I think that this is just nice to know study, but it does not put fundamental limits for the wind power utilization. First is that with optimal scattering of wind turbines, it is possible get significantly more watts per m². Linear rows are the worst in efficiency, but the science of optimization is evolving rapidly and I doubt that this was considered in this Harvard study.
Second argument is that with advanced blades materials, such as carbon fibers and futuristic graphene, it is possible to make rotors up to 250 meters in diameter. This can boost individual wind turbine output up to 20 MW. With 20 MW off-shore wind turbines, the power density can be increased substantially what they modeled on this Harvard study. Wind Turbine Blades Push Size Limits http://www.renewableenergyworld.com/rea/news/article/2012/07/wind-turbine-blades-push-size-limits I would think that more worrisome thing about global scale wind production is how terawatt scale wind power production affects on global climate patterns. Some studies indicate that terawatt scale wind power production may have significant impact on global warming. However I think this as non-issue, because wind power is only good for northern European latitudes, because in the south, solar power with battery storage is the dominant way to produce electricity in near future. The cost of solar is getting exponentially cheaper as the global demand is ramping up to production of solar panels. In 2012 the price of solar systems fell 25 % in Germany and solar is now cheaper than grid electricity for the companies. The system cost of rooftop solar electricity is just 120–140 euros per MWh where as grid electricity costs 110–170 euros per MWh. And this in Germany that is located in latitudes near Alaska and is covered with clouds! And there is absolutely no reasons why the cost of solar would not fall another 25 % in 2013, because we are far from the theoretical potential of solar electricity. New breakthrough on advanced prototypes are reported weekly. Latest breakthrough lab prototype was on the utilization of graphene in solar cells: Photoexcitation cascade and multiple hot-carrier generation in graphene http://www.nature.com/nphys/journal/vaop/ncurrent/full/nphys2564.html —Jouni Ps. thanks Jed for pointing out good argument that domestic cats are killing billions of birds but this is a non-issue, because unlike wind turbines, cats are cute! Only cat haters are using this as an argument against domestic cats. On Feb 25, 2013, at 11:46 PM, Mark Gibbs <mgi...@gibbs.com> wrote: > “People have often thought there’s no upper bound for wind power—that it’s > one of the most scalable power sources,” says Harvard University applied > physicist David Keith. After all, gusts and breezes don’t seem likely to “run > out” on a global scale in the way oil wells might run dry. > > Yet the latest research in mesoscale atmospheric modeling, published in > Environmental Research Letters, suggests that the generating capacity of > large-scale wind farms has been overestimated. > > Each wind turbine creates behind it a "wind shadow" in which the air has been > slowed down by drag on the turbine's blades. The ideal wind farm strikes a > balance, packing as many turbines onto the land as possible, while also > spacing them enough to reduce the impact of these wind shadows. But as wind > farms grow larger, they start to interact, and the regional-scale wind > patterns matter more. > > Keith’s research has shown that the generating capacity of very large wind > power installations (larger than 100 square kilometers) may peak at between > 0.5 and 1 Watts per square meter. Previous estimates, which ignored the > turbines' slowing effect on the wind, had put that figure at between 2 and 7 > Watts per square meter. > > In short, we may not have access to as much wind power as scientists thought. > > http://www.rdmag.com/news/2013/02/rethinking-wind-power?et_cid=3110245&et_rid=523913766&linkid=http%3a%2f%2fwww.rdmag.com%2fnews%2f2013%2f02%2frethinking-wind-power
