An increasing demand in the marine industry to reduce emissions led to investigations into more efficient power conversion using fuels with sustainable production pathways. Solid Oxide Fuel Cells (SOFCs) are under consideration for long-range shipping, because of its high efficiency, low pollutant emissions, and fuel flexibility. SOFC systems also have great potential to cater for the heat demand in ships, but the heat integration is not often considered when assessing its feasibility. This study evaluates the electrical and heat efficiency of a 100 kW SOFC system for marine applications fuelled with methane, methanol, diesel, ammonia, or hydrogen. In addition, cathode off-gas recirculation (COGR) is investigated to tackle low oxygen utilisation and thus improve heat regeneration. The software Cycle Tempo is used to simulate the power plant, which uses a 1D model for the SOFCs. At nominal conditions, the highest net electrical efficiency (LHV) was found for methane (58.1%), followed by diesel (57.6%), and ammonia (55.1%). The highest heat efficiency was found for ammonia (27.4%), followed by hydrogen (25.6%). COGR resulted in similar electrical efficiencies, but increased the heat efficiency by 11.9% to 105.0% for the different fuels. The model was verified with a sensitivity analysis and validated by comparison with similar studies. It is concluded that COGR is a promising method to increase the heat efficiency of marine SOFC systems.

The performance of a 30-kW gasifier–SOFC–GT system was evaluated using thermodynamic calculations. Nickel/Gadolinia Doped Ceria (Ni/GDC) anodes were utilized for Solid Oxide Fuel Cells (SOFCs). These systems can achieve high electrical efficiencies of above 50%. The goal of the study is to evaluate trends in system efficiency when carbon dioxide as a gasifier agent is increased in enhanced carbon dioxide system. Carbon dioxide content was increased in both systems, leading to variants of both systems as compositions changed until they could no longer function efficiently. The trends in system variants were monitored. Although the gross efficiency increased, the net efficiency of the enhanced carbon dioxide system dropped. Absorbed heat and delivered gross which deals with flow of energy in sources / sinks was lower in enhanced scheme. Auxiliary power consumed was higher in enhanced carbon dioxide system variants, indicating that the compressors consume more power. Delivered net power was dropping for the enhanced case variants. Enhanced carbon dioxide system variants seem to have a slightly higher total electrical efficiency by a close range of less than 1%.

The prospect of using Tm²⁺-doped halides for luminescence solar concentrators (LSCs) requires a thorough understanding of the temperature dependent Tm²⁺ excited states dynamics that determines the internal quantum efficiency (QE) and thereby the efficiency of the LSC. In this study we investigated the dynamics in CaX₂:Tm²⁺ (X = Cl, Br, I) by temperature- and time-resolved measurements. At 20 K up to four distinct Tm²⁺ emissions can be observed. Most of these emissions undergo quenching via multi-phonon relaxation below 100 K. At higher temperatures, only the lowest energy 5d–4f emission and the 4f–4f emission remain. Fitting a numerical rate equation model to the data shows that the subsequent quenching of the 5d–4f emission is likely to occur initially via multi-phonon relaxation, whereas at higher temperatures additional quenching via interband crossing becomes thermally activated. At room temperature only the 4f–4f emission remains and the related QE becomes close to 30%. Possible reasons for the quantum efficiency not reaching 100% are provided.