Μπορεί η Τεχνητή Φωτοσύνθεση να Ξεκλειδώσει την Οικονομία του Υδρογόνου;

Αντικατάσταση της Φυσικής Φωτοσύνθεσης

Directly or indirectly, a massive amount of the energy we use has been produced through photosynthesis. This is of course true of the calories powering our bodies, but ultimately also of fossil fuels, which are just “stored” photosynthesis from plants that died eons ago.

Έτσι, πολλές προσπάθειες έχουν αφιερωθεί είτε στη βελτίωση της φυσικής φωτοσύνθεσης είτε στην αξιοποίησή της για νέες χρήσεις, όπως η δημιουργία βιοκαυσίμων από άλγη. Η κλιμακωτή υλοποίησή της θα μπορούσε να αποδειχθεί κρίσιμη για τον περιορισμό της αυξανόμενης συγκέντρωσης CO2 στην ατμόσφαιρα.

Αλλά τι θα γινόταν αν μπορούσαμε να μιμηθούμε τη διαδικασία της φωτοσύνθεσης χωρίς να ασχοληθούμε με ζωντανά οργανισμούς; Είναι, τελικά, μια ηλεκτροχημική διαδικασία που δεν απαιτεί απαραίτητα ζωντανά κύτταρα. Αυτή είναι η υπόσχεση της λεγόμενης «τεχνητής φωτοσύνθεσης».

Θα ανέβαζε την ικανότητά μας να συλλαμβάνουμε την ενέργεια του ήλιου ένα βήμα πάνω από τις φωτοβολταϊκές κυψέλες, οι οποίες μπορούν «μόνο» να δημιουργούν ηλεκτρισμό από το ηλιακό φως αλλά όχι άμεσα να επηρεάζουν χημικές αντιδράσεις.

Three researchers at the Japan Advanced Institute of Science and Technology (JAIST) and the University of Tokyo might have brought this technology one step closer to reality. In a paper published in Chemical Communications under the title “Bioinspired hydrogels: polymeric designs towards artificial photosynthesis¹”.

Πώς Λειτουργεί η Φωτοσύνθεση;

In plants, photosynthesis is, roughly speaking, the process of taking in CO2 and water, using light as an energy source, and producing carbohydrates and oxygen.

Πηγή: Britannica

Αυτό λέγοντας, φαίνεται ότι αυτό μπορεί να μειωθεί σε μια πολύ απλή χημική εξίσωση και να αναπαραχθεί εύκολα τεχνητά.

Πηγή: Britannica

Αυτή είναι μια διαφορετική ιστορία όταν κοιτάζουμε πώς γίνεται. Η φωτοσύνθεση των φυτών είναι στην πραγματικότητα μία από τις πιο σύνθετες βιοχημικές μηχανές, με δεκάδες ενδιάμεσες αντιδράσεις, αμέτρητα υποσυστήματα και μερικές φορές μη τόσο καλά κατανοητούς μοριακούς μηχανισμούς που περιλαμβάνουν πολύπλοκες κινήσεις ηλεκτρονίων.

Η συνθετική εξήγηση αυτού του θέματος στην εγκυκλοπαίδεια Britannica δεν είναι λιγότερο από 10.000 λέξεις. Οι επιστήμονες που το μελετούν πρέπει να αντιμετωπίσουν πολύ πιο σύνθετα διαγράμματα για να αποκτήσουν μια επισκόπηση της φωτοσύνθεσης:

Πηγή: Lumen Learning

Ενώ κυρίως χρησιμοποιείται στη φύση για τη δημιουργία υδατανθράκων, η φωτοσύνθεση θα μπορούσε θεωρητικά να χρησιμοποιηθεί για πολλές άλλες εφαρμογές με το φως ως πηγή ενέργειας, όπως για παράδειγμα η σύνθεση υδρογόνου από νερό (φωτοκαταλύτης).

Βιο-εμπνευσμένα Υδρόζελ για Παραγωγή Υδρογόνου

Καθώς ένα από τα βήματα της φυσικής φωτοσύνθεσης είναι ο διαχωρισμός του νερού σε οξυγόνο και 2H+ άτομα, φαίνεται ότι η αναπαραγωγή μόνο αυτού του βήματος θα ήταν πιο εύκολη από το να προσπαθήσουμε να μιμηθούμε ολόκληρη τη διαδικασία. Αυτό είναι στο οποίο εργάστηκαν οι Ιάπωνες ερευνητές, χρησιμοποιώντας υδρόζελ.

Πηγή: Chemical Communications

They used functional molecules, such as ruthenium complexes and platinum nanoparticles, which work together to simulate the natural process of photosynthesis and are known as powerful photocatalysts. The innovation is in how they organized these particles:

“What’s unique here is how the molecules are organized within the hydrogel. By creating a structured environment, we’ve made the energy conversion process much more efficient.”

Reina Hagiwara – φοιτήτρια διδακτορικού στο JAIST

Πηγή: Chemical Communications

Βελτιωμένη Απόδοση

Another key improvement of using hydrogel compared to previous methods is that it keeps the metallic particles from clumping together, which tends to reduce the efficacy of the process.

“The biggest challenge was figuring out how to arrange these molecules so they could transfer electrons smoothly. By using a polymer network, we were able to prevent them from clumping together, which is a common issue in synthetic photosynthesis systems.”

Kosuke Okeyoshi – αναπληρωτής καθηγητής στο JAIST

The end result was a much more efficient photocatalysis, producing more hydrogen than older techniques.

Πηγή: Chemical Communications

Γέλη Συλλογής Φωτός

Another factor in improved efficiency is that the gel essentially locks in the light, increasing its chance of powering the desired chemical reaction.

