Ammonia is really nasty. While it's technically lighter than air, as a result of spilling it tends to form an aerosol, which travels low to the ground - a clou

Ammonia is really nasty. While it's technically lighter than air, as a result of spilling it tends to form an aerosol, which travels low to the ground - a cloud of death if you will. Hydrogen is impractical, but ammonia just dangerous. Meanwhile methane apparently can be synthesized pretty efficiently: https://news.rice.edu/news/2023/copper-based-catalysts-efficiently-turn-carbon-dioxide-methane https://news.rice.edu/news/2023/copper-based-catalysts-effic... While it doesn't condense into a liquid at reasonable temperatures, there's ample infrastructure to handle it, since natural gas is largely methane.