Nuclear Energy is Frugal in Ressources

Another major concern of our time is resource scarcity. The Canadian scientist Vaclav Smil argues that, at their very core, modern societies rely on four key materials to thrive: ammonia, plastics, steel and cement. [16] Steel and cement industries in particular demand temperatures so high that they can only be practically achieved with fossil fuels, leading to high CO2 emissions. From these essential pillars derives our ability to use and produce energy, food, fresh water, and all the other materials necessary to run the complex technical apparatus that enables our standard of living. Beyond these key materials, our modern societies rely on a great variety of other elements. The European Commission has created a list of critical raw materials, selected for both their economic importance and their supply risk. Its latest version, in 2020, contained 30 entries. [17]

The demand for these resources is rapidly expanding, carried by economic growth and the energy transition. The latter includes not only renewable energy, but also electric mobility. The supply, however, is bounded by physical constraints and potentially hindered by geopolitical tensions. As an illustration, the EU only provides 1% of the raw materials needed for wind energy despite representing around a quarter of the global wind energy production. [18] [19]

In light of these considerations, it is wise to opt for an energy mix that minimises resource consumption–especially if imported. The metric we are interested in is the resource intensity—in other words, the amount of matter or energy that has to be mobilised per unit of energy produced.

Figure extracted from the UNECE “Life Cycle Assessment of Electricity Generation Options” report, published in March 2021 and updated in April 2022. A nuclear power plant is mostly concrete & steel. Thanks to its large energy output, it is best-in-class for low ressources consumptions.

Let us start with bulk materials, which make up most of the resource consumption in terms of mass. In 2015, the US Department of Energy published its Quadrennial Technology Review, a vast report on the status of the different technologies at the foundation of energy systems. [20] In it, the material intensity is estimated based on concrete & cement, iron & steel, copper, aluminium, glass, and silicon. Based on these metrics, nuclear energy is estimated to require 925 tons of materials per TWh: mostly concrete & cement (82%), with some iron and steel (18%). That is more than gas combined cycle, which is as low as 570 tons/TWh, but that figure does not account for the fuel, which will be tackled in another chapter. It is, however, far less than renewables which culminate at over 10,000 tons/TWh.

What about critical materials, which are of high economic importance but also have a high risk of supply chain disruption? These are far less important in terms of mass, but are nonetheless key enablers. Using the number from the IEA’s report on the role of critical minerals in clean energy transitions, nuclear power requires less than 12 tons of these per TWh of energy delivered. [21] [22] That is slightly more than coal and gas, albeit in the same order of magnitude, but ten times less than renewables. The already mentioned UNECE life-cycle assessment has a higher estimate of 85 tons/TWh for nuclear, with minimum 250 tons/TWh for wind and 300 tons/TWh for solar. [23] One notable difference between these two assessments is that the UNECE accounts for aluminium, which the IEA accounts for in bulk materials. Moreover, as stated earlier, these are not firm figures. Life cycle metrics are complex to assess. What matters are the orders of magnitude involved. Questions such as which technology performs the best? or what are the factors between different technologies?

The critical minerals required by nuclear power are largely limited to chromium, nickel, and copper, with trace amounts of manganese and molybdenum. None of these are on the European Commission’s list of critical raw materials. Renewables, on the contrary, will rely on a few elements part of that list, such as rare earths or gallium.

Another key metric is the amount of dissipated water. This accounts for all water used as an ingredient for a chemical product or evaporated, hence not the water immediately returned to the environment. Thermal power plants require water for cooling, and will thus have a higher requirement. This includes nuclear power, with a lifecycle water dissipation of 2.4 L/kWh according to the UNECE. That is somewhat lower than coal, and somewhat higher than gas. Renewables perform much better with that regard, consuming only 0.1 to 1 L/kWh. It should be noted that the cooling water is never in contact with the nuclear part and is thus not polluted by use. Moreover, nuclear power plants have a great flexibility in location, and can thus be sited near coasts where they can use seawater cooling. Last but not least, albeit this is more anecdotal, puncturing a water body is also the occasion to clean it up. The Tihange nuclear power plant in Belgium, for example, removes 40 tons of floating debris from the Meuse river each year. [24]

We learnt earlier that the average person in OECD countries consumes slightly less than 8 MWh of electricity per year. [25] If it was all derived from nuclear energy, it would represent somewhat more than 7 kg of bulk materials, 660 grams of critical minerals, and 18,5 m3 of water. If it was all derived from renewables, it would be in excess of 75 kg of bulk material and 2 kg of critical minerals, but likely less than 1 m3 of water. These figures used the most unfavourable estimations for nuclear, and the most favourable ones for renewables. Nuclear energy is thus more frugal across all metrics but water, once again due to its formidable energy density. As for water, we clearly need to make all efforts possible to preserve it. However, these amounts are relatively small: 18,5 m3 is approximately what is required to produce 1,2 kg of beef steak. [26]

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