Net zero in the Rhine Valley by 2050 technically feasible and economically attractive

The jointly commissioned study confirms that the decarbonisation of the Graubünden Rhine Valley is achievable by 2050 and that the annual costs for the construction and operation of the energy system can even be reduced by up to 30 percent compared to the reference in the best-case scenario. This is therefore an economically sensible investment, but in the current market environment it is only economically viable to a limited extent.

Various measures are required to achieve the net-zero target by 2050. These include heat pumps, the electrification of mobility and the capture and storage of industrial CO₂ emissions, which are difficult to avoid. In addition, an expansion of district heating would increase the efficiency and resilience of the energy system and relieve the burden on the electricity grid. New energy sources such as hydrogen, synthetic methane, biogas and geothermal energy could contribute to a diversification of the energy supply – especially in winter. Building renovations with their efficiency gains would contribute to reducing the overall energy demand by up to 25 %; the electrification of mobility and the provision of heat would therefore not lead to feared electricity shortages.

Unique collaboration between industry, energy suppliers and administration

To address the question of how the Rhine Valley can achieve the net-zero CO₂ emissions target by 2050 with maximum cost efficiency, various stakeholders came together under the leadership of the Graubünden Office for Nature and the Environment (ANU) to form a round table entitled "Graubünden Rhine Valley Energy System 2050" and jointly commissioned Empa to prepare a scientific analysis of the "Rhine Valley Energy System" to enable fact-based decisions for the implementation of the "Actionplan Green Deal" (AGD).

The study should also show how companies can improve their existing measures to achieve decarbonisation. "The Bündner Rheintal Energy System Round Table is a good example of how solutions to reduce CO₂ emissions can only be developed together and in a transparent dialogue," explains Fabio Wider, Plant Manager of the Untervaz cement plant at Holcim. The round table will be continued in order to further examine and plausibilise the measures proposed in the report.

A complex starting position

In order to achieve the net-zero target by 2050, existing oil and gas heating systems in particular must be replaced by heating systems using renewable fuels and private and public transport must be converted to emission-free engines. The decarbonisation of energy-intensive industrial processes is a particular challenge. The Graubünden Rhine Valley is home to four industrial companies facing these challenges: the Holcim cement plant in Untervaz, the waste incineration plant in Trimmis, Ems Chemie and the Axpo biomass power plant in Domat/Ems. If CO₂, which is difficult to avoid, also has to be captured and stored in the future, this will require additional energy on the one hand. On the other hand, these plants produce useful waste heat at various temperature levels, which could be used to replace fossil-fuelled heating systems.

Innovative modelling techniques developed

Due to the complexity, Empa used a new modelling technique. This allows all energy consumption, conversions and flows of the various energy sources to be modelled with a high temporal resolution of just one hour and a high spatial resolution, taking into account the different temperature levels. The mere creation of such a "sector-coupled multi-energy system" represents a scientific innovation. However, realistic modelling was only made possible by the fact that industrial companies and energy suppliers provided their detailed data as part of the project – a novelty and a decisive success factor, as Empa project manager Robin Mutschler says. "This was the only way we could model as close to reality as possible."

This considerable effort on the part of all those involved has paid off: a large number of scenarios and measures have been examined and the most cost-effective way to decarbonise the economy has been identified. Empa's modelling shows that the energy sources used today – heating oil, diesel, petrol, natural gas and coal – can largely be replaced by electricity, biological waste, biomethane, synthetic methane and hydrogen. The importance of wood energy and the total consumption of electricity will remain roughly the same as today. The latter is mainly possible thanks to increased waste heat utilisation.

In principle, the modelling technique used here can also be transferred to other regions. However, the prerequisite is that the companies involved make their consumption and production data available. "If industry, authorities and science work hand in hand, the net-zero target can be achieved by 2050 in the Graubünden Rhine Valley by means of sector coupling," says Empa researcher Mutschler. The system costs could still fall and import dependency could also be reduced. "The key to success is the cleverest possible combination of different technologies" adds Matthias Sulzer, who has headed Empa's Engineering Sciences Department since the beginning of the year and was also involved in the study. "For example, waste heat from waste incineration plants can be used for electricity production as well as for district heating and for the operation of CO₂ capture plants."

Start-up financing by the canton

Although the conversion of the energy system requires initial investments, the results show that these investments are economically worthwhile in the long term. This is where the law on the promotion and financing of climate protection measures in Graubünden (BKliG), which will be discussed by the Grand Council in the April 2025 session, can come into play. The BKliG creates the basis for promoting climate projects that help the canton of Graubünden to reduce costs in the long term, strengthen the domestic economy and reduce dependence on foreign countries.