CO₂ emissions from the combustion of fossil fuels by humans are the main cause of the anthropogenic greenhouse effect. Without a drastic reduction in CO₂ emissions, living conditions on earth will change dramatically. On the other hand, fossil fuels, especially oil and natural gas, are important “convenient” precursors for fuels and a number of chemical products that are essential foundations of our way of life. Their availability is finite, even though not in the short term. An energetically and materially efficient and low-cost process for CO₂ recycling could contribute to reduce CO₂ emissions and the consumption of fossil resources. Achieving these effects requires energy and possibly necessary material inputs stemming from renewable sources. A promising approach is the photocatalytic conversion of CO₂ into energy carriers (such as methane).

The aim of the overall project is to develop a photoelectrochemical reaction cell that recycles CO₂ as a raw material, produces methane and hydrogen peroxide, and thus potentially contributes to a reduction in greenhouse gas emissions. The hydrogen peroxide gained has a comparatively high market value, providing promising economic prospects and incentives for a widespread use of the technology. Hydrogen peroxide is used as bleaching, disinfection, and oxidation agent. In addition, the methane produced can be used as fuel or feedstock for chemical processes. Two innovative approaches will be pursued to achieve the goals:

1. To increase efficiency and lifetime, CO₂SimO photocatalysts will be applied for the first time in gas diffusion electrodes in which carbon dioxide directly reacts with sunlight. This approach allows the direct use of gaseous CO₂.
2. A Life Cycle Assessment of environmental impacts and costs will analyze and evaluate the ecological and economic sustainability of the processes developed in CO₂SimO.

In the ITAS subproject, we aim to provide the project partners with the system analytical information necessary to optimize the efficiency and sustainability of the new processes. Therefore, environmental impacts and costs are investigated using life cycle analysis methods (LCA, LCC) under the following aspects:

1. Optimization of the CO₂SimO processes as such by integrating them into chemical production systems and energy systems.
2. Ranking of the CO₂SimO processes in comparison with competing systems.

The life cycle analyses also consider those processes that are not direct subjects of the R&D work in CO₂SimO, but are unavoidably parts of the overall system to produce the desired products (construction of apparatuses, production of materials, production of additives, etc.). This should ensure that no weak points in upstream and downstream processes remain hidden or are possibly even caused by optimizations in the main process (e.g., functionally optimal new material with increased environmental burden from its production).

The analyses are conducted as R&D support in close cooperation with the technical partners. Thus, sustainability information can be used already in early phases of the R&D work and, if required, necessary changes of the research direction can be carried out with minimized effort.

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