Sustainable at all levels
For the evaluation of the value chain, the research team defined five different scenarios.
- Basic scenario: describes the current system. Fossil methane is used to produce electricity. CO2 emission certificates are purchased to compensate for the negative effects on the climate.
- Scenario 1: hydrogen production using PEC cells in Switzerland, followed by further processing into methane in local reactors.
- Scenario 2: hydrogen production by means of an electrolytic procedure using electricity from photovoltaic power plants, followed by local processing into methane.
- Scenario 3A: the electricity for the production of hydrogen comes from surplus renewable energy sources.
- Scenario 3B: the electricity for the production of hydrogen comes from the current electricity mix.
The environmental friendliness of the scenarios depends not only on how much CO2 is released, but also on other influences that can affect the environment. In scenario 3B, for example, the electricity used to generate hydrogen stems from the current electricity mix. Approximately 35 percent of this mix is produced by nuclear power plants, which generate radioactive waste that needs to be stored safely for a long period of time, thus resulting in a negative impact on the environment.
The financial aspect also plays a part in whether a scenario can be successfully implemented or not. The cost analysis shows that in all cases costs in the order of tens of billions of Swiss francs are to be expected, except in the basic scenario. This is not surprising, since all other scenarios require the implementation of many new technologies. The costs are highest for scenario 1, since harvesting CO2 from the atmosphere is an expensive procedure. In a further step, this CO2 is then to be converted into methane using hydrogen generated by the yet insufficiently tested PEC technology. All in all, this leads to low economic sustainability.
Provided the baseline scenario is not taken into account, scenario 3A performed best in the area of economic viability. However, the amount of available surplus electricity being insufficient, new installations that can provide power from renewable energy sources are required. Scenario 3a is therefore the most favourable and theoretically the easiest to implement.