Volcano Coughs Up New Fuel Cell Catalyst

June 7th, 2014 by Tina Casey

This one begins like a chapter from Jules Verne’s novel The Mysterious Island and ends up with a new fuel cell catalyst that could lead to cost-competitive fuel cell vehicles. The new catalyst is based on an enzyme called H2ase S–77, which was discovered on Kyushu Island in Japan at an active volcano called Mt. Aso, by a researcher from Kyushu University.

The low-cost angle comes in because H2ase S–77 (short for hydrogenase S-77) could replace platinum, which is the very expensive but highly efficient current “gold standard” for fuel cell catalysts.

Dirty Or Clean, Fuel Cells Are Here To Stay

Since we’ve been having a rather lively discussion about fuel cells versus batteries over here at CleanTechnica, let’s begin by stating the obvious: although a fuel cell electric vehicle is a zero emission vehicle at the tailpipe, in terms of the supply chain FCEVs are only as clean as their fuel source, which right now includes a lot of fossil natural gas.

For now, that puts FCEVs in the same pickle as any BEV (battery electric vehicle) that is charged off an electricity grid mix of coal and/or fossil gas (and to a lesser extent in the US, petroleum).

Both BEVs and FCEVs are on the way to solving this problem through the use of renewable energy (solar powered hydrogen production and renewable biogas come to mind), so all else being equal you can start sorting out some of the advantages and disadvantages of actually owning one of these things.

One key advantage that fuel cells have for the driving public is the convenience of a superfast refill rate, but on the other hand the skyrocketing number of BEV charging stations (including home and workplace charging options) also offers a convenience factor.

As for the future of FCEVs, they are already getting a foothold in specialty markets, for example in warehouses and seaport operations. Stationary home fuel cells powered by solar panels are also entering the market, to say nothing of commercial scale fuel cells.

There is also a movement afoot to introduce low cost solar-sourced hydrogen fuel cells to the residential market in remote communities as an alternative to cheap diesel generators.

Another thing to consider is supply chain issues. The growth in clean energy tech is leading to an explosion of diversity in energy storage tech, both stationary and mobile, and that in turn brings up the cost and scarcity of materials such as platinum and other precious metals as well as various rare earths, along with other factors including geopolitical issues.

Put tech diversity in the context of supply chain issues and you can see how the tech balance could swing in the direction of whichever platform gives you the most stable, reliable sourcing, whether that turns out to be batteries or fuel cells.

A New Catalyst For Fuel Cells

Now that we got that out of the way, let’s take a look at that new fuel cell catalyst from Kyushu University, which is described in the online edition of Angewandte Chemie International.

For the record, the Kyushu researcher who discovered H2ase S-77 is Professor Seiji Ogo, with an assist from his wife Saori Ogo, for whom the “S” in S-77 is named.

Hydrogenases themselves are nothing new, but until now they haven’t been applied to polymer electrolyte fuel cells because they don’t play well with oxygen. In fact, they simply deactivate, rendering them useless (btw Oregon State University has a handy overview of polymer fuel cell and their application to vehicles).

H2ase S-77 is not your father’s hydrogenase, though. The Kyushu team discovered that it continues to release electrons from hydrogen molecules even in the presence of oxygen.

Based on that finding, the Kyushu team assembled a working fuel cell without a platinum anode, and here’s where it gets really interesting.

The team found that the enzyme didn’t just replace platinum, it significantly outperformed it:

This enzyme demonstrated a mass activity (roughly the current obtained divided by the mass of catalyst per cm2 of electrode) that was over 600 times greater than that of platinum. Until now, platinum has far exceeded any other catalyst in terms of mass activity, resulting in the exclusive use of this rare and precious metal in commercial fuel cells. The H2ase S–77 result, however, demonstrates that molecular catalysts could be serious contenders as a replacement for metallic platinum.

We’re not saying it’s game over for platinum just yet, but that sure looks promising. The next steps include gaining a better understanding of the working mechanism behind H2ase S-77, and then there are several pesky little durability factors to consider.

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