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SMA Altenso
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WESTRAFO
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STULZ WallAir series, WXUC5, 35kW monoblock air conditioner
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BESS (Battery Energy Storage Systems)
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Large-scale energy storage applications
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Constant and uniform temperature of 25°C inside a 40” container
Reliable, efficient and customized air conditioning for large-scale energy storage
Energy storage is becoming a key technology, especially in connection with renewable energy sources such as solar or wind energy. Currently, the most efficient and mature technology for large-scale energy storage is BESS (Battery Energy Storage Systems) which are based on batteries. These systems are typically represented by containers full of batteries that need to be uniformly cooled at constant temperature of about 23°C during charging and discharging. This is where the work done by STULZ (a leader in customized air conditioning) together with WESTRAFO (a leader in the electromechanical and electrical transformer sectors) comes into play, serving the customer SMA Altenso (Altenso).
The customer
SMA Altenso (Altenso) is an international system integrator of complex large-scale battery storage systems, hydrogen applications, and off-grid & hybrid solutions based in Germany. As a young, diverse, and dynamic company, Altenso is working towards the goal of implementing innovative power projects as a contribution to the energy transition. The company commissioned WESTRAFO to build battery containers for multiple BESS projects around the globe.
The company commissioned WESTRAFO to build battery containers for following BESS projects:
- ENERPAC Project in Büttel, Germany: A 35 MW solar park with 8 MWh of batteries installed in three 40” containers allows an uniform energy input during the day. This is one of the largest hybrid systems in Germany.
- JUWI Project in Australia: The Northern Goldfields solar hybrid plant includes a 27.4 MW solar park in Mt Keith and a 10.7 MW solar park with a 10.1 MWac/5.4MWh battery system at Leinster. It will reduce gas emissions by 540.000 tonnes of CO2 during the first 10 years of operation at both sites.
- DECCI Project in Vranany Czech Republic: The largest battery storage plant in the Czech Republic is based on a hybrid power plant combining a BESS solution, with a capacity of 22 MWh in seven containers, with aeroderivative combustion turbines with a total capacity of 32,4 MW, providing high flexibility and low operating costs.
Focusing on the thermodynamic project, it has been asked STULZ to maintain a constant and uniform temperature of 25°C inside a 40” container totally filled with batteries, except for a narrow central aisle.
After some initial proposals, the WXUC5 was developed based on the WallAir series: 35kW monoblock air conditioner installed on each short side of the container.
Blowing cold air in a double duct placed above the batteries, it was possible to cool and heat the entire 12 meters of the container consistently. Heating, necessary during the battery’s standby phase when external temperatures are particularly cold, such as in Prague, has been achieved using 13kW multi-stage electric heaters.
Furthermore, a tandem scroll compressor, which uses compressors with different capacities, provides the fine cooling control needed to handle load variations during battery charging, standby, and discharging.
Since the solution has been designed for hot as well as cold environments, oversized heat exchangers and winter kit allowed air conditioner to operate in external temperature range of -40°C/+50°C.
Finally, the entire system has been simulated using CFD analysis to optimize the air distribution system via supply vents, ensuring the required airflow and temperatures and maximizing battery life.
The partnership between Altenso, WESTRAFO, and STULZ worked closely together, starting from initial meetings to on-site commissioning, including preliminary design and engineering phases, system integration, and the success of FAT.
WXUC5 represents the perfect solution to cool containers used for BESS, and these three projects: ENERPAC, JUWI, and DECCI acted as springboard. Now 3+2+7 containers with 24 units installed have been realized, but the unit is ready and tested to be an important piece of energy storage systems.
Photo below represents DECCI power plant, detail of WXUC5 installed and indoor view of container full of batteries, respectively.
WallAir
With WXUC5, built based on the WallAir series, STULZ developed a unit dedicated to BESS applications, with following features:
- High performance: 35kW with a monoblock unit;
- Precision and reliability: stable and uniform air temperature of 25°C;
- “Climate Customized”: a solution tailored to the specific, non-trivial requirements of the BESS application.
