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   PID: hpt/lnx 1.9.0-cur 2019-01-08   
   TID: hpt/lnx 1.9.0-cur 2019-01-08   
    Switching to hydrogen fuel could prolong the methane problem    
      
     Date:   
         March 13, 2023   
     Source:   
         Princeton University, Engineering School   
     Summary:   
         Hydrogen is often heralded as the clean fuel of the future, but   
         new research suggests that leaky hydrogen infrastructure could   
         end up increasing atmospheric methane levels, which would cause   
         decades-long climate consequences.   
      
      
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   FULL STORY   
   ==========================================================================   
   Hydrogen's potential as a clean fuel could be limited by a chemical   
   reaction in the lower atmosphere, according to research from Princeton   
   University and the National Oceanic and Atmospheric Association.   
      
      
   ==========================================================================   
   This is because hydrogen gas easily reacts in the atmosphere with the   
   same molecule primarily responsible for breaking down methane, a potent   
   greenhouse gas. If hydrogen emissions exceed a certain threshold,   
   that shared reaction will likely lead to methane accumulating in the   
   atmosphere -- with decades-long climate consequences.   
      
   "Hydrogen is theoretically the fuel of the future," said Matteo Bertagni,   
   a postdoctoral researcher at the High Meadows Environmental Institute   
   working on the Carbon Mitigation Initiative. "In practice, though,   
   it poses many environmental and technological concerns that still need   
   to be addressed."  Bertagni is the first author of a research article   
   published in Nature Communications, in which researchers modeled the   
   effect of hydrogen emissions on atmospheric methane. They found that   
   above a certain threshold, even when replacing fossil fuel usage,   
   a leaky hydrogen economy could cause near-term environmental harm by   
   increasing the amount of methane in the atmosphere. The risk for harm is   
   compounded for hydrogen production methods using methane as an input,   
   highlighting the critical need to manage and minimize emissions from   
   hydrogen production.   
      
   "We have a lot to learn about the consequences of using hydrogen,   
   so the switch to hydrogen, a seemingly clean fuel, doesn't create new   
   environmental challenges," said Amilcare Porporato, Thomas J. Wu '94   
   Professor of Civil and Environmental Engineering and the High Meadows   
   Environmental Institute.   
      
   Porporato is a principal investigator and member of the Leadership Team   
   for the Carbon Mitigation Initiative and is also associated faculty at   
   the Andlinger Center for Energy and the Environment.   
      
   The problem boils down to one small, difficult-to-measure molecule   
   known as the hydroxyl radical (OH). Often dubbed "the detergent of the   
   troposphere," OH plays a critical role in eliminating greenhouse gases   
   such as methane and ozone from the atmosphere.   
      
   The hydroxyl radical also reacts with hydrogen gas in the atmosphere. And   
   since a limited amount of OH is generated each day, any spike in hydrogen   
   emissions means that more OH would be used to break down hydrogen, leaving   
   less OH available to break down methane. As a consequence, methane would   
   stay longer in the atmosphere, extending its warming impacts.   
      
   According to Bertagni, the effects of a hydrogen spike that might occur   
   as government incentives for hydrogen production expand could have   
   decades-long climate consequences for the planet.   
      
   "If you emit some hydrogen into the atmosphere now, it will lead to   
   a progressive build-up of methane in the following years," Bertagni   
   said. "Even though hydrogen only has a lifespan of around two years in   
   the atmosphere, you'll still have the methane feedback from that hydrogen   
   in 30 years from now."  In the study, the researchers identified the   
   tipping point at which hydrogen emissions would lead to an increase   
   in atmospheric methane and thereby undermine some of the near-term   
   benefits of hydrogen as a clean fuel. By identifying that threshold,   
   the researchers established targets for managing hydrogen emissions.   
      
   "It's imperative that we are proactive in establishing thresholds for   
   hydrogen emissions, so that they can be used to inform the design and   
   implementation of future hydrogen infrastructure," said Porporato.   
      
