In discussions of energy and energy policy, hydrogen is one of those topics that keeps popping up.  I’m skeptical about the practicality, for the most part; while clean-burning (its primary exhaust product is water vapor) would require a completely new, nation-spanning infrastructure to work. That’s not really practical.

But as far as making hydrogen, that may be about to become at least more practical than it was.

Scientists in Japan have demonstrated a new proof-of-concept reactor that can harvest renewable hydrogen fuel from sunlight and water.

The new 1,076-square-foot (100 square meters) reactor uses photocatalytic sheets to split apart the oxygen and hydrogen atoms found in water molecules, thus siphoning the hydrogen away to be used as fuel.

While the technology remains in its infancy, the scientists behind the research say that, if more efficient photocatalysts can be developed, their breakthrough could enable the production of cheap, sustainable hydrogen fuel to meet various energy needs. They published their findings Dec. 2 in the journal Frontiers in Science.

There is another, well-known process, of course, that produces chemical energy from sunlight, water, and a few trace elements, and it’s been around for a couple of billion years; it’s called photosynthesis, and the chemical energy it produces is sugar.

This, however, is something completely different.

“Sunlight-driven water splitting using photocatalysts is an ideal technology for solar-to-chemical energy conversion and storage, and recent developments in photocatalytic materials and systems raise hopes for its realization,” senior author Kazunari Domen, a chemistry professor at Shinshu University in Japan, said in a statement. “However, many challenges remain.”

Upon being exposed to light, photocatalysts boost chemical reactions that break water molecules down into their constituent parts. However, most existing “one-step” catalysts — which decompose water into hydrogen and oxygen in one go — are extremely inefficient, leaving most of the hydrogen fuel to be refined using natural gas, a fossil fuel.

To look for a way past this deadlock, the researchers behind the new study investigated a photocatalyst that uses a more sophisticated two-step process, with one step separating out the oxygen and the next step removing the hydrogen.

There are still a lot of problems to be worked out:

Despite these promising gains, the efficiency of the reaction is still too low for commercial use.

“Currently, the efficiency under simulated standard sunlight is 1% at best, and it will not reach 5% efficiency under natural sunlight,” Hisatomi said.

To make the important strides to increase efficiency, the scientists have called on others to create better photocatalysts and larger reactors. Work on safety will also be vital: Hydrogen fuel refining also produces the explosive byproduct oxyhydrogen, which can be safely disposed of in the two-step process.

I’m not an expert on this process; outside of Japan, I’m guessing almost no one is, at least on this specific technology.  It’s interesting, yes, and hydrogen as a fuel may one day have limited utility as an energy source – if they can work out the bugs in a process like this, and if they can scale it up to a production-level process.

But here’s the thing: We solve today’s problems with tomorrow’s technology.  T’was ever thus, and I don’t expect that to change. If the bugs can be worked out of this process, hydrogen may be a part of tomorrow’s tech.

But it doesn’t solve today’s energy problems. For that, we need gas and oil, and we need nuclear reactors. These are our primary energy sources now, and likely will be for some time to come.

• 
•