄B have the highest magnetic parameters of all industrial magnets, Figure 2. The remanence and coercivity of these magnets are significantly higher than those of similar magnets. NdFeB magnets composition includes rare-earth elements such as Nd and Dy. Due to their unique magnetic properties, Dy and Nd are essential in NdFeB magnets. Nd provides high magnetic strength, while Dy helps in maintaining the stability of the magnet’s properties at high temperatures. Combining these elements in NdFeB magnets results in a powerful and stable magnet, making them crucial for various applications like electric vehicles, wind turbines, and electronic devices requiring strong and reliable magnets. Figure 4 shows the production process of NdFeB PMs, detailing each stage from raw material preparation to final magnet shaping and quality control.

There are multiple methods for producing magnets, but the most widely used technique is known as powder metallurgy (PM). In this method, the appropriate material is ground into a fine powder and then compressed and heated to achieve densification through a process called “liquid phase sintering”.

The procedure begins with liquefying raw materials in an induction melting furnace under vacuum or inert conditions. The molten alloy can then be cast into molds, poured onto chill plates, or processed into a continuous strip. The resulting solidified fragments are crushed and ground into a fine powder with particles sized between 3 and 7 microns; they are highly reactive and can ignite in oxygen, requiring precautions against exposure. Compaction techniques align particles for optimal magnetic domain orientation, with isostatic pressing being a key method. This involves sealing the powder in a pliable container, applying uniform pressure through a fluid medium, and placing it in an isostatic press to create large magnet blocks. After compaction, the components are sintered in a vacuum furnace, followed by cooling to achieve the desired magnetic properties. Machining operations refine the magnets to precise dimensions and finishes, employing diamond wheels for grinding and slicing due to the material’s brittleness. For complex shapes, shaped diamond grinding wheels or Electrical Discharge Machining (EDM) are used. Cylindrical parts can be pressed or core-drilled, and thin washer-shaped magnets are produced for motors, sensors, and electronic devices.

Machined magnets often have sharp edges that can chip, making coatings difficult to apply. Vibratory honing is the main method to round these edges, with radii typically between 0.005 and 0.015 inch. Nd magnets require coatings due to their susceptibility to rust, while samarium cobalt is more corrosion-resistant but also benefits from coatings. Common protective coatings include dry-sprayed epoxy; e-coat; electrolytic nickel; and various conversion coatings, like zinc and manganese phosphates. After manufacturing, magnets must be “charged” to create a magnetic field, which can be achieved using solenoids or specialized fixtures. Large assemblies can also be magnetized to simplify handling.

Magnesium-based magnets are an emerging area of research, focusing on developing materials with unique magnetic and dielectric properties. These materials are being explored for various applications, including electronic devices and biomedical fields. Manganese–aluminum–carbon (MnAlC) alloys are emerging as promising candidates for rare-earth-free PMs, offering a potential alternative to traditional magnets, like NdFeB and ferrites. The MnAl compound, particularly in its metastable τ-phase, exhibits ferromagnetic properties with a high coercivity and a maximum energy density of 55.7 kJ/m³, making it suitable for applications in electrical machines [26]. The τ-phase is achieved through quenching and annealing processes, with carbon additions enhancing its stability by preventing decomposition into non-magnetic phases. MnAlC magnets are characterized by their low cost due to the abundance of raw materials and good corrosion resistance, with a density ranging between 5000 and 5100 kg/m³, which is advantageous for reducing the weight of magnetic components in applications [27,28] Despite these benefits, the experimental energy products of MnAlC are currently below the theoretical values due to microstructural challenges, necessitating further research to optimize their performance. The synthesis of MnAlC involves various methods, including hot compaction; spark plasma sintering; and novel powder techniques, like flash milling, which aim to improve the magnetic properties by controlling grain size and phase purity. The environmental and social impacts of MnAlC production are also favorable compared to rare-earth magnets, as they avoid the risks associated with rare-earth mining and processing. Regarding chemical stability, MnAlC magnets exhibit varying leachability of their constituent elements, with differences in Mn and Al concentrations observed in aqueous leachates, which could be attributed to the inherent characteristics of the materials used in their manufacture [29]. Simulations have demonstrated MnAlC’s potential to replace ferrite magnets in certain applications, suggesting that MnAlC could offer a reduced-weight alternative while maintaining performance. However, further work is needed to align simulation assumptions with real-world conditions. Overall, MnAlC alloys represent a significant step toward sustainable and efficient magnetic materials, with ongoing research focused on overcoming limitations and enhancing their applicability in various technological fields.

