World's largest green hydrogen project faces complications

The world’s largest green hydrogen production project is experiencing technical problems with its electrolyzers. This is leading to lower production than expected, according to the international news site Hydrogen Insight.

The Kuqa green hydrogen project, operated by Chinese state-owned company Sinopec in the country’s northwest, uses an alkaline electrolyzer system with an installed capacity of 260 MW.

Three different suppliers are involved in the project: Cockerill Jingli (120MW), Longi (80MW) and Peric (60MW). However, all three models use largely the same components, and the electrolyzers are facing similar problems that are resulting in lower efficiency than promised—and consequently much lower green hydrogen production than the expected 20 000 tonnes per year.

According to the manufacturers, their equipment should be capable of producing hydrogen at between 30 and 100% of rated capacity. However, none of these electrolyzers has been tested for operation at the minimum threshold of 30%. The actual operating range of these systems may therefore be even narrower, realistically between 50 and 100%.

Potential hazards caused by low load

Electrolyzer produces oxygen at the anode and hydrogen at the cathode. The membrane between the anode and cathode separates the two gases and prevents them from mixing and potentially causing an explosion. However, even though the membrane is designed for this purpose, it is not 100% effective, and hydrogen leaks through it, primarily on the anode side. This is due to the small size of hydrogen molecules, which pass easily through the membrane.

This is usually not a problem if the concentration of hydrogen in oxygen is kept below 1,8 % bymeans of a constant supply of electricity to the electrolyzer. An insufficient electricity supply reduces oxygen production and leads to a relatively high concentration of hydrogen leaking through, which could potentially cause an explosion.

Oil giant Sinopec is currently making operational changes. Instead of all the electrolyzers operating in the same mode, as originally planned, a new algorithm allows some electrolyzers to continue operating while others are set to idle. Sinopec aims to ensure that the electrolyzers do not operate at less than 50% of their rated capacity.

Tahe, a Sinopec subsidiary that operates an existing oil refinery, decided to shut down its traditional grey hydrogen production facility, which uses natural gas reforming. It had instead expected a stable supply of green hydrogen, but this has not materialized. Sinopec has admitted that the problems will not be fully resolved until at least the end of 2025.

“The Kuqa project is raising concerns among many potential green hydrogen investors, particularly international developers considering importing cheaper electrolyzers made in China,” BloombergNEF, an energy strategic research provider, told Hydrogen Insight.