🔋Very Intense
🔋Very Intense
What material and mining intensity tell us about our energy supply.
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Climate change seems to be debated on every level of the problem, from whether climate change is even occurring, to what extent is it an existential risk, the role of fossil fuels, which energy sources may replace fossil fuels, and the economic cost of an energy transition. The main metric to gauge climate change is greenhouse gas emissions. The other impact which is extremely important is environmental impact.
In That’s So Metal, I discussed some work that estimated the number of new mines needed just to supply the Li-ion battery market with its materials, the minerals used in each energy source, and the intensity of the material’s relationship to power density of the source. I conclude that facing the projected demand and replacing high energy output sources with lower ones will serve as upward price pressure on most key commodities.
Since then, a report from the Breakthrough Insitute has updated the estimation of the mineral intensity of each energy source. In it, they separate nameplate capacity and actual energy generation which is a key distinction left out in the IEA report (figure below) which is why further analysis is required. This is significant because as I’ve discussed, energy return on energy invested (EROI) and capacity factor have a significant impact on the energy actually supplied to the world. When just nameplate capacity is used, it doesn’t represent reality as capacity is just the maximum rate of energy that can be supplied, not the actual amount of energy supplied to the grid. This is particularly relevant for wind and solar and is another reason why metrics like LCOE are flawed.
According to Breakthrough Institute’s results, nuclear (AP1000, EPR, BWR X-300) holds the crown for the least material to produce 1 GWh of electricity. They show that improvements in wind and solar have made their material intensity much lower than in previous work which is exciting. As far as critical materials go, nuclear has much a smaller requirement as well. When you look at the same figure with capacity instead of generation, the sources are much more similar, and solar is even less than nuclear. Due to the lower capacity factor and shorter lifetime, the gaps increase when we look at actual generation. With further improvements in wind/solar capacity factor and lifetime, the material intensity will go down for solar and wind.
Looking at mining intensity, the kg of rock moved per GWh of energy generation instead, the gap between nuclear and the rest grows. With an 80-year lifetime for a nuclear plant, the mining intensity is 3.5-6 times less than solar and wind.
In addition to improvements in capacity factor and lifetime, improvements in mining efficiency will have a greater impact on lowering the larger intensity of wind/solar. Materials like copper require more mining intensity and solar, wind, and batteries all have more than nuclear.
When zooming out to compare to fossil fuels as well, they consider coal far and away the highest mining intensity with natural gas in second, albeit on a scale more similar to the low-emission sources. This is just the rock moved to generate electricity, so fossil fuels are going to be higher since they need to constantly be extracted. Uranium does as well, but its energy density is so high that it is of a different magnitude.
Material and mining intensity is a very important metric to consider. While having more sustainable emissions is important, it is necessary to also consider the environmental impact locally. While nuclear is a no-brainer along just about any metric, solar and wind have reduced their impact, at least according to this report. This report also suggests that the mining impact of fossil fuels per unit of energy produced is high, which disagrees with other reports. Taking this survey, moving away from fossil fuels would help lower emissions as well as mining impacts.
There are things that cannot or are functionally not included in these reports. These make a difference in which sources are the best in total, but these reports are still very helpful tools. For example, nuclear plants also provide thermal generation in addition to electricity which is something that wind/solar/batteries fail to provide as effectively. Especially with some of the newer advanced reactors, this is a very important factor in determining overall value.
Second, there are many companies innovating on the recycling front in terms of wind, solar, and batteries. While these may not be commercially realized yet, one could picture a world where renewables aren’t just renewable energy sources, but also can recycle a significant amount of resources further reducing the mining impact.
Third, once drilling takes place for oil and gas, the material extracted is the fuel, so it’s not mining in the same sense. While it is extractive, it does not impact the earth in the same way as a mine does. Especially with horizontal drilling techniques, oil/gas drilling is less invasive than a copper mine.
Overall, reports like this should be taken more seriously when leaders favor renewables over nuclear for example. It is clear nuclear has the lowest environmental impact in terms of emissions as well as mining impact. It is also encouraging that renewables and batteries continue to lower their mining and material impacts through improvements to technology and mining efficiency. Until next week,
-Grayson
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