• AliSaket
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    2 months ago

    The main problem with Hydrogen is the efficiency. If we want to get off fossil fuels, we need to talk about primary energy, not only the electricity consumed today. That alone means that we need multiple of the electric production (the physicist in me shudders at that word) of what we have today.

    So instead of the finite resource of oil or gas, there’s a bottleneck in energy production and its infrastructure, which means that we need to be efficient with the energy we have. With Hydrogen, you first need energy for Hydrolysis, then cool it down and pressurize it which uses a lot of energy. And then converting it back in the fuel cell to usable electric energy is again lossy. On a good day that’s an overall efficiency of about 30% (which is around the peak efficiency of the combustion itself in modern ICEs). A good LiPo Battery (which comes with its own problems, and for industrial applications energy density is less of a problem) has a roundtrip efficiency of 98%. So you’d need triple the production infrastructure (PV, wind mills, geothermal, etc.) for your storage, if you’d do everything with H2 compared to everything with batteries.

    Which means, that if there aren’t major breakthroughs, like a totally different technology (e.g. photosensitive bacteria) to produce H2 at a multiple of the efficiency of today’s tech, then H2 and E-Fuels in general have to be reserved for the applications, where energy and power density are un-negotionable (like airplanes, some construction equipment, or for some agricultural applications).

    • Jiggle_Physics@lemmy.world
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      2 months ago

      This is correct, however the idea, at least the one not being pushing by industry, is not that hydrogen will be the primary source of power, nor is it considered efficient. It is just one way that we can, right now, capture some of the excess power generation, as opposed to losing it, or other problems is can create. This is all being considered precisely because we can’t really create batteries at the scale needed to accomplish this, yet. Hydrogen is also something that can be broken down into units that can be transported via numerous different means, such as trucks, rather than needing it to just be grid attached. It is also not being proposed as THE solution here. Most, reasonable, sources discussing this, that I have found, see this as one of many methods needed to accomplish this. All working together, with different strengths, for different uses. This one lacks in efficiency, but is highly portable, and not grid dependent, which makes it attractive to a number of different use cases.

      • AliSaket
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        2 months ago

        Yes these are all good and valid arguments as a bridge technology used when we can’t meet demands through other, already availabe, often better suited technologies. With the power structures today though, it often gets pushed as the ONLY future. Which is what I’m pushing back against. We should use it where it makes sense, not where it serves some particular interest group to consolidate power to the detriment of us all. I mean H2-cars? Really?

        • Jiggle_Physics@lemmy.world
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          2 months ago

          Yeah, given the state of hydrogen fuel cells it isn’t gonna work out, as of now. Even then, there are already better alternatives. But yes, everywhere that isn’t industry propaganda, discusses it as one, of numerous, bridges to what will hopefully be industrial scale power storage batteries. It isn’t being pitched the only one, just that is has qualities that make it more useful for a number of cases, than other bridges that we will need.