Could ‘hydricity’ be the next big energy breakthrough?

With the legally-binding targets of the Paris climate deal reiterating the need for a seismic shift in the development of low-carbon infrastructure and technologies, US researchers are investigating one potential answer.

Purdue University in Illinois is conducting tests on ‘hydricity’ – a solar-hydrogen energy hybrid system which has the potential to power cities around the clock.

Hydricity combines solar generation with hydrogen production and storage that the researchers claim could rival solar PV systems and energy storage technologies in driving a low-carbon transition.

“Hydricity holds the promise to provide electricity around the clock at unprecedented efficiencies and at a scale that is suitable for large cities, using solar energy and environmentally benign processes,” study co-author and Purdue University professor Rakesh Agrawal said.

“The storage density is expected to be three times of the best batteries, which translates into using three times less volume to store the same amount of energy and avoids the use of rare earth elements used in efficient batteries.”

How it works

The concept uses solar-thermal concentrators which can only work in direct sunlight to ‘superheat’ water fat to between 1,000 and 1,300 degrees celsius. The liquid is then sent through a series of turbines running off of the produced steam to reactors, which split the water into hydrogen and oxygen. The hydrogen is then stored so it can be burned in a power plant at night when the solar conductors won’t be running.

“In this round-the-clock process, we produce hydrogen and electricity during daylight, store hydrogen and oxygen, and then when solar energy is not available we use hydrogen to produce electricity using a turbine-based hydrogen-power cycle,” explianed professor Mohit Tawarmalani.

Current tests show that the splitting technique used to generate hydricity is providing an energy-from-sunlight capture efficiency of around 35% which, the researchers claim, matches current commercial PV and battery systems.

The upside to this hydrogen storage is that is can store three times as much as the commercial batteries and the stored energy does not discharge and degrade over time. The researchers say the efficiency of this hydrogen-to-electricity system could reach up to 70%, comparable to the highest reported hydrogen fuel cells.

But the big hurdle for ‘hydricity’, which is still very much in its infancyin terms of development, is the high costs associated with storing the heated and high-pressure oxygen and hydrogen. Speaking with Climate Central, Alan Weimer, a professor of chemical and biological engineering at the University of Colorado-Boulder, stated that large-scale commercialisation of the concept would take between 25-50 years.

Future prospects

However, the emergence of a legally-binding climate deal and the plethora of coalitions that were formed alongside it could spark the financial backing that innovations like this need to reach commercialisation.

As an example of some of the big energy pledges in Paris, a coalition of investors including large insurer Aviva and major public and private funds in the UK, Norway and France, worth £352bn, was launched last week which will pressurise companies to switch to using 100% renewable electricity.

Meanwhile, some of the world’s most powerful figures including Bill Gates, Mark Zuckerberg and Richard Branson also announced a new collaboration aimed at creating affordable and reliable clean energy for the entire planet.

Matt Mace

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