4 ms·

> It is best thought of as an energy carrier, akin to electricity, and as a means of storage, like a battery Can Hydrogen be used to store energy at the scale

• jhgb 5y ago
  > Can Hydrogen be used to store energy at the scale of a power grid ? The peak vs minimum variance in renewable sources is still an unsolved problem, and the only good solution (nuclear) has become politically untenable. To a large part is doesn't even need to. Even just the need for non-fossil chemical feedstock is so high that shaving the peaks of oversized generator fleet is enough to contribute to most of grid balancing. Just for ammonia synthesis at current global consumption levels you'll need hundreds of gigawatts of average power to generate the feedstock hydrogen.
• ashtonkem 5y ago
  > and the only good solution (nuclear) has become politically untenable. Thorium reactors remain an insufficiently explored option here.
  • nuerow 5y ago
    > Thorium reactors remain an insufficiently explored option here. I'm no expert in nuclear power, but it's my understanding that Thorium reactors aren't that much safer due to the higher gamma radiation emissions, and Thorium reactors are far more expensive to build and operate to the point that they are not cost-effective, let alone profitable.
  • pfdietz 5y ago
    Molten salt reactors can be used as thermal breeders, but this is incidental to their safety properties. A MSR using 235U would have the same safety advantages. But there are many problems with MSRs, particularly the kind that dissolve the fuel in a salt. Materials issues have not been solved, despite internet claims to the contrary, and once you're no longer confining the fuel in fuel elements there's radioactivity spread all over your plant. Maintenance will be a bitch, especially (as needed if you're trying to breed w. thorium in a thermal reactor) if you're doing online chemistry on that salt.
• worrycue 5y ago
  > An acre full of pressurized hydrogen sounds like a Port of Beirut moment waiting to happen. You still need oxygen to react no? If it’s pure hydrogen …
  • dredmorbius 5y ago
    Oxygen is available in bulk at eminently reasonable rates.
    • simonh 5y ago
      As long as 20% concentration is sufficient, I've found no difficulty securing local supplies.
      • masklinn 5y ago
        I wonder what the flammability limits of hydrogen in low-ox environments is. It's 4 and 75 in air (so hydrogen will readily ignite between 4% an 75% hydrogen in air at 1atm), and it's 4 and 94 in pure oxygen. And the good news is that there is a limiting oxygen concentration, but the bad news is it's 5% (so over 5% oxygen by volume at STP it becomes possible for hydrogen to ignite), but I could not find flammability limits at sub20.
    • worrycue 5y ago
      The original post had a reference to the Port of Beirut which had a ammonium nitrate explosion. That type of explosion don't require oxygen to my knowledge - denotation is caused by shockwave and in fact ammonium nitrate is itself a strong oxidizer, from what I read; "While ammonium nitrate is stable at ambient temperature and pressure under many conditions, it may detonate from a strong initiation charge. It should not be stored near high explosives or blasting agents." "Pure ammonium nitrate does not burn, but as a strong oxidizer, it supports and accelerates the combustion of organic (and some inorganic) material." - https://en.wikipedia.org/wiki/Ammonium_nitrate#Safety,_handling,_and_storage https://en.wikipedia.org/wiki/Ammonium_nitrate#Safety,_handl... Hydrogen would behave more like gasoline. It's only when there is a fuel-oxygen mixture do they start explosively burning - i.e. it should not go off all at once unless you pump the tank with oxygen and mix them/give the oxygen time to diffuse through the tank.
• pjc50 5y ago
  Can occasionally be a problem with fossil fuels: https://en.wikipedia.org/wiki/Buncefield_fire https://en.wikipedia.org/wiki/Buncefield_fire "News reports described the incident as the biggest of its kind in peacetime Europe and certainly the biggest such explosion in the United Kingdom since the 1974 Flixborough disaster."
• cinntaile 5y ago
  > Can Hydrogen be used to store energy at the scale of a power grid ? The peak vs minimum variance in renewable sources is still an unsolved problem, and the only good solution (nuclear) has become politically untenable. Nuclear has mostly an economics problem. The capital costs are massive and the path to profitability is unclear during the continued buildout of renewables.
• GlennS 5y ago
  > the only good solution (nuclear) has become politically untenable Not just politically: also economically untenable. At the moment, gas peakers remain the only good solution to this. Hopefully in the future overbuilding renewables or some sort of advancement in storage will work. Unsolved problem for the 2040s. > Can Hydrogen be used to store energy at the scale of a power grid? Probably not because of the inefficiencies. It may well be useful as a kind of "last line of defence" to handle low probability situations where a lot . However, it does seem like it may be the best solution for air travel, and perhaps also shipping and heavy good vehicles.
  • pfdietz 5y ago
    The inefficiency of hydrogen doesn't matter as much for the use cases hydrogen would be good for: long term storage, and rare event backup (like, no wind over Europe for two weeks). There are few charge/discharge cycles for these use cases, so low capital cost is far more important than round trip efficiency.
  • coderenegade 5y ago
    The efficiency argument implicitly assumes that electricity will be scarce, but this is unlikely to be the case if the majority of the world's energy needs are met through wind and solar. To give you an idea of why, Germany and California, at less than 50% renewable penetration, already curtail around 9TWh of energy a year due to mismatched supply and demand. This is enough to charge on the order of 130 million BEVs. As renewable penetration increases, so too does the need to provide statistical confidence in generation capacity. If you want to ensure that your wind farm is able to provide X units of power, say, 80% of the time, you'll be overproducing pretty much constantly. Connecting cities doesn't really change this either, because the problem is one of stochasticity and confidence. In order for two sites A and B to cover shortfalls for one another, it has to be true that both A and B are capable of overproducing, and that at least some of the time, both will overproduce (unless they're perfectly negatively correlated). If you want to ensure that A and B both have enough power with some statistical confidence, then your system will produce excess most of the time.
• coderenegade 5y ago
  The US already has 330GWh of hydrogen storage in operation, of which 90GWh has been in use since 1983. You store it at around 200 bar in salt caverns. The technology is well established, for decades at this point. Last I checked, the projected storage capacity in Europe alone is in the tens-to-hundreds of PWh. The US is somewhere in the same ballpark.
  • rapsey 5y ago
    What is it used for?
    • coderenegade 5y ago
      AFAIK, the Praxair and Air Liquide sites are bulk storage for hydrogen supply lines running through Texas. I'd imagine the ConocoPhilips site is similar. As for what the hydrogen is used for? Probably for oil and gas extraction, though there's zero reason the technology couldn't be appropriated for storing and distributing green hydrogen.
      • pfdietz 5y ago
        Ammonia synthesis, hydrodesulfurization of petroleum, other more minor uses.