The proposed project will demonstrate a vanadium flow (VRF) battery energy storage system (BESS) technology to provide resilient and economical energy supplies for essential Tribal facilities in the Yurok Tribe community in Weitchpec, CA within the investor-owned utility service territory of Pacific Gas and Electric. The VRF BESS will integrate existing and planned distributed energy resources (DER) to provide resilient and economical energy supplies for essential Tribal facilities. The proposed VRF BESS, with a nameplate capacity of 0.5 Mega Watt (MW)/3.0 MW hours (MWh), has the ability to discharge at least 100 kilo Watt for durations up to 24 hours, and as much as 0.52 MW for short durations. Demonstrating these capabilities will deliver greater resiliency and grid-infrastructure benefits and lifetime energy cost savings over competing technologies. The project will demonstrate a technology that is more flexible, allowing 100% depth of discharge without impairing BESS capacity or lifespan, and achieving MWh-scale battery hibernation to substantially eliminate self-discharge. This technology will avoid the safety, flammability, and recyclability drawbacks of Li BESS technologies.
Construction is expected to begin on September 1st, 2026, and be completed by May 1st, 2029. The project is expected to operate for approximately 25 years beginning in 2029. The project is expected to utilize 3 VRF BESS energy unit containment vessels, which will be pad mounted side-by-side. A single VRF BESS power unit will sit atop the middle energy unit. The total estimated layout for the VRF BESS units is about 1,090 square feet. Additional equipment includes microgrid controls and switchgear, a lithium iron phosphate BESS, an emergency back-up diesel generator, and associated transformers, power conditioning equipment, controls and switchgear. These pad mounted components will occupy an additional approximately 2,290 square feet. All of this equipment will be located on an existing 12,700 square foot graded flat area with an existing home. The graded flat will be enlarged to approximately 22,000 square feet. The disturbed area will occupy approximately 43,000 square feet, including cut and fill slopes and an access road, and approximately 1,025 cubic yards of cut and fill will be generated and completely utilized on the site. In addition, an area approximately 64,000 square feet in area will be disturbed to clear land for a solar PV array and associated maintenance roads, including an estimated 975 cubic yards of additional cut and fill.
The BESS electrolytes are the main hazardous materials associated with the project. The three VRF BESS energy units contain approximately 146,000 liters of electrolyte, with an integrated secondary containment capable of containing the entire volume of electrolyte, as a safety container. All plumbing is located within the envelope of the secondary containment bundle. The VRF BESS is delivered to the site in a zero percent state of charge, fully discharged, but ready to operate and fill with electrolyte. During shipping electrolyte is contained within 1,000 L IBC totes, with sixteen totes per truckload. Shipping during inclement weather consisting of rain, fog, snow, or high winds as defined by the National Weather Service, is prohibited and a pilot vehicle will accompany the shipment with each load. Electrolyte is not handled on-site during construction or operations, except to transfer the electrolyte from the IBC totes to the energy units. The electrolyte transfer process is conducted by skilled technicians with appropriate safety gear and precautions, including a spill containment system. The lithium iron phosphate BESS has fully contained electrolyte, is shipped filled, and the possibility of an electrolyte spill from the lithium iron phosphate BESS is very remote due to the absence of free liquid electrolyte (it is largely absorbed within the cell materials). The lithium iron phosphate BESS also has small quantities of
coolant and refrigerant that are considered hazardous materials.
Sitework is expected to require access by approximately 10-20 light, medium, and heavy-duty construction vehicles each day for several weeks during land clearing and grading, active excavations for equipment pads and PV array supports, and deliveries of equipment and materials for the project. These vehicles will include personal vehicles for construction personnel as the bulk of the equipment, with water trucks, delivery vehicles, forklifts, and similar being the remainder. Previously disturbed vacant land in the immediate vicinity will be designated for parking and staging of equipment and materials during construction activities. The VRF BESS delivery will require four 40-foot shipping containers delivered and unloaded at site, and ten truckloads to haul the VRF electrolyte in IBC containers. In addition, trucks will deliver a control building, lithium iron phosphate BESS, emergency diesel generator, associated balance of system equipment, and approximately 1,160 solar PV modules. During commissioning, staff will require two vehicle trips per day, for approximately one month. Less than 30 construction workers will be on-site for several months during active construction, with fewer than 10 on-site during commissioning and testing activities. Chain-link fencing around the battery and power conditioning equipment is planned as part of the project, as typically required by electrical codes.
Trenching for electrical conduits and conductors between battery pad and equipment location and existing facilities will be required. Minor excavations of a few feet in depth or less will be required for installation of concrete pad mounted equipment. Clearing and grubbing will be required, as will some leveling, however, no import or export of soils is anticipated. The BESS and other related distributed energy equipment will be housed in outdoor-rated container enclosures, and no new small structures are planned for the project.
