Over the years, a wide assortment of traits have tried to define human beings in a manner they deem fit, but honestly speaking, none have managed to be as accurate as our trait of improving under all circumstances. This commitment towards continuous growth would bring the world some huge milestones, with technology emerging as quite a major member of the group. The reason why we hold technology in such a high regard is, by and large, predicated upon its skill-set, which guided us towards a reality that nobody could have ever imagined otherwise. Nevertheless, if we look beyond the surface for one hot second, it will become abundantly clear how the whole runner was also very much inspired from the way we applied those skills across a real world environment. The latter component, in fact, did a lot to give the creation a spectrum-wide presence, and as a result, initiated a full-blown tech revolution. Of course, the next thing this revolution did was to scale up the human experience through some outright unique avenues, but even after achieving a feat so notable, technology will somehow continue to bring forth the right goods. The same has turned more and more evident in recent times, and assuming one new discovery ends up with the desired impact, it will only put that trend on a higher pedestal moving forward.

The researching team at Massachusetts Institute of Technology has successfully developed a train-like system of reactors that can harness the power of sun to produce “solar thermochemical hydrogen.” You see, driven by the sun’s heat, the system is able to directly split water and generate hydrogen, a type of fuel which can power long-distance trucks, ships, and planes, without producing any greenhouse gas emissions whatsoever. Now, in order to understand the significance of such a development, we must acknowledge how hydrogen, at the moment, is largely produced through processes that demand natural gas and other fossil fuels to be an important ingredient. This, like you can guess, hampers our prospects as far as producing fully green fuel is concerned. The solar thermochemical hydrogen or STCH, on the other hand, has no such shortcomings to it, considering it relies entirely on renewable solar energy to drive hydrogen production. However, despite its clear upside, most existing STCH designs suffer from limited efficiency. To give you a concrete picture, only about 7% of incoming sunlight is used to make hydrogen. Marking a major jump over the figure, MIT’s latest brainchild is expected to harness up to 40% of the sun’s heat to generate that much more hydrogen. The enhanced efficiency should, in turn, conceive a major cut back on the costs that are generally involved, thus helping the technology grow into a more affordable option for decarbonizing the entire transportation industry. But how will it achieve all that on an actionable level? Well, the answer is rooted in its design, which will see MIT system getting paired with an existing source of solar heat, such as a concentrated solar plant (CSP), a circular mirrors’ assortment given the task of collecting and reflecting sunlight to a central receiving tower. Once the two components are paired, STCH system then absorbs the receiver’s heat and directs it to split water and produce hydrogen. On a granular level, though, the thing supporting that STCH system is a two-step thermochemical reaction. During the first step, water in the form of steam is exposed to a metal. The metal then grabs oxygen from the emerging steam and leaves hydrogen behind. Given the fact that hydrogen is now fully separated, the oxidizer metal is reheated in a vacuum, which acts to reverse the rusting process and regenerate the metal. In order to achieve the required repeatability for a wider use, you can again expose the regenerated metal to produce more hydrogen.

“We’re thinking of hydrogen as the fuel of the future, and there’s a need to generate it cheaply and at scale,” said Ahmed Ghoniem, lead author on the study and Ronald C. Crane Professor of Mechanical Engineering at MIT. “We’re trying to achieve the Department of Energy’s goal, which is to make green hydrogen by 2030, at $1 per kilogram. To improve the economics, we have to improve the efficiency and make sure most of the solar energy we collect is used in the production of hydrogen.

Resembling a train of box-shaped reactors running on a circular track, the technology would see each reactor possessing the metal which undergoes the redox, or reversible rusting, process. In practice, every reactor would first pass through a hot station, where it would be exposed to the sun’s heat at temperatures of up to 1,500°C, causing the heat to extract oxygen out of a reactor’s metal and sending it into a reduced state. Ready to grab oxygen from steam and produce hydrogen, the reactor would move to a cooler station at temperatures around 1,000°C. As ingenious as it sounds, though, this is where most STCH concepts have faced the ultimate blow. Despite the thought-out mechanism, a question always remained i.e. what to do with the heat released by the reduced reactor as it is cooled? If you cannot recover and reuse the heat, it will eventually impact the system’s efficiency. Hold on, there is more. Another challenge here would talk to creating an energy-efficient vacuum for metal to de-rust. MIT researchers, in their groundbreaking bid, used a design which carries several energy-saving workarounds. They, for instance, allowed reactors on opposite sides of the circular track to exchange heat through thermal radiation, instead of letting it escape the system. The team also installed an extra batch of reactors that would circle around the first train, moving in the opposite direction. The second train’s purpose is to leverage its relatively cooler temperature to evacuate oxygen from the hotter inner train, and more importantly, do so without needing any energy-consuming mechanical pumps. The outer circle will also be given a metal type which one can easily oxidize, meaning they are going to absorb oxygen from the inner reactors and de-rust the original metal. This way both reactor trains would run continuously but generate separate streams of pure hydrogen and oxygen.

“If this can be realized, it could drastically change our energy future—namely, enabling hydrogen production, 24/7,” said Christopher Muhich, an assistant professor of chemical engineering at Arizona State University, who was not involved in the research. “The ability to make hydrogen is the linchpin to producing liquid fuels from sunlight.”