Ducting cross-winds to make highways more efficient

There are many stretches of highway are exposed and hence suffer from crosswinds. It occurs to me that it may be possible to harness the energy in the crosswinds using ducts at the side of the highway. The entrance to the duct is parallel to the carriageway, and the exit points in the direct of traffic flow (on each side of the road). The force of the wind blows air through the duct, creating a flow in the direction of the traffic, which reduces fuel consumption of the vehicles travelling on the highway.