Volume 13, Number 35: 1 September 2010
"It takes energy to produce energy, even when the primary source is energetically cost free, such as solar or wind." So writes Goncalves da Silva, Emeritus Professor of Physics at the State University of Campinas (Brazil) in a recent issue of Energy, where he considers the oft-neglected energy expenditures involved in readying so-called renewable or free energy technologies for the magnitude of deployment that would be required to offset a significant portion of the enormous amount of the world's total energy production that is currently provided by fossil fuels.
The professor notes, for example, that the implementation of any desirable new energy-supply technology requires devices that can convert the original primary source into either electricity or transportation fuel in a carbon-free or neutral way, and that "the manufacturing, installation, regular operation, and fuelling of such devices involve an energy cost," which for the magnitude of fossil-fuel offsetting envisioned could be huge. In addition, he notes that these devices "have a finite lifetime, after which they must be decommissioned and replaced, bringing in additional energy costs," and that "a new energy technology has to be capable of producing enough energy to cover these costs and to generate a surplus for external consumption."
In light of these requirements, and under what he calls "ideal circumstances," Goncalves da Silva examines the deployment rate for any new energy technology, evaluating the net energy output to the existing energy infrastructure, which itself may be in need of significant modification or even wholly new development. This he does via the construction of a general model, the use of which he illustrates with simulations of the deployment of photovoltaic electricity at national and global scales, adding that any real-life situation is bound to show even worse results than those he derives in terms of the net energy delivered to the grid by the new technology.
So what does the professor finally conclude? He finds that "the new technology may actually be an energy sink, instead of an energy source, relative to the global total primary energy supply for many years or decades, depending on its intrinsic energy costs and deployment path, even though stated aims for its gross energy output are achieved [italics added]." Consequently, he says that "to achieve terawatts output from renewable sources, in order to displace massive quantities of fossil energies, will be a slow process, extending over many decades," and that we should "not place undue hope in new energy technologies to save the world from fossil energies until well after many decades of deployment." Or, we would add, if ever!
Sherwood, Keith and Craig Idso
Reference
Goncalves da Silva, C.E.T. 2010. The fossil energy/climate change crunch: Can we pin our hopes on new energy technologies? Energy 35: 1312-1316.