Why just have signs over the highway? Joe at Arizona State University thinks that horizontal wind turbines might zip around from the turbulence created from cars and trucks. Those cyclists who have tried drafting behind transport trucks know that there is quite a bit of suction there, more than enough to spin these turbines. Joe says "Average vehicle speeds on the valley highways are approximately 70 mph. Using average annual wind speeds of 10 mph as a baseline, each single wind turbine will produce 9,600KwH of energy, annually (enough to fully power my 700 s.f. apartment). This power production estimate will increase exponentially with an increase in wind turbulence speed. I believe that the wind stream created over the freeways by our primary mode of transportation will create an average annual wind speed well beyond the baseline of 10 mph." ::Archinect via ::Inhabitat
Combine this with Kara's turbine equipped Jersey Barrier and we could suck the wind out of every passing truck. But is this all like that silly British ramp generator that is just burning more gas, or is this free energy?