Energy resource limits

In an interesting article in the Ecologist, Gareth Dale argues that the rising cost of plundering nature presents major problems for the continued expansion of capitalism. For example, he says the ‘energy return on energy invested’ (EROI) for fossil-fuel extraction is plummeting: ‘In plain English, ever more energy is consumed in squeezing each drop of oil from the bowels of the earth’. He notes that a recent study has found that, at present, over 15% of the oil extracted was being use to extract more oil and that this will rise as easily accessed reserves deplete. 

It’s the same for nuclear – as high grade ore reserves deplete, the energy cost of mining/processing uranium rise, with EROI ratios falling from 15:1 as now, to maybe 5:1 or less over time.  Meantime the EROIs for renewables are mostly higher and improving- e.g. solar was poor in the early days, but is now at around 25:1, wind is around 50:1 on good sites, and may get to 80:1 offshore, hydro is at around 200:1.

These EROIs are tentative and site specific, and there are methodological disputes about how to calculate them and where to draw the system boundary. For example, if you include any backup capacity needed to balance variable renewables, then the total system EROI may be lower, and if you exclude the energy needed to make reactor fuel, then the nuclear EROI is much higher. 

Even so, EROEIs do seem useful as general guides and the situation for fossil fuels, where the historical data is more solid, is certainly worrying. In a challenging new article, Nafheez Ahmed notes that ‘in just 13 years, global oil production could enter into a terminal and exponential decline, accompanied by the overall collapse of the global oil and gas industries over the next three decades. But this is not because the earth is running out of oil and gas. Rather, it’s because they are increasingly eating themselves to stay alive. The oil and gas industries are consuming exponentially more and more energy just to keep extracting oil and gas. That’s why they’ve entered a downwards spiral of increasing costs of production, diminishing profits, rising debt and irreversible economic decline’.

Oil in decline 

All of  this is explored in a new academic study of Energy Return On Investment,  that Ahmed and Dale refer to. It found that, as noted by Dale, 15.5% of the energy produced from oil worldwide was now being used to keep producing more the oil. In 1950, the EROI of global oil production was about 44:1, meaning that for every unit of energy we put in, we were getting 44 out. By 2020, it reached around 8:1, and it is projected to decline and plateau to around 6.7:1 from 2040 onwards.  In parallel, it said ‘while we’re currently using 6.7% of global energy to produce gas, that quantity is growing at an exponential rate and will reach nearly a quarter by 2050’. 

The faster the system expands, the more energy inputs it needs to keep expanding, and there are obvious resource and costs limits to this. That’s quite apart from environmental impact limits and costs. Switching over to renewable like wind and solar may avoid some of those limits. They are zero carbon in operation and generally have low local eco-impacts. And as indicted above, the EROIs look good and may get even better. 

However, there may still be constraints on continued economic expansion due to other resource limits e.g. the scarcity of some key materials and the eco-impacts of extracting them. This can be overstated. For example, the IEA has claimed that ‘an offshore wind plant requires thirteen times more mineral resources than a similarly sized gas-fired power plant’. It also sees renewables as needing more materials than nuclear. But it is hard to make useful comparisons amongst the options just on the basis of the weights of the materials needed. The social and ecological impacts of extracting some scarce materials can be high, especially for rare earth materials like neodymium, which is used in wind turbine power generators, but the amount needed of that may be small. There may been more problems with somewhat less rare materials, like Cobalt, Lithium, Indium and Vanadium, which may be needed in larger amounts for green energy systems, but we will need more detailed studies of kg of specific material/kWh output needed and the likely impacts of extracting these amounts. 

The materials issue is not trivial, but it is not a problem unique to renewables. For example one study of nuclear power 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’. 

It does seem likely that nuclear plants will continue to require a range of exotic materials, as well as uranium- or maybe thorium. Nevertheless, while the silicon for PV cells comes from (plentiful) sand, some do also need small amounts of exotic (and sometimes toxic) material, and wind turbines use steel and also specialist materials for their power generators, including rare earths. So we need to develop policies to reduce resource use, and hence extraction impacts, as much as possible- via recycling and substitution. That is in hand, with, for example new (non-toxic) PV cell materials, wooden wind turbine towers and recyclable wind turbine blades. There are also new ways of making low carbon steel, concrete and other materials, using renewable energy sources, and ways to capture CO2 from some fabrication processes, although we have to careful not to get sucked into the carbon removal trap - we can’t just carry on producing and storing CO2 to offset fossil fuel use. 

A recent Green Alliance study suggested that a combination of materials recycling and improved energy efficiency might limit the UK requirement for some key materials, including those needed for EV batteries. However, the expansion of BEVs may still face limits e.g. in our ability to find substitute materials, so we may need to look at other green transport options, as well as at ways to reduce road transport demand. That may also be true in other sectors. Technology can take us some way to sustainability, but we also have to reign in our demands on it, across the board. That is certainly how some radical ‘degrowthers’ see it- we need an energy decent, with demand for all things cut back in all sectors and population growth also constrained. Pretty challenging all of that- some thing to chew on over the Christmas break!