The centerpiece of this solar simulator is a tiny photoelectrochemical cell, capable of pushing hydrogen from water without the need for standalone renewable energy facilities (courtesy of University of Tübingen under copyright by Valentin Marquardt/University of Tübingen).

Red-Hot Green Hydrogen Field Just Got Hotter (& Greener)

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The Intertubes have been burning up with news of the first billion-dollar unicorn to emerge from the boiling stew of green hydrogen startups. That’s all well and good but another new development in the hydrogen field is also bubbling up under the surface. Spoiler alert: How do you pronounce “photoelectrochemical?”

Green Hydrogen & The Billion Dollar Unicorn

For those of you new to the topic, hydrogen is the lube that greases the gears of the modern industrial society and its food systems. Hydrogen is the foundational input for fuels, fertilizers, refinery operations, pharmaceuticals, toiletries, health drinks, and more.

In terms of the global supply chain, though, hydrogen is the opposite of healthy. The main source of hydrogen is natural gas, with coal and other fossil inputs coming in second.

Green hydrogen is a new development on the scene, having been made possible by the falling cost of wind and solar power since the early 2000s.

Green hydrogen is produced by electrolysis systems that jolt hydrogen gas from water with an electrical current. Sustainably speaking, that makes zero sense if the electricity comes from a conventional grid mix larded with fossil resources. However, green hydrogen purists emphasize that only renewable energy is to be used.

The technology behind electrolysis has been known for over 200 years, but it lay dormant in the hydrogen supply chain all this time while fossil fuels dominated. With low-cost renewables comes the opportunity for innovators to attract investor dollars with better, faster, cheaper electrolysis systems.

That’s where the billion-dollar unicorn comes in. Last week, a US startup called Electric Hydrogen raised $380 million in a Series C round of funding on the basis of building a better electrolyzer.  That raised the company’s valuation over the $1 billion bar, earning it the title of the industry’s first unicorn from The Wall Street Journal (paywall alert).

Green Hydrogen Unicorn Goes To Texas

The deep red state of Texas has become Republican-famous for all the usual reasons, such as fossil energy protectionism along with voter suppression, cozying up to white supremacists, anything-goes gun regulation, draconian abortion laws, book bans, drag bans, various public health crises and other such matters.

Nevertheless, Texas has been an epicenter of wind and solar development in the US since the early 2000s. It is poised to snatch the sustainable H2 garland as well, having set the wheels in motion for a renewables-sourced hydrogen industry several years ago.

Electric Hydrogen (EH2 for short) is one among a growing number of out-of-state green hydrogen firms to set up shop in Texas, where it is putting its turnkey business model into action. The company is already manufacturing its electrolyzer stacks in its home state of Massachusetts, at an anticipated rate of up to 2 gigawatts annually. The stacks will be shipped to Texas for assembly into the company’s site-ready, modular system. EH2 expects the Texas plant to be up and running before the end of next year.

All that activity has caught the eye of the global energy startup New Fortress Energy. NEF launched in 2014 with a focus on liquefied natural gas but the emerging green hydrogen field appears to have motivated a pivot into electrolysis.  According to a press release issued by Electric Hydrogen in September, NEF has included EH2’s new electrolyzers in its plans to construct a major new green hydrogen production facility in Texas. Located at a site to be named later, the new facility will churn out up to 50 tons of green H2 daily.

How Do You Pronounce “Photoelectrochemical?”

The whirlwind of activity in the electrolysis industry has somewhat masked other important developments in the green hydrogen field, and that’s where photoelectrochemistry comes in.

Loosely speaking, a photoelectrochemical cell cuts out the energy middleperson. In contrast to electrolysis systems that import electricity from standalone facilities, the photoelectrochemical cell is an all-in-one device that deploys sunlight to catalyse a chemical reaction in water.

The direct solar-to-reaction capability of photoelectrochemical cells would, in theory, render them far more efficient, and far less expensive, than conventional electrolysis systems.

Photoelectrochemical cells also lend themselves to downscaling, opening up the potential for photochemical reactors to join the list of standard household and commercial appliances alongside HVAC systems, heat pumps, laundry equipment and kitchenware.

