Fuel Cells for London Underground?
To the editor: After reading about fuel cells in Tim Queeney’s article on what the future will bring for inboard engines (Issue 115 July/August 2001), I thought I would like to make a couple of points. I worked on hydrogen/oxygen fuel cells in the late 1950s. The automotive market was the golden apple we coveted, but we realized niche markets were where we could get started.
We were approached by a promising group, the London Metro system. They were interested in regenerative braking. Subway cars stop frequently in stations, and when they do, all the kinetic energy of the train is converted into heat by the brakes. Perhaps the fuel cell, by its reversibility, could convert that energy back into hydrogen and oxygen for later use.
We found an additional advantage for underground railways. The heat generated by braking builds up in the tunnels and stations and has to be removed by air conditioning, which of course entails still more energy consumption. Fuel cells would have offered double savings. Unfortunately, the plan was never fully developed.
With global warming on everyone’s mind, I must point out that although fuel cells will reduce global warming by the increased efficiency of fuel use, the types that use hydrogen made by cracking hydrocarbons will still void greenhouse gases, like CO2, to the atmosphere.
Many people worry about the explosive potential of hydrogen, but it is not as dangerous as it appears. Hydrogen is such a small molecule and so light that it diffuses rapidly: hydrogen will not accumulate in your bilge. Back in those days, as safety trainer for new technicians, I put on a demonstration explosion.
I made foam by bubbling oxygen into a plastic bucket with some soapy water in it. Next, I would add some hydrogen to the foam and with all the gas tanks closed off I would throw a match into the bucket. The shock wave in a hydrogen-oxygen explosion is so sharp that even in a relatively open space it will make your head ring for a microsecond.
Although it was a bit of showmanship, technicians always did pay attention to closing valves properly.
I was the youngest of the development team. We always hoped the auto market was just around the corner, but I may be the only one who makes it to drive a fuel cell car - or a boat.
Henry Perry is a retired engineer who lives in Madison, Conn.