The initial step involves smelting Mn, Al, and C to form an alloy, typically using vacuum induction or arc melting methods. This process results in the formation of an ingot, which is often cast into rods for further processing. The alloy initially forms in the ε-phase, which is non-magnetic. To achieve the desired ferromagnetic τ-phase, the ε-phase must be transformed through controlled annealing. This involves heating the alloy to specific temperatures (e.g., 550 °C) for a set duration to promote the phase transition.

Mechanical milling and compaction: The alloy can be mechanically milled to produce fine powders, which are then compacted under high pressure. This process enhances the material’s coercivity by reducing grain size and promoting a more uniform microstructure.

Hot-pressing and extrusion: Techniques such as hot-pressing and hot-extrusion are employed to densify the material and improve its mechanical properties. These methods also help align the magnetic domains, as doing so is crucial for achieving high anisotropy and coercivity.

Annealing and tempering: Post-processing heat treatments, such as annealing and tempering, are essential to stabilize the τ-phase and eliminate secondary phases that can degrade magnetic performance. These treatments also help achieve high saturation magnetization and coercivity.

Magnetic field orientation: Applying a magnetic field during processing can enhance the material’s anisotropy, leading to improved magnetic properties. This step is crucial for achieving high remanence and coercivity in the final magnet.

Additive manufacturing: Recent advancements include the use of additive manufacturing techniques, such as laser powder bed fusion, to produce MnAlC magnets. This method allows for precise microstructure and phase composition control; however, challenges remain in achieving strong preferential orientation in the τ-phase.

Hydrolysis and decrepitation: Innovative approaches like targeted hydrolysis and decrepitation of Mn₃AlC precipitates offer novel pathways for precursor preparation, potentially enhancing the texture and magnetic properties of the final product.

While the production of MnAlC magnets involves well-defined stages, each step presents unique challenges that must be addressed to optimize the magnetic properties. The transition from ε-phase to τ-phase is particularly critical, requiring precise control over temperature and pressure conditions. Additionally, mechanical processing techniques such as milling and compaction play a significant role in enhancing coercivity and anisotropy. Despite these challenges, ongoing research and technological advancements continue to improve the efficiency and effectiveness of MnAlC magnet production, making it a promising alternative to rare-earth-based magnets.

In this study, an attributional Life Cycle Assessment (LCA) methodology is applied to evaluate and compare the environmental impacts associated with different types of PMs: NdFeB (neodymium–iron–boron), ferrite, and MnAlC (manganese–aluminum–carbon) magnets. The goal is to understand the environmental implications of producing these magnets from virgin materials, considering the entire life cycle, from raw material extraction to manufacturing.

3. Comprehensive LCA Methodology Utilizing OpenLCA for Magnet Sustainability Analysis

Life Cycle Assessment (LCA) represents a rigorous methodological framework employed to quantitatively assess the environmental ramifications associated with a product’s life cycle—ranging from the extraction of raw materials through manufacturing and transportation to usage, end-of-life treatment, and disposal. This comprehensive methodology facilitates the identification of potential environmental hotspots while assisting in formulating informed strategies to mitigate emissions, enhancing resource efficiency, and reducing overall ecological footprints. International standards conduct LCA, predominantly the ISO 14040 and ISO 14044, which delineate the principles and protocols requisite for executing an LCA. These standards are instrumental in ensuring LCA investigations maintain transparency, reproducibility, and coherence with global practices. In this section, we concentrate on using OpenLCA software [30] to execute an LCA on PMs, with particular emphasis on the sustainability profiles of conventional NdFeB, ferrite magnets, and innovative Mn−Al−C magnets. OpenLCA facilitates the application of diverse impact assessment methodologies, notably the Environmental Footprint (EF) 3.0 method [31], which the European Commission has endorsed for evaluating product environmental footprints. The principal objective of this investigation is to assess and juxtapose the environmental consequences of traditional NdFeB, ferrite magnets, and Mn−Al−C magnets utilizing OpenLCA software 2.3.1. The scope of this assessment encompasses the entire life cycle of these magnets, from the extraction of raw materials to their ultimate disposal at their end-of-life stage.

