Expanding on marginal yields, I want to put it in a visual context for everyone:
Notable things about this graph are that as time progresses, the distance between gross energy (blue) and net energy (green) increases and the ratio of gross energy (capital expense) to net energy (the marginal yield) increases. The result is not only less total energy available due to the finite nature of conventional energy sources (causing the peak shape), but also a decreasing surplus yield from those sources, making them less worthwhile to exploit. Another point worth mentioning is that peak net energy precedes peak gross energy. If gross global energy supplies are peaking, then that just puts us that much further behind the 8 ball.Here's another one (it's a bit more colorful):
So, given that society needs energy, how is society even going to be able to maintain its energy supplies when the benefits society confers demands an increasing share itself? Society will not be able to do both. Increasing societal benefits means increasing the energy strain, so any new benefits
(e.g. raising global standards of living) are largely going to consume whatever new energy
is brought online.
Anyways... have a nice read