If this is beginning to ring some bells, you may be thinking of the “artificial leaf” concept. It crossed the CleanTechnica radar in 2011, when Dr. Daniel Nocera of MIT introduced the vision of a card-sized photoelectrochemical device mimicking the natural systems that produce hydrogen from water (see more coverage here).

Photoelectrochemical Cells Meet Green Hydrogen, Eventually

Of course, the devil is in the details. For starters, photoelectrochemical cells need to be engineered with corrosion-proof elements that can withstand a lifetime of being dunked in water.

Nevertheless, science loves a challenge and work continues apace. In the latest development, last week a research team at the University of Tübingen in Germany announced a milestone in their efforts to produce an artificial leaf, aimed at decentralizing the production of green hydrogen for industry.

The heart of the effort is a new high-efficiency solar cell. You can read all about it in the journal Cell Reports Physical Science, under the title, “Photoelectrochemical Schlenk cell functionalization of multi-junction water-splitting photoelectrodes.

For those of you on the go, the gist of it is that that the team focused on a nanometer-scale fix for the crystalline defects that can hamper the efficiency and stability of a photoelectrochemical cell, while also making progress on the corrosion front.

In terms of converting sunlight to usable hydrogen energy, the Tübingen team reported an efficiency of 18%. That is a significant improvement compared to the 12% mark achieved by initial attempts dating back to 1998, at other research institutions. The Tübingen team did not set a new record, though. That claim is still held by a US team that achieved a 19% conversion efficiency record five years ago, in 2018, which just goes to show how difficult it can be to build a better mousetrap.

In any case, the highest conversion efficiency is not tied in lockstep to commercial-readiness. The school cites Erica Schmitt, the first author of the study, who states: “What we have developed here is a technology for solar hydrogen production that does not require a high-performance connection to the electricity grid.”

“This means that permanent smaller stand-alone solutions for energy supply are also conceivable,” Schmidt adds.

Onward & Upward For The Artificial Leaf Of The Future

Next steps include transferring the technology to a more economical silicon-based platform along with a continued focus on stability and cost.

That could take a while, but the team has some help at the ready. Their work is part of a broader photoelectrochemcial R&D program in Germany called H2Demo. The program launched in 2021 with support from Germany’s Federal Ministry of Education and Research (in German, BMBF for Bundesministerium für Bildung und Forschung), and Fraunhofer ISE at the helm.

Other partners include AZUR SPACE, Helmholtz Zentrum Berlin, HQ Dielectrics, LayTec AG, Philipps University of Marburg, Plasmetrex GmbH, SEMPA, Ilmenau University of Technology, University of Munich, and the Universiy of Ulm.

If you’re wondering how the US is faring in the field, that’s a good question. The Department of Energy has set up a standing Photoelectrochemical Working Group to keep things moving along with an assist from the new Liquid Sunlight Alliance, an artificial leaf initiative that combines multiple Energy Department labs and other stakeholders.

Where’s Congress?

Of course, no news about renewable energy would be complete without a mention of Republican leadership in Congress, or not as the case may be.

At a time when the global economic and military might of the US should be focused squarely on helping its allies — namely, Ukraine and Israel — the Republican-led House of Representatives has been focused squarely on undercutting the very American exceptionalism they purport to champion.

For example, now would be a good time for Republican Senator Tommy Tuberville of Alabama to drop his hold on hundreds of military promotions. That’s just one example. If you can think of others, drop us a note in the comment thread.

Photo (cropped): The centerpiece of this solar simulator is a tiny photoelectrochemical cell, capable of pushing hydrogen from water without the need for standalone renewable energy facilities (courtesy of University of Tübingen under copyright by Valentin Marquardt/University of Tübingen).

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Tina Casey

Tina specializes in advanced energy technology, military sustainability, emerging materials, biofuels, ESG and related policy and political matters. Views expressed are her own. Follow her on LinkedIn, Threads, or Bluesky.

Tina Casey has 3143 posts and counting. See all posts by Tina Casey