Anti-Smoke Stack

One of my big ideas to improve traffic in cities is to build layers in central downtown areas. Vehicles would be confined to dedicated lower levels and pedestrians would have the top level all to themselves. If vehicles were powered by electricity, there should be no problem with fumes. However, I do not see the internal combustion engine going away anytime soon. In this case, we would need to provide ventilation for these lower levels.

One way to do this would be to build "smokestacks". These would be very similar to the smoke stacks used by coal burning furnaces: essentially tall, hollow pipes. The bottom end would be open to the levels used by the motor vehicles and the top would be open to the sky. Natural convection would cause the air (laden with fumes from the engines) to rise through these pipes and empty out into the air hundreds of feet up. Fresh air would be drawn in from the surrounding area at ground level. This would ensure a supply of fresh air for the people on these lower levels.

On multi-story buildings you may have noticed that they invariably have two sets of doors at each entrance, something like an airlock. Or they may have revolving doors. The reason for this is that with tall buildings the elevator shafts act like air ducts, and without some restraint, air comes in off the street and flows up the elevator shafts. The effect is so strong that it will make something of a windstorm, and in the winter a great deal of heat is lost to air going out of the top of the building. The two sets of doors help keep this breeze from starting.

Our smokestack takes advantage of this phenomena. Of course blowing the fume laden air out the top does not really do anything to reduce pollution, it just spreads it out over a larger area. But there might be something more we could do.

Imagine a smoke stack made of glass, about one hundred feet in diameter and five hundred feet high. Now line the inside wall with planters planted with green plants. Perhaps build a framework inside the stack to support more planters. Add automatic irrigation. Giving the stack a large diameter and a relatively small opening at ground level should reduce the velocity of the air to levels that would not damage the plants.

Now when the air flows up through the anti-smoke stack, it runs into the leaves of plants, where it may interact. This interaction could reduce the amount of pollution in the air. So besides providing fresh air to the vehicle occupants on the lower levels, it would also reduce the amount of pollution being generated by those vehicles. The plants would act something like a filter to clean the air coming through this pipe.

An embellishment would be to integrate this filter pipe into a building. You could make the pipe into a building by surrounding the central pipe with layer of rooms. Each floor would be circular with a circular hole cut in the center. However, if we do that, then there would not be much light to support plant growth at the lower levels of the central pipe. Lining the inside surface with mirrored glass could help with that.

Here is a video about solar updraft power project. It has a couple of features in common with my "anti-smoke stack", though it is an order of magnitude larger. Plans are being made to build one in Spain and one in Australia.


Update April 2015: Replaced video on account of the old one disappeared. I think it's the same video, though.