Energy storage is crucial to balancing the inherent variability of renewable energy generation such as solar photovoltaic, reducing fuel consumption, and providing critical power in the event of power outages. Solar photovoltaic, wind and other renewables are widely being adapted by the Navy for utility and micro-grid energy production.  

As with utility grid operators, the US Naval Facilities Engineering Command, Engineering & Expeditionary Warfare Center (NAVFAC EXWC)  is being faced with the challenges of intermittent and variability in energy production from such renewables.  As a result, utility operators must reduce their primary load generation to offset the incoming renewable energy.  In cases in which renewable generation is high, and consumption is low, the primary power generators must be reduced to their minimum operating load and excess renewable energy must be curtailed if energy storage is not available.  

To meet the Navy’s goals toward net zero emissions, NAVFAC EXWC has been looking towards novel energy storage technologies and power systems to supply clean renewable energy to their facility operations.  There has been particular interest in reversible solid oxide fuel cells (RSOFCs) in the energy sector for energy storage, grid stabilization and improvement to power plant system efficiency due to favorable thermodynamic efficiencies of high temperature steam electrolysis.  

In these systems, 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. Boeing has been active in the development of both PEM and SOFC system development and is working with NAVFAC EXWC to develop a novel fully integrated, grid tied RSOFC system for remote islands, military forward operating base microgrids and commercial utility energy storage.  

The RSOFC system is the largest fully integrated grid tied reversible solid oxide fuel cell system to be demonstrated, scalable from 50 kW to several MW (enough to fuel 40 average size homes for 12-24 hours) and can be utilized in nearly any location to help ensure energy secure and steady power supply while at the same time utilizing renewable energy sources. Its modular design helps support rapid deployment of energy solutions for the Navy and commercial utilities.  

The system is currently under operational testing and will be fully deployed in 2016.  

The fuel cell stack passed all tests conducted onsite at the manufacturer’s (Sunfire) factory in Dresden, Germany in July.  The stack will be integrated with the system in Huntington Beach in September 2015.  Of note the RSOFC only requires two resources to operate in a perfect hydrogen economy 24/7 with degradation less than 1%/1,000 hours of operation:  water and electricity (from the sun via solar photovoltaics).