This idea came to me while being buffeted about by a semi passing me on the freeway, and then buffeted again by a semi coming toward me. We burn an awful lot of gas just to push air around. Wouldn't it be cool if the air pushed by one truck, could be redirected 180 degrees and help push a truck coming the other direction? Think of a rollerskating rink, where you end up with a vortex of air, just by everyone skating around the oval in the same direction. Or a revolving door where one person pushes in one direction, and it conserves the energy by pushing the door for someone coming the other way.
One way to accomplish this would be a covered highway (tunnel) segment with rounded ends, and a wall separating the two sides, like a very elongated donut.
So the cars going north push the air at 60 mph. At the end of the highway, the tunnel curves 180 degrees and pushes the air southward at 60 mph, so everyone always travels with a tail wind, and gets much better gas mileage. The tricky part is getting the cars in and out of the tunnel without losing the air flow. I envision a long slanted metal mesh ramp, so the cars could drive up and out of the tunnel, while the air continues flowing thru the mesh, and into the curved part.
Another benefit is that you could have air scrubbers on the thing to reduce smog.-- SeattleBrad, May 29 2002 Covered bicycle way http://www.biketrans.com/Similar idea, missing the circular part. [pashute, Mar 31 2008] Might be better to make cars, trucks, etc. more aerodynyamic. That saves gas in the long run.-- phoenix, May 29 2002 We're missing something here, aren't we?-- angel, May 29 2002 Just have tunnels filled with vacuums to reduce air resistance. What do you mean you wouldn't be able to breathe?
No, but wouldn't the air from the other cars behind you (and partial vacuum from cars ahead of you) give as much propulsion already as anything in this idea, without involving ramps, huge air ducts, etc.?-- pottedstu, May 29 2002 //filled with vacuums//
nice.-- stupop, May 29 2002 i have this image of a whole bunch of hoovers, electolux and the like running along in the tunnel. very clean place.-- rbl, May 29 2002 Forget about the rounded ends, just have long sections of twin tunnels with giant fan(s) pulling air from the sides and top near one tunnel exit opening, with the (filtered) exhaust connected back near the tunnel entrance on other side of the highway. Same thing at the other end of the tunnels and you get a powerful loop of air.
I saw a Mythbusters episode where they got amazing fuel-economy results from tailgating a semi-trailer. I think this would work just as well.
You would need to do some aerodynamics work to optimize the flow, probably design the tunnel to encourage airflow in one direction.
I think this combines nicely with solar panels on the roof of the tunnel cover for lighting, and to help power the fans.
You would also get a bonus of not needing salters or snowplows in winter.
Excellent.-- DrFever, Apr 21 2009 If this is a closed loop, then why not have a semi with a large sail create the air flow like a continual piston? It would just go round and round, pushing the air in front of it, pulling the air in back of it.-- twitch, Jul 23 2010 //filled with vacuums//
How many vacuums does it take to fill? How do you know when it's full?
This idea means that instead of the drag created by the vehicles moving against the air, you have the drag created by moving much more air against a huge area of tunnel walls. Granted, the tunnel wall could be made very smooth to reduce drag, but it's still a massive area. I suspect the total energy used to shift the air would be greater than the saving to the vehicles.-- Twizz, Jul 23 2010 random, halfbakery