Table of Contents
Introduction
Modern renewable energy systems depend on a wide range of materials. Some of these are common, such as steel, concrete, glass, and aluminum. Others are far less common and are often called critical minerals. As the world expands solar, wind, batteries, and electric vehicles, the demand for these materials is increasing quickly. Understanding how materials are used in renewable technologies, and why some minerals are considered critical, is essential for assessing the true sustainability of the energy transition.
This chapter focuses on the specific link between renewable energy technologies, their material needs, and the concept of critical minerals. It connects to life cycle and environmental assessment, but here the emphasis is on what materials are required, where they come from, and what risks and opportunities they create.
Materials In Renewable Energy Technologies
Every renewable technology has a characteristic material “fingerprint.” Solar photovoltaic panels, for instance, are mostly made of glass, aluminum frames, silicon or other semiconductor materials, polymers for encapsulation, and smaller amounts of metals like silver, copper, and tin for electrical contacts and wiring. Wind turbines use large amounts of steel in the towers and nacelles, fiberglass or carbon fiber reinforced plastics for blades, concrete in foundations, and sometimes specialized magnets in the generators.
Batteries for electric vehicles and grid storage rely heavily on metals such as lithium, cobalt, nickel, manganese, graphite, and sometimes phosphorus and iron. Hydropower facilities largely use concrete and steel, while power electronics, inverters, and control systems across all technologies rely on copper, aluminum, and various semiconductor materials. Cables that connect renewable plants to the grid are especially copper intensive.
Although many of these materials are abundant on a global scale, their extraction, processing, and refining are concentrated in a limited number of regions. This concentration, combined with rapid demand growth, is one of the main reasons some materials are labeled “critical.”
What Makes A Mineral “Critical”
The term “critical mineral” does not mean that a material is rare in nature. Instead, it is a policy and risk concept that combines two main dimensions: how important the material is for key technologies and how vulnerable its supply is.
A mineral is typically considered critical if it has high economic or strategic importance for technologies or sectors that a country or region sees as essential, such as clean energy, defense, or digital infrastructure, and if its supply faces significant risks due to limited production locations, unstable politics, challenging extraction or refining, long lead times to open new mines, or environmental and social constraints.
Many governments periodically publish lists of critical minerals that reflect their own industries, geology, and security concerns. While the exact lists differ, they often share a core group of minerals associated with clean energy technologies and digital systems.
A mineral is considered critical when it combines:
- High importance for key technologies or sectors, and
- High supply risk due to concentration, instability, or constraints in extraction, processing, or trade.
Key Critical Minerals For Renewable Energy
Several groups of minerals are particularly important for the renewable energy transition. Each plays distinct roles in technologies and comes with specific supply risks.
Rare earth elements, such as neodymium, praseodymium, dysprosium, and terbium, are used in high performance permanent magnets for wind turbine generators and electric motors. These magnets allow compact and efficient designs, especially in direct drive wind turbines and many electric vehicles. Although rare earths are not geologically rare, economically viable deposits and processing capabilities are heavily concentrated in a few countries, which raises supply security concerns.
Lithium, cobalt, nickel, and manganese are key ingredients in many modern lithium ion batteries for electric vehicles and stationary storage. Lithium is central to the battery chemistry. Cobalt improves stability and safety in some cathode formulations, while nickel and manganese influence energy density and cost. Global extraction of these metals has increased rapidly, but deposits and refining are again concentrated geographically, which makes supply sensitive to political and social conditions in those regions.
Graphite, both natural and synthetic, is widely used for battery anodes. Copper is critical for wiring, motors, transformers, and cabling, and is particularly important because electrification of transport and heating requires much more copper infrastructure. Silver and sometimes other precious or specialty metals are used in solar PV, particularly in cell contacts, although there is ongoing research to reduce and replace silver use.
Indium, gallium, selenium, tellurium, and cadmium are important for certain thin film solar cells and specialized semiconductors. While they are used in smaller volumes than bulk materials like steel, they can become bottlenecks because they are often byproducts of mining other metals, which limits the flexibility of their supply.
Supply Chains And Geographical Concentration
Critical mineral supply chains are long and complex. They usually involve exploration, mining, concentration of the ore, refining into pure metals or compounds, and finally manufacturing into components like magnets, battery materials, or wafers. Each step can be located in different countries. For several critical minerals, not only the mining but especially the refining and processing are highly concentrated in one or a few countries.
This concentration creates vulnerability for the renewable energy sector. Disruptions from political tensions, export restrictions, environmental incidents, labor disputes, or natural disasters in a limited set of regions can reverberate globally. Long lead times to develop new mines and refining facilities mean that supply cannot quickly adjust to demand surges, which can cause price spikes and uncertainty for project developers and manufacturers.
At the same time, new mining projects can encounter resistance or delays due to local environmental and social impacts. The result is a tension between the global goal of rapidly deploying renewables and the local realities of increased mineral extraction, often in communities that bear the environmental and social costs.
Environmental And Social Dimensions Of Critical Minerals
Mining and refining critical minerals can have significant environmental and social impacts. These impacts include land disturbance, habitat loss, water contamination, tailings management challenges, greenhouse gas emissions from energy intensive processing, and local air and water pollution. Rare earth processing, for example, often involves chemically intensive steps that generate waste streams requiring strict management.
Social issues can include labor rights violations, unsafe working conditions, conflict financing, and displacement of local communities or Indigenous peoples. In some documented cases, cobalt mining has involved child labor and informal, unsafe operations, which has prompted calls for more transparent and responsible supply chains.
