Sodium-Metal-Halide Battery Energy Storage for DoD Installations
Daniel Cohee | PDE Total Energy Solutions
Objectives of the Demonstration
This project had a goal of demonstrating and assessing the energy security, energy efficiency and reliability benefits realized from the integration of a 1 Mega Volt Amp (MVA), 250kW, 576 kWh, Battery Energy Storage System (BESS) at a US Department of Defense (DoD) base of operations. This BESS unit was based upon the Sodium Metal Halide technology which was being produced in Schenectady, NY by the General Electric Company.
The objectives of the demonstration program were:
- Co-Gen Power Factor Improvement; to improve the efficiency of the main co-generation plant by providing reactive power support with the BESS
- Peak Shave Functionality (and economic benefit) to reduce the monthly electricity demand charge by reducing the peak power draw via BESS discharge during the peak hours
- Renewable Energy Smoothing 1 (grid tied), to assist with renewable power intermittency by dispatching the BESS power
- Renewable Energy Smoothing 2 (grid independent), to help leverage more renewable energy during grid independent mode, by dispatching the BESS to smooth the power profile and ensure frequency and voltage stability
- Durathon™ Battery Bank Availability, monitoring the reliability of the BESS
The team lead by PDE Total Energy Solutions (PDE), designed, built, and tested the BESS at the Dynapower facility in Burlington, VT. The installation of the BESS unit at the Marine Corp Air-Ground Combat Center (MCAGCC) base was delayed several times due to panel failures in the solar field and other infrastructure upgrade projects, some of which also required utility interconnection agreements.
Eventually a mutual decision was made by ESTCP, MCAGCC and PDE to pre-maturely terminate this project before the final demonstration, due to:
- Failure of the Sodium-Metal-Halide technology’s ability to succeed in the marketplace, and its subsequent termination as a public product offering, after 4 years of production
- Concerns that the prototype BESS unit could not be operated by other entities due to its status as an experimental prototype, which had product liability concerns
- Changes in the infrastructure at the MCAGCC which reduced the benefit and impact of the proposed BESS
The key technology demonstrated was the Sodium Metal-Halide battery system, which was marketed by GE as the Durathon™ product line. This battery technology featured robust packaging that was insensitive to ambient temperatures, it had benign failure modes, and long cycle life. The major limitation on the technology was the pricing and performance was not competitive with recent developments in Lithium-ion based solutions. There were only two manufactures of the Sodium Metal-Halide (also known as Sodium-Nickel Chloride).
The performance of the system was never evaluated at the DoD base, but the technology was tested at the Dynapower facility in Burlington, VT before shipment to base. Most of the operating modes were verified prior to shipment to the MCAGCC.
The effectiveness of the BESS to meet the objectives are summarized here.
- The Sodium-Metal-Halide technology could operate at extreme ambient temperatures, but the early prototypes did struggle with managing sand ingress.
- The Sodium-Metal-Halide technology was not successful in the marketplace and was overcome by competition from multiple vendors and developers of Li-Ion technology, hence it was terminated as a product offering.
- Calculations show that a BESS unit can technically address the functions of peak power shaving, renewable smoothing, and power factor assistance, but there is little to no financial benefit for serving these during normal grid tied operation. This is due to either the lack of financial incentives, or dis-incentives, or a tradeoff between losses in the network vs. losses in the BESS.
- Demonstrate how a BESS could assist DoD installations during microgrid island operations to achieve more energy surety.
No transition or future implementation of the technology will occur due to GE no longer supporting the battery technology.
The inverter was specifically designed for the Durathon prototype battery used on this project and it has been determined the cost to reconfigure the unit is more costly than procuring a new unit. The inverter will be removed from site and trucked to a government facility for scrapping or redeployment.
The Durathon battery will also be removed from site and trucked to a government facility. It was determined that the batteries were not warranted, nor did support from GE existing to energize the battery. It is in PDE's opinion the batteries should be recycled due to lack of appropriate personnel who need to perform pre-energization safety checks and procedures.
The Microgrid controller GE was to integrate to the U90 has also been abandoned in lieu of a new control system, thus all control equipment onsite will be turned over to the base personnel.
It should be noted that when installing experimental equipment on an active base the following challenges were encountered:
- Timely submission of utility interconnect agreement due to competing projects and base decision to submit the BESS interconnect with the new co-gen plant that was installed. Had this not been a hurdle the technology could have been tested
- Change in MCAGCC 29 Palms project management personnel caused a restart of the project three times. New personnel required time to familiarize themselves with the project prior to being able to implement construction and processes required to energize the BESS
- Delays caused additional costs for both PDE and GE requiring contract amendments