Euan Mearns at the Oil Drum blog draws this depressing chart from BP’s (one good deed) Statistical Review of World Energy.
World primary energy production 1970-2009. In 2009 fossil fuels (oil, natural gas and coal) accounted for 87.5% of all the energy we used. Wind, solar and geothermal combined accounted for 0.4%. (Mearns’ caption, edited)
But compound interest comes to our rescue.Â I played with BP’s data too. The 10-year annual growth rates for geothermal, wind and solar PV capacity were respectively 3.0%, 28.3%, and 35.1%, as fitted by Excel. The boom is not slowing down; the one-year rates 2008-2009, during a sharp downturn, were evenÂ a tad higher.
Total primary energy consumption fell in 2009; in the OECD countries, by more than GDP, offsetting rising use in China and India. It’s reasonable for a simulation therefore to assume flat total primary energy demand over the coming decades. I converted everything to electrical units – continuous MW equivalentsÂ – using BP’s conversion factors. Mearns follows BP in converting everything to tonnes of oil equivalent, a piece of propaganda we should resist.
If you just project these historic growth rates on that basis, primary energy from renewables can replace coal entirely by 2023 and all fossil fuels by 2028.
This won’t and can’t happen just like that.Â Long before we get near full replacement, intermittent solar PV and wind will hit constraints of energy management that require expensive retooling of the electric grid and cultural changes in patterns of use. Replacing oil for transport requires a major shift in technology for cars, and something entirely new for aviation, shipping and metals. These discontinuities are concealed by any blithe conversion of energy to a single metric like electricity, for different forms are not true substitutes.
On the other hand, the exercise excludes solar thermal energy. It’s also not credible on geothermal. This combines one old technology of tapping underground steam, which is only available in a few places, and a new one, fracking deep hot dry rocks, which has vast potential but is still experimental with an insignificant installed base. So geothermal will either stall or, hopefully, take off. (Note to Brett: it’s continuous. Note to language police: I concede in advance that geothermal is only truly renewable on timescales of centuries, in the short run it’s a form of mining, but even temporary exhaustion is millennia ahead.)
Credit GÃ©othermie Soultz (European hot rock demonstration plant)
The exercise underlines my earlier point that policy should concentrate on maintaining effective demand for the shift to renewables rather than spending fortunes looking for an unnecessary magical breakthrough. Precommercial technologies like hot rocks and fusion still need direct support, to widen the portfolio. But even without them, we have working technologies, we have businesses making money out of them, we have engineers making them better every day. The main thing we need to do is keep the market prices in their favour, and plan ahead to keep the road to sustainability clear. If the closet socialist American public insists on regulation against fossil fuels [update: but see Robert Waldmann’s stout defence of the great A~P~ in comments] rather than the more efficient market mechanisms preferred in Europe, that will also do.
Spreadsheet with my working here.