Field Demonstration of a Novel Reversible SOFC System for Islanded Microgrid Energy Storage

Abstract

The high cost and energy security of importing fuel to islanded grids and communities has led to a growing need to generate power onsite with alternative and renewable energy technologies while reducing logistics costs of importing electrical power. The ability to provide independence, endurance, reliability, and resilience of power compels both remote and critical infrastructure loads to integrate greater capabilities into their microgrid systems. However, grid operators are being faced with the challenges of variability and intermittent energy production from renewables. Therefore, energy storage has become a critical component to balance micro and utility grids, improve efficiency, reduce fuel consumption, enable localized grid independent energy secure power in cases of emergencies or unreliable traditional grid use, and provide critical power in the event of power outages. There has been particular interest in reversible solid oxide fuel cells (RSOFCs) in the energy sector for electricity, energy storage, grid stabilization and improvement to power plant system efficiency due to favorable thermodynamic efficiencies of high temperature steam electrolysis. With funding from Naval Facilities Engineering Command and Expeditionary Warfare Center (NAVFAC EXWC), Boeing’s Advanced Technologies Program, using Sunfire fuel cell technology, has developed the largest ever fully integrated grid tied RSOFC system that uses sunlight and sea water to generate and store energy with no logistical tail. In this system, excess grid energy or curtailed power generated by renewables is sent to the system operating in electrolysis mode to produce H2. The H2 is stored and then used in the system’s fuel cell mode to provide supplemental power to the grid during peak hours or as needed. The system was designed to run off of sea water for cooling and water feed for electrolysis via an internal desalination unit or via the water recycle system. As part of this program, Boeing has developed a H2 storage and compression system, power distribution system, and master controller to interface with the fuel cell subsystem developed by Sunfire. Previous results showed that the system exceeded expectations with an electrolysis efficiency of > 80% LHV and an overall system efficiency of 60% LHV with compression and liquid water feed. The system has been shipped to Pearl Harbor on the island of Oahu, Hawaii to undergo a 6 month demonstration in the field on a working island microgrid. The intent of this demonstration is to validate the opportunity to insert reversible fuel cell systems with greater power generation (e.g. up to 1 MW) into microgrids on both remote islands and expeditionary applications. This paper will discuss test results and challenges of demonstrating a RSOFC system in island microgrid environments. It will also discuss how the RSOFC system fits into the overall microgrid concept for NAVFAC and helps to address a logistic free hydrogen economy in remote areas.