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Ensure Unmatched Thermal Management to Foster Reliable Performance Across the Grid
The Importance of Temperature Uniformity (±1.5°C) to Achieve Consistent Frequency Control
Liquid cooling optimally maintains the temperature of battery storage containers within a range of +/- 1.5 degrees Celsius. Temperature stability of this level is crucial to enable batteries to respond rapidly and accurately to changes in frequency. In the absence of such uniform temperature control, the batteries become lethargic and their efficacy declines rapidly. These systems, as proven, are able to control grid frequency within a 0.1 Hz range throughout sudden demand changes. In contrast, air-cooled systems almost always demonstrate a 5 degree temperature differential, which, in addition to other factors, results in frequency control problems and affects the reactive power output. UL 9540A tests show that proper heat management results in a 40\% reduction in frequency-related problems as compared to air cooling systems. In large-scale grid applications for renewable energy sources, it is necessary to achieve this level of thermal uniformity to avoid larger systemic failures.
Case Evidence: AES Alamitos 400 MWh Project – 99.2% Availability with Liquid-Cooled Battery Storage Containers
The AES Alamitos 400 MWh project achieved 99.2% annual availability with liquid-cooled battery storage containers. This level of availability demonstrates how effective the thermal design is and how operationally resilient the entire system is. For a full year, this configuration was operational and contracted to the grid, including periods of continuous discharging, shifting demands, and long operational durations. The configuration was also contracted to provide active frequency response and load balancing for the period in question. How was this achieved? The system’s integrated liquid cooling system effectively eliminated the thermal issues caused by other systems and maintained a consistent optimal temperature for each individual cell. This resulted in a 50% reduction in unplanned maintenance and thermal issues. This configuration achieved additional revenue from fast response ancillary services during the project’s operational period, in addition to a decreased operational and maintenance (O&M) cost. This project is further evidence and a viable solution to the rapidly growing need of liquid-cooled containers at large-scale energy storage projects.
Improved Safety With Additional Integrated Mitigation of Thermal Runaway
Data from UL 9540A Testing: Why 78% of BESS Events are Caused by Air-Cooled Dependable Hot Spots
Per UL 9540A testing, uneven heating is the largest safety hazard present in large scale battery energy storage systems. The largest challenges we face derive from the aforementioned hot spots on air cooled systems. When the air being cooled in these systems cannot be cooled by more than 15 degrees Celsius between battery packs, some batts are cooled to far below their safe operating temperatures which accelerates degradation. They quickly create a significant imbalance in electrical resistance, and increase the likelihood of thermal runaway during high state of charge cycles. Once this runaway condition is reached, the heat will rapidly spread to adjacent cells, as the aforementioned cooling system will not be providing sufficient cooling, and there will be ample airborne oxygen to feed the fire. Within just a few minutes, what could have been a minor issue will develop into a fully involved fire.
Dielectric Coolant + Real-Time Fire Detection: 67% Reduction in Propagation Time
When combined with immersion dielectric cooling, multi-sensor predictive analytics can reduce thermal runaway propagation time by as much as 67%. The specialty non-conductive cooling liquid soaks up heat 3.5 times more than air and also blocks oxygen, as well as physically keeping failing cells separated. Real time monitoring systems can detect early signs of trouble such as small changes in voltage, sudden increases of CO2, and localized temperature increases. Once a system detects these phenomena, it can autonomously isolate the affected modules in mere seconds. This means that instead of controlling problems that can spread to other containers, issues are contained right where they originate. In field test studies, we have seen an average response time of 8 minutes drop to 2.5 minutes. This time improvement significantly increases the level of incident containment, and also increases the safety of personnel potentially exposed to hazardous conditions.
Longer Lifespan and Lower O&M Costs with Precision Cooling
DOE 2023 Benchmark: 15–20 Year Cycle Life vs 10–12 Years for Air-Cooled Systems
US Department of Energy 2023 BESS Performance Benchmark Report, for example, with regard to precision liquid cooling for lithium-ion batteries, it involves incorporating cooling mechanisms that regulate temperature to within a band of approximately ±1.5°C. This helps reduce the aggressive capacity loss experienced with air cooled systems. So, it helps the batteries offer more cycle life. Instead of running for a typical 10 to 12 years with conventional cooling, the batteries can run for 15 to 20 years while maintaining more than 80% of their original capacity. In general, the repeat cycle life of the batteries means that they will need to be replaced three times less often. This reduction in the frequency of replacement batteries translates to a lower cost with each replacement. The Ponemon Institute's lifecycle cost analysis, in this regard, demonstrates that over time, companies will save approximately $740,000 for every 100 megawatt hours of storage capacity.
Hot-Swap Modularity in Battery Storage Containers Reduces Downtime by 92%
Storage containers are designed to allow technicians to perform battery module replacements on-site. This means entire systems can remain operational while modules are swapped out and the time spent on maintenance can be greatly reduced. ERCOT's 2023 test program confirmed modules can reduce monthly downtimes, on average, from 14.5 hours to just over 1. In conjunction with some of the predictive health tools, system uptime can be brought to nearly 99% and operational and maintenance labor costs can be reduced by approximately 60%. Another significant advantage of this modular design is the ease with which additional modules can be integrated into the system. Modular battery solutions are designed to be integrated into existing systems without the need to reposition or reconfigure foundations, electrical wiring, or cooling systems. This significantly reduces the need for expensive retrofits and allows new setups to be deployed much more quickly compared to conventional solutions.
Cost-Effective and Space-Efficient Scalable Storage Solutions for High-Density Locations
Liquid cooled battery storage containers provide about 40% more storage per cubic meter than air cooled containers and are therefore more cost effective for dense urban environments such as city power substations and manufacturing sites, as well as off-grid microgrid systems where land costs are very high. dense packing Beyond 1 megawatt per battery unit, air cooled systems pose a risk of “hot spot” failures and reduced life of packed assemblies. liquid cooled battery containers distribute cooling liquid Even packed over 1 megawatt per container to assist in controlling imbalances in temperature and allowing for vertical and closer battery packing. Modular containers also help to reduce time and costs by minimizing onsite manufacturing. Compared to other container designs, air cooled systems are ready for 3x faster deployment.
F.A.Q.s
Why is liquid cooling more optimal than air cooling for batteries?
For batteries, air cooling frequently experiences larger temperature swings and uneven cooling. This leads to poor performance, decreased battery life, and increased maintenance or replacement needs. Liquid cooling avoids these problems by providing and keeping temperatures consistent.
Why is precision cooling beneficial for batteries?
By preventing battery temperatures from exceeding optimal, precision cooling prolongs battery life and helps batteries maintain usable capacity. Therefore, liquid cooled batteries will have a lifespan of 20 years, while air cooled batteries will only have a lifespan of 10-12 years.
What is the importance of thermal runaway mitigation regarding the safety of batteries?
Mitigation of thermal runaway plays an important role in safety of batteries because it limits the rapid movement of heat, and fire, in battery systems. Integrated systems for dielectric cooling and active fire detection reduce the time of heat propagation and mitigate damage.