The careful crafting of the microgel was optimized to create diameters smaller than the wavelength of visible light. This also allowed to integrate the platinum and ruthenium microscopic particles in the gel into an organized mesh.

Πηγή: Chemical Communications

Το Κλειδί για την Επανάσταση του Υδρογόνου;

Hydrogen, or ammonia made from hydrogen, has long been considered a potential ideal fuel to power the world with green energy.

By being in a chemical form instead of electrical, hydrogen could store green energy over a much longer period and be a better replacement for fossil fuel than batteries in key applications like shipping or heavy industries.

The problem is that the production of hydrogen through electrolysis is a very energy-consuming process and a fairly inefficient one as well. This results in most of the green energy used to produce hydrogen being wasted, damaging the economics of the idea.

This efficiency problem of green hydrogen is fundamentally that the current concept requires too many steps: light -> DC current -> electrolysis -> hydrogen generation. Each extra step reduces efficiency and costs extra capital & resources for the machinery involved.

This gets even worse if the DC current needs to be turned into AC and carried away by the grid from solar farms to the hydrogen synthesis site.

Direct photocatalysis would turn it into “light -> hydrogen generation” without any intermediary steps.

Τα Επόμενα Βήματα

Καλύτερα Πολυμερή

This publication demonstrates that a carefully organized network of photocatalytic particles can be a game changer in hydrogen production. The hydrogel used here might be just a stepping stone.

The researchers expect that more advanced polymer networks will be designed. This could include fixing the catalytical components not only as small particles but as long, thin molecular chains, increasing the contact surface and light-catching. The future use of natural supramolecules, such as tubulin/microtubules, is also possible.

Περισσότερο από το Υδρογόνο

The study focused on hydrogen generation, but this is by far not the only chemical reaction that could be catalyzed by sunlight.

For example, Japanese researchers at Osaka have found a way to generate fumaric acid from bicarbonate and biomass-derived pyruvic acid, by using another form of artificial photosynthesis.

Πέρα από την Πλατίνα

Many of the hydrogen generation methods rely on splitting water molecules using platinum or other rare metals of the same family as ruthenium. And this could be one of the arguments for investing in platinum, besides hybrid vehicles’ growing popularity.

At the same time, the high cost of platinum has encouraged researchers to find alternatives that are more cost-efficient.

You can read some examples in Προόδους στην Παραγωγή Υδρογόνου με Ηλεκτρόλυση Βασισμένη σε Νικέλιο and “Παραγωγή Υδρογόνου με Διάσπαση Νερού με Ενσωματωμένο Σκουριά”.

Maybe these advancements in alternatives to platinum could be combined with the hydrogel and photocatalysis discussed above, to create a very low-cost hydrogen production method using only cheap metal, polymers, and sunlight.

Επένδυση στην Τεχνητή Φωτοσύνθεση & Υδρογόνο

Artificial photosynthesis is for now very much a developing experimental field. However, the potential of the hydrogen economy is large enough to get many companies ready to invest in the possibility.

As many hydrogen production methods rely on platinum, this can be an option: It is actually possible to directly buy platinum for investment in physical metal form, with most precious metal bullion sellers offering coins and metal bars of platinum. Platinum jewelry is also a possibility.

Traded physical platinum stockpile can also be accessed through the abrdn Physical Platinum Shares ETF (PPLT) and the GraniteShares Platinum Trust (PLTM).

You can invest in hydrogen-related companies through many brokers, and you can find here, on securities.io, our recommendations for the best brokers in the USA, Canada, Australia, and the UK, as well as many other countries.

If you are not interested in picking specific hydrogen-related companies, you can also look into ETFs like the VanEck Rare Earth and Strategic Metals ETF (REMX) for the platinum angle, or hydrogen-focused ETFs like the Global X Hydrogen ETF (HGEN) or the VanEck Hydrogen Economy UCITS (HDRO) which will provide a more diversified exposure to capitalize on the potential of hydrogen as an energy source.

Εταιρεία Υδρογόνου

BLDP Διάγραμμα τιμής

Ballard is a fuel cell manufacturer, and a pioneer of the technology with its first fuel cell bus in 1993.

The company is focused on heavy-duty markets: buses, trucks, trains/trams, ships, mining/construction, and power. While buses have been the core of the business, the company expects that by 2025, trucks will be a major business segment. It also expects Europe to stay its main market (50-60%), followed by North America (25%).

Trucking fuel cells are expected to keep growing and represent a $7.5B market in 2030 (from a $195B TAM), almost as large as all the other hydrogen/fuel cell applications combined.

Πηγή: Ballard

Because of the higher power required and the need for quick charging, heavy-duty vehicles have been a good pick for hydrogen and fuel cells over lighter vehicles like cars.

It also reduces the need for catenary wire for rail and fast recharging for long-distance hauling.

Πηγή: Ballard

The company is not a stranger to ammonia either, with for example a recent contract with Amogy to provide it with fuel cells for its “ammonia-to-power platform which relies on unique ammonia cracking technology”.

While EVs have a reasonable chance to quickly take over the car markets, heavier vehicles are harder to decarbonize.

With its established leadership in the sector, Ballard would be a prime beneficiary of a policy push toward a hydrogen economy.

The focus on fuel cells also allows the company to benefit from any cost-cutting in hydrogen generation technology, no matter the method, with or without platinum, and with or without photocatalysis.

Αναφορά Μελέτης:

^{1. Hagiwara, R., Yoshida, R., & Okeyoshi, K. (2024). Bioinspired hydrogels: polymeric designs towards artificial photosynthesis. Chemical Communications, 60, 13314–13324. https://doi.org/10.1039/D4CC04033C}