What's wrong with hydrogen? You can produce it with renewables, it basically works with existing IC technology and the exhaust is just water. The only hangup is the energy/volume ratio, which is an area of ongoing research.

Large-scale hydrogen production is commonly based on fossil fuels right now, and that's what many fossil fuel companies push when they talk hydrogen. End-to-end efficiency is also not that great. That doesn't necessarily disqualify hydrogen, but it's not as obvious as often presented.

It seems like a good hydrogen chain could look like: solar panels floating in the ocean split the water and store it, a tanker picks it up and takes it to port. Burn hydrogen at a power plant for the grid, condense the vapor and use it for drinking or farming.

It seems like a great fit for...a lot of use cases. (if we can get over some of the storage hurdles)

Even then it's comparatively trivial to capture the carbon dioxide from steam reforming, as opposed to gasoline in a car.

Hydrogen burns and produces greenhouse gas!

Although water vapor is technically a "greenhouse gas", it is not responsible for forcing any global warming. That's because at the temperatures we're interested in water is a liquid, not a gas, and what small amount of water remains gaseous is entirely determined by the air's temperature. So water vapor can't force any warming, it can only amplify other forcings.

uh, no?

Well technically yes

Yes

》Water vapor is known to be Earth’s most abundant greenhouse gas

https://www.nasa.gov/topics/earth/features/vapor_warming.htm...

Run it through a condenser, feed it into a holding tank and dispose of the water at each filling station?

No need, the atmosphere is a sufficient condenser. Unless you heat the atmosphere with a lot more energy than the little bit you get from combusting the hydrogen in question... but then you'll have bigger problems as your oceans begin to evaporate.

Hard to imagine a solution to climate change that doesn't involve the fossil fuel companies given their enormous political importance.