Round-the-clock power supply and a sustainable economy via synergistic integration of solar thermal power and hydrogen processes

Emre Gençer, Dharik S. Mallapragada, François Maréchal, Mohit Tawarmalani, Rakesh Agrawal

Research output: Contribution to journalArticlepeer-review


We introduce a paradigm-"hydricity"-that involves the coproduction of hydrogen and electricity from solar thermal energy and their judicious use to enable a sustainable economy. We identify and implement synergistic integrations while improving each of the two individual processes. When the proposed integrated process is operated in a standalone, solely power production mode, the resulting solar water power cycle can generate electricity with unprecedented efficiencies of 40-46%. Similarly, in standalone hydrogen mode, pressurized hydrogen is produced at efficiencies approaching ∼50%. In the coproduction mode, the coproduced hydrogen is stored for uninterrupted solar power production. When sunlight is unavailable, we envision that the stored hydrogen is used in a "turbine"-based hydrogen water power (H2WP) cycle with the calculated hydrogen-toelectricity efficiency of 65-70%, which is comparable to the fuel cell efficiencies. The H2WP cycle uses much of the same equipment as the solar water power cycle, reducing capital outlays. The overall sun-toelectricity 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. In comparison, our proposed process has the following advantages: (i) It stores energy thermochemically with a two- to threefold higher density, (ii) coproduced hydrogen has alternate uses in transportation/chemical/petrochemical industries, and (iii) unlike batteries, the stored energy does not discharge over time and the storage medium does not degrade with repeated uses.

Original languageEnglish (US)
Pages (from-to)15821-15826
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number52
StatePublished - Dec 29 2015


  • Electricity
  • Hydrogen
  • Process synthesis
  • Solar
  • Solar thermal power

ASJC Scopus subject areas

  • General


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