Suppose the world suddenly changed and we needed to use human slaves to replace fossil fuels. How many slaves would it take to do tasks we now take for granted.
A pump station sends water
3000 feet over one mountain pass. At full capacity, it uses 2,460,000 energy
slaves of power.
If the entire population of the city of Los Angeles did nothing but pedal
hard and sleep, they would generate this much energy. -Source
A Ford Expedition SUV—1700 energy slaves. Arranged on bikes four abreast
(a bit wider than a standard ten foot road lane) and squeezed so there was just
a few feet between the front wheel of one and the rear wheel of the next, the
Ford Expedition would require a column of energy slaves nearly a mile long... -Source
So depending on how we count, each American has
somewhere between 75 and 400 “energy slaves” working for him or her (24 hours a day), and
the richer ones have thousands. The global average energy use is of
course lower, and represents figures between 18 and 90... -Source
In an austere environment, whether due to resource depletion, issues with distribution or scarcity created by political disagreement, a robust distribution system will diminish resources allocated to lower-utility uses to protect higher-utility uses. For example, rational people would choose to not air condition their garage if it means they have energy to transport their wife-in-labor to medical help.
Planned economies...socialism/communism...historically are terrible at efficiently allocating resources. Political elite eat strawberries in January while peasants starve. Celebrities fly private planes to distant locations to discuss "justice" while women walk fifteen miles a day to collect firewood to cook their family's bread.
Technologies that can convert waste to either food or mechanical/electrical energy will be the Philosopher's Stones that converts dross to gold. Those technologies can be draft animals, gasifiers or steam engines. They can also be structural, using the waste heat in a loft to dry herbs, for instance.