The exceptional versatility of electricity storage is a double-edged sword for military microgrids.  

Storage, in its various battery chemistries and non-battery forms, can perform more functions and respond more quickly than any other power asset in a microgrid. Storage is increasingly deployed on military installations, in a variety of scales and for a range of resilience, renewable energy integration, and cost saving uses. That, along with improving technology cost and performance, is its positive.

However, the same versatility brings challenges in answering fundamental questions – Is electricity storage a more cost-effective and robust way to provide back-up power than other assets? If so, what types of storage, in what configurations, in what locations, and with what operational rules perform best? I.e., how can its energy security contributions be isolated and replicated for tech transfer? 

Those are the questions addressed by ESTCP’s “Large Scale Energy Storage and Microgrids” R&D topic. Six project teams, each with a different analytic and operational approach and often with different storage technologies, began work on these questions in late 2018. They are nearing finalization of their Phase I results in what is intended to be a three-phase effort for the most promising teams.

To create a rich data set of results applicable to military installations of various sizes, missions, locations, and Services, the project teams utilized a common set of representative hourly electricity data from the seven installations pictured below, along with actual utility rate and electricity market price data for the respective locations.

The project teams are expected to publish their Phase I findings on ESTCP’s website late in 2019, and the initial results have been extremely useful. They point to several types of electricity storage and operational patterns that can be included in microgrids to both lower lifecycle microgrid costs and enhance reliability performance during utility outages ranging from 1 hour to 1 week, compared to microgrids relying exclusively on diesel generators and uninterruptible power supply (UPS). Just as importantly, the results highlight where storage assets make less valuable and more costly contributions to resilience.

CHIL - Controller Hardware in the Loop; PHIL - Power Hardware in the Loop

To yield results applicable to a wide cross-section of installations and to focus investment dollars on the most promising resilience uses of storage, ESTCP structured this effort in three phases as shown at right. Phase I involves detailed hourly simulation of storage-enabled microgrid performance over a 20-year period compared to an ESTCP-provided baseline microgrid model without storage.

Phase II is likely to include testing of key storage system components and their integration with actual microgrid controllers in specialized, government-sponsored “hardware-in-the-loop” test facilities to validate or expose weaknesses of key simulation factors. As Phase II results warrant, field tests at one or more military installations will occur in Phase III to reach full fidelity in the technology validation process.

For more information on the work of the six project teams, see:

Ameresco: Demonstrating the Benefits of Long-Duration, Low-Cost Flow Battery Storage in a Renewable Microgrid

Electric Power Research Institute: Energy Security for Military Installations through Optimized Integration of Large-Scale Energy Storage into Microgrids

Raytheon Integrated Defense Systems: Advanced Phasor-based Control of Energy Storage Microgrids

Siemens Corporation: Comprehensive Microgrid Energy Storage Designs with Guaranteed Optimality

Southern Research Institute: Design, Modeling, and Control of Hybrid Energy Storage System for Defense Installation Microgrids

AccordEI: Modeling of a High-Efficiency, Resilient, Dual-Battery Microgrid combined with Diesel GenSet and Solar PV