MSGID: 1:317/3 643e1cee   
   PID: hpt/lnx 1.9.0-cur 2019-01-08   
   TID: hpt/lnx 1.9.0-cur 2019-01-08   
    A solar hydrogen system that co-generates heat and oxygen    
      
     Date:   
         April 17, 2023   
     Source:   
         Ecole Polytechnique Fe'de'rale de Lausanne   
     Summary:   
         Researchers have built a pilot-scale solar reactor that produces   
         usable heat and oxygen, in addition to generating hydrogen with   
         unprecedented efficiency for its size.   
      
      
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   FULL STORY   
   ==========================================================================   
   A parabolic dish on the EPFL campus is easily overlooked, resembling a   
   satellite dish or other telecommunications infrastructure. But this dish   
   is special, because it works like an artificial tree. After concentrating   
   solar radiation nearly 1,000 times, a reactor above the dish uses that   
   sunlight to convert water into valuable and renewable hydrogen, oxygen,   
   and heat.   
      
      
   ==========================================================================   
   "This is the first system-level demonstration of solar hydrogen   
   generation.   
      
   Unlike typical lab-scale demonstrations, it includes all auxiliary devices   
   and components, so it gives us a better idea of the energy efficiency   
   you can expect once you consider the complete system, and not just the   
   device itself," says Sophia Haussener, head of the Laboratory of Renewable   
   Energy Science and Engineering (LRESE) in the School of Engineering.   
      
   "With an output power of over 2 kilowatts, we've cracked the 1-kilowatt   
   ceiling for our pilot reactor while maintaining record-high efficiency   
   for this large scale. The hydrogen production rate achieved in this work   
   represents a really encouraging step towards the commercial realization of   
   this technology."  The work builds on preliminary research demonstrating   
   the concept on the laboratory scale, using LRESE's high-flux solar   
   simulator, which was published in Nature Energy in 2019. Now, the team   
   has published the results of their scaled-up, efficient, and multi-product   
   process under real-world conditions in the same journal.   
      
   Waste not, want not Hydrogen production from water using solar energy   
   is referred to as artificial photosynthesis, but the LRESE system is   
   unique for its ability to also produce heat and oxygen at scale.   
      
   After the dish concentrates the sun's rays, water is pumped into   
   its focus spot, where an integrated photoelectrochemical reactor is   
   housed. Within this reactor, photoelectrochemical cells use solar energy   
   to electrolyze, or split water molecules into hydrogen and oxygen. Heat   
   is also generated, but instead of being released as a system loss, this   
   heat is passed through a heat exchanger so that it can be harnessed --   
   for ambient heating, for example.   
      
   In addition to the system's primary outputs of hydrogen and heat, the   
   oxygen molecules released by the photo-electrolysis reaction are also   
   recovered and used.   
      
   "Oxygen is often perceived as a waste product, but in this case,   
   it can also be harnessed -- for example for medical applications,"   
   Haussener says.   
      
   Industrial and residential energy The system is suitable for industrial,   
   commercial, and residential applications; in fact, LRESE-spinoff SoHHytec   
   SA is already deploying and commercializing it. The EPFL start-up   
   is working with a Swiss-based metal production facility to build a   
   demonstration plant at the multi-100-kilowatt scale that will produce   
   hydrogen for metal annealing processes, oxygen for nearby hospitals,   
   and heat for the factory's hot-water needs.   
      
   "With the pilot demonstration at EPFL, we have achieved a major   
   milestone by demonstrating unprecedented efficiency at high output power   
   densities. We are now scaling up a system in an artificial garden-like   
   setup, where each of these 'artificial trees' is deployed in a modular   
   fashion," says SoHHytec co-founder and CEO Saurabh Tembhurne.   
      
   The system could be used to provide residential and commercial central   
   heating and hot water, and to power hydrogen fuel cells. At an output   
   level of about half a kilogram of solar hydrogen per day, the EPFL   
   campus system could power around 1.5 hydrogen fuel cell vehicles driving   
   an average annual distance; or meet up to half the electricity demand   
   and more than half of the annual heat demand of a typical four-person   
   Swiss household.   
      
   With their artificial photosynthesis system well on its way to scale-up,   
   Haussener is already exploring new technological avenues. In particular,   
   the lab is working on a large-scale solar-powered system that would   
   split carbon dioxide instead of water, yielding useful materials like   
   syngas for liquid fuel, or the green plastic precursor ethylene.   
      
       * RELATED_TOPICS   
             o Matter_&_Energy   
                   # Solar_Energy # Thermodynamics # Alternative_Fuels #   
                   Materials_Science   
             o Earth_&_Climate   
                   # Energy_and_the_Environment # Renewable_Energy #   
                   Environmental_Science # Water   
       * RELATED_TERMS   
             o Scale_model o Absolute_zero o Fujita_scale o   
             Distributed_generation o Fuel_cell o Solar_power o   
             Greenhouse_effect o Richter_magnitude_scale   
      
   ==========================================================================   
   Story Source: Materials provided by   
   Ecole_Polytechnique_Fe'de'rale_de_Lausanne. Original written by Celia   
   Luterbacher. Note: Content may be edited for style and length.   
      
      
   ==========================================================================   
   Journal Reference:   
      1. Isaac Holmes-Gentle, Saurabh Tembhurne, Clemens Suter, Sophia   
      Haussener.   
      
         Kilowatt-scale solar hydrogen production system using a concentrated   
         integrated photoelectrochemical device. Nature Energy, 2023; DOI:   
         10.1038/s41560-023-01247-2   
   ==========================================================================   
      
   Link to news story:   
   https://www.sciencedaily.com/releases/2023/04/230417142442.htm   
      
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