Andreas Bittig: While many projects and efforts are underway for heating and mobility, the decarbonization of industrial high-temperature processes, which are often based on natural gas, still remains a niche activity. The AfDI intends to use and further develop methane pyrolysis, an interesting new technology for such applications. The exciting thing about it is that this technology allows the decarbonization of fossil natural gas, which enables rapid CO2 reductions; it even leads to negative emissions if renewable methane is used.
How can synthetic methane enable negative CO2 emissions?
Christian Bach: Synthetic methane is produced from renewable hydrogen and CO2 from the atmosphere and can be transported around the world at low cost. To prevent the re-formation of CO2 when the methane is being used later on, the carbon is split off from the CH4 molecule beforehand – in solid form! – in a process known as pyrolysis. Solid carbon can then be used as a new raw material in construction and agriculture. Thus, we only use the hydrogen part of the synthetic methane for energy production. Thus, overall CO2 is removed from the atmosphere for the production of synthetic methane, which is eventually stored in the form of solid carbon in construction or agriculture – and is therefore no longer climate-relevant.
Christian Bach: True, around half the energy is lost during the production of synthetic methane, and around another third is lost through the splitting off of carbon. What looks like a disaster from an efficiency perspective nevertheless makes sense – namely when methane production takes place in regions where energy is abundant. This is the case in the sun belt around the globe. There, solar radiation is twice as high as in our latitudes, and there are huge uninhabitable and unused areas. Moreover, the existing infrastructure can be used for transportation. Twice the solar radiation in the Earth's sun belt means a significantly higher yield per square meter of solar cells than here. This puts the high energy losses of this approach into perspective.
What does it take for this global system to become a reality?
Andreas Bittig: Methane pyrolysis is considered one of the most cost-effective production processes for hydrogen. The technology is on the threshold of industrial implementation. For the overall system to become a reality, demonstration plants, such as the one planned in Zug, are needed to gather both data and know-how. Tech Cluster Zug AG provides the ecosystem for demonstrating the feasibility of this approach. We definitely see the Zug demonstrator as the start of industrialization of this system, because we are very well positioned through close cooperation between industry and research.
A demonstration plant at the Tech Cluster Zug
The Association for the Decarbonization of Industry (AfDI) was founded in the spring of 2022. Association members include representatives from industry, energy suppliers, the financial sector and research. One of the association's main activities is to build a demonstration plant at Tech Cluster Zug in the coming years, in which methane (CH4) is split into its components, hydrogen (H2) and solid carbon (C(s)), by means of pyrolysis. The pyrolytically produced hydrogen is to replace fossil natural gas in the enamelling furnaces of V-ZUG AG. For the solid or powdered carbon, applications in construction and agriculture are being developed and validated – for example as an admixture in building materials or to enrich humus. What is special about this new approach: If synthetic methane is used for pyrolysis instead of fossil natural gas, the overall CO2 emissions are negative (see interview). However, since Swiss industry alone has an annual energy demand of around 20 TWh, the potential for the domestic production of renewable hydrogen or synthetic methane to meet this demand is insufficient. The situation is different in the Earth's sun belt: Imports of synthetic energy sources from sunny regions could meet the demand for renewable energy and provide new resources for construction and agriculture – with overall negative CO2 emissions (see graphic on page above). Empa contributes to the AfDI both with its applications-oriented expertise in the field of synthetic energy sources (for example in its mobility demonstrator, move) and with its expertise in the fields of concrete and asphalt. This would be one option to use the carbon obtained from synthetic methane.