I do in fact believe in communism. Just not in Stalinism and that kind of repression. Repression based on "ideological purity" that exists very much outside of socialism too you know? Just because I believe in communism doesn't make me evil or suspicious. And obviously I was joking about robot slaves. Are we done with this shit?
Anyway we don't have infinite solar. Even kite power, the most efficient wind power costs resources and space. I generally do agree that energy isn't really the issue though, it's resources and infrastructure.
If you have a small knee high greenhouse, it will always be more efficient to actually generate chemical energy than vertical farming. Just replace the photovoltaic panel with glass. And for most crops and sensible farming you don't need greenhouses anyway. Shit just grows in the dirt.
Vertical farming calories (to actually feed people) can only be sensible if you have fusion power sometimes in the future. Fission power will eventually run out and is too expensive. Vertical farming is only used for salads and no calorie stuff, but it's fundamentally a dead end as a large scale solution.
Also if you look at the most calorie efficient crops like corn, wheat and potatoes, you need about the size of France to produce enough calories for all 8 billion people. Space is not the issue. With advances in robotics and open source farm bots you can just grow the stuff in the ground without greenhouses and democratize the process.
And about the arcology, instead of sitting in a city and growing and harvesting food or collecting water and and transporting all of it from far away, you just put it in nature and harvest all the basic things directly there using minimal energy. I mean water just falls down from the sky and only needs to be stored. You'd use solar or kite power for energy and grid scale batteries.