Wind energy for dummies
Part 3: (Rare) Materials and the road ahead
Introduction
In part 1 and 2, we have discussed several technical aspects of wind turbines. In this article we will focus on a more “boring” subject: materials.
Physical flow constraint is an overlooked topic in public discussion. Most people prefer talking about the shiny new technologies that will save us from climate change, but few ask the important question: Do we have enough physical resources to build that future ?
Recent geopolitical events show that securing a reliable supply of materials is getting harder and harder. This is even truer with the renewable sector as it depends on rare earth elements (REE), which are concentrated in few countries, notably China.
Market status & the road ahead
In 2021, 93.6 GW of wind energy has been added globally, only 1.8% lower than the 2020 record. This brings global wind power capacity to 837 GW for a year-over-year growth of 12%.
Despite two years of good numbers, the current rate of wind growth is simply not rapid enough to allow the world to reach its Paris Agreement targets.
Zooming in Europe, only 17 GW is inserted into the grid last year. This is not even half of what the EU should be building to be on track to deliver its 2030 Climate and Energy goals.
If we want to catch up with our targets of around 3000 GW of wind energy in 2030 and 6000 GW in 2050, there will be A LOT of wind turbines to be built in the next three decades.
The first step to appreciate the scale of this ambition is to understand what it takes to build one turbine.
Anatomy of a wind turbine
Technology
Based on the generator type, there are three main families of wind turbine:
- Gear box: the traditional design with electromagnet generators.
- Direct drive: a lighter design thanks to permanent magnet generators.
- Hybrid: gear boxes with small permanent magnets.
Around 30% of the wind turbines installed in 2020 used direct or hybrid drive generators. This number is expected to increase to 50% globally by 2025. The reason being they are ideal for offshore installation given their weight advantage compared to gear box models.
In the scope of this article, what interests us most is the presence of permanent magnet generators, the main consumers of REE in a turbine. As these generators are employed in the blooming direct and hybrid-drive models, there will be more and more of them in the future.
Materials and Material Intensity
Materials for a wind turbine can be classified into two types:
- The structural materials are those used to build the main structural components of a wind turbine: the foundation, the tower and the nacelle. This includes concrete, steel, zinc, copper, etc.
- The technology-specific materials are mainly the REE used for the permanent magnets (in direct or hybrid-drive generators). This includes dysprosium, neodymium, praseodymium, terbium and boron.
Side note: the term “rare earth elements” usually made me think that there was only a tiny tiny quantity of them in each turbine (like the quantity of gold that can be found in a computer). This is not really the case because of the hugeness of a turbine. On average, a permanent magnet weighs up to 4 tonnes and contains 28.5% neodymium, 4.4% dysprosium, 1% boron and 66% iron. This means there is ~1 tonne of neodymium per turbine, quite a lot).
While structural materials represents more than two-third of the total mass, they have a fairly global production supply chains. The principal supply risk lies in the technology-specific materials.
The above numbers reflect the current state of wind technology. To reason about the future trend of material usage, we employ the notion of material intensity: the mass of material per unit of installed capacity.
Concerning the future evolution of material intensity in 2050, structural materials are expected to stay at this level, or with just a slight decline of 10–20%.
For technology-specific materials, it depends on the future mix of turbine technology and the scientific advancement, but it’s possible that the material intensity of REE will be half of the current value. In others words, we will use less of them in the future to produce the same unit of energy as of today.
What does it mean for material demands ?
General trends
We need to emphasise that long-term projections about the future mix of wind technologies and estimated growth are challenging because of several uncertainty factors: the evolution of the energy system, the material intensity for different technologies, the material efficiency and innovation speed.
For offshore environments, despite the fact that permanent magnets are expensive and REE intensive, they are still the necessary choice going forward. According to the World Bank, by 2050 offshore wind capacity will mostly (75%) rely on direct-drive generators.
For onshore installation, increasing concerns regarding the stability of REE supply sources will result in the use of either conventional electromagnets or ferrite permanent magnets without rare earths.
Different scenarios of REE demand
In [1], they lay out the following scenarios:
- Low-demand scenario (LDS): an uptake of offshore high-temperature superconductor generators replacing permanent magnets and thus reducing the needs of REE. Note that this new technology is still currently in R&D phase.
- Medium-demand scenario (MDS): a high penetration of generators with permanent magnets in the offshore sector and, to a lesser extent, in the onshore sector.
- High-demand scenario (HDS): extrapolation based on the current state of technology mix.
For each of the scenario, they run simulations to estimate the material demands based on various factors discussed above: the potential mix of technology, the material intensity, the annual installation rate etc.
The following graph reports the estimated yearly demand of the main REE in 2030 and 2050 as a ratio of the current global supply.
In the high-demand scenario, almost all REE demands will surpass the current global supply capacity. This is definitely bad news.
In the others two scenarios, the estimated demands are much lower. However, even in a reasonable medium-demand scenario, the deployment of the necessary number of turbines may require up to half of the current global supply of REE. This paints a worrying picture if we think about all others technologies for the energy transition that also require REE (solar PV, electric cars, batteries…).
Conclusion
To meet the ambitious climate goals established at EU and at global level, the power generation capacity of wind systems will have to increase rapidly in all possible scenarios. This mass deployment of new power plants will lead to an increased need for components and raw materials, especially REE.
In the medium or high-demand scenario, the roll-out of this plan will require in 2050 anywhere from half to all of the neodymium, praseodymium, dysprosium and terbium currently available globally.
Given that those REE are also necessary for other clean technologies, a strong pressure on supplies is expected in the future. This entails two important observations:
- There will be new mineral mines to be built. Given that we have almost exhausted the “easy” resources, we will have to dig deeper and deeper into the soil to extract lower and lower quality minerals. This entails a huge impact on the environment and creates a vicious cycle: we need these resources for the green technologies, but by extracting them we will worsen the environmental situation. For french speakers, I highly recommend this excellent talk by Aurore Stephant on this complex topic.
- The above problem with resource scarcity leads to an even more complex (and sensitive) topic: sobriety. It deserves an article on itself, but the main point is that we won’t probably be able to reach climate goals without a well-planned reduction in energy consumption. We get into this sad position because of our patterns of overconsumption/overproduction, and we simply don’t have enough natural resource to just, again, produce stuffs to solve these problems.
Electric cars or wind turbines, we gonna need to choose.
Reference
[1] Carrara, Samuel, et al. “Raw materials demand for wind and solar PV technologies in the transition towards a decarbonised energy system.” doi 10 (2020): 160859.
[2] Global Wind Energy Council. “Global Wind Report 2022”.
[3] European Commission (2018), Commission communication – A Clean Planet for all – a European long-term strategic vision for a prosperous, modern, competitive and climate neutral economy, COM(2018) 773 final.
[4] Giurco, D., Dominish, E., Florin, N., Watari, T. and McLellan, B. (2019), ‘Requirements for minerals and metals for 100% renewable scenarios’, in Teske, S. (ed.), Achieving the Paris Climate Agreement Goals – global and regional 100% renewable energy scenarios with non-energy GHG pathways for +1.5°C and +2°C, Cham, Springer.
[5] JRC (2018a), Cost development of low carbon energy technologies – scenario-based cost trajectories to 2050, 2017 edition, Luxembourg, Publications Office of the European Union.