Key aspects of the scope definition include the following:

• System boundaries: The study covers cradle-to-gate boundaries, encompassing all stages from material extraction to production.
• Functional unit: Two functional units are defined to ensure a comprehensive comparison between magnet types: 1 kg of magnet material, providing a mass-based standard, and 1 kJ/m³ of maximum energy product, offering an energy density perspective to assess performance in applications requiring high energy output. (

  Table 1. The functional unit of permanent magnets.

  Parameter	Functional Unit
  Maximum energy product	1 kJ/m3 of maximum energy product
  Mass	1 kg of a NdFeB magnet

  ) [32].

• Impact categories: The Environmental Footprint (EF) 3.0 method is used to evaluate a comprehensive set of impact categories, including climate change, resource depletion, human toxicity, and more.
• Data resources: The study utilized the Idemat 2023, ecoinvent 3.8 cut-off, and eco-costs 2023 [33] databases as primary data sources. These databases provided comprehensive information on raw material extraction, energy consumption during production processes, emissions, and other environmental impacts. Information about the magnet production process and data sources was based on scientific works [34,35] and additional resources. This study adopts the cradle-to-gate approach in the LCA methodology. This approach focuses on the life cycle phases from raw material extraction through material processing and manufacturing until the product exits the manufacturing facility. This approach is particularly useful for understanding the environmental impacts associated with the early stages of the product’s life cycle, as such stages often represent significant portions of its overall environmental footprint.

The inventory analysis phase collects data on the inputs (e.g., energy and raw materials) and outputs (e.g., emissions and waste) for each magnet’s life cycle stage.

OpenLCA’s EF 3.0 implementation allows for standardized and detailed analysis of impacts across multiple categories, ensuring alignment with European Commission guidelines (

Table 2. Set of impact categories included in the EF3.0 method.

Impact Category	Units
Acidification	Mole H⁺ eq.
Climate change—total	kg CO2 eq.
Ecotoxicity, fresh water—total	CTUe
Eutrophication—fresh water, marine	kg P eq., kg N eq.
Eutrophication—terrestrial	Mole N eq.
Human toxicity, cancer—total	CTUh
Human toxicity, non-cancer—total	CTUh
Ionizing radiation, human health	kBq U235
Land use	Pt
Ozone depletion	kg CFC-11 eq.
Particulate matter	Disease incidences
Photochemical ozone formation, human health	kg NMVOC eq.
Resource use, fossils	MJ
Resource use, minerals, and metals	kg Sb eq.
Water use	m3

).

The interpretation phase in OpenLCA involves analyzing the impact assessment results to draw conclusions and make recommendations. This includes identifying environmental hotspots; comparing the performance of NdFeB, ferrite, and Mn−Al−C magnets; and suggesting areas for improvement.

This section presents a case study of an LCA conducted using OpenLCA for NdFeb, ferrite and Mn−Al−C magnets. The study follows the methodology outlined above and provides a detailed comparison of the environmental performance of these magnet types.

The results of the classification and characterization steps in the LCA allow us to assess the environmental impact associated with the production of NdFeB, ferrite, and MnAlC magnets across three key categories: environmental conservation, resource depletion, and human health. These assessments are based on a functional unit of 1 kg mass of product, as shown in Figure 5.

