Body Heat as green energy?

Omar Gamel
23 January 2012

Can body heat provide green energy?

Remember that scene in the Matrix, when Morpheus reveals to Neo that the machines have enslaved humans to use their body heat as an energy source? While the plot doesn't make sense since humans consume more energy than they release as body heat, it turns out that it's not such a crazy idea.Fast Fact: The human body emits roughly 100 Watts as body heat when at rest — about the same as a standard light bulb, and equal to 1/7 horsepower. This can go up more than ten-fold with vigorous exercise.

But clever engineers around the world have found a way to use body heat that would otherwise go to waste by heating up the atmosphere. Simply put, crowd large numbers of people in a small space, and pretty soon, the ambience warms up.

About a quarter of a million commuters go through Stockholm's Central Station, in Sweden, every day. Add to this the heat produced from all the trains, and you have quite a toasty environment, even during the winter. This led to a clever idea; why not use this energy to heat up nearby buildings? All it takes is some pipes to pump water warmed up in the station to neighbouring offices. You end up with a renewable and practically free energy source.Fast Fact: Geothermal energy is based on the same idea; water is pumped through pipes several kilometers into the earth, closer to the earth's molten core, and returns warmer.

Sweden has already implemented this system, and there are plans for France and Austria. But there is no such thing as a free lunch. This method requires much insulation, and clever engineering to be efficient. It can only be used for buildings within about 100 metres of the station due to heat loss from the pipes to the environment.

Some researchers even say that there will come a day when your body heat is used to charge your cell phone and your laptop. Who knows?

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Article first published on October 4, 2010.

Omar Gamel

I am a PhD student studying Physics @ the University of Toronto. I study Quantum Optics, and love all things quantum. I enjoy teaching science, and have a great interest in education. In my spare time, I am an avid reader, and volunteer in various organizations. I also learned to juggle, in case physics doesn't work out.

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