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> For example, from food waste through yeast and other methods. How is it better than generating biogas from biomaterial, something we already do at industrial

• weswpg 6y ago
  isn't methane much worse for the environment than generating power from hydrogren?
  • ncmncm 6y ago
    It depend where the (carbon in the) methane comes from. If it comes from the ground, the exhaust contributes to global climate disruption. Venting methane is worse, but that would be wasteful, too.
    • godelski 6y ago
      It also depends where the hydrogen comes from. If you produce it from water, your byproducts are oxygen. If you produce it from methane, your byproducts are carbon dioxide. Issue is that water has 2 hydrogens and methane has 4, so typically it is produced by using methane.
      • xyzzyz 6y ago
        Issue is that water has 2 hydrogens and methane has 4, so typically it is produced by using methane. It’s not really about that, we don’t lack water or methane. The issue is rather about the energy required to produce given amount of hydrogen. Electrolysis requires 2-3 as much energy as steam methane reforming already if you just look at energy of chemical reactions, and moreover, steam reforming requires just heat, while electrolysis requires electricity, which again is more expensive than heat: we produce most of our electricity from heat, and the conversion efficiency from heat to electricity is around 20-30%, so it makes more sense to use all the heat directly instead of going through electricity production stage.
        • ncmncm 6y ago
          1. Electricity is getting cheaper all the time. The cheapest forms, wind and solar, involve no detour through heat. Anything that uses electricity instead of something that produces CO2 is a big net win. 2. Huge efficiency gains are to be had, in electrolysis, via catalytic action, needing only transition from lab to production funded by sufficient demand for the hydrogen. 3. There has been great success with direct solar -> H2, needing, again, only sufficient demand for the hydrogen produced to be made industrially practical.
          • xyzzyz 6y ago
            Yes, it is conceivable that you could use cheap electricity from renewables, but it would have to be a lot cheaper than electricity from natural gas for it to make economic sense, probably something on the order of 5-6x cheaper. You get a factor of 3x just by using natural gas to heat directly, and then you need to account for bigger capital expenses for building plant and storage, because the cheap renewables are not available round the clock, so your production capacity must be significantly higher to produce more when they are available, to match the same average production of a standard natural gas plant, which can have smaller reactors etc but work around the clock. I think hitting 5-6x cheaper costs on average might be hard.
            • ncmncm 6y ago
              It is a mystery to me why you keep talking about heat. Heat is the lowest grade of energy, and least useful. Not taking a wasteful detour through heat is the first rule of efficient conversion. While duty cycle of solar is under 50%, when there is not sunshine there is very often wind. So 50% idle capacity is unlikely. Catalytic conversion of electricity to hydrogen will probably exceed 90% efficiency in short order, and from H2 back to electric via fuel cell is already over 90%. Liquified and pumped into aircraft, nothing comes close to H2 for efficiency. Likewise, in rockets. When we finally get sensible carbon taxation, 6x cheaper than CH4 will be easy to achieve.
              • xyzzyz 6y ago
  • xyzzyz 6y ago
    If you generate the methane from biomass, and then burn it all without leaking any, I can’t see how it can be in any way worse for environment than biohydrogen.
  • smegger001 6y ago
    Not in the case of bio-gas, as it uses carbon already in the carbon cycle. If you pipe it out of the ground then yes.