While solar energy has long been recognized as a sustainable energy resource, the question of producing electricity when sunlight is not available has persisted for just as long. More highly-refined technologies developed in recent decades have resulted in the more efficient collection of solar power and better battery storage, but in late 2015 researchers at Purdue University and in Switzerland together presented a concept that could be a solar energy game changer.
They call it “hydricity,” a combination of the words hydrogen and electricity. Rakesh Agrawal is a professor of chemical engineering who works on the project with other colleagues from Purdue and Ecole Polytechnique Federale de Lausanne in Switzerland. He says, unlike standard solar-to-electricity to production, hydricity makes two products.
“Normally we would just produce electricity, not co-produce anything, then we store that electricity in batteries. We store them as chemical energy and then in the nighttime we use batteries for the electricity,” Agrawal explains.
The hydricity process uses concentrated solar energy to superheat water that operates both electricity-generating steam turbines and reactors that split water into hydrogen and oxygen. The hydrogen and oxygen can be stored on-site while electricity is sent to the grid, and the hydrogen can be used to produce electricity when solar energy is unavailable. Because much of the same equipment would be used for both daytime and nighttime functions, the systems would be able to transition between each other seamlessly and without shutdowns. An important bonus is that it produces no greenhouse-gas emissions; additionally the stored hydrogen doesn’t lose its energy over time in the same way batteries do.
“Here what we’re doing by co-producing hydrogen, we avoid a step of making electricity and then storing it. We directly make hydrogen from sunlight, and that’s what makes it more efficient.” Agrawal says, because electricity and hydrogen are building blocks of nature, hydricity presents the potential to create a sustainable economy. “We can do almost anything: purify water, produce chemicals, create fertilizer for food production.”
Agrawal and the other researchers realize they’re a long way from realizing their vision of these more practical uses of hydrogen culled from solar energy production, and Agrawal himself admits the financial hurdle is formidable. However, the process has been identified, and he’s confident that, when the world needs it, it will be ready.
To start paving the way, the team has made proposals to fundraising agencies. Agrawal says they expect to hear back on their efforts to move the hydricity concept forward into reality in the next couple of months.
Purdue chemical engineering professor Agrawal explains the upside of using turbines both day and night .