Solar: salvation or solace?
March 11th, 2010 by Jim JustBig Gav has an interesting post at The Oil Drum: Australia/New Zealand on solar energy, and approaches being pursued to make it economically competitive with coal fired power generation.
Bill Gross, founder of the Californian company IdeaLab, offers some lessons learned:
- Use software to analyse and optimise performance of plants.
- Don’t build plants, get utilities (customers) to.
- Avoid environmental conflicts and transmission line costs by building smaller plants on brownfield sites near cities.
- Leverage energy storage and volume of scale in manufacturing to reduce costs.
Big Gav expands on these points in his post. It’s worth checking out.
On the other hand, John Michael Greer has a post voicing cautionary notes about the prospects for solar:
The first is that familiar nemesis of renewable energy schemes, the problem of net energy. It would take a pretty substantial amount of highly concentrated energy to build that hundred square mile array of mirrors, counting the energy needed to manufacture the mirrors, the tracking assemblies, the pipes, the steam turbines, and all the other hardware, as well as the energy needed to produce the raw materials that go into them – no small amount, that latter. It would take another very substantial amount of concentrated energy, regularly supplied, to keep it in good working order amid the dust, sandstorms, and extreme temperatures of the Nevada desert; and if the amount of energy produced by the scheme comes anywhere close to what’s theoretically possible, that would probably be the only time in history this has ever occurred with a very new, very large, and very experimental technological project. Subtract the energy cost to build and run the plant from the energy you could reasonably (as opposed to theoretically) expect to get out of it, and the results will inevitably be a good deal less impressive than they look on paper.
The second is another equally common nemesis of renewable energy schemes, the economic dimension. . . . If investing billions of dollars (and, more importantly, the equivalent amounts of energy and resources) in mirrors in the Nevada desert doesn’t produce as high an economic return as other uses of the same money, energy, and resources, the mirrors are going to draw the short end of the stick. Political decisions can override that calculus to some extent, but impose an equivalent requirement: if investing that money, energy, and resources in mirrors doesn’t produce as high a political payoff as other uses of the same things, once again, the fact that the mirrors might theoretically allow America’s middle classes to maintain some semblance of their current lifestyle is not going to matter two photons in a Nevada sandstorm.
Stuart Staniford at Early Warning takes issue with Greer, noting that photo voltaic systems can produce a positive energy return in the range of 4.8–13.9, a range pretty consistent with the findings in this 2009 report that net life-cycle EROEI for PV was in the range of 3.75:1 to 10:1. Regarding solar thermal, the same report did not give numerical findings, but rather stated:
The energy balance of this technology is highly variable depending on location, thus few studies have been done. In the best locations (areas
with many sunny days per year), EROEI is likely to be relatively high.
Even the most optimistic estimates for thermal energy are a long way from the 100:1 return on energy investment that oil gave in the 194os – though not quite so far from the 23:1 energy return that oil provided in the 1970s. Oil EROEI has certainly dropped even more today. For example, oil production in deep water currently achieves an EROEI of less than 5. For the production of Canadian syncrude the EROEI is less than one – that is, it takes more energy to produce a barrel of oil than the barrel of oil contains.
If – as Greer suggests – the future is unlikely to fulfill our cornucopian fantasies, it need not be grim:
When concentrated energy is scarce, local production of relatively diffuse energy for local use is a far more viable approach for a great many uses. This will allow the highly concentrated energies that are left to be directed to those applications that actually need them, while also shielding local communities from the consequences of the failure or complete collapse of centralized systems. The resulting economy may not have much resembance to today’s fantasies of a high-tech future, but the barbarism Frank Shuman feared is not the only alternative to that future; there’s something to be said for a society, even a relatively impoverished and resource-scarce one, that can still reliably provide its inhabitants with hot baths, warm rooms in winter, and well-done pot roasts – and, of course, good brandy.




This map shows the flow of carbon emissions embodied in trade among the major exporting and importing countries. Net exporting countries are in blue and net importers in red. China is by far the largest exporter of carbon dioxide emissions. Arrows indicate direction and magnitude of flow; numbers are megatonnes. (Steven Davis/Carnegie Institution for Science)






Ice-front retreat of the Wilkins Ice Shelf from 1947 to 2009