Solid Oxide Cell based system for Sector Coupling Applications

System Design & Techno-economic Analysis

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Abstract

The energy transition towards a fossil fuel free society presents ambitious challenges ahead. The highly potential renewable energy sources are becoming competitive and increasingly adopted for power generation, while for sectors such as residential, industrial or transportation still solutions have to be found. Sector coupling and energy storage are presented as alternatives to increase RES integration and reduce emissions. Given the different applications and requirements in each of these sectors the combination of multiple technologies with different characteristics will be needed. Among these technologies, Solid Oxide Cells have shown huge potential and increasing attention based on their unique characteristics. This research advocates for pushing further the integration of renewable energy sources trough Solid Oxide Cell based systems.

At first, a review of the state-of-the-art technologies for sector coupling and energy storage is presented, the limitations and challenges at the sector level are addressed, and the value and research status of Solid Oxide Cell systems is conveyed. A selection of suitable sector coupling applications has been done based on SOC unique characteristics. Their functional requirements have been investigated for the future system design. The selected processes have been modeled in Aspen Plus to further conduct an energy and exergy analysis with the objective to understand the effect of the operating conditions and functional requirements on the thermodynamic performance. To conclude, a techno-economic analysis has been performed to determine the economic competitiveness and feasibility of these systems.

Through the thermodynamic optimization, in electrolysis mode exergy efficiencies of 78.93% and 80.38% are achieved for the methane-based and methanol-based system respectively. When operating thermoneutral, lower temperatures are desirable for both systems, but pressurization only has positive effects in the methane case. The upgrading process has a considerable impact on the process performance highly dependent on the operating conditions. In fuel cell operation, the methane-based system achieves 60.33% in comparison with 52.10% for methanol at high temperatures and environmental pressure. From a techno-economic perspective, stack cost is the main driver of the plant capital cost highly influenced by current density and lifetime, while the operational costs are mainly determined by electricity and carbon price. Onshore wind is presented as the best alternative for renewable energy supply due to higher capacity factors, under realistic considerations a 445 EUR/tn LCOMEOH is accomplished which could become market-competitive for future carbon emission’s prices.