And we can't be talking floating versions of the movie Elysium here either. These have to be pedestrian working cities that can accommodate a wide cross section of the world's growing refugee problem. After all, if it's going to mostly be "NIMBY" (and even if more than a few areas remember their humanity, and offer to take folks in, the need will still outsrtip supply) as a reaction to finding a place for people to go, no matter what dry land you might want to focus on, then an alternative has to be developed, and quickly. An alternative that would integrate both environmental concerns with practical new approaches to materials, so that what you build, would be sustainable no matter what other source stocks might become scarce, and/or directly, physically, detrimental in their use. An approach that would also leverage every other angle of concurrent benefit the imagination can come up with.
Which is why, over the years, that I've been so focused on a very specific way to do wind power out at sea. Including wind power is obvious, of course, but the rest of it deserves a bit of explanation.
One thing you have to understand about me is that, being from the Pacific Northwest, and having a father who started out with aviation with the Navy back in the forties, (and went on to be a commercial aircraft mechanic), is that I grew up living aerospace; knowing flying machines from the hangar out, as the old man used to take me along on his selling trips, once he moved from working a wrench, and went on to run his own surplus parts business. And a part of that was growing up reading Aviation Week & Space Technology. I can, in fact, remember reading back issues of that mag, when it was just Aviation Week, that the old man had that came out before the fifties. As such, it was a mainstay for quite a while for on matters of aerotech, at least for me.
Oddly enough, however, the one tech I would spend a lot of years promoting would not be anything to do with flying machines, and yet it was in an AW&ST issue back in the seventies (See Aviation Week & Space Technology, March 1, 1976, page 50.) that it was featured. It was a radical new approach to doing wind energy and it was in Aviation Week because a Grumman Aerospace engineer by the name of Yen had come up with the idea, and was, at that time, doing wind tunnel, demonstration studies.
On the face of it it's a pretty simple concept. Use a large cylinder shaped object, with specially placed openings on it walls so what wind could come in, but only escape out the top of the structure. The idea behind this was to, in effect, create a cyclonic circulation inside the cylinder so that, at the center of the base, you put a hole where a significant pressure differential would be created. A hole through which ducted fans of various types could be placed to exploit that differential directly to a generator.
Even as amazing as creating your own, harnessed tornado might be, the really cool thing about this design approach was what it did to the old notion of wind power not being very dense; as in you have to have a lot of units to get large power numbers, as opposed to gigawatts out of a single nuke reactor; because with this thing, the thing collecting the wind is not the same thing also doing the translation to shaft power. Here you simply make the cylinder much bigger in order to collect more wind, and so you don't have to worry about impossibly large turbine blades. You could, in fact, with this design, have a wind turbine capable of putting out a gigawatt of its own.
The downside of it, though, does become quickly apparent. Expressed exactly in whose backyard is anybody going to allow something as big as this would have to be (like on the order of 300 feet in indiamer and 900 feet tall). And the universe only knows how noisy such a thing might be. So where to put it otherwise? Out at sea of course.
But that just serves to create a new problem. Nine hundred foot tall structures at sea? Are you seriously demented?
So, as you might imagine, how to do it bugged me for quite a while. It wasn't till years later, and thinking how cool composites had become, as well as having just seen some TV thing on just how strong bamboo scaffolding could be, that it hit me; why not some kind of pumped up, composite scaffolding; something you could use, in the vein of modularity, to really make floating platforms come together faster than stacking rebar, and pouring concrete could ever hope to achieve. Not to mention the fact that concrete itself might become a premium item now that concrete capable sand supplies are getting ever morse scarce.
So that's why I settled on an approach that would use hemp composite material to make a special kind of scaffolding; a reinforced scaffolding where the tube would be formed around an interior, long axis, center beam; a beam that would have the attach point arms already connected. The tube wall itself would be wound around the center beam, and the platters to fix beams in place, with pre-cut holes for the attach point arms to fit through. And with each successive layer of tube wall, a sleeve of composite would be fitted over each attach point arm so that the flaps at its base could be set down before the next tube wall layer came on. Thus, with each new layer, and each new sleeve, the interleaved flaps would provide an interwoven, extra connecting factor, with the tube wall.
With your basic building block then a tube enclosed, composite beam tree, even medium thickness factors, all the way around, would buy you a substantial amount of support capability. And the fact that you are then just doing attach point connecting, over and over again, building to whatever size needed, the structures would come together pretty damn quick, and with a lot of inherent flexibility on what you are able to end up with in configuration variations; a particular boon if you want to do, say very large, square bases, a few layers tall, and then pyramiding up as needed, so as to make lowering the ultimate structure's center of gravity significantly, a lot easier. And as heights in the 900 feet, or more, range are what we are talking about here, the more of that kind of easier you get the better.
So now you're wondering why I'm talking about making wind turbine platforms as fast, cheaply, and environmentally friendly, as possible, when the subject is supposed to be about floating cities. And the reason for that is this: energy creation systems based at sea are going to need people to maintain them. So, bingo, right out of the gate, building Tornado Turbine, hydrogen production, platforms creates a an anchor function for folks to build a living around. And as long as you're stacking repeatable part, platform structures to support the turbines, why not stack a few more to make platform arrays sufficient for 100K cities? Hell, even the function of platform assembly adds an anchor function to help these places make things that they can trade for the things they can't make as easily.
But then the question becomes: why should our country, let alone the other nations of the world, contribute the serious effort it's going to take to make this happen? And the simple answer is (if ordinary human compassion isn't enough for your) enlightened self interest.
That hydrogen is going to be a big part of what helps us save this planet. It certainly won't be the only fuel in an intelligent mix, but the fact that it creates water as a by product, gives it a leverage in usage that we can't afford not to take advantage of. In any case, though, if we do choose to start relying on it we will be required to make it in unprecedented quantities, for any fuel, ever. That means a pretty big lead time involved in getting the infrastructure set up to make that requirement achievable. The faster you can get that going, certainly, the shorter the lead time. Partnering with as much of the rest of the world as we can possibly manage gives the potential of shortening the lead times substantially. That this partnership might also buy us into a solution for the possible population displacements that are coming, would be icing on a very sweet cake indeed.
What I am talking about here is a major world effort to provide us some buffer time, so we can switch some tooling, and our attitudes on better organizational methods, to put as near term, as it is possible for us to do, fixes in place to handle the main areas of concern that are the primary cause of tensions in the world. In this plan we would be hitting fuel scarcity, population displacement, and major structural changes that would be a big start in stopping bad inputs that are going into the environment now. We would be applying effort to those very urgent problems, and we would be building bridges of cooperation. Ways to engage that would indicate that win win is indeed possible.
Even with careful engineering, big as the oceans are, the numbers of 100K+ cities we can put upon them is still going to be limited. How could they not be given that our population is unlikely to every stop growing completely (assuming, of course, we don't bite the big one at some point). Which is why it should be seen only as a temporary solution. Getting off the planet in a big way will provide the rest of the answers we need, but that's a discussion of infrastructure I'll leave for another day.
This, unfortunately low res, animation illustrates how the composite beam, scaffolding tubes might be assembled: