[ cover story ] of alkaline electrolysis with innovative flexibility improvements , minimize compression losses , and avoid the use of rare metals , making it both environmentally and economically viable .
An electrode cell stack from Danfoss Heat Exchangers being installed in the pressure vessel
Housing the electrode stack in a pressure vessel allows for direct pressurized hydrogen delivery of up to 35 bars . This pressurized operation eliminates the need for additional compression systems in many use cases , providing a significant advantage in terms of efficiency and cost .
Additionally , the pressure vessel serves as a climate screen for the electrode stack , allowing for outdoor installation and eliminating the need for buildings . This setup further simplifies operations and maintenance , ensuring safer and more efficient handling of the electrolyzer .
Alkaline electrolysis is one of the oldest and most established methods for hydrogen production . Despite its advantages , alkaline electrolyzers have been traditionally characterized by relatively slow start-up times and poor ability to handle dynamic operation . Stiesdal Hydrogen saw an opportunity to address these challenges . “ We believed we could solve some of the traditional challenges of alkaline technology , such as slow start-up times and poor ramp-up rates , which are critical for integration with renewable energy sources ,” explains Nielsen .
Dynamic operation and short ramp-up times
One of the significant achievements of Stiesdal Hydrogen ’ s technology is its capability for dynamic operation . “ Our dynamic ramp-up rate , with a start-up time under five minutes and ramp-up at 1 % load per second , facilitates the use of alkaline technology in combination with fluctuating renewable electricity sources ,” says Nielsen .
The company has also developed a separate cooling circuit to address the issue of shunt currents , which are unwanted electrical paths that can lead to efficiency losses in electrolysis . “ We integrated a separate cooling circuit with large manifolds , cooling with feed-in water to achieve high thermal control in the stack ,” Nielsen explains . This non-conductive cooling system reduces losses at the DC level and improves the electrolyzer ’ s efficiency .
Core electrolyzer technology
Starting in 2020 , the Stiesdal Hydrogen team selected pressurized alkaline technology for its electrolyzer , aligning with the company ’ s approach and expertise . After a thorough review , they chose this technology for its potential to combine the proven benefits
“ Our dynamic ramp-up rate facilitates the use of alkaline technology in combination with fluctuating renewable electricity sources .”
The dynamic capability of Stiesdal ’ s electrolyzers is crucial for integrating hydrogen production with renewable energy sources , which are inherently variable . It allows the system to follow volatile electricity spot prices and adapt to standalone wind and solar PV output . By debunking the myth that alkaline technology is slow and inflexible , Stiesdal Hydrogen opens new possibilities for using alkaline electrolyzers in applications currently dominated by
14 Hydrogen Tech World | Issue 17 | August 2024