One of the best ways to determine the viability of any future scenario is to examine its assumptions (aka its initial conditions). For example, there's an interesting 2001 report from Shell on energy futures called, "Energy Needs, Choices and Possibilities: Scenarios to 2050." This report paints a rosy picture of a technological fix (through an energy substitution process, which is commonly conveyed via intellectual fast food like the Whale oil story) to future energy needs. However, if you dig into the assumptions you find this:
“Personal Choices – related to values, the environment and lifestyles – influence the energy system. Affordability is not the key constraint in OECD countries.” (page 24)
and this:
"... scarcity of oil supplies -- including unconventional and natural gas liquids -- is unlikely before 2025... Technology improvements are likely to outpace rising depletion costs for at least the next decade, keeping new supplies below $20 per barrel. The costs of biofuels and gas to liquids should both fall well below $20 per barrel of oil equivalent over the next two decades, constraining oil prices." (page 18)
Of course, seven years of hindsight makes it easy to see these assumptions are false. It is much harder to find assumption errors that have yet to play out.