It can be through electrolysis, but it is almost never done that way. It's less efficient than simply using the grid to charge batteries, in that usecase the ONLY benefit it has its energy density (and that might not last either).
In practice the main source is as a byproduct from refining fossil fuel like oil or gas which is separated and collected.
Perceptual hash collision generators can take arbitrary images and tweak them in invisible ways to make them collide with whichever hash value you want.
Trusted timestamping protocols and transparency logs exists and does that more efficiently
Positioning using distance bounded challenge-response protocols with multiple beacons is possible, but none of the positioning satellite networks supports it. And you still can't prove the photo was taken at the location, only that somebody was there.
Codes which don't embedd any information about what you're saying or doing can be copied over to faked images.
In theory you could have such a pendant record your voice, etc, and continously emit signatures for compressed versions of your speech (or a signed speech-to-text transcript)
If you set the download manager icon in the browser as permanently visible, then dragging it there could trigger the verification to also run if the metadata is detected, and to then also show whichever metadata it could verify.
Most hash functions are 256 bit (they're symmetric functions, they don't need more in most cases).
There are arbitrary length functions (called XOF instead of hash) which built similarly (used when you need to generate longer random looking outputs).
Other than that, yeah, math shows you don't need to change more data in the file than the length of the hash function internal state or output length (whichever is less) to create a collision. The reason they're still secure is because it's still extremely difficult to reverse the function or bruteforce 2^256 possible inputs.
I run /r/crypto at reddit (not so active these days due to needing to keep it locked because of spam bots, but it's not dead yet), usability issues like this are way too common
But then the journalists have to check if the source is trustworthy, as usual. Then they can add their own signature to help other papers check it
Microsoft Hololens (glass and transparent screen) and Google Glass (tiny screen)
Hydrogen is simply less efficient. Switching to it would increase total load on the grid, even if you try to distribute production then the losses takes away available energy for other uses. At some point it becomes cheaper to invest to connect the grid together.