NdFeB is the predominant contributor to acidification, associated with the emission of sulfur oxides and nitrogen oxides, primarily from industrial activities and energy generation. The elevated acidification potential of this material may signify more significant emissions throughout its life cycle, thereby exacerbating the acidification of soil and water resources. Conversely, ferrite exhibits a considerably reduced impact, indicating its potential as a more environmentally sustainable option for mitigating acid rain and the consequent ecological harm. MnAlC occupies an intermediary position between these two materials, demonstrating moderate impacts on acidification. The climate change potential, quantified in kilograms of CO₂ equivalents, elucidates the greenhouse gas emissions associated with each material’s life cycle. NdFeB, characterized by the most substantial climate change impact, is the most carbon-intensive, presumably due to its energy-demanding production processes, including extracting and refining rare-earth elements. Ecotoxicity in fresh water assesses the potential detrimental effects on aquatic ecosystems arising from toxic substances released throughout the life cycle of the material. The elevated ecotoxicity value of NdFeB indicates significant hazards to freshwater biota, potentially attributable to toxic chemicals or heavy metals utilized in manufacturing this magnetic substance. Ferrite and MnAlC present a comparatively lower ecotoxicity profile; however, both still pose considerable risks. Freshwater eutrophication, frequently instigated by excessive phosphorus inputs, results in algal blooms, which can deteriorate water quality and biodiversity. NdFeB exhibits a more significant eutrophication potential than the alternative materials, while ferrite shows a markedly lower impact, suggesting a reduced introduction of nutrient pollutants into freshwater ecosystems. Marine eutrophication is predominantly influenced by nitrogen, which contributes to forming dead zones in marine environments by fostering excessive algal proliferation. In this context, NdFeB demonstrates the highest potential for marine eutrophication, significantly surpassing ferrite and MnAlC values. This suggests that NdFeB may be responsible for more extensive marine ecosystem degradation. Terrestrial eutrophication, driven by nitrogen deposition on terrestrial ecosystems, can disrupt natural habitats, facilitating the proliferation of invasive species to the detriment of native biodiversity. Once again, NdFeB contributes most significantly to this impact category, indicating a potential threat to terrestrial ecosystems. With the least values, ferrite represents a reduced risk to land-based environments. MnAlC exhibits a moderate eutrophication potential, positioning it between the abovementioned materials. NdFeB has the highest ozone depletion potential, indicating significant environmental impact due to energy-intensive manufacturing processes.

Neodymium–iron–boron (NdFeB) exhibits the most pronounced impact in the land-use category, necessitating substantial land for its extraction and production processes. Conversely, ferrite demonstrates the lowest land requirement, suggesting a preferential stance toward environmental sustainability. Manganese–aluminum–cobalt (MnAlC) occupies an intermediary position, demanding fewer land resources than NdFeB, yet more than ferrite. Use of fossil resources: NdFeB also ranks as the most resource-demanding in terms of fossil fuel utilization, indicating a pronounced energy resource dependency. Ferrite, by contrast, exhibits the minimal impact within this category, rendering it a more environmentally sustainable alternative. Once again, MnAlC occupies a middle ground, reflecting a moderate consumption of fossil resources. Use of mineral resources and metals: In the realm of mineral resources and metals utilization, NdFeB remains at the apex of impact, necessitating a greater quantity of rare-earth elements and other metals within its production chain. Ferrite, conversely, has a lower demand for these resources, thereby demonstrating reduced dependency on mineral inputs. MnAlC, situated centrally, requires fewer mineral resources than NdFeB but more than ferrite. Water consumption: NdFeB also manifests a high level of water consumption, indicating its considerable impact on water resources. Ferrite is characterized as the most environmentally benign material in this domain, necessitating a minimal volume of water for its production. Similarly, MnAlC reveals intermediate consumption metrics, as observed in the preceding categories.

