• Nicolas Polfer
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For a resource-conscious sustainability in the energy transition

Néckel Polfer – 07.04.2024

Besides the CO₂ balance, the impact on limited resources should also be taken into account. Which energy source will ultimately prove the most sustainable remains to be seen, argues guest author Néckel Polfer.

In its energy transition, Europe is relying above all on the expansion of renewable energies such as solar and wind. But because these are not reliable, storage is required, which in turn drives up costs. This inefficiency also takes its toll on the environmental balance.

The debate on a sustainable energy transition is almost exclusively focused on the potential climate impact of CO₂ emissions. But sustainability can also be viewed more holistically. What are the effects of a technology on other limited environmental resources, such as soil, water, air, and biodiversity? How available are the raw materials needed to scale up these technologies? Which energy sources will really prove the most sustainable in the long run remains to be seen — especially since these technologies are still evolving.

The resource consumption of renewables

Compared to conventional power plants, the land use of wind turbines and photovoltaics is considerably higher. The batteries needed for storage contain large quantities of raw materials, such as lithium, copper, and cobalt. Extracting these limited raw materials requires vast amounts of earth to be dug up, which destroys part of the landscape and consumes a great deal of energy.

In addition, mining causes groundwater contamination, often in regions of the world where drinking water is already scarce, such as in South America. With cobalt, there is the social problem of child labor, especially in the Congo in Africa. Finally, a huge wave of waste from wind turbines, photovoltaic scrap, and batteries is heading our way, because recycling strategies are still underdeveloped. If one considers the full resource consumption of renewables including storage, their environmental balance turns out considerably worse.

Even with renewables, resource conservation should be emphasized. Recycling raw materials is a must; wind turbines, solar panels, and batteries should be designed so that they can be recycled as efficiently as possible. Here, it's up to lawmakers to set up the right legal framework. Policy can also pull the right levers when it comes to the extraction of raw materials, in order to prevent groundwater contamination and child labor.

The competition of technologies

Besides renewable energies such as solar, wind, and hydropower, there are a number of other low-CO₂ energy sources and technologies.

In Carbon Capture and Storage (CCS), CO₂ from fossil-fuel power plants is stored underground (1). Research is still ongoing into how permanently this CO₂ can be stored. This technology would be especially useful for coal power plants, since burning coal emits particularly large amounts of CO₂. In addition, confirmed coal reserves could still supply humanity with energy for hundreds of years.

Similar to fossil energy deposits, significant deposits of so-called "white" hydrogen lie dormant deep within the Earth's crust (3 km down) (2). Unlike coal and oil, however, these did not originate from fossils, but were formed by the reaction of water with iron minerals. Since these deposits were only recently discovered, it is not yet possible to foresee how large the reserves are, or how easily they can be tapped.

Geothermal energy is normally only available at volcanically active spots on Earth. By drilling very deep (20 km) into the Earth's crust, it would in principle be possible to harness geothermal energy anywhere on Earth. When the technical challenges of deep drilling technology are solved, our energy supply would be secured for millions of years (3).

In nuclear power, nuclear fission releases energy without producing CO₂. Radioactive waste, however, is and remains the key problem of conventional nuclear energy. That said, the generation of nuclear waste can be considerably reduced with other reactor types, such as molten-salt or liquid-metal reactors. These have been known for decades, but have only recently been further developed again with a view to commercialization (4). Confirmed reserves of uranium and thorium would be sufficient for hundreds of years. With breeder reactors, reserves would last for tens of thousands of years.

In nuclear fusion, small atomic nuclei are fused together, just as happens in the sun (5). In the process, even greater amounts of energy are released than in nuclear fission, while radioactive waste is much lower. Unfortunately, the technical challenges of nuclear fusion are very demanding. In particular, materials need to be developed that can withstand the high radiation levels. It is therefore not yet possible to predict when nuclear fusion will become a commercial energy source. Once it finally arrives, our energy problems would be solved for several million years, because the raw materials are so abundant.

Conclusion

The coming decades will show which technologies prevail. Governments can fund research and set the legal framework; but they should not pick the winners themselves in advance. Patience is called for.