# Investigation of Nanogrids for Improved Navy Installation Energy Resilience
###### Abstract  
Military bases perform important national security missions. In order to perform these missions, specific electrical energy loads must have continuous, uninterrupted power even during terrorist attacks, adversary action, natural disasters, and other threats of specific interest to the military. While many global military bases have established microgrids that can maintain base operations and power critical loads during grid disconnect events where outside power is unavailable, many potential threats can cause microgrids to fail and shed critical loads. Nanogrids are of specific interest because they have the potential to protect individual critical loads in the event of microgrid failure. We present a systems engineering methodology that analyzes potential nanogrid configurations to understand which configurations may improve energy resilience and by how much for critical loads from a national security perspective. This then allows targeted deployment of nanogrids within existing microgrid infrastructures. A case study of a small military base with an existing microgrid is presented to demonstrate the potential of the methodology to help base energy managers understand which options are preferable and justify implementing nanogrids to improve energy resilience. nanogrid; microgrid; resilience; systems engineering +
Footnote †: journal: Applied Sciences  
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Footnote †: journal: Applied Sciences  
energy during events that cause a base to be disconnected from the larger grid which improves base energy resilience [2]. However, events that occur within a base perimeter (e.g., airplane crash, adversary action, stored munitions explosion, fire, etc.) can disrupt, disable, or destroy a base microgrid which can cause critical loads necessary to support national security missions to be un-served even when grid power is available [5]. One potential avenue to improve energy availability to critical loads on military bases is nanogrids where highly localized generation, storage, and consumption of electricity is implemented to allow for individual critical loads to continue to be served even when microgrids go down. Efficiency, reliability, and resilience (sometimes called resiliency in certain DoN source documents) are the three pillars of energy security defined by DoN and Naval Facilities Engineering Command (NAVFAC) issuances [6]. The desire to increase energy security ushered in a new age of smart grid infrastructure for DOD installations and installations of other militaries with a focus on developing base microgrids. DOD installations adhere adhere defined as secure land locations where the maintaining and projecting of war-fighting strength is critical for executing national security missions to preserve the United States of America's national defense [7]. Microgrids have been used in many DOD installations to improve resilience and reliability [8]. Resilience, defined by the NAVFAC as \"the ability to respond, adapt, and recover from a disturbance\" is the focal pillar of energy security for this research [6]. In general, DOD microgrids aim for either 7 or 14 days of grid independence where only local generation and storage resources can support critical loads [8]. However, current DOD and DoN guidance (including NAVFAC guidance) has not addressed potential disruptions occurring to microgrid infrastructure. In addition to the three pillars of energy security, DOD has mandated that 25% of all power used on bases be renewably generated by 2025 which is often achieved by some combination of solar and wind power [9]. Microgrids are considered one of the key building blocks of current and future ashore and military power infrastructure. Hallmarks of microgrids include local energy generation and storage resources that are connected to loads within a clear microgrid system boundary such as an installation perimeter [10]. Many military microgrids also have the ability to connect and disconnect from the larger grid as needed [10].