Techno-economic modeling and optimization of solar-driven high-temperature electrolysis systems

Abstract

a b s t r a c tWe present a techno-economic analysis of solar-driven high-temperature electrolysis systems used for the production of hydrogen and synthesis gas. We consider different strategies for the incorporation of solar energy, distinguished by the use of differing technologies to provide solar power and heat: (i) thermal approaches (system 1) using concentrated solar technologies to provide heat and to generate electricity through thermodynamic cycles, (ii) electrical approaches (system 2) using photovoltaic technologies to provide electricity and to generate heat through electrical heaters, and (iii) hybrid approaches (system 3) utilizing concentrated solar technologies and photovoltaics to provide heat and electricity, respectively. We find that system 3 generates hydrogen at a high efficiency (g STF = 9.9%, slightly lower than the best performing system 1 with 10.6%) and at a low cost (C fuel = $4.9/kg, lowest cost of all three systems) at reference conditions, providing evidence for the competitiveness of this hybrid approach for scaled solar hydrogen generation. Sensitivity analysis indicates an optimal working temperature for system 3 of 1350 K, which balances the increased thermal receiver losses with the reduced electrolysis cell potential when increasing the temperature. Lower working pressure always favors high system efficiency and low cost. The working current densities for thermoneutral voltage were determined for various temperature and pressure combinations, and trends for efficient and cost-effective thermoneutral operation were identified. The water conversion extent was optimized to avoid mass transport limitations in the electrodes while ensuring large fuel generation rates. For synthesis gas production, a H 2 /CO molar ratio of 2 can be achieved by tuning the inlet feeding molar ratio of CO 2 / H 2 O, temperature, and pressure. This study introduces a flexible simulation framework of solar-driven high-temperature electrolysis systems allowing for the assessment of competing solar integration approaches and for the guidance of the operational conditions maximizing efficiency and minimizing cost, providing pathways for scalable solar fuel processing.

Experiences from the urban planning process of a solar neighbourhood in Malmö, Sweden

“…Examples in literature that looked at both the energy performance of a renewable energy system and the economic performance are many (Esen, Inalli, & Esen, 2006, 2007Lin & Haussener, 2017;Thaker, Olufemi Oni, & Kumar, 2017). Li and Liu (2018) specified that the economic merits of a PV system mainly are determined by the system cost (including labour and maintenance), and the generated electricity.…”

Research advances towards large-scale solar hydrogen production from water

“…While it has been shown that integrating a concentrated solar thermal plant into the system to supply the heat and steam for SOSE could reduce the LCH to 6.6 USD/kg, the calculation was based on the optimistic assumption of 100% capacity factor for the electrolyzer. 330 LCH 92 of as low as 5.7 USD/kg has been estimated for similar systems, 331 but we note that the specific capital cost of the electrolyzer in this work, 0.17 USD/W, was an order of magnitude lower than the demonstrated value of 3-4 USD/W and even lower than the ~0.4 USD/W of PEM electrolyzers. 327,330 Furthermore, the discount rate or interest rate used in the financial calculation has a major but often overlooked influence on the LCH.…”

“…330 LCH 92 of as low as 5.7 USD/kg has been estimated for similar systems, 331 but we note that the specific capital cost of the electrolyzer in this work, 0.17 USD/W, was an order of magnitude lower than the demonstrated value of 3-4 USD/W and even lower than the ~0.4 USD/W of PEM electrolyzers. 327,330 Furthermore, the discount rate or interest rate used in the financial calculation has a major but often overlooked influence on the LCH. In fact, the sensitivity of levelized cost of energy from photovoltaics has been found to be highest towards the discount rate rather than energy efficiency or specific capital cost.…”

“…In fact, the sensitivity of levelized cost of energy from photovoltaics has been found to be highest towards the discount rate rather than energy efficiency or specific capital cost. 332 Indeed, optimistic values of 6% are found with reports of low LCH 326,330 and more conservative values of 10-12% with high LCH. [328][329] The economic feasibility of integrated and modular PEC water splitting has been directly compared in the same framework of assessment, with the former showing slight economic advantage (12.3 versus 13.1 USD/kg) because it does not require electrical interface equipment between the photovoltaic and electrolytic components.…”

The CPV “Toolbox”: New Approaches to Maximizing Solar Resource Utilization with Application-Oriented Concentrator Photovoltaics

“…The elevated temperature of the steam boosts the efficiency of the electrolysis process by lowering the effective energy barrier to water splitting [62]. This could be favorable if a source of "free" heat is available, which might be the case with a suitably economical PVT system [63]. Another possible application could be as a source of heat for carbon capture via amine scrubbing in industrial processes [64].…”