Research paving the way for a green hydrogen future

20 Jul 2023

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Researchers around the world are discovering new ways to create, store and efficiently harness green hydrogen.

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Green hydrogen has been rising in popularity in recent years, being viewed as a way to decarbonise parts of society and support other forms of renewable energy production.

The EU has been focused on growing its green hydrogen sector for years and established a Clean Hydrogen Alliance in 2020 to support the growth of this technology.

Earlier this month, the Irish Government revealed its long-awaited hydrogen strategy, which sets out the ways the country can make hydrogen a “key component of a zero-carbon economy” and boost “difficult to carbonise” sectors like transport.

Many hydrogen projects are being developed worldwide, but there are still challenges associated with scaling up this energy source, including costs, storage and efficiency.

However, a number of research projects are being conducted that could lead to breakthroughs in this sector.

A new form of green hydrogen

There are many ways to produce hydrogen fuel. One is through a process called electrolysis, which uses electricity to split water into hydrogen and oxygen. When renewable electricity is used for this method, it is known as green hydrogen.

But there are currently problems with this method of production, such as cost and efficiency. There is evidence that green hydrogen is significantly more expensive than blue hydrogen, which is produced from natural gas.

There is also a loss in energy through electrolysis. In a recent discussion on pathways to net zero, NexSys director Prof Andrew Keane told that there tends to be a loss of energy in conversion processes, such as in converting electricity into hydrogen.

However, a new method has been discovered that could be more efficient than electrolysis. Researchers from Tel Aviv University claim to have succeeded in producing green hydrogen with more than 90pc efficiency, which is far higher than the current estimates of electrolysis efficiency.

The researchers used a water-based gel (hydrogel) to attach an enzyme to an electrode and were able to produce green hydrogen using a biocatalyst. The team behind this study claimed this method presents multiple advantages over electrolysis, such as not requiring rare metals or distilled water.

“We hope that in the future, it will be possible to employ our method commercially, to lower the costs, and to make the switch towards using green hydrogen in industry, agriculture and as a clean energy source,” said Dr Oren Ben-Zvi, who was involved in the study.

Researchers have also been working to improve the efficiency of electrolysis, however. A study released last year claimed to achieve 98pc efficiency when using an “alkaline capillary-fed electrolysis cell”.

Easier, cheaper storage

Another challenge for growing the hydrogen sector is storage, a problem that exists for other forms of renewable energy.

The US Office of Energy Efficiency and Renewable Energy claims current storage options “typically” use large-volume systems that store hydrogen as a gas, but bringing the necessary amount of storage to vehicles remains a challenge.

One potential method being explored by researchers is utilising ammonia (NH3) as a form of storage, since the compound contains multiple bonds of hydrogen. Typically, ammonia is stored either in high pressure, or fully refrigerated at well-below freezing temperatures.

In a recent study published in the Journal of the American Chemical Society, researchers from the Riken Center for Emergent Matter Science in Japan claim to have found a new, easier way to store ammonia. The method involves the use of a compound that contains the mineral perovskite.

The researchers claim this compound can chemically store ammonia through “dynamic structural transformation” and that this can be reversed to extract the ammonia, presenting a new potential method of storage and transport.

“These findings will pave the way for further exploration of dynamic, reversible and functionally useful compounds for chemical storage of NH3,” the team said in the study.

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Leigh Mc Gowran is a journalist with Silicon Republic