Survey: Overheating batteries are not the reason for the disruption of the world's largest energy storage project

　　Vistra Energy, the owner of the world's largest battery storage project, expects the first phase of the Moss Landing energy storage plant to be back online in the first half of this year. As planned, the first phase (300MW/1,200MWh) of the Moss Landing battery energy storage project deployed in Monterey Bay, California, will come online by the end of 2020, followed by the second phase (100MW/100MW/h) in August last year. 400MWh).

　　(The Moss Landing battery energy storage project uses batteries from LG Energy Solution)

　　However, according to industry media reports, the first phase of the battery energy storage project suffered a battery thermal runaway event on September 4 last year, which interrupted operations and is still unable to operate. The second phase of the project is still in operation.

　　Vistra Energy earlier this January published the main findings of the accident at the Phase 1 project and the corrective actions related to the incident. The company said the incident caused partial damage to about 7 percent of the batteries in the first phase of the project, while other facilities and control systems were also damaged in the incident.

　　The investigation indicated that the incident did not appear to be caused by an overheating of the battery modules, but rather that the sprinkler system reacted to fumes from the air handling facility.

　　Vistra Energy said the early smoke detection device (VESDA) in the field was triggering the water spray function because of certain setpoints, which may have been caused by a programming error in the early smoke detection device (VESDA).

　　The specific failure process is that some of the joints between the hose and the pipe are not tight, causing the sprayed water to leak onto the battery rack, resulting in an electrical failure that causes the battery to overheat. The overheating of the batteries released more fumes, which in turn caused the thermal suppression system of the first phase of the project to activate more water sprays, which damaged more batteries.

　　The findings indicated that the battery pack was in the normal operating temperature range before the improper water spray was triggered.

　　Local firefighters rushed to the scene for disposal, but did not need their assistance to control the fire. The incident did not cause harm to the personal safety of staff, nor did it negatively impact the local community.

　　The first phase of the project with an installed capacity of 300MW consists of three 100MW battery storage projects with a total of 99,858 LG Energy Solution batteries installed.

　　Vistra Energy said it hopes to bring the first phase of the project back online in an alternating fashion, with 100MW of battery storage systems expected to be brought back online in the first quarter of this year, and the rest of the battery storage systems to be brought back online in the second quarter of 2022. The company is now repairing and commissioning the Phase 1 project and implementing improvements to improve the Phase 1 original design.

　　Corrective actions will be updated: stress test the thermal suppression system and identify the type of leak, install an air monitoring system to continuously monitor the thermal suppression system wiring, review VESDA system programming, and install smoke detectors in the air handling unit.

　　Another problem is that water leaking onto the upper cells of the energy storage system battery rack falls through the gaps and onto the lower cells. Those gaps will be sealed, Vistra Energy said.

　　Vistra Energy recently announced plans to further scale up the Moss Landing battery storage project by an additional 350MW/1,600MWh, which will bring its total size to 750MW/3000MWh. The company has signed a 15-year resource adequacy agreement with California Utilities (IOU) Pacific Gas & Electric (PG&E) for the expansion of the project, which is pending approval by the California Public Utilities Commission (CPUC).

　　Vistra Energy said that while the expansion could be completed by June 2023, the Moss Landing battery storage project involves repurposing much of the natural gas-fired power plant and leveraging its grid interconnection and transmission and distribution (T&D) infrastructure, if market conditions and contracts provide more deployment opportunities, the final deployment scale may reach 1,500MW/6,000MWh.

　　SES Power believes that lithium battery energy storage systems have shown a global explosive growth trend. Customers often focus on price. In fact, the price should be based on comprehensive considerations such as performance, safety, and stability. The ternary lithium battery with high energy volume ratio has more energy than the lithium iron phosphate battery, but the safety is superior to the lithium iron phosphate. SES Power has rich experience in lithium battery packs for energy storage systems. It is recommended that customers use lithium iron phosphate batteries first, such as 12V100Ah, 12V200Ah, 24V100Ah, 48V100Ah and other modular lithium batteries. If the customer adopts a ternary lithium battery with a higher capacity ratio, we will increase the safety protection of the battery according to the actual situation. This is not only in terms of electronic structure, but also needs to be comprehensively dealt with in terms of mechanical mechanism, damage and impact.