Just Where Do You Find The Energy These Days?

9th February 2012

A month ago I pulled a hamstring and am still having to forego my weekly ten mile run. With the help of a physio I am at least able to spend some time on a cross-trainer. Anyone familiar with gym equipment understands that running on the spot gives you plenty of time to think – in my case pondering how warm a room gets after you have been exercising in it for any length of time. In fact if you use equipment in a gym you usually do so under a hefty jet of cool air from a crude air conditioning system. Here, I think, the makers of cross-trainers and rowing machines are missing out on a trick. If exercise machines were fitted with generators gym operators would have access to as much carbon free electricity as is generated by a medium sized wind turbine. It would probably also be worth their while recovering some of the heat from the warm air they currently throw out into the atmosphere.

But gyms are not the only off beat energy sources.

For decades trains running on the London Underground system have been dumping waste heat into tunnels below the capital. In some places substantial amounts of heat energy is stored in the clay surrounding these tunnels. This stored energy heats the air in tunnels, trains passing through the tunnels and passengers in the trains. In recent years many London Underground stations have been upgraded – unfortunately heat reclamation has not been part of this makeover. In fact, as with gyms, energy is used to cool down trains and air in tunnels.

A few years ago I attended a presentation given by a high technology company in a hotel in San Francisco. It was a hot day - the temperature was over a 100 F. Once inside the hotel I was shown into a mock Tudor banqueting room with a roaring fire at the far end. To make this piece of theatre a little bit more atmospheric the air conditioning had been cranked up so that the ambient temperature of the room was well below 60 F. That evening there was a power cut in Silicon Valley. OK, this was actually down to shady practises on the part of Enron - but the blazing fire illustrated a problem we have with energy. How can we persuade people to do clever things with energy they could get for free when they do such stupid things with energy they have to pay for?

Peter Kruger

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