Monday, December 31, 2018

The Approach to Arcologies in Alien Civilizations

Arcologies and massive recycling go hand-in-hand. An alien civilization which reaches the stage where it is aware of resource constraints on their home planet will gradually improve recycling, and work to decrease the fraction of materials used in production that come from resource extraction, using recycling instead. Having the population concentrated in arcologies makes high-level recycling easier and more efficient.

An alien civilization cannot just decide that on some date everyone will move into an arcology. It must be a gradual process. But just what might that process look like? Are there any stumbling blocks along the way that might interfere with the civilization's eventual decision to leave their solar system and travel to another?

Recycling itself grows bit by bit. On Earth we are familiar with collection of a few materials which can be reprocessed and re-submitted to manufacturing. There is also other forms of recycling going on here that we do not necessarily categorize as recycling, but which would be a major feature of life on any advanced planet that had decided it wanted to survive for eons. One is re-use. If an item is not discarded while still being useful, but instead is transferred to a new user, this is a form of recycling. Not much is recycled here, perhaps clothing and children's toys, a small amount of furniture and a few other things are simply sold or transferred to new owners, such as family members or friends. Housing is the other large component of goods which are transferred from owner to owner, along with vehicles.

Refurbishing of goods prior to resale also occurs in a few instances here on Earth. Recycling of organic materials in compost is used on Earth and has been for thousands of years, being perhaps the first of all recycling that humans have done. All of these techniques and several others would be needed to push the level of recycling in an alien civilization up to 80%, 90%, 95% or higher. These high levels translate into large increases in longevity for the alien civilization, provided catastrophes do not occur. A long duration alien civilization is needed to prepare for and conduct space flight between stars.

Recycling, to reach the high levels that might be mandatory for longevity, needs to increase both in degree and in extent. The increase in degree means that, if copper is being recycled, as time passes, the percentage that is mined dropped, and the percentage that is lost and unrecoverable diminishes. This limits the type of usage that can be done. Losses occur when a substance is too completely mixed with diverse other substances to be economically separated, or when it is used in consumption, such as the liner of rocket nozzles, where ablation would remove it and irretrievably disperse it. A mixed material that can be simply treated and reused in the same or similar function is certainly categorizable as recycling, and it is only if the material is dispersed would it be lost. The combination of mixing and dispersal might remove some substance that either one of them would not.  The expansion of extent means more and more substances are submitted to recycling, eventually approaching 100%.

There will certainly be a preference for making all items in the civilization out of parts which can be recycled, and in increasing the lifetime of all parts as well. A bearing which lasts for fifty years cuts losses by 80% over a similar bearing which only lasts for ten. Such longevity increases might come from simple design changes, not involving any different materials. It is not clear immediately how the selection of design will be made and by whom in any particular alien civilization, but it is clear that one of the strongest constraints on design will include reliability and the possibility to remove all or most of the materials for recycling as a materials or as parts.

If the population of the alien planet is spread out everywhere, with low density, the transportation costs of recycling will be larger, and it will be more difficult to collect waste. To get to very high levels of recycling, it might be necessary to collect dust from manufacturing areas or perhaps elsewhere, or even to filter the atmosphere. Thus, one of the pressures in the alien society is to bring everyone who consumes resources into one of the locales where collection and reprocessing can be done. This means more population in large cities and less in non-urban areas.

Another aspect of resource usage minimization is the introduction of efficiency in every process that occurs in the alien civilization. Earthlings know a little about this, as we understand that reducing gasoline per distance helps cut losses of resource, as does home insulation. Efficiency becomes another strong design driver in an advanced alien civilization on its pathway to the stars. Transportation efficiency comes not just in fuel usage, but in mode of transport and distance between sites as well. In an arcology, elevators and the horizontal equivalents can be used as the distances are smaller, and this is yet another factor that will tend to make arcologies the only viable choice for a long-term alien civilization.

Not only will distances that are mandatory for transportation be reduced in an arcology, but so also will the mass involved in transportation. If something universal, such as food, needed by all aliens, has to be transported, having an apparatus within the arcology to do it is likely many times more efficient in transportation costs than any other options.

It would seem reasonable, after recycling technology reaches a certain point, that large buildings would be built in cities, not like the small ones we have today, but ones which occupy much more space and house much more population, thus making this type of transportation apparatus sufficiently economical to replace other types of transportation. Then, recycling centers can be constructed at short distances from other components of the system, such as refurbishing facilites, collection of materials for preprocessing facilities, waste handling facilities and all the other needed to bring the civilization up to a high level of recycling and cut resource usage down to a small fraction of what it was before these sequential changes take place.