A Cogeneration System Based on Solid Oxide and Proton Exchange Membrane Fuel Cells With Hybrid Storage for Off-Grid Applications

Abstract

Solid oxide fuel cells (SOFC) have developed to a mature technology, able to achieve electrical efficiencies beyond 60%. This makes them particularly suitable for off-grid applications, where SOFCs can supply both electricity and heat at high efficiency. Concerns related to lifetime, particularly when operated dynamically, and the high investment cost are however still the main obstacles toward a widespread adoption of this technology. In this paper, we propose a hybrid cogeneration system that attempts to overcome these limitations, in which the SOFC mainly provides the baseload of the system. Introducing a purification unit allows the production and storage of pure hydrogen from the SOFC anode off-gas. The hydrogen can be stored, and used in a proton exchange membrane fuel cell (PEMFC) during peak demands. The SOFC system is completed with a battery, used during periods of high electricity production. We propose the use of a mixed integer-linear optimization framework for the sizing of the different components of the system, and particularly for identifying the optimal trade-off between round-trip efficiency and investment cost of the battery-based and hydrogen-based storage systems. The proposed system is applied and optimized to two case studies: an off-grid dwelling, and a cruise ship. The results show that, if the SOFC is used as the main energy conversion technology of the system, the use of hydrogen storage in combination with a PEMFC and a battery is more economically convenient compared to the use of the SOFC in stand-alone mode, or of pure battery storage. The results show that the proposed hybrid storage solution makes it possible to reduce the investment cost of the system, while maintaining the use of the SOFC as the main energy source of the system.

Review of Fuel Cell Technologies and Applications for Sustainable Microgrid Systems

“…However, certain limitations exist when technology, such as the solid oxide FCs, for instance, is employed as the only power source in grid-independent applications. These are reflected in the degradation of the system's life span, especially when the operation is dynamic, and the high capital cost, which affects the proliferation of FC systems [139]. The degradation of FCs' lifetime will unavoidably affect their durability.…”

“…Then, it is of interest to put in place some control strategies to coordinate the operation of microgrid systems that are based on multiple energy systems. [140] A recent study considered a CHP system that is based on solid oxide and proton exchange membrane FCs integrated with a hybrid storage configuration for off-grid purposes [139]. The authors proposed the hybrid CHP solutions that seek to overcome the mentioned limitations, in which case the solid oxide FCs are used to satisfy the system's baseload, while the production and storage of pure H 2 from the solid oxide FC anode off-gas was achieved by integrating a purification unit with the system arrangements.…”

Achieving Climate Targets via the Circular Carbon Economy: The Case of Saudi Arabia

“…One report showed that underground gasification can be integrated with a solid oxide fuel cell (SOFC) system generating electricity from syngas leading to a net efficiency of 34% which is 4.2% higher than the efficiency for UCG when coupled with steam turbines [22]. SOFCs are the most promising types of fuel cells for clean power generation, especially when coupled with carbon capture systems, and its theoretical efficiency can be as high as 90% [23][24][25]. Nonetheless, many technical and economic issues remain for its wide implementation including scaling-up, cost, safety, and reliability.…”

A Comprehensive Review and Technical Guideline for Optimal Design and Operations of Fuel Cell-Based Cogeneration Systems

“…Several studies in the literature have also focused on optimizing the size of the various components of the cogeneration system [38,59,60]. From these studies, comparisons of various configurations on the cogeneration performance is essential to avoid oversizing or under sizing of the system for the specific energy demand and applications.…”