# Investigation of Nanogrids for Improved Navy Installation Energy Resilience
## 5 Discussion and Future Work  
This paper presents a methodology that can be used to determine if supplementing existing microgrids on military bases with nanogrids may improve energy resilience. Through proper sizing of generation and storage resources, it is possible for nanogrids to eliminate or greatly reduce many of the energy disruptions to critical loads that can impact national security on military bases. We believe that the methodology will aid base energy managers in identifying which critical loads will benefit from implementing nanogrids for specific threats that are of concern to individual military bases. While we advocate for some threats to be analyzed in all cases, many threats are not universal across all bases. Thus, we assert that there is not universal guidance on which loads should or should not be outfitted with nanogrids.  
The methodology is specifically meant as a high-level systems engineering analysis of existing microgrid infrastructure and proposed nanogrid infrastructure. The time step on the simulations in the case study is 1 h. This large time step and the simple power flow model ignore real concerns such as transients that can trip protection equipment; the ability of specific generation and storage equipment, and power electronics hardware to be grid-forming; and other issues. If implementing nanogrids at a specific military base proves promising based on the results produced by the methodology, then detailed electrical engineering analysis should be conducted to verify no other concerns exist.  
Developing threat probabilities can be challenging especially for human-caused threats and even more so for situations where adversaries are involved. Producing detailed methods of estimating such probabilities are beyond the scope of this work. Natural disasters and other nature-caused threats have significant historical data available to estimate their probabilities of occurrence. However, climate change and other related factors may begin to call into question using historical data to estimate future probabilities of occurrence of natural threats.  
We specifically do not address the cost of increasing energy resilience through the implementation of nanogrids. Other work has investigated the costs associated with increasing resilience and has attempted to produce energy resilience versus cost curves for decision-makers to understand how much resilience may be gained with a specific level of investment [35]. A potential future expansion of this work is to include cost analysis.  
After recent events in Texas [3], we believe renewed focus will be placed on upgrading military microgrids to be more self-sufficient and not rely upon fossil fuels or regular fossil fuel delivery. Furthermore, price shocks in regional and global oil markets due to issues such as the closing of key sea lanes to tanker traffic have occurred in the past and are starting to occur as of writing this article due to things such as war and most recently a stuck cargo ship blocking a canal [70] can significantly impact military budgets. Removing highly variable diesel fuel bills from base energy manager budgets could be a significant stabilizing force on year-to-year management of energy infrastructure.  
We use MDI scoring to understand the relative importance of critical loads to national defense. However, MDI has several significant flaws and other recently proposed metrics have their own issues. Future work needs to develop a new method of understanding how each load on a military base impacts national security. One potential avenue to explore is mission engineering where tying specific mission objectives to specific loads under specific force protection postures may help to produce a better measure.