As I’ve argued elsewhere, I believe we must scale back our overall energy use (and therefore production). An annual reduction in consumption (by mass) of 14 percent per year over 50 years would result in world energy production that is less than a tenth of a percent of its current value (a final average value of about 29 thousand Btu per person per year for a population of 6.9 billion people). The annual reduction in production would be at roughly the same rate. According to my consumption model, this reduction would be required to avoid both the crash of other species and any human population loss.
How much energy is 29 thousand Btu (British thermal units)? There are 100 thousand Btu in one therm, which is a common unit used by utility companies. According to the U.S. Census Bureau the average U.S. household consumed over three thousand times this much energy in 2001.
It is tempting to think of any reduction as a voluntary measure, until we recall that, if we survive to continue our profligate energy use, by the end of this century ALL FOSSIL FUELS WILL BE GONE. In 2004, fossil fuels accounted for 86 percent of world energy production, with the rest taken up by such alternatives as hydroelectric (six percent), nuclear (six percent), and other renewable sources for the remaining two percent (solar, wind, and bio-fuels among them). Of the alternatives, nuclear energy has the best chance of long-term growth; but it can only be applied to generation of electricity and has well known issues (such as waste disposal and use for weapons proliferation) that may in practice be very restrictive.
We will be forced to choose the energy sources of the next century to offset the losses of this one, and whatever we choose must have zero or less than zero (that is, beneficial) environmental impact to help Earth’s natural systems recover from the damage we have done so far.