The potential detriment to human health, particularly concerning carcinogenic risks, is attributable to toxic substances emitted throughout the material’s life cycle. MnAlC and NdFeB demonstrate elevated levels of cancer-related toxicity, with MnAlC marginally surpassing NdFeB in this regard. In contrast, ferrite exhibits significantly reduced toxicity concerning cancer, suggesting its potential as a safer alternative in contexts where exposure to carcinogenic substances poses a risk. The potential for non-cancer human toxicity assesses the hazards to human health presented by substances that inflict damage without inducing cancer (e.g., respiratory ailments and organ dysfunction). Once again, NdFeB registers the highest toxicity value, succeeded by MnAlC. Ferrite, possessing the lowest non-cancer toxicity, indicates its comparatively minimal harm to human health concerning non-carcinogenic effects. This category evaluates the consequences associated with ionizing radiation, frequently linked to energy production (notably nuclear energy) and material processing. NdFeB exhibits the most significant impact from ionizing radiation, potentially attributable to the energy-intensive methods employed in its production, particularly the extraction and refinement of rare-earth elements. Following this, MnAlC presents a moderate radiation impact. At the same time, ferrite is characterized by the lowest values, implying it may entail diminished exposure to radioactive materials or energy sources within its production cycle. Particulate matter plays a role in air pollution, correlated with respiratory and cardiovascular diseases. NdFeB again registers the highest impact from particulate matter, with MnAlC following closely. Photochemical ozone formation pertains to generating ground-level ozone, a deleterious air pollutant, through reactions between nitrogen oxides (NOx) and volatile organic compounds (VOCs) in sunlight.

NdFeB magnets offer superior magnetic performance; their production is associated with significant environmental impacts and complex processing requirements. BaO·6Fe₂O₃, on the other hand, provides a more environmentally friendly alternative with adequate magnetic properties for specific applications. MnAlC represents a cost-effective option with moderate performance. The choice between these materials depends on the specific application requirements, balancing performance, cost, and environmental considerations.

Figure 6 illustrates the assessments based on a functional unit of 1 kJ/m³ of maximum energy product. These assessments pertain to the production of NdFeB, ferrite, and MnAlC magnets and are categorized across three key dimensions: environmental conservation, resource depletion, and human health.

NdFeB exhibits moderate acidification potential and is the most carbon-intensive material, contributing significantly to climate change and nutrient pollution, particularly in eutrophication. It has the lowest ecotoxicity impact, indicating less risk to freshwater organisms, and shows the least ozone depletion potential. Human toxicity is moderate, with notable cancer-related risks, while its particulate matter emissions are moderate. NdFeB requires less land but has high mineral and water demands, making it less sustainable in water use.

Ferrite is the least impactful for acidification and has a lower carbon footprint than NdFeB, but it poses the highest ecotoxicity risk to freshwater environments. It has the highest ozone depletion potential and the highest non-cancer toxicity, while showing the lowest ionizing radiation impact. Ferrite requires the most land but has the lowest water use, indicating better sustainability in water conservation.

MnAlC presents the highest acidification potential and a moderate climate change impact, with high ecotoxicity but lower than that of ferrite. It has the lowest eutrophication potential, making it suitable for nutrient-sensitive applications. MnAlC has the highest cancer-related toxicity and significant particulate matter emissions, indicating health risks. It has moderate resource demands and water use, requiring more land than ferrite but less than itself.

Figure 6 illustrates the assessments based on a functional unit of 1 kJ/m³ of maxi-mum energy product. These assessments pertain to the production of NdFeB, ferrite, and MnAlC magnets and are categorized across three key dimensions: environmental conser-vation, resource depletion, and human health.

4. Summary of Findings and Future Directions

The decreasing reliance on rare-earth magnets in industrial applications poses a formidable challenge, primarily driven by the prohibitive costs and the significant environmental repercussions of their extraction and processing. PMs are integral to the functionality of electric motor systems and power generation technologies, playing a crucial role in their efficiency and effectiveness [2]. The core properties of PMs, notably coercivity and permanent magnetization, are intricately tied to their microstructural characteristics. A thorough grasp of the metallurgical processes involved, alongside an understanding of phase stability and microstructural changes, is essential for the innovative design and enhancement of PMs. This knowledge allows for the optimization of magnet performance in various applications. The widespread adoption of PM in traction motors for electric vehicles and in wind energy systems is mainly due to the inclusion of rare-earth elements such as Nd and Dy, which are prized for their exceptional maximum energy product. Dy is crucial for maintaining the coercivity of NdFeB magnets, especially under high-temperature conditions, ensuring that these magnets retain their performance standards. However, the substantial supply risks associated with rare-earth elements—especially Dy and Nd—have led several international organizations to classify these materials as critical. This classification underscores the urgency of addressing supply chain vulnerabilities and the need for sustainable alternatives [28]. In response to these challenges, many strategies have been developed to alleviate dependence on rare-earth elements. These strategies encompass exploring alternative machine designs, advancements in materials science, and innovative recycling methodologies. Such approaches aim to sustain or enhance productivity while reducing reliance on rare-earth elements, fostering a more sustainable industrial ecosystem. By leveraging these strategies, the industry can work toward a future where the performance of PMs is not solely contingent upon the availability of rare-earth materials.