These impacts link critical minerals directly to environmental assessment and life cycle thinking. Evaluating the sustainability of renewable technologies must account for the upstream extraction and processing stages, not only emissions during operation. Certification schemes, corporate due diligence, and regulatory requirements are increasingly used to trace mineral origins and improve practices, but implementation and enforcement remain uneven.
Material Intensity Of Renewable Technologies
The shift from fossil fuels to renewables changes the type of resources the energy system relies on. Fossil energy systems use large amounts of coal, oil, and gas, which are extracted and burned continuously. Renewable energy systems require large upfront material investments to build infrastructure, but once in place, they run on free natural flows like sun and wind.
This means that renewables are often more material intensive per unit of installed capacity than fossil fuel power plants. For example, a typical onshore wind turbine uses more steel and concrete per kilowatt of capacity than a gas plant, and offshore wind is even more material intensive due to foundations and offshore structures. Solar PV uses glass, aluminum, and other materials per square meter of panel.
However, when material use is expressed per unit of electricity produced over the entire lifetime of a plant, the picture can be more nuanced. High capacity factors and long lifetimes can spread the material input over many kilowatt hours. Proper comparison requires consistent life cycle metrics that relate material mass to useful energy output.
A common way to express material intensity is:
$$\text{Material intensity} = \frac{\text{Mass of material used over life}}{\text{Total energy generated over life}} \quad \left[\frac{\text{kg}}{\text{kWh}} \text{ or } \frac{\text{kg}}{\text{MWh}}\right]$$
This links material use directly to useful energy delivered.
Understanding material intensity helps identify where efficiency improvements, design changes, or substitution of less critical materials can have the greatest effect in reducing reliance on constrained resources.
Substitution And Technology Choices
Not all renewable technologies rely equally on the same critical minerals. This creates opportunities for substitution and strategic technology choices. For example, wind turbines can use permanent magnet generators that rely on rare earths, or they can use electrically excited generators that do not. The latter design may be slightly larger or have different performance characteristics, but it reduces dependence on rare earth elements.
Battery technologies are evolving in ways that change critical mineral demand. Some modern lithium ion chemistries use less or no cobalt and reduced nickel, such as lithium iron phosphate (LFP) batteries. These reduce reliance on certain critical minerals, though they may have trade offs in energy density or temperature performance. Research into sodium ion, solid state, and other battery chemistries aims to further diversify material needs.
Solar PV has already shifted over time, with changes in wafer thickness, cell efficiency, and metallization techniques that decrease silver use per watt. Alternative contact materials, improved recycling of production scrap, and development of new cell architectures can further reduce critical metal intensity.
Substitution is not always straightforward, since new materials can introduce other environmental or supply risks. A careful life cycle perspective is needed when shifting from one material to another, so that problems are not simply moved from one place to another.
Recycling And Circular Approaches
As installed capacity grows, end of life solar panels, wind turbine components, and batteries will represent a large secondary resource of metals and materials. Recycling is a central strategy to reduce pressure on primary mining for critical minerals, especially over the medium and long term.
Currently, recycling rates for some critical minerals are still low, particularly for rare earth elements and certain battery metals. Technical challenges, dispersed product designs, economic factors, and lack of collection systems limit recovery. However, policy and technology developments are starting to improve this situation, particularly for lithium ion batteries, where recovering cobalt, nickel, lithium, and other materials can become a significant secondary supply source.
Designing products for disassembly, using standardized components, and improving labeling and traceability can increase recycling efficiency. Extended producer responsibility schemes can require manufacturers to take back and manage products at their end of life, encouraging the creation of closed loop material cycles where possible.
Although recycling cannot immediately replace primary mining, over time it can help stabilize supply, reduce environmental impacts, and support a more circular use of critical minerals in the energy system.
Strategies For Reducing Critical Mineral Risks
Several complementary strategies can reduce the risks associated with critical minerals for renewable energy. Diversifying supply sources, both geographically and across multiple suppliers, can limit vulnerability to disruptions in any single region. Investing in exploration, responsible mining, and refining capacity in more locations can support this diversification.
Improving material efficiency, by reducing the quantity of critical minerals used per unit of capacity or per kilowatt hour, directly lowers demand growth. This can be achieved through better design, higher efficiency, thinner wafers or films, and more effective use of materials in manufacturing.
Encouraging innovation in alternative technologies and chemistries can shift demand away from the most constrained minerals, while maintaining or improving performance. At the same time, strengthening environmental and social standards in mining and processing, supported by transparent reporting and certification, can improve conditions in existing supply chains.
Finally, integrating recycling and circular economy principles into policy and industry practice helps gradually build a secondary supply base, which in the long term becomes increasingly important as installed renewable capacity matures and reaches the end of its operating life.
Conclusion
Material use and critical minerals are central issues for the sustainability and resilience of the renewable energy transition. Renewable technologies rely on a mix of common and specialized materials, some of which face significant supply risks due to geographic concentration, complex processing, and environmental and social challenges in extraction.
By understanding which minerals are critical, how they are used in different technologies, and where their supply chains are vulnerable, decision makers and practitioners can better plan technology choices, policy measures, and innovation priorities. Combined with life cycle thinking, strategies such as material efficiency, substitution, diversification of supply, and recycling can help ensure that the shift to renewables not only reduces greenhouse gas emissions but also manages material use in a responsible and equitable way.