By “legacy oil’ I meant the oil we are extracting / using now from oilfields discovered in the 1940s/60s.
Popular concensus has it, that oil production in the 1930s gave a return of 100:1 — -maybe calculation methods have changed in recent years. (by whom?) I don’t pretend to have knowledge of advanced physics to arrive at figures independently. I try to make up for that with logic and common sense.
However, I can’t find anything contradictory in the arithmetic of Prof David Mackay:
who was scientific advisor the the UK government
Whatever the EROEI figure was/is, we used fossil fuel to construct our current industrial infrastructure and modern civilisation. What we see around us represents energy surplus. Every piece of glass, plastic, brick in every house represents surplus fossil fuel. As does every road, railway line and aircraft.
To equate available EROEI (at the time) with the launch of the Apollo programme is misleading in the extreme.
The Apollo space programme was itself a legacy enterprise built at the top of a pyramid of energy/industrial/technological input started by the Wright brothers. (or the steam engine, depending on your perspective). That meant a buildup of almost 2 centuries of industrial strength to deliver a series of moonshots. The ultimate propulsion system was no different from that of Chinese fireworks 1000 years ago. (exploding chemical combustion/reaction).
Try to think of it as a 200 year pull on a catapult, rather than a Kennedy speech.
It was affordable only through the colossal industrial “machine” of the United States itself delivering the tax flow to the government to pay for it. i.e. — energy surplus again, entirely derived from fossil fuels. Ultimately it was a job creation scheme to boost national self esteem and show that US technology was more advanced than the Russians.. Benefits obviously, satellite technology and so on, but little more than that. The programme ceased because the 1970s saw the end of cheap oil. It became unaffordable. The EROEI was effectively zero.
As it will be for Mars or wherever. (because as we approach feasibility for a Mars expedition, the industrial complex to support it will not be available)
The efforts of a few private individuals (or aspiring nations) cannot recreate the energy surpluses of previous eras, because their sources no longer exist.
Had there been actual commercial benefits in space travel, it would have happened decades ago.
All our employment is dependent on fossil fuel usage. True, basic jobs can go on without it, but by ‘basic’ I mean food production and ancilliary work. But there are 7.5 bn of us engaged in non-jobs. We demand to keep those jobs. On a planet that can support 1 or 2Bn at that fundamental level.
Unfortunately everyone expects to remain in gainful employment and wind turbines are not going to supply that. Neither will they deliver food.
We have turned oil into food, but electrical energy isn’t fungible . No doubt electricity can be used to synthesise fertiliser from various sources, but not on the scale we need it. (let alone all the other stuff we need)
1bn people might get by on solar power, 7 or 9 bn + people certainly will not.