The superior magnetic performance of NdFeB magnets is fundamentally tied to the atomic structure of rare-earth elements, such as neodymium and dysprosium. The high magnetic anisotropy of these elements enables the alignment of magnetic domains, which is essential for maintaining coercivity and magnetization. Dysprosium’s ability to stabilize the structure at elevated temperatures by increasing the energy barrier for domain wall movement highlights the physical mechanisms underlying its importance in high-temperature applications. This atomic-level interaction is a key reason for the current reliance on rare-earth elements in PMs, despite their supply chain and environmental challenges. Alternative designs of electrical machines are persistently pursued to attain an elevated level of efficiency while concurrently minimizing the reliance on PMs. The advancement of variable-flux flux-intensifying interior PM machines (VFI-IPMs) characterized by variable and intensified magnetic flux represents a promising strategy [36].

Implementing partial segmentation techniques for magnets and rotor clamps diminishes eddy current losses, reducing the required magnetic material. Although this methodology presents inherent complexities, it enhances machine productivity and mitigates reliance on rare-earth elements.

Recycling technologies for NdFeB magnets are crucial for addressing the increasing demand for rare-earth elements (REEs) and reducing environmental impact. Various methods have been developed to recycle these magnets, each with its advantages and challenges. Understanding the microstructural evolution during recycling—particularly in processes like hydrogen decrepitation—is critical for retaining magnetic properties. For example, during the Hydrogen Processing of Magnet Scrap (HPMS), hydrogen atoms penetrate grain boundaries, weakening intergranular cohesion and facilitating the mechanical breakdown of the magnet into powder. This ensures minimal degradation of the original microstructure, allowing recycled magnets to retain comparable coercivity and energy product properties. The Hydrogen Processing of Magnet Scrap (HPMS) is a notable method for recycling NdFeB magnets [37]. This process involves hydrogen decrepitation, which breaks down the magnets into powder form, facilitating the separation of REEs from other materials. The HPMS process is effective at room temperature and under low hydrogen pressure, making it commercially viable. It has been successfully applied to magnets from loudspeakers, yielding recycled magnets with comparable magnetic properties to the original ones [37].

High-pressure selective leaching is another effective method for recycling NdFeB magnets. This technique uses low-concentration nitric acid to separate REEs from iron, achieving over 95% leaching efficiency for REEs while minimizing iron dissolution. The process also allows for removing impurities like aluminum and boron, making it suitable for closed-loop recycling and remanufacturing of PMs. A mechanochemical approach involving grinding, roasting, and water leaching has shown high efficiency in recovering REEs, cobalt, and boron from spent NdFeB magnets. This method completely separates these elements, offering a green and efficient recycling process [38].

Pyrometallurgical and hydrometallurgical methods are traditional techniques for recovering REEs from NdFeB magnets [39]. Due to their simplicity and effectiveness, these methods are well-suited for industrial-scale applications. However, they often involve high energy consumption and environmental risks, which must be addressed [40].

While these recycling technologies offer promising solutions for recovering valuable elements from NdFeB magnets, challenges remain regarding scalability, cost, and environmental impact. Developing hybrid processes that combine the strengths of different methods could address these issues, leading to more sustainable and efficient recycling practices. Additionally, establishing a closed-loop system within regions like the European Union could reduce import dependency and enhance supply chain security.

The optimization of rotor configurations in machines equipped with Interior PM Machine (IPMM) enables the reduction of materials that incorporate PMs. This process entails modifying particle width and pole arc dimensions to diminish the spatial harmonics of the particulate flow, thereby decreasing the reliance on rare-earth materials while preserving operational efficacy [41].

