"The Limits to Growth" https://en.wikipedia.org/wiki/The_Limits_to_Growth

Carrying capacity https://en.wikipedia.org/wiki/Carrying_capacity

> The carrying capacity of an environment is the maximum population size of a biological species that can be sustained by that specific environment, given the food, habitat, water, and other resources available. The carrying capacity is defined as the environment's maximal load, which in population ecology corresponds to the population equilibrium, when the number of deaths in a population equals the number of births (as well as immigration and emigration). The effect of carrying capacity on population dynamics is modelled with a logistic function. Carrying capacity is applied to the maximum population an environment can support in ecology, agriculture and fisheries. The term carrying capacity has been applied to a few different processes in the past before finally being applied to population limits in the 1950s.[1] The notion of carrying capacity for humans is covered by the notion of sustainable population.

Sustainable population https://en.wikipedia.org/wiki/Sustainable_population :

> Talk of economic and population growth leading to the limits of Earth's carrying capacity for humans are popular in environmentalism.[16] The potential limiting factor for the human population might include water availability, energy availability, renewable resources, non-renewable resources, heat removal, photosynthetic capacity, and land availability for food production.[17] The applicability of carrying capacity as a measurement of the Earth's limits in terms of the human population has not been very useful, as the Verhulst equation does not allow an unequivocal calculation and prediction of the upper limits of population growth.[16]

> [...] The application of the concept of carrying capacity for the human population, which exists in a non-equilibrium, is criticized for not successfully being able to model the processes between humans and the environment.[16][20] In popular discourse the concept has largely left the domain of academic consideration, and is simply used vaguely in the sense of a "balance between nature and human populations".[20]

Practically, if you can find something sustainable to do with brine (NaCL; Sodium Chloride and), and we manage to achieve cheap clean energy, and we can automate humanoid labor, desalinating water and pumping it inland is feasible; so, global water prices shouldn't then be the limit to our carrying capacity. #Goal6 #CleanWater

Water trading > Alternatives to water trading markets (*)
https://en.wikipedia.org/wiki/Water_trading

LCOE: Levelized Cost of Electricity
https://en.wikipedia.org/wiki/Levelized_cost_of_electricity

LCOW: Levelized Cost of Water: https://en.wikipedia.org/wiki/Levelized_cost_of_water

TIL about modern methods for drilling water wells on youtube: with a hand drill, with a drive cap and a sledgehammer and a pitcher-pump after a T with valves for an optional (loud) electric pump, or a solar electric water pump

Drinking water > Water Quality:
https://en.wikipedia.org/wiki/Drinking_water#Water_quality :

> Nearly 4.2 billion people worldwide had access to tap water, while another 2.4 billion had access to wells or public taps.[3] The World Health Organization considers access to safe drinking-water a basic human right.

> About 1 to 2 billion people lack safe drinking water.[4] Water can carry vectors of disease. More people die from unsafe water than from war, then-U.N. secretary-general Ban Ki-moon said in 2010.[5] Third world countries are most affected by lack of water, flooding, and water quality. Up to 80 percent of illnesses in developing countries are the direct result of inadequate water and sanitation. [6]

A helpful risk hierarchy chart:
"The risk hierarchy for water sources used in private drinking water supplies": From Lowest Risk to Highest Risk: Mains water, Rainwater, Deep groundwater, Shallow groundwater, Surface water

TIL it's possible to filter Rainwater with an unglazed terracotta pot and no electricity, too

Also, TIL about solid-state heat engines ("thermionic converters") with no moving parts, that only need a thermal gradient in order to generate electricity. The difference between #VantaBlack and #VantaWhite in the sun results in a thermal gradient, for example

Is a second loop and a heat exchange even necessary if solid-state heat engines are more efficient than gas turbines?

Any exothermic reaction?! FWIU, we only need 100°C to quickly purify water.