Testing Long-Term Microgrid Energy Storage for Military and Indigenous Applications

Long-term energy storage (LDES) is best suited for applications where energy is needed for extended periods of time and when renewable or distributed energy sources are not producing power. And these technologies can provide additional resilience to microgrids, said Jana Gerber, president of Microgrid North America at Schneider Electric.

The US military is particularly interested in implementing the LDES system at mission-critical facilities to counter cyberattacks and extreme weather conditions, she added.

In California, where wildfires are causing power outages and public safety concerns, the California Energy Commission (CEC) is working with Indian Energy—a Native American-owned microgrid developer that focuses on utility installations for government and tribes—to learn more about LDES technologies through a series of grants.

How LDES Helps Tribal Communities

For tribal communities prone to outages, LDES can play an important role. A primary goal for these communities is to achieve energy resilience through the implementation of microgrids and renewable energy. They also want to take control of their energy future and reduce energy costs.

According to the U.S. Department of Energy (DOE), LDES technologies can store electrical energy for more than 10 hours, whereas more common high-power lithium-ion batteries store electrical energy for 1.7 to 4 hours.

LDES options include chemical, thermal, and electrochemical technologies. Most LDES technologies are scalable, have modular designs, and use relatively inexpensive and abundant materials. They are also less susceptible to ignition than lithium-ion.

Moving to LDES levelized costs of $50/kWh

LDES suppliers are working to lower the levelized cost of the technology as much as possible, with the DOE targeting a levelized cost of $50/kWh. Larry Zulch, CEO of Invinity Energy Systems, which supplies vanadium flow batteries, said its battery levelized costs are now below $100/kWh. And ESS, which supplies iron flow batteries, expects its batteries to drop below $200/kWh by 2030, said Hugh McDermott, senior vice president of business development and sales at ESS.

Solar Microgrid with LDES for Rincon Reserve

CEC recently funded the use of 18 4-MWh Invinity flow batteries in a solar microgrid project for the Rincon Band of Luiseño Indians on the Rincon Reservation near Valley Center, Calif. The batteries, which will be installed by PowerFlex near a new 1-MW expansion of the existing solar array, will be used to store excess solar energy that can be discharged to provide power during the day or night.

Jan Petrenko, Invinity’s regional manager for North America, said the microgrid’s solar capacity is 0.96 MW, which will be added to the 1 MW currently deployed on the reserve. Without the use of diesel or other fuels, the microgrid can be offline for up to 10 hours. The facility will provide grid service to San Diego Gas & Electric, reducing demand charges on the reserve’s monthly bill, she said.

Testing Different LDES Technologies at Miramar Air Station

Meanwhile, Marine Corps Air Station Miramar’s Rapid Integration and Commercialization Unit (RICU) is testing how advanced LDES technologies can be incorporated into a utility microgrid, an effort that is a collaboration between Indian Energy, CEC and the Department of Defense. Phase II of the study was funded in May by CEC through a $4.85 million agreement between CEC and Indian Energy, according to a news release from ESS, which is participating in the project.

In addition to the ESS battery, LDES technologies being studied at RICU include the Viridium battery, the EOS zinc-based liquid water battery and Amber Kinetics’ supercapacitor and flywheels, said Craig Reiter, CEO and chief sustainability officer at Maada’oozh, a Native American-owned energy and environmental company involved in the project.

He said the research could lead to more than one LDES technology being deployed at a given site because different technologies offer different energy delivery capabilities.

In addition to CEC, the US DOE is supporting LDES projects. The DOE Office of Loan Programs has made a conditional commitment to partially guarantee a $72.8 million loan for the development of a solar plus LDES microgrid for the Viejas Band of the Kumeyaay Indians. The 10-MWh Invinity flow battery system is being built, funded as part of a $31 million grant to Indian Energy to provide 100% renewable backup power and sustain critical operations for the tribe.

LDES performs better in some applications – for now

LDES technologies are seen as key to harnessing intermittent renewable energy sources, increasing the resilience of power grids and reducing dependence on fossil fuels.

But their costs and benefits vary depending on the application.

The CEC study found that LDES can be a cost-effective support for grid decarbonization and environmental justice projects, but customer microgrid resilience requirements may make LDES less cost-effective.

“New revenue streams, electricity rate structures, and progressive environmental policies could change the relative economics of LDES microgrids,” the report says. “Tariff reforms that shift utility revenue requirements from volume-based to fixed-cost would hurt microgrids, while reforms toward real-time pricing would benefit them.”