V-shaped magnet arrangement: In the context of electric vehicles, implementing a V-shaped magnet configuration within IPM engines can markedly diminish the requisite quantity of NdFeB magnets. This architectural innovation enhances the magnetic circuit by amplifying drag torque, consequently lessening the dependence on rare-earth materials [41]. Improved rotor structures: Innovative rotor architectures in PM synchronous motors (PMSMs) have been conceived to curtail the consumption of rare-earth magnets substantially. These configurations can achieve torque performance comparable to conventional models while facilitating a reduction in rare-earth magnet volume of up to 57.5% [42].

While the strategies above present encouraging prospects for diminishing the dependency on rare-earth magnets, it is imperative to evaluate potential trade-offs. For instance, implementing alternative materials and design approaches may mitigate reliance on rare-earth elements; however, such alternatives may introduce new challenges, including heightened production intricacy or a possible decrease in overall productivity.

5. Conclusions

The study demonstrated using the Life Cycle Assessment (LCA) approach with cradle-to-gate boundaries, covering all stages from raw material extraction to producing permanent magnets. Including two functional units—1 kg of magnetic material and 1 kJ/m³ of maximum energy product—enabled a comprehensive comparison between different magnets. This approach highlighted the importance of considering energy density when evaluating the efficiency of magnets in high-performance applications. The Environmental Footprint (EF) 3.0 methodology assessed impact categories, including climate change, resource depletion, and human toxicity. Modern databases provide accurate data on raw material extraction, energy consumption, and the environmental consequences of production processes. Based on scientific publications and additional resources, these data allowed for the creation of a reliable and comprehensive Life Cycle Assessment of magnets. This study introduced approaches to conducting LCA for permanent magnets, including new functional units and analytical methods that enable more precise environmental-impact data. For the first time, it was shown how choosing a functional unit can significantly alter the perception of the environmental efficiency of materials such as NdFeB magnets compared to ferrites and MnAlC.

Life Cycle Assessment (LCA) faces many challenges and limitations that can significantly affect the accuracy and reliability of its results. These problems arise from various aspects of the LCA procedure, including data quality, the choice of methodological approaches, and the complexity of the systems under study. PMS must have accurate data about the supply chain, as well as mining, processing, and production methods. These processes are usually complex and multi-stage, so the lack of comprehensive data can lead to a distorted environmental impact assessment. Clearly defining the objectives and scope of the LCA is paramount; decisions to include and exclude processes and setting boundaries can significantly affect the representativeness and significance of an assessment. The definition of functional units and the distribution of influence between by-products are important methodological tasks that may reduce the accuracy of LCA results. These critical decisions play a fundamental role in establishing the comparability and reliability of the assessment. The selection of the functional unit in Life Cycle Assessment (LCA) significantly influences the evaluation of environmental and health impacts. It should be noted that when using a different functional unit—energy density (1 kJ/m³)—Nd magnets no longer show such a significant difference from ferrite and MnAlC in impact indicators as they do with the mass-based functional unit (1 kg). This suggests that less material is required to achieve the same energy output, highlighting the efficiency of Nd magnets in applications where a high energy density is essential. Methodologies that reduce the use of rare-earth magnets face difficulties, such as the complexity of separating magnets and the need to evaluate alternative materials. Exploring new deposits of rare-earth elements is also important to ensure reliable supplies. Despite progress in reducing dependence on rare-earth magnets, further research and development is needed, including creating new strategies for designing electromechanical systems and using adaptive control algorithms. Investments in research and interdisciplinary collaboration are critical to achieving a balance between technological progress and environmental protection. The integration of renewable energy sources can contribute to the circular economy. The studying of non-rare-earth PMs and alternative magnetic systems, such as manganese-based alloys, is also becoming relevant for reducing dependence on rare-earth materials. These innovations can lead to cost-effective solutions that are in line with sustainable development goals, as well as to the creation of sustainable supply chains and new technologies for the transition to clean energy sources. The development of such technologies requires the active participation of scientific and industrial communities, which will accelerate the introduction of effective solutions on the market, ensure long-term sustainability, and mitigate some of the negative effects with NdFeB, making it a more sustainable option in the long run.