Here is a bit of info you might find useful when thinking about energy usage and sources.
Total Worldwide Energy Production 10,209,142
Total Worldwide Energy Consumption 10,029,096
Breakdown of sources
Coal & Coal Products 25.3
Natural Gas 26.0
Solid Biomass 10.0
Biogas & Liquid Biomass .17
I take away a few ideas from this list.
A. Coal is a huge source, and is not considered to be anywhere close to fully exploited.
B. Biomass is way higher than I would have suspected. I also suspect it is a major potential for the future. This includes the production of energy from discarded biomass (garbage, yard trim, industrial bi-products and waste) as well as product specifically grown or harvested for this purpose (sugar, corn, soy, switch grass, ocean crops.)
C. Nuclear is a major contributor now, and is substantially underexploited.
D. Natural Gas is almost limitless in supply and very versatile.
E. Solar, wind, geothermal are making very little contribution, but breakthroughs seem likely.
It really doesn't seem like we'll miss oil that much, assuming we are running out. And if I were an oil company, I'd be more worried about gas, biomass, and coal as competitive threats to $75 a barrel oil, than I would about running out.