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- By Chez Oxendine
- Energy | Environment
As California ramps up its renewable energy capacity, tribal nations are leading the charge in the state’s push for reliable and sustainable power.
By integrating long-duration batteries that can double the capacity of traditional microgrid storage solutions, tribes are not only securing critical infrastructure against outages, but also setting a new benchmark for energy resilience.
In transitioning major enterprises and community installations to renewable energy, tribes have grappled with the question of keeping the lights on through frequent power outages. Getting solar panels up and running is only one part of the solution. The energy also has to be stored for emergencies during periods of low generation, or heavy use.
Lithium ion batteries are usually the storage part of that solution. In California, which has the most battery storage in the country at 7.4 gigawatts, lithium ion batteries currently represent around 60 to 70 percent of existing energy storage per the California Energy Commission (CEC). These are typically employed alongside solar arrays to create a microgrid.
Existing lithium ion batteries can support a grid for between 1.5 to 4 hours each, depending on the size of the grid and the battery. Building sufficient arrays of lithium batteries can become both a technical challenge as well as a cost issue, says Mike Gravely, team lead for the CEC’s Energy Storage Team.
In response, tribes are tapping into long duration storage — or LDS — batteries, which provide 8 or more hours of storage. The CEC’s focus on LDS technology began in 2022, Gravely said, coinciding with its commitment to support more tribal energy projects. Despite initial higher costs, the state has invested $140 million in LDS research and development, with an additional $190 million budgeted in 2023-2024.
“We’re investing in it here for two reasons: we believe, one, it will provide California with more stability to have a diverse storage portfolio,” Gravely said. “Two, we believe these technologies will be cheaper as they mature.”
Going with the flow
Flow batteries, an increasingly popular LDS technology, use a liquid medium like bromine or vanadium to store energy as opposed to solid lithium. While flow batteries cost an estimated $444 per kilowatt hour compared to about $304 per kilowatt hour, according to Energy Storage News, flow batteries can store and distribute more than 10 hours of energy, making them an attractive option for tribes like the Rincon Band of Luiseno Indians.
The tribe has been subject to rolling brownouts and other power outages as heat and wildfires pummeled California’s grid in recent years. Using a $31 million grant from CEC awarded in 2020, the Rincon Band secured a vanadium flow battery from UK-based energy company Invinity.
Prior Tribal Business News reporting highlights that tribal interest in flow batteries extends beyond using them in California. In April 2024, the Puyallup Tribe in Washington invested in flow-battery firm Skip Technologies Inc. and announced plans to manufacture bromine-based flow batteries for the Portland-based company.
Flow batteries avoid extractive mining that lithium batteries typically require, Skip Tech Chief Strategic Officer Ben Brown told Tribal Business News at the time.
“You're ripping up the earth to get (it),” Brown said. “It's a huge impact to get the lithium that we need for electric vehicles and other technology.”
That is another upside of flow batteries: the materials required are much easier to acquire than lithium, whose demand could end up outstripping supply “in a few years,” Gravely said.
Lead by example
By using a flow battery as a long-duration storage solution, the Rincon Band hopes to reduce the threat of important tribal buildings — such as the fire station or the tribe’s resort — losing power in critical moments.
“It took a lot of research, but this was the technology we decided best fit our needs,” Mazetti told Tribal Business News. “The capacity means we don’t have to worry about reliability.”
The Rincon Band microgrid grant is one of ten such tribal microgrid projects being developed in partnership with the CEC, totalling $110 million in investments since 2020. Seven of those projects feature some manner of LDS storage; one, for the Viejas Band of Kumeyaay Indians, could become the largest LDS installation in the state.
The Viejas Enterprise Microgrid will utilize a total of 70 megawatts of flow battery storage by September 2025. Financing recently closed on the microgrid project, which will cost a total of $150 million, and will be the first project served by the Department of Energy’s Tribal Energy Financing Program.
Viejas chairman John Christman said the storage will enable the tribe’s microgrid to fulfill its overall goal of improving tribal energy sovereignty and reliability. The project will also lighten tribal operations’ impact on the overall power grid.
“As a large-scale electricity consumer, we recognize our responsibility to lead by example in lessening our burden on the electric grid,” Christman said in a statement. “It is our sincere hope that the demonstrated financial and environmental merits of this project will serve as a repeatable model for others.”
Energy sovereignty
Across the board, tribal enthusiasm for long duration storage — and microgrids in general — has been high, said CEC Director of Tribal Affairs and Tribal Liaison Sierra Graves.
“Since the 2022 CEC resolution to support tribal energy, we've seen tribes looking at energy sovereignty in various ways,” Graves said. “But the most common thing we hear is a desire for microgrids and that full energy independence, so we've had some really exciting projects happen as a result.”
LDS-enabled microgrids like those with the Viejas Band and Rincon Band will serve as demonstration projects for the technology, Gravely said. In addition to providing tribes with access to much-needed reliability, these projects can impact the wider renewable energy sector in California by showing off new configurations of short term and long term storage.
The upside for the state is valuable data on how best to approach large-scale energy storage, Gravely said. The upside for tribes is access to the new technology - and the requisite funding that comes along with it, which can be crucial given that microgrids often don’t generate revenue on their own, Gravely noted.
In the long-term, thanks to demonstration projects spearheaded by these tribes, California’s overall energy storage portfolio should become more varied and effective, Gravely said.
“There's a general optimism not only here but at the Department of Energy, and in Europe and Asia, that long duration storage has a role,” Gravely said. “We are very interested in these technologies, but also there is a real desire to help the tribes in California - to give them choices, to help them fund projects and make decisions on their own. We're able to demonstrate these projects, and prove these technologies, and then share that with the rest of California.”
