by Robert Maynard.
Frequent readers of True North Reports may be familiar with the argument that energy sources like wind power are not likely to generate as much power as the general public is led to believe because of its intermittent nature and its low energy density. The first factor is obvious. Wind simply does not blow all the time. The second factor is related to the amount of usable energy that can be generated when the stored potential energy in the source material undergoes a conversion process. A fuel source with a low energy density needs an extensive conversion process to generate very much usable energy from the potential energy stored in the fuel. In other words, there is not much bang for your buck. Given these two factors, it should come as no surprise that research at the Harvard School of Engineering and Applied Science has revealed that the generating capacity of wind farms at large scales has been overestimated. The results of this research was announced in an article entitled “Rethinking Wind Power,” which appeared on the school’s website:
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.
It looks like we need to add yet another drawback to large scale wind power.