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Hydrogen
Tailored cooling solutions for large hydrogen electrolyzer systems: Why one size doesn’ t fit all
As the capacity of green hydrogen production plants increases to multi
100 MW, managing the resulting waste heat becomes a critical challenge. Huge amounts of waste heat occur and must be properly removed from the process and, unless it has no further use, be emitted to the ambient air. Temperature differences are low, and the cooling system design needs sensitive attention. A one-size-fits-all cooling concept doesn’ t work.
Instead, each project demands a tailored approach. This article explores how to identify the best-fitting ambient air-based cooling solution, with a special focus on Kelvion’ s cascade cooling system- an intelligent, central cooling concept designed for efficiency, flexibility, and early integration into plant planning.
Alexander Gernhardt, Senior Application Engineer Green Technologies, Kelvion
Green hydrogen is produced from renewable energy by the electrolysis process. This means using an electric current to split water molecules into hydrogen and oxygen. Alkaline electrolysis( AWE) and Proton Exchange Membrane electrolysis( PEM) are among the major technologies for producing green hydrogen. However, these systems have just a 60-80 % efficiency rate, which represents the level of electrical energy that will be transformed into hydrogen. The remaining 20-40 % becomes heat that can either be recovered and reused in, for example district heating, or emitted into the ambient. This means that an electrolyzer system with 100 MW installed capacity will transform around 20-40 MW of the electrical energy supplied to the process into heat. To ensure that the electrolysis occurs in stable and efficient conditions, it is therefore essential that all plant equipment interacting with the process, especially the heat exchangers, are carefully chosen and designed. The biggest share of the waste heat is emitted by the stacks themselves, but other sub-systems, like the power supply, the purification system and the compressor also emit waste heat that must be removed. If the waste heat is not reused, a central cooling system is essential. A water-based system is a good option if a river or an ocean is nearby and cooling by this is allowed. If no water-based heat sink is available, an ambient airbased cooling system is the obvious choice.
Dry, adiabatic or wet cooling system An ambient air-based cooling system can in general be executed as dry, adiabatic or wet type. In a dry cooling system air coolers are used. The cooling media, mostly a water-glycol mixture, flows within the tubes and is cooled by the ambient air.
Photo courtesy of Kelvion.
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