Tuesday, April 12, 2016

Fusion Under the Ocean

One way of siting fusion reactors in an alien civilization is to parcel them out to each city, or rather arcology, or group of arcologies. For assurance of power, perhaps there would be two or three of them linked together, with redundant levels of power, so that all the arcologies would always be powered up. Redundant cabling between the reactor site and the arcologies would eliminate that source of black-outs, and having several reactors operating in tandem would allow the task of disassembling one when it had reached its normal lifetime, right after replacing it with a successor.

Simple, easy, reliable, what could go wrong? The alien civilizations past asymptotic technology do not ask what could go wrong, as they know from long experience and high mental capability that nothing will. They ask, what could be better. There may be something.

Fusion, like fission, like fossil fuel combustion, even like wood-powered generators, is just a way of making heat, and then there has to be a way to turn the heat into something more useful. Nowadays on Earth, we would all answer in chorus that we know what is more useful, and that is electricity. Surely the aliens would put some sort of turbine generators in their fusion plants so that electricity could be made. Then the electricity could be sent into the network to travel to wherever aliens would congregate to use it.

Conversion of power to electricity doesn't actually work to 100% efficiency. Turbine generators might get 30 or a bit more percent conversion, and all that extra heat has to go somewhere. Maybe there is a lake or a river near the reactor site, and a bunch of water is vaporized to use up the heat. Or perhaps it would be better to site these reactors where there is a lot of water, like under the ocean. With the amount of water there, nothing needs to be vaporized, and in fact there is so much water, not even heated up too much. Running massive cables inshore from the offshore plants might be a small problem, but why do it? What the arcologies want is power, and why not give them hydrogen instead? We on Earth are on the verge of figuring out how to run cars on hydrogen, but the obvious extension is: why not run the whole arcology on hydrogen? Just have the fusion reactor be coupled into a hydrogen generator, and pipe it to the surface where tankers could ship it to wherever it was needed. No need for a city to be near a reactor, just near a transportation network.

Fusion has a habit of using hydrogen as well. Supposing the fuel used is deuterium, you get that from hydrogen. Giving the arcologies hydrogen that is a little depleted in deuterium would have no bad effects whatsoever. So there is a bit of a synergy here.

Hydrogen contributes to recycling in a very simple way. When you put it into a fuel cell, or whatever advanced alien civilizations use to get the power back out of the hydrogen, the exhaust is water. Water going into the atmosphere does not need to be recycled out. Oxygen taken from the atmosphere to combine with the hydrogen does not need to be separated, although we have to let the aliens do it however they want to. With a fuel cell in each apartment or domicile, each activity center, and wherever else needed, there is no need to wire up the arcology. Just a corridor is needed for deliveries, although some piping could be used instead. With this decentralized power generation, the arcology could be simplified considerably. No wiring for power; no wiring for communication, just a network of some sort, no piping for waste or water delivery if reconstitution was also decentralized. This type of arcology could be instrumental in pushing up the recycling percentages into the high numbers. Since recycling of everything is part and parcel of every alien's goals, having a decentralized arcology might be just what they need. Of course, this is all from early 21st century Earth ideas, which are likely to be replaced by better stuff shortly.

Past the genetic grand transition, it would be easy to create creatures which can tolerate high pressures in an under-ocean fusion reactor station. These intellos would be designed to perform whatever tasks were appropriate for a biological organism, which is whatever tasks are left over from having robotics or some other type of automation do it. Swimming intellos could be designed to inspect the outside of the reactor when needed, and something based on an octopus design designed for external work tasks.

Depending on the levels of radiation which build up in the fusion plant, some parts of it can be simply dissolved when it comes time to terminate one of the reactors. If the alien planet has the same sort of crustal geology as we do here on Earth, subduction might be used to dispose of radioactive waste, without any need to bring it out of the ocean.

There is one other advantage, which will not be familiar with anyone here on Earth. The aliens might want their planet to be beautiful, and fusion reactors might be designed to look impressive, but beautiful? Putting them under the ocean eliminates that problem before it even gets started. The transport of hydrogen still has to be done, but land transportation could be effected in a way which was not unpleasant to look at, and dispersal within an arcology could be done in a way which was not obtrusive. So, if one of their goals is to have an attractive planet, under-ocean reactors and a decentralized hydrogen economy seems to play in that direction.

The alien atmosphere would likely not have much hydrogen in it, since life would produce oxygen which has the unmistakable tendency to combine with it. This means, since hydrogen is the lightest element, that on any alien home planet dirigibles would be possible. While we humans may have a like or a dislike for the idea of dirigibles, on a planet where no one has to work and time is mostly leisure, traveling from arcology to arcology on a dirigible doesn't sound like too bad an idea.

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