Unfortunately, the planned switch to low-carbon energy sources and the electrification of heating and transport technologies will not decrease our dependency on the steel industry – on the contrary. A low-carbon power grid requires much more steel (and other materials) than an infrastructure based on fossil fuels. Wind and solar power are very diffuse power sources compared to fossil fuels. Therefore, it takes much more materials (and land) to produce the same energy. In jargon, wind and solar have low “power density” or high “material intensity.”2829303132
A low-carbon power grid requires much more steel than an infrastructure based on fossil fuels.
The “steel intensity” of thermal gas and coal power plants is between 50 and 60 tonnes of steel per megawatt of installed power.33 Hydroelectric power plants have a lower steel intensity, with 20-30 tonnes of steel per MW.733 Atomic power’s steel intensity is also lower at between 20 and 40 tonnes of steel per installed MW.3334 On the other hand, solar PV requires between 40 and 170 tonnes of steel per installed MW.3335 Although there is little or no steel in the solar panels themselves, it’s the material of choice for the structures that support them.
Steel and wind power
The most steel-intensive power source – by far – is the modern wind turbine. The steel intensity of a wind turbine depends on its size. A single, large wind turbine requires significantly more steel per megawatt of installed power than two smaller wind turbines.36 For example, a 3.6 MW wind turbine with a 100-meter tall tower requires 335 tons of steel (83 tons/MW), while a 5 MW wind turbine with a 150-meter tall tower needs 875 tons of steel (175 tons/MW).37 The trend is towards taller wind turbines and a higher steel intensity.
Steel consumption further increases for offshore wind turbines. Onshore wind power plants rely on reinforced concrete for their foundations, but offshore wind turbines need massive steel structures such as monopiles and jackets.38 The steel intensity for offshore wind turbines is calculated to be around 450 tonnes per MW for a 5 MW turbine – eight times higher than the steel intensity of a thermal power plant.36. As these wind turbines get taller and move into deeper waters, their steel use further increases.
The most popular offshore wind turbine nowadays has a capacity of 7 MW, while the largest ones have a capacity of 14 MW.36 If we make a conservative estimate based on the data above (the steel intensity doubles for every doubling of the power capacity), a 14 MW offshore wind turbine would require 1,300 tons of steel per MW or 18,200 tonnes in total. Such a wind turbine thus consumes 24 times more steel than a coal or gas power plant of the same power capacity.
Power transmission infrastructure
The data above only include the steel used in the power plants themselves. For fossil fuel power plants, they do not include the steel used in the pipelines, oil rigs, coal excavators, and the like. However, the same goes for the low-carbon power sources. Because they need much more resources than thermal power plants (steel but also other metals and materials), they depend on a global mining and transport infrastructure that is just as steel-intensive as the supply chain for fossil fuels.
Furthermore, because they are more diffuse power sources with intermittent and unpredictable power production, often located far away from energy consumption centers, renewable power plants drive the expansion of transmission infrastructure. That infrastructure is also based on steel – from switchyard equipment over towers to conduction cables.282930313242
Finally, low-carbon power sources also have a high need for special grades of steel, which are more energy-intensive to produce. Steel for off-shore wind turbines should resist corrosion, and stainless steel is increasingly used for solar panel support structures.43 Electrical lamination steel (iron-silicon) is indispensable for transformers in the power network.7 Nuclear power plants may have a relatively low steel intensity but are completely built up of energy-intensive specialty steels. For example, cladding the fuel elements containing fissionable uranium requires zirconium steel, while all structural elements contain austenitic stainless steel.