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What Is ‘Hydricity’ and Why Are Green-Energy Experts Excited About It?

A breakthrough in clean power production offers a tantalizing glimpse at one possible eco-fueled future.

Image via (cc) Flickr user ericvery

In a paper published this week in the journal Proceedings of the National Academy of Sciences, a team of scientists from Switzerland and the United States announced a breakthrough in green energy production in the form of a new system which combines solar power with hydrogen production and storage. Dubbed “hydricity,” it represents what some hope will be the next stage in sustainable energy, a round-the-clock system that not only efficiently generates electricity, but also stores power—in the form of hydrogen—without any degradation or loss. It’s a form of integrated system that reportedly has been studied through modeling but never experimentally, until now.


Entitled “Round-the-clock power supply and a sustainable economy via synergistic integration of solar thermal power and hydrogen processes,” the paper is the work of academics from Purdue University, in Indiana, and École Polytechnique Fédérale de Lausanne, a research university in Switzerland. In it, the authors describe the creation of an integrated system in which solar panels concentrate the sun’s energy to superheat water, which would power a series of electricity-generating turbines as well as reactors that split the H20 into oxygen and hydrogen, the later of which would be stored for subsequent use.

“Traditionally electricity production and hydrogen production have been studied in isolation,” explained Rakesh Agrawal, a professor of chemical engineering at Purdue University and one of the study’s authors, to Phys.org. “What we have done is synergistically integrate these processes while also improving them.”

The integrated system’s improvements, the study argues, are threefold. As stated in the paper’s abstract:

(i) It stores energy thermochemically with a two- to threefold higher density.
(ii) coproduced hydrogen has alternate uses in transportation/chemical/petrochemical industries.
(iii) unlike batteries, the stored energy does not discharge over time and the storage medium does not degrade with repeated uses.

Practically speaking, what this means is that the system can provide power regardless of whether it’s day or night, using the solar power when there’s sun, and the self-generated hydrogen in its absence.

“In the round-the-clock process we produce hydrogen and electricity during daylight, store hydrogen and oxygen, and then when is not available, we use hydrogen to produce electricity using a turbine-based hydrogen-power cycle,” study co-author Mohit Tawarmalani told Phys. “Because we could operate around the clock, the steam turbines run continuously and shutdowns and restarts are not required. Furthermore, our combined process is more efficient than the standalone process that produces electricity and the one that produces and stores hydrogen.”

As the study explains, that efficiency is comparable to—and sometimes surpasses—current high-level industry standards in both solar and hydrogen power. When used in tandem, the study points out, “the overall sun-to-electricity efficiency of the hydricity process, averaged over a 24-h cycle, is shown to approach ∼35%, which is nearly the efficiency attained by using the best multijunction photovoltaic cells along with batteries.”

Couple that with the three aforementioned systematic improvements, and it’s no wonder hydricity’s creators describe it as “a potential breakthrough solution for continuous and efficient power supply and also an exciting opportunity to envision and create a sustainable economy to meet all the human needs—namely, food, chemicals, transportation, heating, and electricity.”

[via phys.org, ieee]

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