High Temperature Hydrogen and Hydrocarbon Production through Cyclic Thermochemical Processes

Abstract

Hydrogen and its derivates will play an essential role as fuels and energy carriers in the energy system of the future. The advantages of comparable power density and reliability to fossil fuels, as well as their versatile applications, make them an important component of the energy transition. Our research group is developing technologies that ensure the efficient production of such chemical energy carriers and chemical commodities from renewable resources. On the way to climate neutrality, we are supporting market entry through investigations along the entire value chain. In that context thermochemical multistep processes are promising options, in particular related to the transport sector and to chemical industry. Such processes can be used to enhance the availability of solar energy in terms of energy transport, of energy demand/supply management and of potential energy related applications. Coupling concentrated sunlight to suitable sequences of thermochemical reaction enables the production of hydrogen, syngas and chemicals derived from those precursors by water- and CO2-splitting as well as the storage of solar energy by breaking and forming chemical bonds in suitable reversible reactions. The processes are sustainable and environmentally attractive since only abundant resources like water, CO2, air and solar power are used as feedstock. All other materials involved are recycled within the process. The concentrated solar energy is converted into storable and transportable chemicals and fuels. Some of these processes generate inherent side products like sulfur which can be used for thermochemical energy storage.

One of the major barriers to technological success of many of those processes is the identification of suitable active materials like catalysts and redox materials exhibiting satisfactory durability, reactivity, selectivity, and efficiency. Furthermore, materials play an important role in the construction of key components of the respective high-temperature processes and for the implementation in commercial solar plants. Besides materials aspects also process engineering tasks need to be tackled. One of the most striking challenges is to couple an intermittent energy source to a chemical process while keeping it practical and reliable. Some prominent and promising examples of thermochemical processes are being described and discussed with respect to further development and future potential. The main challenges of those processes are being analyzed. Technical approaches and development progress in terms of solving them are addressed and evaluated with respect to their future potential.