Resource scarcity and Renewables

Some worry that there will be resource constraints on the expansion of renewables, with the emphasis often put on the large material requirements, e.g. for steel, aluminum and copper.  However, a full life-cycle resource analysis has suggested that renewables could supply the world’s entire electricity needs by mid-century without major problems with resource (materials) use or associated eco-impacts. It assessed the whole-life costs and materials souring impacts of solar, wind, hydro, in relation to the demand for aluminum, copper, nickel and steel, metallurgical grade silicon, flat glass, zinc and clinker. The overall conclusion was that ‘bulk material requirements appear manageable but not negligible compared with the current production rates for these materials. Copper is the only material covered in our analysis for which supply may be a concern’. Issues still remain for concrete, although there are lower carbon versions emerging.

Rare earths

There are however also concerns in relation to some other materials e.g. rare earth minerals used in power generator magnets (Neodymium) and lithium for batteries. Their use is certainly growing, although recycling of some of these materials can help and in some cases substitutes can be found, or systems redesigned to avoid or limit the need for these materials. It has also been argued that more efficient use of the scarce materials can help (evidently there is some wastage during production). The discovery of new reserves in a wider range of countries, and possibly also via sea-bed mining, should also help. Especially given that the main problem is often where the reserves are: that is a locational, commercial and geopolitical issue which ought to be resolvable. That’s what  IRENA says.  Even so there are some key issues of environmental justice and sustainability- mining minerals can be very invasive and involve significant health issues.

Water resources

Access to water resources could also be a major issue, possibly made worse by climate change. That is usually more of an issue for fossil and nuclear plants, which need large amount of water for cooling, but so do some renewable energy technologies, notably Concentrated Solar Power (CSP) plants. They use focused solar heat to create hot gases to drive turbines, much as with conventional plants.  To allow for efficient focusing, CSP plants have to be in areas with direct, non-diffuse solar, such as deserts, and water is one thing such areas do not have. Air cooling in an alternative option but is less efficient. More likely water will have to be piped in, which suggests that locations reasonable near the sea would be best- as in the North Africa.  Water is also needed for cleaning CSP mirrors and lenses and also for PV solar arrays, small or large. That will mount up in the years ahead. So will water use for biomass growing. Hydro plants also obviously need water and, with decreased rainfall in some areas in recent years, output from some hydro plants has fallen. In some parts of the world, droughts have meant that hydro outputs have become increasing unreliable. This is likely to get worse with climate change. 

Fossil fuel resources

In what may seem like another substantial concern, some fear that the diminishing fossil energy resources cannot support a transition to renewables. This even troubles some renewable supporters, one of whom said that renewables ‘currently require fossil fuels for their construction and deployment, so in effect they are functioning as a parasite on the back of the older energy infrastructure. The question is, can they survive the death of their host?’

It certainly could be argued that we should be reserving as much of whatever fossil energy is left as possible to support the process of building up renewable-based systems, rather than just burning it off for no long-term gain. It is also true that there are important non-energy uses for fossil resources, so some should be reserved for that too- although it may be that we will want to produce fewer plastics, given their ecosystem impacts. Using fossil fuel to build the renewables system will also lead to emissions debts and eco impacts. We will clearly want to limit that as much as possible. However, to some extent, the first wave of renewables can provide energy to support the next wave, in a self-sustaining breeding process. The energy returns on energy invested i.e. lifetime energy output in relation to required energy input, for most renewables are quite high (compared to current fossil fuel based system), so perhaps fossil fuel use for building the next wave of renewables can be progressively minimized, depending on how quickly the transition needs to be made. BECCS and/or other negative carbon options might help compensate for some of the emissions produced during the early stages of that process, though reafforestation might be a better bet.

Limits to growth

No one says the energy transition will be easy and we really do need to pay attention to resource issues. Certainly growth of the sort we have had so far cannot continue for ever for a range of reasons- there are limits. So we may need to rethink growth, although material and energy resource limitations are only part of that. We are not going to run out of solar energy, or sand for PV cells…but we may run out of space to put them on. It the same for wind and biomass. In the end land may be the scarcest long term resource, unless we can make use of marginal areas like deserts and also focus on offshore wind, wave and tidal stream power. There is a lot a sea and there are also a lot of desert areas. Its worth noting that the worlds deserts receive more energy from the sun in six hours than humankind uses in a year, while the total wind resource, including in the upper atmosphere, has been put at about 100 times more than the total current global primary power demand.

It also has to be said that whichever technological route forward we take we will need energy and materials to build the systems to replace the plants and systems we have now, as they become obsolete. Renewables are not notably much different in that respect from any other energy technology, and some may actually use less resources/kWh produced over their lifetimes, although there may be material resource limits to the use battery storage systems, including lithium Ion batteries for electric vehicles. We may need to rethink that.