Developed by a team at the Fraunhofer Society in Germany, the self-sufficient module – which also produces oxygen – could be well-suited for off-grid hydrogen production, one of its creators told Professional Engineering.
Conventional electrolysers are often large, highly complex systems, resulting in high costs and maintenance requirements. The new modular system, developed in the Neo-PEC project at three Fraunhofer institutes, could provide an alternative solution for some applications.
Dr Arno Görne, group leader of functional materials at the Fraunhofer Institute for Ceramic Technologies and Systems (IKTS), explained how the 0.5m2 unit works. Lifting up the bubble-wrapped cell to the camera during a call this week, he explained that the central part of the ‘tandem’ cell is float glass, a “simple, cheap glass” coated with the active semiconducting ceramic material on both sides.
When sunlight hits the glass, short wavelength light is absorbed on one side and long wavelength light passes through and is absorbed on the reverse side, generating a current running from one side to the other. A photovoltaic element is also included, providing some additional voltage to accelerate activity and boost efficiency.
With a thin layer of water on each side of the active material, the reactor generates hydrogen on the cathode side, and oxygen on the anode side. The two products are kept separate by design, to prevent any explosive mixing.
“This is something which keeps us separate from other developments,” said Dr Görne. “Other people have developed even larger scale modules. But these large-scale modules have always produced this technology on the same side, so you had to make other engineering solutions to be safe.
“There are also smaller scale modules that work like ours, but I think ours is the biggest PEC cell that works with separate chambers for hydrogen [and oxygen].”
The cell’s practical size – bigger than lab-based experiments, but small enough for straightforward installation – could be the key to its success, Görne said. The compact elements can connect to cover large areas.
“I think it's paramount that we can show that this works at a large scale. It's not just something tiny in the lab,” he said. “Of course, there's much buzz around hydrogen, but it needs to be in a way that people actually want to install it and that they feel safe having it there.”
Direct generation of hydrogen without additional electricity could make it well-suited for decentralised off-grid applications. “You don't have to wait for centralised hydrogen access – you can do it yourself. You can start with these relatively small modules, put a couple of them together, get the hydrogen. You don't have to have a big field [of solar panels], or wind power next to your house”, Dr Görne said.
During the three-year project, the Fraunhofer researchers developed high-purity semiconductor materials, which they applied using ‘ultra-gentle’ coating methods to increase the method’s hydrogen yield.
“We use the vapour phase to form layers just a few nanometres thick on the glass. The structures created in the process have a huge impact on reactor activity, in addition to the actual material properties, which we have also optimised,” said Dr Görne.
Modules covering 100m2 (a 10mx10m square, for example) could generate over 30kg of hydrogen per year in typical European conditions.
The team aims to improve the efficiency “similar to solar cells, which also improved and improved over the years to get their performance up,” Dr Görne said, with an ambitious target of five-times higher production levels. “I'm not sure where the physical limits are… it will definitely be a few years until we can reach that, maybe even more.”
The reactor could also probably be made cheaper and simpler by the private sector, he added. A streamlined production process for mass manufacture would come later.
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Content published by Professional Engineering does not necessarily represent the views of the Institution of Mechanical Engineers.