Closed-loop economy

[daylen]

@sky

Human waste can be processed into fertilizer just by burying it with a little grey water and waiting. As long as the feces are not directly dumped onto the edible plants, risk of infection is low.

Superinsulated housing can be replaced by thermal mass housing (store heat in solids as opposed to air). The energy would come directly from the sun to heat up high thermal mass walls (or barrels of water), and the heat would be gradually released into the air during the night. The walls and floor would be partially isolated from the surrounding earth by constructing an insulated trench around the house at least 5ft deep. This design can allow for increased air-flow which is good for health.

Plant foods are not necessarily more efficient than animal foods, because labor is a major limiting factor in such a community. Animals can provide other inputs in a holistically integrated system (like fertilizer).

A biodigester, superinsulation, and electricity would not be very sustainable due to the high-energy inputs and processes required to maintain them.

[iopsi]

Let me define "closed-loop economy" as an ecosystem that is man-made, with at least 1000 persons living in it, is self-sustainable for more than 100 years. The problem is, what would be the incentive of doing such project? If we have the resources to do it, I bet the same resources will bring a much greater return healing our natural ecosystem.

Yes essentially the bold is what i meant. Man-made ecosystem which is sustained by technology as much as possible instead of natural processes. The incentive is that such system would be (almost) completely under human control, be protected from (almost) all natural -uncontrollable- disruptions and be possible to replicate in (almost) any climate and environment.

For example a biointensive garden vs an hydroponic greenhouse. The former seems more sustainable, but can it for example withstand a strong and long heat wave? I'm not so sure (could be wrong tho) and these kind of disruptions will supposedly become more and more common in the future.

An hydroponic greenhouse can produce fresh products literally in arid deserts with only salt water, solar energy and heat, and nutrients (the only external component). https://en.wikipedia.org/wiki/Sundrop_Farms
If even the nutrients were produced in a sustainable way, we would have an example of a mini "man-made closed-loop economy" as we defined it.

@sky

Well that's one way to achieve a self-sufficient community, like with earthships.

But i think a community can be (almost) self-sufficient even if the individuals are not. I would say it's probably inefficient for every single individual to become so.
For example organic and human waste can be taken by (private or state-owned) companies, made into compost, and then sold to farmers. No need for single citizens to do it.
Same for electricity, it can be produced by big renewable energy companies and given to citizens by the grid.

So essentially still a market economy, but sustainable.

[daylen]

I agree that defining "closed-loop economy" even more rigorously will render this hypothetical arbitrary/meaningless. What is the difference between technological and natural solutions? What is human control? Sustainable for what? What is being sustained?

[prognastat]

Another thing that would probably improve efficiency and thus increase the odds of success it would be beneficial to share lodgings. So rather than having 1-2 bedroom dwellings with one family living in it needing at least 1 kitchen, bathroom etc in each home you would want Lodgings with more rooms yet fewer kitchens, bathrooms etc per room.