Speaker
Description
In the context of climate change, reducing greenhouse gas emissions is necessary to achieve carbon neutrality by 2050. This requires action on several fronts: industrial decarbonisation, production of new heat sources, energy storage, solar fuel production, etc.
Solar fuels refer to molecules of interest synthesised using solar radiation as an energy source. These molecules are varied and include dihydrogen (H2), carbon monoxide (CO), syngas, ammonia (NH3), methane (CH4), etc. Solar thermochemistry is one of four ways to produce these solar fuels. It uses the heat provided by concentrated solar radiation to reach the high temperatures required for chemical reactions that are already known and understood, such as hydrocarbon cracking, methanation, and the dissociation of water (H2O) or carbon dioxide (CO2). Here we will focus on the process of producing green hydrogen through solar thermochemistry using a porous ceria (CeO₂) based exchanger. This ceramic allows green hydrogen to be produced by introducing water vapour (H2O) through a redox cycle (reduction at 900°C and oxydation at 1500°C) at low partial oxygen pressure Po2. However, prior knowledge of the thermophysical (thermal diffusivity) and radiative (normal spectral emissivity) properties of ceria allows to optimise its porous architecture in order to maximise the efficiency of the process.
In this work, an experimental setup for estimating the normal spectral emissivity of cerium at H2 production temperatures is first described. Next, the estimation methodology is developed and presented. Finally, the results obtained on a dense ceria sample are presented and discussed.
