Affordable, green hydrogen — it is here, near, or nowhere in sight (again)?

0
1075

News arrives from Israel’s Technion Institute that they have developed a stable catalyst that can split water at extravagantly low energy-levels – and haven’t ruled out being able to split water with energy levels obtainable from the sun.

Before you skip this story to check out more pulse-quickening items such as Oscar nominees or pre-Olympics coverage, let’s put it this way: splitting water via a stable industrial process using only solar energy would rank somewhere between the Discovery of the Wheel and the Taming of Fire as a scientific discovery.

In fact, the hope of rapid transformation in the field is one of the reasons that AkzoNobel Specialty Chemicals and Gasunie New Energy have partnered in a project aiming at “large scale conversion of sustainable electricity into green hydrogen via the electrolysis of water.”

Intended for Delfzijl in the Netherlands, the installation would use a 20MW water electrolysis unit, the largest in Europe, to convert sustainably produced electricity into 3,000 tons of green hydrogen a year – enough to fuel 300 hydrogen buses.  A final decision on the project is expected in 2019.

Why — and why now — is green hydrogen such a big, big deal?

Two reasons, really.

One, you’d solve the energy-storage problem of solar power, in a snap — you’d just split water to make hydrogen. (Don’t worry, when you use the hydrogen to, for example, power a car, the water re-forms out of the tailpipe. This isn’t a Water vs Fuel situation.)

Two, you’d have an affordable, biobased (hydrogen fuel) fuel you could make anywhere, in quantities exceeding the petroleum industry.

In fact, “affordable hydrogen” is a convenient cocktail party answer to virtually any roadblock or opportunity in the advanced bioeconomy. Try it.

“Why are you having trouble beating petroleum on cost?” Affordable hydrogen.

“What do you need that would take you to true world-class liquid fuel scale? “Affordable hydrogen.

“What’s your break-through and why should I  invest in you?” Affordable hydrogen.

So, what’s the hold-up?

It’s a frustrating thing, because as many fourth-graders can explain, plants split water routinely, using only solar energy. In fact, photosynthesis is driven by it, and the oxygen you are breathing as you read this is in part provided by it.

Scientists have not been able to crack the problem, in part because the catalyst that Nature evolved is complex, and has been described as the “the strongest biological oxidizing agent yet discovered”.

It comes down to controlling manganese, which is abundant and cheap, but the manganese catalysts yet developed never last and consume way too much energy.

The hydrogen vehicle and Toyota backstory

Consequently, though Toyota has been working very hard on hydrogen vehicles, hydrogen as currently obtained via natural gas reforming is not green, nor competitively affordable. So, there might be a hundred hydrogen refueling stations in the US, about half of them in California.

Toyota keeps at it with diligence because they see that vehicles that have only water as their tailpipe emission, are quickly and easily re-fueled, store energy very efficiently for range and weight purposes — these could be long-term winners in the marketplace.

More about hydrogen’s promise here: Are electrics a bridging technology, and hydrogen fuel cells the future?

And hydrogen’s challenges here: The Hydrogen Spring that became the Year without a Summer 

The breakthrough

In an article published in Nature Catalysis, Assistant Professor Galia Maayan of the Technion-Israel Institute of Technology presents a molecular complex (also called an artificial molecular cluster) that dramatically improves the efficiency of water oxidation. It does so by biomimicry – a field of engineering inspired by nature (bio=life, mimetics=imitation). In this specific case, the inspiration comes from the process of photosynthesis in nature.

The water-splitting backstory

It’s a simple process to describe, a complete bear to achieve.  Each molecule of water, H2O, contains one oxygen atom and two hydrogen atoms, which are split using energy from an electric current. This is done with a cathode and an anode; the cathode contributes electrons to the water and attracts oxygen, and the anode takes electrons from the water and attracts hydrogen.

More on Hydrogen

It’s not an idle area of science.

Try this:US DOE tips $15.8M for Hydrogen, Fuel Cell technologies

Or this: U Can’t Have Enuf H2: The Digest’s 2018 Multi-Slide Guide to renewable hydrogen via pyrolysis

Or this: The electrochemical approach: The Digest’s 2017 Multi-Slide Guide to Upgrading Biorefinery Waste to Industrial Chemicals and Hydrogen

The manganese catalyst breakthrough

The molecular complex developed by Maayan is expected to change this situation. This cluster, which is actually a complex molecule called Mn12DH, has unique characteristics that are advantageous when splitting water.

Experiments conducted with this complex demonstrate that it produces a large quantity of electrons (electric current) and a significant amount of oxygen and hydrogen, despite a relatively low energetic investment. No less important, it is stable – meaning that it is not easily demolished, like other Mn-based catalysts.

The molecule in question

You’ll never decode this one if it ever comes up on Wheel of Fortune, Pat, I’d like to buy a parenthesis. But here it is:

[Mn12O12(O2CC6H3(OH)2)16(H2O)4].

For short they call it Mn12DH.

What’s happening?

According to Maayan, “In nature, evolution created a protein shell around the manganese core that stabilizes it and prevents its dissolution. Inspired by this natural structure, we developed an organic shell that enables the manganese complex to dissolve in water and stabilizes it.”

And according to grad student Naama Gluz, who carried out much of the work here as part of her M.Sc. studies under the supervision of Maayan:

A possible explanation for the electrocatalytic activity of Mn12DH may be related to the nature of the organic group shell – the phenol type hydroxyl groups of the 3,5-dihydroxybenzoate ligands. The surrounding ligands might act as additional proton acceptors in this reaction, shifting the reaction equilibrium toward the direct reaction side; thus, facilitating the oxygen evolution.

Next steps: solar energy only?

This is a low-energy option. But what about the “free energy option”, that is, solar. The one that would redefine civilization as we know it?It’s not out of the question (but it’s a long ways down the road, we suspect).

Gluz is continuing to research the unique manganese complex as part of her doctoral studies. In preliminary experiments, she was able to demonstrate that the complex is capable of splitting water through exposure to light from a simple lamp. In the future, this will make it possible to produce oxygen and hydrogen in large quantities and very rapidly. The idea is that eventually the process will work with solar energy, without requiring electricity.

The Bottom Line

As the researchers write:

The use of Mn and readily available carboxylate ligands makes this result particularly pertinent to the search for efficient, cheap and environmentally benign catalysts that are highly active and robust in aqueous media.

Checks most of the boxes, already. Cheap, benign, efficient. Oorah! as the Marines might put it.