Short on sustainable hydrogen? Here comes new water-splitting tech to save the day

January 6, 2016 |

BD TS 010716-H2-smYou may not know it, but you are short on hydrogen. Right now. We live in a hydrogen-starved world, and it’s expensive to make. And most of what we make is unsustainable, produced from fossil sources.

All that might be ready to change. The Digest investigates.

Making syngas for efficient production of fuels? Need hydrogen. Fuel-cell advocate? Need hydrogen. Need to make renewable diesel or jet fuel from waste fats, oils or greases? Need hydrogen. Making margarine or other foods, refining metals, using fertilizer, munching vitamins, using stainless steel, manufacturing electronics, making nuclear power plant fuel, refining petroleum, or making glass? Need hydrogen.

In fact, somebody really has to explain why NH3 should refer to “ammonia” instead of Need Hydrogen, Hydrogen, Hydrogen. Because that’s the way it is. Carbon, we obsess over. Oxygen, we know we need every time we take a breath. But good old hydrogen? It’s the Rodney Dangerfield of molecules, it gets no respect. So you have to chant it a few times. NH3, NH3, NH3. Need Hydrogen, Hydrogen, Hydrogen.

One of the reasons we don’t fuss over it? We get our hydrogen from methane steam reformation, more or less. We are currently replete in fossil methane, because US producers have lost their minds and are pumping out more than anyone needs. Check back in 2200 or so on the wisdom of that one. Or, if you’d rather not wait, see how the same production theory worked out with phosphorus and Nauru.

The other way to make hydrogen is splitting water. And, if you have hydrogen and oxygen you can use a fuel cell to generate power and water. That’s the system we use in spacecraft, and we hope to use it widely, one day, down here on the good Earth. Fuel cells are important enough that last October 8, 2015 was recognized by the United States Senate as National Hydrogen and Fuel Cell Day. Toyota is marketing a fuel cell vehicle — but as clean as it is branded, it is using hydrogen from fossil methane because it is simply the affordable way to make it.

Here’s how you split water, conventionally. You need two electrodes that use iridium and platinum, respectively. Apply an electric current and water splits, with oxygen bubbling up around the one electrode and hydrogen around the other. Simple enough.

But not cheap, if you’ve looked up the cost of platinum or iridium lately. So, it was big news last summer when a team of Stanford researchers reported in Nature Communications that they had developed a system that splits water using “lithium-induced, ultra small nickel-iron oxide nanoparticles” with better rates than iridium and platinum catalysts, and based on far cheaper materials.

The dream? Organic catalysts, found or able to be generated in nature, that eliminate the possibility that the world will swap dependence of countries rich in petroleum for countries rich in metals, and drop the cost, and not as environmentally challenging to manufacture.

So, it’s big news when a team of scientists at Indiana University relate that they have created that self-assembling biomaterial that catalyzes the formation of hydrogen, a discovery which appears in the latest issue of Nature Chemistry.

The Discovery

The breakthrough lies in placing what otherwise is a fragile enzyme, hydrogenase, within the protein shell — or “capsid” — of the bacterial virus bacteriophage P22. Hydrogenase is an enzyme produced via by two genes (hyaA and hyaB) found in e.coli.

“Essentially, we’ve taken a virus’s ability to self-assemble myriad genetic building blocks,” says Trevor Douglas, the Earl Blough Professor of Chemistry in the IU Bloomington College of Arts and Sciences’ Department of Chemistry, who led the study. “And we’ve incorporated a very fragile and sensitive enzyme with the remarkable property of taking in protons and spitting out hydrogen gas. The end result is a virus-like particle that behaves the same as a highly sophisticated material that catalyzes the production of hydrogen.”

Result? It’s 150 times more efficient than the unaltered form of the enzyme. And “P22-Hyd” as it is known  is produced through a simple fermentation process at room temperature.

And, it’s robust enough to use in real-world manufacturing and in cars. By contrast, conventional hydrogenase breaks down at temperatures above room temperature, and can be readily attacked by chemical compounds in our everyday environment.

These sensitivities are “some of the key reasons enzymes haven’t previously lived up to their promise in technology,” said Douglas. “No one’s ever had a way to create a large enough amount of this hydrogenase despite its incredible potential for biofuel production. But now we’ve got a method to stabilize and produce high quantities of the material — and enormous increases in efficiency.”

“This material is comparable to platinum, except it’s truly renewable,” Douglas added. “You don’t need to mine it; you can create it at room temperature on a massive scale using fermentation technology; it’s biodegradable. It’s a very green process to make a very high-end sustainable material.”

And wait, there’s more.

Yikes, what will happen to all our water?

Yes, if you water split, you destroy water to make hydrogen and oxygen. But when you use hydrogen in a fuel cell it is mixed with air, and you make water all over again. So, it’s a renewable cycle, and we won’t run out of water by water-splitting to feed fuel cells.

In fact, P22-Hyd both breaks the chemical bonds of water to create hydrogen and also works in reverse to recombine hydrogen and oxygen to generate power. “The reaction runs both ways — it can be used either as a hydrogen production catalyst or as a fuel cell catalyst,” Douglas said.

So, what’s next?

This is a step towards one of those Holy Grail technologies, which is using micro-scale solar power to water split, and running a fuel cell off the hydrogen. Thereby, powering a car and producing only water as the byproduct. No gaseous emissions.

So, it’s good news that Douglas and his colleagues continue to craft P22-Hyd into an ideal ingredient for hydrogen power by investigating ways to activate a catalytic reaction with sunlight, as opposed to introducing elections using laboratory methods. “Incorporating this material into a solar-powered system is the next step,” Douglas said.

The bottom line

OK, it’s early days, this is lab work, not something running at vehicle scale. But, it’s a material step forward as we move towards adding fuel cells into the list of technologies that power mobility, at civilization scale rather than niche or concept scale. One of the things on our “shopping list for running Earth better” is a low-cost, low-impact organic catalyst to split water to make sustainable hydrogen, instead of fossil hydrogen.

Check that box.

Who to thank?

Besides the afore-mentioned Douglas, the research team included Megan C. Thielges, an assistant professor of chemistry; Ethan J. Edwards, a Ph.D. student; and Paul C. Jordan, a postdoctoral researcher at Alios BioPharma, who was an IU Ph.D. student at the time of the study. And a shout-out to the oft-maligned Department of Energy, which shared the vision and funded the work.

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