Our global economic crisis is really a crisis of energy resources. The economies of most nations revolve around producing and obtaining energy in some form or another. I'll not go into the energy chain in this post, but suffice it to say there is plenty of ink/bandwidth out there dedicated to energy flows on Planet Earth. Our consumption of energy is the real problem, not the actual amount that we have used or what is still available to consume by mankind.
The debates typically center around the specific energy sources and how we have historically used them, how we currently use them and how we think we should use them in the future. Clean coal vs. solar. Wind vs. hydro. Nuclear vs. everything else. Fossil fuels vs. renewables.
What is the most reliable source of energy that most human beings have access to? Human power. It's true! We've basically lost the art of animal husbandry as it relates to power generation. I'm sure if the electric went off for good some resourceful members of the community could cobble together a horse or ox powered grist mill. And each community could build an animal driven mill. I have that much faith in the human race to believe in that possibility. What I don’t have faith in is our ability to scrounge up enough horses, oxen, mules and donkeys to provide a viable alternative to the energy sources we currently depend on at the rates to which we are accustomed.
In the Post Carbon Apocalypse life is necessarily going to become much more human scaled. The primary source of energy will be FOOD. Energy efficiency will be counted in calories, not kilowatts.
This is why the bicycle is important to our future. Once a bicycle is built it really only needs muscle power and it will enable a human being to travel great distances at a high rate of speed (compared to an unaided human being). The efficiency the bicycle provides will greatly replace the work of animals. Of course you won’t be plowing fields with your mountain bike, but for transportation purposes the bike will fill in the gaps left with the decline of fossil fuels. And this is why I see cargo bikes, whether longtail or front load, as being crucial to the movement of human beings in the future. Even non-cargo bikes allow a person to transport small amounts of goods over distances with drastically improved efficiency over arms and legs alone.
Human energy will endure, no matter what else transpires in the realm of energy and economy.