There are many ways to make hydrogen, but only green hydrogen is climate-neutral—unfortunately, it isn't nearly as cost competitive as other energy sources.
A new proof-of-concept reactor, developed by scientists at Shinshu University in Matsumoto, Japan, aims to split water using photocatalysts and good ole sunlight.
Although the idea needs more time in the oven before being commercially viable, it offers a possible pathway for green hydrogen to be a useful for tool for helping humanity kick its fossil fuel addiction.
Hydrogen fuels come in many colors—each one an indicator of how the fuel was initially created. Blue hydrogen refers to fuel created from steam and capturing the resulting carbon underground, pink hydrogen means nuclear energy powers the electrolysis process, and black and brown carbon (as their name denotes) splits H20 using fossil fuels, which isn’t exactly helpful with the whole cutting emissions thing.
The industry’s holy grail is what’s known as “green hydrogen,” a climate-neutral process that uses renewable sources to create hydrogen. But according to the World Economic Forum, only 0.1 percent of all hydrogen production can be described by this verdant hue because it requires too much renewable energy to create. For green hydrogen to really take off, the industry needs a material breakthrough to lower the cost of this energy-dense alternative. Luckily, scientists at Shinshu University, located in Matsumoto, Japan, think they may be on to something.
Detailed in a new paper published in the journal Frontiers in Science, the researchers describe a proof-of-concept panel reactor built with photocatalytic sheets that can split water using the power of sunlight.
“Sunlight-driven water splitting using photocatalysts is an ideal technology for solar-to-chemical energy conversion and storage,” Shinshu University’s Kazunari Domen, a senior author of the study, said in a press statement, “and recent developments in photocatalytic materials and systems raise hopes for its realization.”
Photocatalysts are materials that promote a chemical reaction, in this case, splitting hydrogen and oxygen. A one-step excitation system breaks apart the two elements, but the researchers say this process is inefficient and delivers a low solar-to-hydrogen energy conversion rate. A two-step excitation process, however, where one photocatalyst is dedicated to the evolution of each element is much more efficient.
“Obviously, solar energy conversion technology cannot operate at night or in bad weather,ut by storing the energy of sunlight as the chemical energy of fuel materials, it is possible to use the energy anytime and anywhere,” University of Shinshu’s Takashi Hisatomi.
Sounds great, right? Well, Domen readily admits that some challenges still remain. While the two-step excitation process is more efficient, they still need to find materials robust enough to withstand daily start-up and shut-down operations when the sun is and isn’t shining while also increasing conversion efficiency so these reactors can be as small as is physically possible. Designs also need to incorporate the safe handling of oxyhydrogen, which can be highly explosive.
But there is also some good news because as Domen and his team operated their proof-of-concept reactor for three years, and the machine actually performed better under natural sunlight compared to laboratory conditions.
“The most important aspect to develop is the efficiency of solar-to-chemical energy conversion by photocatalysts,” Domen said in a press statement. “If it is improved to a practical level, many researchers will work seriously on the development of mass production technology and gas separation processes, as well as large-scale plant construction.”
Japan is the world’s leader in hydrogen fuel, but some experts, including the Renewable Energy Institute, have worried that the country’s extreme focus on the technology has caused it to lag behind on implementing other green energy technologies. If scientists could somehow make the production of green hydrogen economically feasible, Japan’s dream of a “hydrogen society” could one day become a reality.
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Darren lives in Portland, has a cat, and writes/edits about sci-fi and how our world works. You can find his previous stuff at Gizmodo and Paste if you look hard enough.