I'm Feeling Hot, Hot, Hot!

What do you get when you pack 250,000 commuters into a toasty train station like sardines each day? (Besides a herd of cranky, sweaty humans in a rush, of course.) Energy!

Well, this is what Sweden has found in any case.

Stockholm’s Central Station has been scrounging warmth from its hubbub of bodies and bustling shops for nearly a decade now. Leftover body warmth is caught in the station’s ventilation system and used to heat an office building almost 100 yards away! And this nifty technology is far from unheard of. In fact, if you have ever popped into the Mall of America in Minneapolis, you too have been used as a green energy source!

As per usual, mention of thermal energy often calls another one of our renewable rock stars: geothermal energy, a distant cousin of solar energy, to mind! And despite the fact that geothermal energy is less finicky about working a night shift than solar and does not let a cloudy day get it down, we cannot deny several downsides of our bid to pilfer energy from hot water in the Earth’s crust.

Photo by A. Dombrowski.

For one, even though geothermal energy yields a plunge in carbon emissions, it hands hydrogen sulfide, another less than friendly gas, a get out of jail (aka. the Earth’s crust) free card! And to make matter worse: surprise! The fluids in the Earth’s crust we stir up can contain some bonus ingredients that just so happen to be a wee-bit toxic. Of course, there is also the intricate pipelines and power plants to consider, along with the fact that geothermal commotion beneath the Earth’s surface always seems to be on the move.

So why not follow the lead of Stockholm, Minnesota, and even the Tube in London? Let’s think more along the lines of human-thermal!

Photo from Chris Brown.

7.6 billion strong, each one of us is a tiny warm-blooded heat factory, pumping out warmth as if there’s no tomorrow! With an internal body temperature of a whopping 98.6 degrees Fahrenheit, our insides enjoy a 24/7 sauna. (Although it might not feel that way during these wintry months in Happy Valley.) And we’re hot to the touch too, with a surface temperature only around 9 degrees lower!

But according to Forbes Magazine, we lose around 80 percent of our body power to heat. Imagine the possibilities if we could harness it!

But we aren’t always crammed into a train station or shopping center; in fact, we quite enjoy our personal space, so is there a means to capture this on a smaller, more individualized scale?

Well, Forbes also mentions that one average resting male can produce 100-120 Watts alone. This is enough juice for more than 100 cell phones or for nearly three laptops!

But, as you might anticipate, since plugging your phone into your finger to charge has yet to become all the rage, we haven’t quite gotten this technology down pat.

Not to worry though; we’re well on our way!

What is all the rage right now, is research on this technology! Or more specifically, research on miniature power cells and personal body heat-catching devices to power wearable or personal electronics. This technology effectively boils down to a sheet of a thermoelectric material. And this is just a fancy title for a substance turned traffic cop whose superpower is playing favorites! Thermoelectric substances don’t pay any mind to electrons, allowing them to cavort around freely, but put their feet down when it comes to temperature.

Being stingy with temperature traffic means that when exposed to our balmy, 89.6-degree skin on one side and cooler air on the reverse, these materials wind up with a discrete “hot side” and “cold side.” And since electrons do not seem to enjoy being hot and sweaty any more than we do, they tend to migrate from the sweltering, tropical side to the refreshing, cool side. Ding, ding! This mass flow of negative charge gives us the golden egg of energy technology: an electric current!

Intended to be worn as a tiny patch, integrated into wristwatches, or sewn into clothing, prototypes for this technology tend to be diminutive by design. This is only exacerbated by the fact that the temperature differential between our bodies and our surroundings can be as slight as a few degrees and that modern usage of thermoelectric materials is enormously inefficient, converting a mere 0.4% of heat energy to electric current.

This means our current prototypes put out only a few thousandths of a Watt! In other words, reminiscent of our jelly-power, this technology calls for vast refinement, innovation, and a boost in efficiency.

And who knows, our next fashion fad just might be personal power cells!