Dependence on the national electric grid threatens the ability of the Department of Defense (DoD) to secure and sustain affordable power to perform missions on installations nationwide. The integration of microgrids offers a potential means to improve energy security at reduced cost. However, current state-of-the-art DoD microgrids generally use diesel generators as their primary power source. The cost of diesel fuel, fuel logistics, and environmental restrictions generally limit the use of generators in grid-tied service. This, in turn, limits achievable tangible economic benefits to motivate third party financing of microgrid implementation and sustainment.
To address this challenge, this project sought to demonstrate technical feasibility, provide a business framework, path find policy and procedural issues, and provide implementation guidance for high penetration renewable energy and energy storage microgrids. This entailed demonstrating reliable islanding using high penetration wind and energy storage, cybersecure execution of regulation services for Independent System Operator – New England (ISO-NE), and demand management capabilities.
Two primary technologies were employed in this project. The first was the UltraBattery® lead carbon (lead-acid/ultra-capacitor) Battery Energy Storage System (BESS). The UltraBattery® was developed to compete with Li-ion in High Rate Partial State of Charge applications such as frequency regulation, and renewable generation smoothing. The second was the Intelligent Power and Energy Management (IPEM) Microgrid Control System (MCS). The IPEM MCS combined “fast” distributed commercial off the shelf controls with a cyber-secure central supervisory microgrid controller and control architecture, building off of an earlier successful IPEM prototype demonstrated at Marine Corps Air Station Miramar under ESTCP project EW-201242.
Due to Air Force policy restrictions surrounding the use of the microgrid critical load generator, demonstration efforts were limited to grid tied operation, specifically focusing on cyber-secure provision of frequency regulation services using the BESS. The system successfully completed 335 hours of ISO-NE Regulation Test Environment testing with an average performance score of 97.4%. This enabled the system to enter full market operations, achieving an average hourly gross revenue of $24.80/hour at 1 megawatt regulating capacity, equivalent to $217K/year for 24/7 operations. This outcome, to the knowledge of the project team, is the first demonstrated example of cyber-secure frequency regulation in the U.S. Air Force.
This project shed light on several key implementation issues, most of which were non-technical in nature. The most significant issue was the constraints surrounding the use of critical load generators, and lack of Air Force policy regarding microgrids. These factors ultimately proved to be a major stumbling block and prevented islanding demonstration. Reconciliation of relevant Air Force (e.g., Air Force Instruction 32-1062) and DoD policy (e.g., DODI 4170-11: Installation Energy Management) remains an issue to implementation of microgrids at Air Force installations. Extensive efforts were made to the optimize microgrid design and operations to local market conditions, while conforming to policies put forth by the utility, ISO, and DoD. Careful attention to these factors would be essential to any project seeking to replicate aspects of the design.