Before the summer holidays, pyrolysis was an unknown technology for most people, or an easy way to clean your oven. But after the green tripartite at the end of June came up with a proposal for a climate tax, where at the same time 10 billion kroner is set aside for pyrolysis until 2045, there has suddenly been a big focus on this technology and biocoal. In the report they published recently, the Climate Council has also counted on pyrolysis as a climate technology in all four scenarios for how Denmark can achieve climate neutrality in 2050. The tripartite agreement stipulates that pyrolysis must already in 2030 contribute with a CO₂-reduction for agriculture of 0,3 million tonnes and will allocate money so that agriculture can reach up to 0,6 million tonnes of CO₂-reductions from pyrolysis in 2030.

But it is not the first time that politicians have invested heavily in pyrolysis as a technology. Back in October 2021, the parties to the agreement behind the agricultural agreement chose to bet that pyrolysis could ensure agriculture a CO2 reduction of 2 million tonnes in 2030. The government had to come up with a strategy for how the potential could be realized no later than one year after the conclusion of the agricultural agreement. Almost three years have now passed and the strategy has not yet arrived. Meanwhile, the target for how big reductions pyrolysis can contribute in 2030 has been reduced drastically. But there are still more questions to be asked about pyrolysis and biochar than there are answers. The question is therefore whether we should once again bet such a large part of agriculture's climate action on a technology that has not been fully developed? If pyrolysis cannot deliver the expected CO₂-reductions, we risk once again being in a situation where agriculture meets the climate targets via new calculation methods rather than real reductions.

It is unrealistic that pyrolysis can deliver a climate effect before 2030

For the record, let's review how far we are from a major rollout of pyrolysis in Denmark. We do not yet have a single full-scale pyrolysis plant in operation. There is therefore a long way up to the optimistic potential of 0,6 million tonnes of CO₂ in just six years. We also do not know the long-term consequences for the application of biochar on fields, groundwater and crops. Those studies will not be completed until 2033. We also still lack a calculation method for how pyrolysis should be included in Denmark's climate accounting. We won't have it until 2027. In other words, there are many pieces that have to fall into place before it can be seen as realistic that biochar can have a climate effect for agriculture in six years.

In addition to the more practical aspects of pyrolysis, which must fall into place, there is another significant challenge with pyrolysis as a climate technology. There is a time lag in when biomass is put into a pyrolysis plant and when a net climate effect from the technology can be seen. The calculation is not simple and depends to a large extent on which biomass you want to pyrolyze and which conditions are taken into account. Calculations we have made in the Green Transition Denmark show, that straw has a net climate effect after just a few years, while this only happens after between eight and 40 years in the case of pyrolysis of degassed manure - compared to if the biomass is simply spread on fields.

The next 20-30 years will be decisive for whether we can reduce the impact of global warming. It is therefore essential that the net climate effect of pyrolysis is thoroughly investigated if pyrolysis is to contribute to achieving agriculture's climate goals. If we take the right precautions, pyrolysis might be a sensible climate technology towards 2050, as the Climate Council has proposed. But we need to know the long-term environmental consequences for soil, environment, groundwater and crops before pyrolysis is rolled out on a larger scale. And if we bet on the technology too early, and pyrolysis cannot deliver the necessary reductions, for example for 2030, agriculture must find reductions elsewhere. It will be difficult to achieve and risks becoming an expensive operation for agriculture.

This debate article has been published in Politiken's Climate Monitor on 6 September.