DIt was foreseeable that the heat transition would cause disputes, protests and rejection. No one likes to be told by the state what to do with their private property – or what not to do with it, not even in the boiler room. In addition, there are immense costs that a new, climate-friendly heating system entails.
However, it was not foreseeable that the discussion about the heat transition this spring would slide into the absurd. The heating dispute goes into another round. It’s about an energy source that many municipalities and private individuals have chosen as a replacement for oil and gas heating: wood pellets.
The small pressed sticks, which according to the industry are mainly made from wood waste, have long been considered a sustainable and climate-friendly source of energy. In Germany, more than 600,000 private households are heated with pellet stoves. In the planned heating law by Climate Minister Robert Habeck, however, heating with wood should no longer be classified as renewable, which is why it should be banned in new buildings and no longer subsidized in existing buildings.
What is true?
The opposition to this plan was fierce. Wood is sustainable and means active climate protection, said leading Union politicians such as Thorsten Frei and Julia Klöckner. Instead of scientific knowledge, the traffic light can be guided by ideology, it said. Criticism came not only from the opposition. The Greens in heavily forested Bavaria demanded that wood be allowed to continue to be burned. Now Habeck also seems to be tipping over, he is ready to make concessions, he said.
But what is true? Do pellets fuel climate change, or are they a sustainable climate saver? Achim Dittler no longer understands such assessments. The professor at the Karlsruhe Institute of Technology has been investigating the consequences of wood burning for years and is amazed at the ignorance with which politicians and the public react to the findings that have long been available. In science, it has long been clear what fatal consequences the burning of wood has for the climate, he says. In relation to the energy content, no other fuel emits more carbon dioxide and pollutants. Pellets are just as clearly harmful to the climate as firewood and therefore more harmful than gas or oil. “Ultimately, it’s heating wood in a somewhat controlled way,” says Dittler.
Wood pellets are mostly made from sawmill residues here – but forests are illegally cleared abroad for this purpose.
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Image: Mauritius
The forest scientist Jürgen Bauhus from the University of Freiburg does not doubt this, but considers the mere comparison of the energy densities to be too easy to calculate the climate impact of pellets. Rather, one must consider the entire circulatory system in order to balance the carbon flows. According to Bauhus, the decisive factor is whether the wood for the pellet production comes from sustainably managed forests and what would have happened to it if it had not been burned. This is exactly what the proponents of pellet heating see as their strongest argument: Useless residual wood such as branches, bark or brushwood would simply rot in the forest and ultimately emit just as much carbon dioxide as when it was burned in the pellet heating system.
From an ecological point of view, this is nonsense: dead wood is an important habitat and source of nutrients for the forest, and countless organisms depend on it. In addition, not all carbon compounds escape into the atmosphere, but end up in small amounts in the soil. In addition, rotting takes considerably longer than burning, sometimes decades. Therefore, these two processes cannot be equated. Time is the most critical factor in climate protection, emissions must be reduced as quickly as possible. However, if a lot of wood is burned, a lot of carbon is released – and this immediately has an impact. And the new sequestration of carbon takes decades.
