Let me tell you why this doesn't make sense, either economically or environmentally. Nearly all of these "green" ideas are just robbing Pete to pay Paul. Carbon-neutral is a pipe dream. Humans haven't been carbon-neutral since they learned how to use fire. Nearly all of human technological development has been based around one fact: that we live on a planet where there's enough oxygen to support combustion non-explosively, and where there's substantial amounts of heavy metals available on the surface. This has made it possible to develop literally every single technological artifact you take for granted, from the zipper in your pants, to the hinges in your eyeglasses, to the tiny screws that hold your iPhone together, to the massive turbine shafts in the generators that provide your power, to the shiny stainless steel Elon Musk uses on his yet-to-fly-anywhere Starship. And it all requires heat, most of which derives from combusting carbon and oxygen at some stage. This is reality, and ignoring it just ignores the point.

The reality is that there probably isn't enough lithium available to power a fully electrified planet in any realistic near-term scenario, we haven't hit that wall yet, but will soon. This will cause prices to spike and possibly upend a developing market. Hydrogen and fuel cells are even more un-leverageable. Cracking hydrogen either requires vast amounts of electricity, which we don't have available (and most of what is available creates carbon dioxide), or you can crack it from natural gas, which actually creates more carbon dioxide than simply burning the natural gas, and natural gas has a much better energy density to start with.

Fuel cells aren't an answer to any large-scale need, they're extremely expensive, require significant amounts of precious metals that are already in high demand for other industrial processes, and don't work well in cold weather, requiring additional outside energy sources to keep them heated. And here you seem to be suggesting the solution is to build a vast fleet of rockets to haul infrastructure to the asteroid belt looking for more platinum and iridium, when the fact is launching rockets is one of the most polluting and carbon-unfriendly things we do. One launch produces more pollution and carbon dioxide than a thousand jet flights or a million car trips. It's absurd. It reminds me of the articles I used to read in old Popular Science magazines, about how we could have nuclear-powered cars by the 1980's, as the technology was "perfectly feasible". They weren't wrong, the technology was perfectly feasible, just completely impractical. We've had miniature nuclear reactors for 60 years. But they were expensive then and they're more expensive now. And nobody wants a nuclear reactor in their garage. Mining asteroids isn't infeasible, just impractical. Hydrogen fusion isn't infeasible, just impractical. My shitty old Nissan isn't carbon-neutral, but it's way more carbon neutral than building a new EV, or cracking hydrogen which costs six times as much as gasoline, or launching rockets to the asteroid belt looking for platinum, which may or may not be there.

Now, if you'll excuse me, my car is warmed up and I'm going to be driving down to a non-carbon neutral restaurant to have a non-carbon neutral sandwich.