New 'hydricity' concept for round-the-clock power

Scientists, including those of Indian-origin, have proposed a new "hydricity" concept for round-the-clock power by not only generating electricity from solar energy but also producing and storing hydrogen from superheated water.
"The proposed hydricity concept represents a potential breakthrough solution for continuous and efficient power generation," said Rakesh Agrawal from the Purdue University in US.
"The concept provides an exciting opportunity to envision and create a sustainable economy to meet all the human needs including food, chemicals, transportation, heating and electricity," said Agrawal.
Hydrogen can be combined with carbon from agricultural biomass to produce fuel, fertiliser and other products.
"If you can borrow carbon from sustainably available biomass you can produce anything: electricity, chemicals, heating, food and fuel," Agrawal said.

Hydricity uses solar concentrators to focus sunlight, producing high temperatures and superheating water to operate a series of electricity-generating steam turbines and reactors for splitting water into hydrogen and oxygen.

The hydrogen would be stored for use overnight to superheat water and run the steam turbines, or it could be used for other applications, producing zero greenhouse-gas emissions, researchers said.
"Traditionally electricity production and hydrogen production have been studied in isolation, and what we have done is synergistically integrate these processes while also improving them," Agrawal said.
In superheating, water is heated well beyond its boiling point - in this case from 1,000 to 1,300 degrees Celsius - producing high-temperature steam to run turbines and also to operate solar reactors to split the water into hydrogen and oxygen.

"In the 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," said Mohit Tawarmalani, Professor at Purdue University.
"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," said Tawarmalani.
The system has been simulated using models, but there has been no experimental component to the research.

"The overall sun-to-electricity efficiency of the hydricity process, averaged over a 24-hour cycle, is shown to approach 35 per cent, which is nearly the efficiency attained by using the best photovoltaic cells along with batteries," chemical engineering doctoral student Emre Gencer said.
The findings were published in the journal PNAS.