Area and material consumption

Of all low carbon sources, nuclear has the lowest spatial and material requirements. Renewable energy has much lower power densities than other non-renewable sources. Solar and wind power also have the highest consumption of critical metals.

Land and material requirements are key parameters to be dealt with when the world is going to reduce its dependency on fossil fuels. The use of land is conflicted because it affects areas that can be used for something else, and because it makes significant interventions in our nature. Also, the high material throughput for renewables means increased mining activity that takes time to establish and creates challenges when limited amounts of raw materials are available.

Nuclear energy requires far less acreage than renewables

In a 2018 study, authors John van Zalk and Paul Behrens compare the total footprint (including mines, roads and more), efficiency and capacity factor for nine different energy sources. The study builds on a number of publications, including work by world-renowned energy expert Václav Smil, and considers power densities, which are measured in watts per square meter of infrastructure. The study relates only to the United States but will, according to the authors, also apply to comparable countries.

The difference between renewables and fossil/nuclear power is enormous, as much as two or three orders of magnitude. Biomass and hydropower have the least power production per area, 0,1 W/m2. While hydropower has largely been developed, increasing biomass use will compete with other land use, including food production. And because of the low power utilization, large land areas are required. Wind and solar power have better, although not impressive, area utilization, 2 and 7 W/m2 respectively. In comparison, nuclear power has 130 times higher power density than wind and is only matched by natural gas. Nuclear power is superior to other low-carbon sources when it comes to area requirement.

Nuclear power has the lowest material throughput

One of the major challenges of scaling up renewables is the increased material demand. While nuclear power has a consumption of just under a thousand tons of materials per TWh, by far the lowest of all energy sources, the demand of wind is over ten times as high. Hydropower and solar requires even more materials, fourteen and eighteen times respectively, where the vast majority is concrete and steel. This is problematic, partly because of the steel and cement industries’ demand for high temperatures which are difficult to achieve with electricity, leading to high CO2 emissions.

Renewable energy makes use of non-renewable resources, including a variety of rare earth metals. These are the vitamins of chemistry and contribute to increased efficiency in wind turbines, solar panels and batteries. They exist in limited quantities in nature and cannot be easily replaced. Among them are dysprosium and neodymium used extensively in wind turbines. In addition, other metals, such as copper, silver and indium are used in solar panels. An EU report from last year expresses concern about the supply of critical raw materials, where solar and wind have the greatest consumption.

For solar and wind, it is not only the construction of the energy parks that are demanding for land and material throughput. When these energy sources are scaled to become dominant, solutions must be established that ensure stable power delivery when the sun is not shining or the wind is not blowing. If this is to be done with batteries, the area and material requirement will increase significantly, both for the batteries themselves, but also for the establishment of the necessary overcapacity of solar and wind needed to recharge the batteries. The more dependent you become of solar and wind, the more battery capacity needs to be installed. More battery capacity, on the other hand, requires more solar and wind to charge the batteries.

Metals are also needed for the transport sector and scientists at the Natural History Museum in London stated in a letter to the Climate Panel last year, that in order to provide electricity to the entire world's fleet by 2050, the annual production of neodymium and dysprosium must increase by 70%, cobalt production by 350%, while doubling the world's copper production. If wind power is to be used to recharge the batteries, it will require one year of global production of cobalt and ten years of global production of neodymium and dysprosium. This must be seen in light of the fact that it typically takes 10-20 years to open a mine that will extract these raw materials.

While solar, wind, and hydropower use a lot of materials to make energy from perpetual resources, it is the energy source itself, i.e. the fuel, that constitutes the biggest challenge for biomass and fossil fuels. Biomass requires the most, simply because the energy density is much lower than for fossil fuels. In 2018, 11.7 billion tons of oil equivalents in the form of oil, coal and gas were consumed to produce 136.000 TWh of energy. This amounts to an average "material consumption" of 86,000 tons per TWh, which is far higher than both renewable (almost one order of magnitude) and nuclear power (almost two orders of magnitude). To put it in perspective, an oil field of 50 million barrels will deliver energy equivalent to what 278 3 MW wind turbines will deliver in 23 years, i.e. the entire life of the wind farm. The world's oil consumption is currently at around 100 million barrels each day.

Phasing out nuclear power is clearly problematic

Even disregarding CO2 emissions, the large consumption of fossil fuels is not sustainable in the long term simply because fossil fuels are limited resources. Today, less than one-tenth of fossil fuels are used for something else than energy, such as plastic products. In the long run we will benefit from changing this in favor of products rather than energy production. This requires fossil energy to be gradually replaced by something else.

Nuclear energy is superior to other low-carbon sources in both material and spatial requirements. This represents a paradox in the discussion about phasing out fossil fuels as each nuclear power plant that shuts down, requires large areas of land in order replace the energy with renewables. At the same time, heavy industry and mining industry must be scaled up drastically to produce enough steel, concrete and critical metals – of which we may not have enough supply.