Wind and solar technologies use renewable, naturally replenished, resources to make energy. However, as has increasingly become recognized, the materials needed to build these systems, and their associated energy stores, are not renewable and have to be extracted from the ground, with, often, major environmental damage occurring. And some may become increasingly scarce.
Certainly the shift to renewable energy requires a mix of metals, such as copper, cobalt, nickel, rare earths, lithium and silver, some of which have only previously been mined in small amounts. Under an expanding renewables scenario, demand for these metals could rise dramatically, and require new sources of primary and recycled metals.
A recent Earthworks review noted that, on the basis of a global scenario with renewables supplying two-thirds of electricity by 2050, as well as batteries for electric passenger cars, commercial vehicles, buses and stationary storage, ‘demand from renewable energy and storage technologies could exceed reserves for cobalt, lithium and nickel, and reach 50% of reserves for indium, silver, tellurium.’ However, it added that ‘primary demand can be reduced significantly, with the greatest potential to reduce demand for metals in batteries through high recycling rates, and for PV metals through materials efficiency’.
Demand for new materials will of course vary with time, decreasing once the new energy supply system has been fully established. Assuming efforts are made to limit overall energy demand growth, there will then only be a need for upgrades and planned replacement- batteries will need regular replacement. While recycling can help meet some of this demand, there will also be pressure to develop new cheaper less resource limited materials, for example for batteries. Certainly there will be pressures to avoid any materials that have major environmental impacts, or at the very least to develop new extraction techniques and sources that reduce impacts. As I mentioned in an earlier post, efforts are also being made to use new less scarce and hazardous materials for wind turbines and PV cells and to look for new less constrained resources.
A Renewable limit?
Although some resource limitations may be avoidable, there will be constraints, and, given the environmental impacts of resource extraction, some see materials issues as being a show stopper for renewables. However, that may be to overstate the problem. As the IEA has noted, the main constraints may relate to a limited area of material use- Lithium Ion batteries for power storage in particular. That of course could be very significant. For example, in terms of personal transport, it may well be that the use of battery electric cars cannot be as widespread as some have hoped, whereas hydrogen fuel cell vehicles of all sorts may win out- the material constraints being less. It may be the same for aviation.
Green hydrogen production by electrolysis does of course have it own materials constraints- electrolysers use platinum electrodes to boost efficiency and platinum is rare and costly. But that will not directly constrain the use of hydrogen as a storage media, although it may limit hydrogen production overall, unless other catalytic materials can be used. However, other storage media and technologies may be less material constrained- pressurized air storage and liquid air storage for example. Pumped Hydro too. And for some contexts, heat stores as well.
While materials limits may become increasingly important for battery storage applications, their impact on renewable generation hardware is less clear, with only relatively small amounts of rare materials being used e.g. for the magnets in wind turbine generators. However, even with recycling and substitution, demand for new materials may still build up, and, for the longer term future, some look to a more constrained approach to energy development, using scarce materials frugally, so as to allow us to use renewables in a more limited, sustainable, and not indefinitely expanding, way.
Dematerialisation
The extent to which the use of renewables might have to be limited will of course depend on how successful we are at cutting energy use through improved end-use technical efficiency and also via behavioral change - the potential for reducing energy demand is very large. Some look to structural changes in the economy helping, with energy and material intense industries being replaced by electronic services in an increasingly dematerialised world. However, although it is true that computers and telecom systems now support vast areas of the economy, these activities still require energy and materials, and, in any case, people still need heat, light, food transport. So we are a long way away from full dematerialization.
Are there any other ways out? Some may look to escaping from the material constraints on energy generation by going for nuclear power. However, the materials requirements for high tech nuclear are likely to be equal to if not higher than those for relatively simple renewable energy wind and solar driven systems. That is in addition to shortages of fissile material, reserves of which are inevitably finite.
Material constraints are of course not the only limitation on the potential for growth of renewables or for that matter nuclear, but clearly, if the growth of energy use is limited, then the materials limits are avoided or reduced. In some variants of sustainable growth, there would still be some economic and energy growth initially, mainly in the change over to renewable supply, but once that is done, we would move to a steady-state system-maintenance basis. To get to there, economic growth would have to be dethroned as the economic driver- and that would involve the acceptance of some radical degrowth changes. Painfully, Covid 19 may have opened up/forced us to adopt some of these options, as of course does climate change, although it is far from clear if we really are set for the sort of sustainable green de-growth that some look to. However, materials scarcity could add an extra push.
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