Shannon Larratt is Zentastic

Operating under the assumption that “peak oil” is real and we will either run out or have drastically less over the next fifty years, I've read articles that say it's impossible for us to generate our power needs using alternative power sources, and I've read others that suggest we've got “nothing to worry about”. So, I thought I'd try and estimate just how large our alternative power platforms would need to be to meet our needs.

Last year the US consumed 337 million BTU per person. Let's expand that to a world scale (6.5 billion people), bringing us to a total desired world consumption of about two quintillion (2,190,500,000,000,000,000) BTU. Let's say we could reduce energy use to 1/5 what it is now (personally I think that's possible and reasonable while still maintaining “first world” standards). That brings us down to 438.1 quadrillion BTU, the equivalent of 128.4 trillion kWh.

Here's some ways to generate that power:

• Biofuels currently yield about 375 gallons of fuel per acre. Each gallon of fuel is about 132,000 BTU, but if you factor in the cost of production (using current European plants as a model), you're only able to retrieve about half of that. So if one acre of biofuel crop generates 24,750,000 BTU, to generate world needs using biofuel, we would need 1.7 billion acres (about half of all the current arable land on the entire planet).

• Nuclear reactors generate about seven million MWh (23,918,304,000,000 BTU) per year. This does not include the cost of production, maintenance, and so on. I don't know what these costs amount to. If they're low (say 10%), we'd need to build about 20,000 nuclear reactors to meet energy needs. If they're high that number could double…
• Solar power plants optimistically generate about 350,000 kWh per acre per year (assuming they're in a prime location and have consistent sun). Not including the cost of construction and maintenance, that means we'd need about 365 million acres of solar plants to power the world.
• Giant wind turbines (like the forty story high ones) generate about 6,570,000 kWh per year (5 MW maximum generator at their observed 15% efficiency), and that doesn't count the cost of construction and maintenance. In any case, we would need to build about 20 million of the biggest towers in the world to meet world needs, and they'd need to be replaced on a regular basis.

Anyway, I apologize if I made any mathematical errors; feel free to double check them. As I'm reading these numbers, meeting energy needs in a way that's equitable (which it must be if we're to be a peaceful planet). My personal feeling is that we need to cut our energy consumption by a lot more than 80%, and that we also need to cut our population radically in order to maintain even a semblance our current life.

Seriously though, feel free to offer alternate numbers or point out errors and other options in the comment forum (like the math for tidal power plants and so on). I could have easily put a comma in the wrong place in any of these.