Material limits

Simon Michaux, Associate Research Professor of Geometallurgy, Geological Survey of Finland, says that we do not have enough metals and materials to build the new sustainable energy system needed to replace fossil fuel use. ‘The quantity of metal required to make just one generation of renewable tech units to replace fossil fuels is much larger than first thought. Current mining production of these metals is not even close to meeting demand. Current reported mineral reserves are also not enough in size. Most concerning is copper as one of the flagged shortfalls. Exploration for more at required volumes will be difficult.’ 

So overall he doesn’t think we can make the transition, certainly not fast. We have built ‘an industrial ecosystem of unprecedented size and complexity, that took more than a century to build with the support of the highest calorifically dense source of cheap energy the world has ever known (oil) in abundant quantities, with easily available credit, and unlimited mineral resources. We now seek to build an even more complex system with very expensive energy, a fragile finance system saturated in debt, not enough minerals, with an unprecedented …human population, embedded in a deteriorating environment.’ 

This may be overly gloomy, although, even given the potential for technological improvements, there certainly could be problems with some materials, as has been widely recognised e.g. in the case of copper as Michaux says and also some rare earths. Another recent study says that Europe faces ‘critical shortfalls’ in the next 15 years without more mined and refined metals to supply batteries needed for electric vehicles, energy storage systems and renewable power infrastructure. In addition, there are also obviously extraction impact issues- there can be large scale social and environmental impacts from mining of some materials. A big, hard to duck, set of eco-issues.  As Michaux argues, looking overall, it could be that ‘minerals are the new oil’– very important, increasingly scarce and also very problematic. 

However, while there's no question that there will be materials-related constraints, and that may slow the transition, this all has to be set in a changing dynamic context. Technology changes and new ideas emerge. For example, there may be many opportunities for materials substitution and system redesign, using new less problematic, scarce or costly materials, and also recycling options, using new techniques, like rare earth mineral recycling via Ligand Chromatography. More generally, the existing energy system will have to be replaced anyway, as it ages, and some of the materials needed for the new one can be recycled from it. So its scarcity and extraction impacts may be less of a problem.

More? 

The suggestion from Michaux is that the new system will need more materials than the old one.  That’s also been claimed by others. For example, a study by Timothy Laing noted that ‘harnessing and storing solar or wind energy requires larger infrastructure than that needed to produce energy by burning fossil fuels. This fundamental difference is reflected in the nature of the technology itself. Renewable generation requires the building of large amounts of infrastructure, which then gathers energy over a long time period with minimal input beyond maintenance. This ‘kit’ requires a greater amount of a wider range of materials compared with what is required for traditional fossil fuel technologies. Therefore, the rapid deployment of renewable technologies will require the production of a vast range of materials over the coming decades.’ 

Although the main focus of this study was on aluminium for solar PV use, its conclusion sounds fairly definitive- there will be issues. But is it true for all materials and technologies? Quite apart from finding substitute materials, couldn’t we generate and use energy more efficiently, so that we do not need so much generation, or materials for it? And won’t the new energy technologies also be cheaper, not more expensive, as Michaux suggests. Wind and PV are already beating all else on cost. 

Michaux’s study looks to a future with 36,000 TWh of power demand, 90% of it being met by renewables in 2050, with the necessary backup also in place. This future, and the technology mix within it, is based on an IRENA scenario.  However it’s not the only possible mix: in reality, some technical flexibility is possible- with a range of possible technologies. Clearly the material requirements of the new system will depend on the mix of energy supply technologies and also the end-uses. For example, in the transport context, battery EVs use more materials than hydrogen fuel cell powered EVs, and, more generally, we may change our lifestyles and our consumption preferences, in this context, opting for public rather than private transport.  

All of that makes it hard to assess the significance of material constraints and impacts, so as to be able to run that alongside comparative total life cycle carbon-impacts. It is not easy to come up with useful metrics for total impacts. Simple tonnages are not very helpful. Some rare earths may be scarce, but the amounts used (e.g. for the magnets in wind turbine generators) is relatively small. The extraction of some materials also has much more environmental impact than that of others. The carbon content/MW or MWh is also not a good enough measure. What about water use and biodiversity? And if we are looking at nuclear, what about fuel cycle radiation effects? A recent comparison of renewables and nuclear just makes use volumes and weights of materials. So it’s hard to know if its conclusions that ‘nuclear and renewables have similar impacts’ are useful/valid.   

New metrics 

We need better metrics- certainly more than just ‘masses’. For example, the IEA has asserted that ‘an offshore wind plant requires thirteen times more mineral resources than a similarly sized gas-fired power plant,’ while the Bulletin of the Atomic Scientists noted that ‘A host of exotic, rare metals are used to control and contain the nuclear reaction. For example, hafnium is a neutron absorber; beryllium is a neutron reflector; zirconium is used for fuel cladding; and many other exotic metals, such as niobium, are used to alloy steel to make the vessel withstand 40 to 60 years of neutron embrittlement.’   

We need a way to assess what is really being said here, so that we can make plans for the future. For a key new example, as well as there being major potential resource and impacts limitations to Lithium Ion battery production for EVs, there could also be issues with electrolytically produced green hydrogen- which looks like being a key energy vector for the future for a range of end uses. Evidently there are hydrogen electrolyser materials issues, including potential scarcity of iridium and scandium. How important is that?

Clearly, materials issues are important, and we will need policies to reduce resource use, and hence extraction impacts, as much as possible, via recycling and substitution, and the more efficient use of resources. Some like Michaux fear that it will be ‘show stopper’, slowing the transition, although there seem to be technical options for improving the situation, at least to some degree. But to choose optimally amongst them it would be helpful to have a better idea of the eco-impact issues of the various types of resource use.