Summit County Citizens Voice

Given political and social will, windpower could easily meet half the world’s energy needs by 2030

Downstream turbulence is visible in this aerial shot of the Horns Rev turbines off the coast of Denmark. Photo courtesy Vattenfall.

By Summit Voice

SUMMIT COUNTY —By now it should be clear that the main obstacles to making a wholesale switch to clean, renewable energy are social and political — if the will is there to commit to that path, the resources are abundant.

In a hypothetical exercise meant to provide a frame of reference for those renewable energy discussions, scientists from Stanford University and the University of Delaware showed that all of the world’s power demands could be met by wind energy.

The researchers developed a sophisticated model to show enough wind power could be generated to exceed total demand by several times if need be, even after accounting for reductions in wind speed caused by turbines.

The modeling involved calculating the theoretical maximum wind power potential on the planet taking into account wind reduction by turbines, assuming wind turbines could be installed anywhere and everywhere, without regard to societal, environmental, climatic, or economic considerations.

The new paper contradicts two earlier studies that said wind potential falls short of ambitious goals because each turbine steals too much wind energy from other turbines, and that turbines introduce harmful climate consequences that would negate some of the positive aspects of renewable wind energy.

The new model provides a more sophisticated look than previously possible by separating winds in the atmosphere into hypothetical boxes stacked atop and beside one another.

“Modeling the climate consequences of wind turbines is complex science,” said Mark Z. Jacobson, a professor of civil and environmental engineering at Stanford. “This software allows that level of detail for the first time.”

With a single model, the researchers were able to calculate the exposure of each wind turbine in the model to winds that vary in space and time. Additionally, the model extracts the correct amount of energy from the wind that gets claimed by the turbines, reducing the wind speed accordingly while conserving energy. It then calculates the effect of these wind speed changes on global temperatures, moisture, clouds and climate.

Among the most promising things the researchers learned is that there is a lot of potential in the wind — hundreds of terawatts. At some point, however, the return on building new turbines plateaus, reaching a level in which no additional energy can be extracted even with the installation of more turbines.

“Each turbine reduces the amount of energy available for others,” said Cristina Archer, an associate professor of geography and physical ocean science and engineering at the University of Delaware.

The reduction, however, becomes significant only when large numbers of turbines are installed, many more than would ever be needed.

“And that’s the point that was very important for us to find,” Archer said.

The researchers have dubbed this point the saturation wind power potential. The saturation potential, they say, is more than 250 terawatts if we could place an army of 100-meter-tall wind turbines across the entire land and water of planet Earth.

Alternatively, if we place them only on land (minus Antarctica) and along the coastal ocean there is still some 80 terawatts available — about seven times the total power demand of all civilization. Hypothetical turbines operating in the jet streams six miles up in the atmosphere could extract as much as an additional 380 terawatts.

“We’re not saying, ‘Put turbines everywhere,’ but we have shown that there is no fundamental barrier to obtaining half or even several times the world’s all-purpose power from wind by 2030. The potential is there, if we can build enough turbines,” said Jacobson.

Knowing that the potential exists, the researchers turned their attention to how many turbines would be needed to meet half the world’s power demand — about 5.75 terawatts — in a 2030 clean-energy economy. To get there, they explored various scenarios of what they call the fixed wind power potential — the maximum power that can be extracted using a specific number of wind turbines.

Archer and Jacobson showed that four million, five-megawatt turbines operating at a height of 100 meters could supply as much 7.5 terawatts of power — well more than half the world’s all-purpose power demand — without significant negative affect on the climate.

“We have a long way to go. Today, we have installed a little over one percent of the wind power needed,” said Jacobson.

In terms of surface area, Jacobson and Archer would site half the four million turbines over water. The remaining two million would require a little more than one-half of one percent of the Earth’s land surface — about half the area of the State of Alaska. However, virtually none of this area would be used solely for wind, but could serve dual purposes as open space, farmland, ranchland, or wildlife preserve.

Rather than put all the turbines in a single location, Archer and Jacobson say it is best and most efficient to spread out wind farms in high-wind sites across the globe — the Gobi Desert, the American plains and the Sahara for example.

“The careful siting of wind farms will minimize costs and the overall impacts of a global wind infrastructure on the environment,” said Jacobson. “But, as these results suggest, the saturation of wind power availability will not limit a clean-energy economy.”

The findings were published in the Proceedings of the National Academy of Sciences.

Filed under: energy, Environment, renewable energy Tagged: | energy, Mark Z. Jacobson, renewable energy, Stanford University, University of Delaware, wind turbines, windpower