The Oil Drum presents a guest post by Carlos de Castro, a professor of Applied Physics in the University of Valladolid in Spain. Carlos is the lead author of an article that looks at the technological and physical limits on wind power in an attempt to determine its real, rather than theoretical, possibilities in providing electrical energy for humanity.

His conclusion is that wind has a maximum global limit of 1 TW (terawatt), or about 1/3 of what has been projected in previous studies which have focused on wind turbines in specific locations. He reaches this lower figure via the fact that his model takes into account the principle of energy conservation which other studies ignored.

If his model is correct, then it means that the race to build wind turbines across the globe could reach that 1 TW level in 15 years. After that, every new wind farm would be useless.  Moreover, other renewables (tidal, wave, geothermal) may also have upper limits as well.  He recommends that similar studies be undertaken to see if this is the case in order to understand their possibilities for creating electricity on a global scale.

 

Abstract:
This paper is focused on a new methodology for the global assessment of wind power potential. Most of the previous works on the global assessment of the technological potential of wind power have used bottom-up methodologies (e.g. Archer and Jacobson, 2005, Capps and Zender, 2010, Lu et. al., 2009). Economic, ecological and other assessments have been developed, based on these technological capacities. However, this paper tries to show that the reported regional and global technological potential are flawed because they do not conserve the energetic balance on Earth, violating the first principle of energy conservation (Gans et al., 2010). We propose a top-down approach, such as that in Miller et al., 2010, to evaluate the physical-geographical potential and, for the first time, to evaluate the global technological wind power potential, while acknowledging energy conservation. The results give roughly 1TW for the top limit of the future electrical potential of wind energy. This value is much lower than previous estimates and even lower than economic and realizable potentials published for the mid-century (e.g. DeVries et al., 2007, EEA, 2009, Zerta et al., 2008).

His model looks at several constraints that subtract the energy that cannot be transformed into electricity.  These include:

  • the energy of the lowest layer of the atmosphere
  • reachable areas of the Earth (geographical constraint)
  • % of the wind that interacts with the blades
  • areas with reasonable wind potential
  • % of the energy of wind speeds that are capable of producing electricity
  • efficiency of the conversion of kinetic energy (the energy of motion) into electric energy

Our conclusions:

The global assessment of the technological potential of wind power to produce electricity, based on the top-down approach, shows quite different results to those of previous works. The technical assessment potential that has been obtained is one or two orders of magnitude lower than those estimated by other authors. This means that technological wind power potential imposes an important limit on the effective electric wind power that could be developed, against the common thinking of no technological constraints by economic, ecological or other assessments.

According to the World Wind Energy Association, the electrical wind power produced today is ~0.045 TW and this type of energy is growing at an annual rate of > 25%. If the present growth rate continues, we would reach the 1 TW we estimated in less than 15 years. Therefore, probably in this decade, we will see less growth than we saw in the previous decade.

This limit poses important limitations to the expansion of this energy. Since the present exergy consumption of all energies is ~17 TW, it implies that no more than 6% of today’s primary energy can be obtained from the wind.

Furthermore, if the electric wind power of the world were to approach 1TW, we could generate a new class of “tragedy of the commons” with the necessity of the international regulation of rights to winds. Without an effective regulation, in a medium-term future, we will see “wind park effect and wake effect” on a global scale, making new and old installed parks less efficient.

Global assessment of potential energy based on bottom-up methodologies has been used for renewable energies such as tidal, wave or geothermal.

A top-down review of the global assessment of potential energy from these renewable sources may be necessary in order to obtain the best estimation for the top limit of primary energy that our society is able to use in a sustainable

The comments on this post at The Oil Drum are also will worth reading as several people question the approach taken by the author and he responds to them.  These include the extent to which one wind farm prevents others from using wind, the depletion of wind resources,  and the potential for airborne and floating windfarms.

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