They did things differently there.

A scary chart from the US Energy Information Administration (via Ezra Klein):

The problem is, it’s rubbish, at least as far as renewables are concerned.

What they did was lazily take the past growth rate for all renewables (about 3 percent) and project it into the future. The past of renewables is dominated by hydropower, with limited growth potential. However, the category includes wind (compound growth rate 28 percent over 10 years) and solar PV (compound growth rate 35 percent). Don’t believe me? Check here.

Applying the EIA’s shoddy methods, I split the renewables into “hydro and geothermal” (growth rate 3%) and “wind and PV” (combined growth rate 29 percent), using data from the BP Statistical Review of World Energy 2011. Projecting these historical rates I got this much more cheerful chart:

Spreadsheet with data and working here.

I don’t ask you to believe this armchair exercise. Wind energy for one may well tend to a constant-returns plateau as the technology matures; solar power will eventually run into land use conflicts; and above 20% or so penetration the need to balance all intermittent power sources becomes an increasingly expensive constraint. All such problems lie ten years ahead, but will no doubt become significant after that.

But it’s far less unrealistic than the EIA projection. This is based on the fallacy that there is a technology called “renewable energy”. There isn’t. Hydro, wind, solar, geothermal and biomass – and that’s leaving out solar thermal, OTEC, wave, tidal, and hot dry rock geothermal, which are so far invisible in the numbers – are far more different from each other than are oil, gas, and coal. Each technology will follow its own learning curve. You cannot sensibly aggregate them ex ante.

BTW, the fact that the prospects for affordable renewable energy supply are very good is not a reason for complacency. The amount of time we have to stop global warming shrinks as we (that is, those of us prepared to make the effort or listen to the qualified) understand more. There’s not much time left to close the coal mines and recycle the Hummers.

Alert readers will notice my starting total for renewables is a lot lower than the EIA’s. I haven’t bothered to reconcile them as my demonstration works on BP’s lower numbers. Incidentally, my 29 percent combined growth rate for solar and wind is itself an underestimate for the reasons I describe: it’s dominated by the greater installed base of wind. Recent 5-year growth rates are higher for all renewables except hydro than the 15-year ones I used.

[Cross-posted at The Reality-Based Community]