Leading the charge on PEM technology


Proton Exchange Membrane (PEM) electrolysers are a well-established technology, having been in use for more than half a century. But Hystar’s new, significantly more efficient design is helping make PEM electrolysers a key part of the energy transition. Here, Hystar’s Luke Idiculla outlines how…

If you’re on the market for an electrolyser, you might be a bit uncertain about which option to go with: why PEM vs alkaline? While it will depend on your use case, one of the main advantages of PEM is its ability to operate at higher current densities and a wider range of current densities than alkaline. This makes PEM an excellent electrolyser to pair with renewable energy sources, for example, due to its ability to rapidly transition between variable power levels.

There are additional advantages to PEM as well. Such as increased rates of hydrogen production, higher energy efficiencies and, not the least, better safety. The enhanced safety features are enabled by Hystar’s patented way of operating the stacks, where the hydrogen concentration on the anode side is diluted with the help of ventilated ambient air. PEM electrolysers are also significantly more compact than alkaline.

Why Hystar

Ok, all that sounds great. You’ve decided PEM is the electrolyser for you. But why should you choose a Hystar PEM electrolyser? The answer is simple:
…has the most efficient PEM electrolysers on the market
…has the safest electrolysers in the world and
…has designed our products to be mass manufacturable from the get-go (meaning when you want to go large-scale, we’ve got you covered!)

Luke Idiculla is one of Hystar’s stellar Applications Engineers. He explains why Hystar’s electrolysers stand out: “Thanks to the unique stack design, Hystar’s electrolysers are able to utilize significantly thinner membranes, which leads to superior efficiencies when compared to conventional PEM electrolysers.”

Traditionally, PEM electrolysers have utilized a relatively thick membrane in order to keep hydrogen crossover sufficiently low (to avoid an explosive gas mixture). So how can Hystar claim to have an inherently safer electrolyser while also utilizing significantly (90%) thinner membranes?

“In Hystar’s patented solution, we’ve moved the water intake to the cathode side,” explains Luke. “This frees up the anode side, which gives us the opportunity to introduce ambient air flow on the anode. The added air dilutes the hydrogen concentration and, thanks to the controllability of the air flow, Hystar is able to control the hydrogen composition at around 1%.”

Thinner membranes

That explains the safety aspect. If you’re new to the industry, however, you might be wondering how thinner membranes have such an impact on efficiency.

The biggest loss in PEM electrolysers is due to the ohmic resistance in the membrane, which is directly affected by membrane thickness. Reduce the membrane thickness, and you reduce the losses. Hystar’s patented stack technology allows us to use membranes 90% thinner than the industry standard.

“Depending on your application, we tailor our solution to fit either a high efficiency need, with our Vega electrolyser utilizing 10% less electricity. Or you might prefer a high production rate, using our Mira electrolyser running at 150% higher current density, yielding very compact solutions while achieving the same energy consumption rates as conventional electrolysers,” explains Luke.

Even more love

In addition to increased efficiency and an even safer system, Hystar’s electrolysers are also designed for mass manufacturing, right from the start. Those thinner membranes we’ve mentioned a time or two? They can be sourced from the fuel cell industry, which has a better developed supply chain than the electrolyser industry. This allows for a more stable supply chain than our competitors.

The thinner membranes also result in a more compact cell-stack design; ideal for automated stacking and assembly techniques. So as demand for electrolysers grow, we’re able to scale up our production to meet those needs.

Want to learn more? Reach out to Luke or one of our other team members for a chat!