/r/solarpunk is a sub for those interested in “solarpunk aesthetics” which means carbon free degrowth utopias for their scifi stories/games, etc.
Naturally their zero CO2 emissions world has no place for planes.
https://old.reddit.com/r/solarpunk/comments/113j3et/how_do_we_travel_overseas_in_a_solarpunk/
A bit arduous is quite an understatement
Once we get rid of capitalism everyone will be free to sail around the world 
This is literally how it was done for all of history until the mid-1800s.
Sailing across the oceans was quite dangerous back then, I doubt redditcels will enjoy being in the middle of the Atlantic during a storm.
https://old.reddit.com/r/solarpunk/comments/r267s1/the_future_of_long_distance_air_travel_airships/
sail boats. people will have a lot more time to travel. in fact the voyage will be as important as the time spent in the destination, if not more important.
in fact i'm willing to bet that, in the future people will spend way more time travelling the world than we do now. because our "union" will not be because we share products it will be because we will share experiences.
humanity will not be tied economically it will be tied because we, our friends and family will have shared real experiences all around the world. no longer people will look at someone else from another country as another species because we will all travel around the world.
Bonus, some discussion on their meme ideologies
https://old.reddit.com/r/solarpunk/comments/1bbgodf/political_ideologies/
Oh no !neolibs bros 
Lot's of “wholesome degrowth”
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Am I r-slurred or why did no one suggest a solar powered engine plane? They are talking about a hypothetical all green world anyway. Is it a logistics issue, as in modern planes require way more than what a solar panel could provide, or something else? Why did they jump into dirigibles and other gay shit?
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Electric planes are simply far from being as efficient as jet planes and that is unlikely to change in the foreseeable future. As for why do they bother if it's all fantasy anyway? Because they want to use “existing technology” for their utopia and despise “techbro” solutions (they haaaate carbon capture for instance), so they focus on trains, sail boats and dirigibles as they already exist.
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That really baffles me. Imagining this hypothetical world is science fiction so why limit what current tech can do in your imagined utopia
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