The photo is sourced from breakthroughenergy.org
Alkaline electrolysers use a liquid electrolyte solution to produce hydrogen, while proton exchange membrane units use a solid polymer electrolyte for that purpose. Both types of units operate at a temperature of no more than 80 degrees Celsius, while the optimal temperature for solid oxide electrolysers, which use thermal and electric energy to split water into oxygen and hydrogen is above 1,000 degrees Celsius.
The need for an external source of thermal energy is one of the reasons for the relatively low popularity of solid oxide electrolysers, which, unlike alkaline and proton exchange units, are just beginning to become commercially available. Hydrogen producers need visible evidence that solid oxide electrolysers are more energy efficient. This is why the tests carried out by Elcogen and Convion could become a step towards the commercial introduction of this type of electrolyser.
In addition to the operating costs of water splitting, the costs of green hydrogen production depend on the cost of wind and solar energy, which hinges on weather conditions that change throughout the year. For instance, the average utilisation rate of solar panels in the United States stood at 24.4% in 2022, but that figure dipped below 17% in January, November and December while rising above 30% in May, June and July. Wind generators demonstrated a slightly different pattern with an average utilisation rate of 35.9% in 2022: in the period from February to May, it exceeded 40%, going below 30% between July and September. These fluctuations can affect the costs of hydrogen production regardless of the type of electrolysers used.