   For hydrogen referred to as green hydrogen, which is produced by splitting   
   water into hydrogen and oxygen using electricity from renewable sources,   
   Bertagni said that the critical threshold for hydrogen emissions sits at   
   around 9%. That means that if more than 9% of the green hydrogen produced   
   leaks into the atmosphere -- whether that be at the point of production,   
   sometime during transport, or anywhere else along the value chain --   
   atmospheric methane would increase over the next few decades, canceling   
   out some of the climate benefits of switching away from fossil fuels.   
      
   And for blue hydrogen, which refers to hydrogen produced via methane   
   reforming with subsequent carbon capture and storage, the threshold for   
   emissions is even lower. Because methane itself is the primary input   
   for the process of methane reforming, blue hydrogen producers have to   
   consider direct methane leakage in addition to hydrogen leakage. For   
   example, the researchers found that even with a methane leakage rate as   
   low as 0.5%, hydrogen leakages would have to be kept under around 4.5%   
   to avoid increasing atmospheric methane concentrations.   
      
   "Managing leakage rates of hydrogen and methane will be critical,"   
   Bertagni said. "If you have just a small amount of methane leakage   
   and a bit of hydrogen leakage, then the blue hydrogen that you produce   
   really might not be much better than using fossil fuels, at least for   
   the next 20 to 30 years."  The researchers emphasized the importance of   
   the time scale over which the effect of hydrogen on atmospheric methane   
   is considered. Bertagni said that in the long-term (over the course of   
   a century, for instance), the switch to a hydrogen economy would still   
   likely deliver net benefits to the climate, even if methane and hydrogen   
   leakage levels are high enough to cause near-term warming. Eventually,   
   he said, atmospheric gas concentrations would reach a new equilibrium,   
   and the switch to a hydrogen economy would demonstrate its climate   
   benefits. But before that happens, the potential near-term consequences   
   of hydrogen emissions might lead to irreparable environmental and   
   socioeconomic damage.   
      
   Thus, if institutions hope to meet mid-century climate goals, Bertagni   
   cautioned that hydrogen and methane leakage to the atmosphere must be   
   held in check as hydrogen infrastructure begins to roll out. And because   
   hydrogen is a small molecule that is notoriously difficult to control   
   and measure, he explained that managing emissions will likely require   
   researchers to develop better methods for tracking hydrogen losses across   
   the value chain.   
      
   "If companies and governments are serious about investing money to   
   develop hydrogen as a resource, they have to make sure they are doing   
   it correctly and efficiently," Bertagni said. "Ultimately, the hydrogen   
   economy has to be built in a way that won't counteract the efforts in   
   other sectors to mitigate carbon emissions."   
       * RELATED_TOPICS   
             o Matter_&_Energy   
                   # Alternative_Fuels # Fuel_Cells # Energy_and_Resources   
             o Earth_&_Climate   
                   # Renewable_Energy # Climate # Energy_and_the_Environment   
             o Science_&_Society   
                   # Environmental_Policies # Energy_Issues #   
                   Transportation_Issues   
       * RELATED_TERMS   
             o Methane o Hydrogen_vehicle o Alternative_fuel_vehicle o   
             Hydrogen-like_atom o Hydrogen o Climate_change_mitigation o   
             Fuel_cell o Global_warming   
      
   ==========================================================================   
   Story Source: Materials provided by   
   Princeton_University,_Engineering_School. Original written by Colton   
   Poore. Note: Content may be edited for style and length.   
      
      
   ==========================================================================   
   Journal Reference:   
      1. Matteo B. Bertagni, Stephen W. Pacala, Fabien Paulot, Amilcare   
      Porporato.   
      
         Risk of the hydrogen economy for atmospheric methane. Nature   
         Communications, 2022; 13 (1) DOI: 10.1038/s41467-022-35419-7   
   ==========================================================================   
      
   Link to news story:   
   https://www.sciencedaily.com/releases/2023/03/230313162740.htm   
      
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