As mammals, we are warm blooded (also known as endothermic). In fact, 80% of our body power is released as excess heat. We seem to be wasting a large amount of energy that can have many productive uses. A resting male produces around 100 watts of power per day. This can be translated to about 2000 calories, which explains why the recommended amount of calories eaten per day is 2000 calories too. Current technology is attempting to harness this natural and abundant energy.
How the Thermoelectric Device Works
A thermoelectric device is a technology that converts temperature contrasts to electricity or vise versa. This technology exploits what is called the Peltier-Seebeck effect. A thin, conductive material is put between a hot and cold surface. When one end of the material is heated electrons move to the cold end and give rise to an electrical current. There are a couple problems with using this. One is that this device depends on great temperature contrasts so the air temperature must be much colder than body heat. This requirement decreases the efficiency of such devices along the equator where the ambient temperature is fairly warm. Another issue is that the material is extremely cold on skin. So far it has been uncomfortable on the user. The last problem is that heat flows from warm to cold objects. Eventually body heat increases the temperature of the cold side of the metal and there is less of a contrast and a corresponding decreased efficiency of the material. Despite these setbacks, scientists are convinced that one day this can be a worthwhile source of energy.
Examples of the Thermoelectric Device
The most popular thermoelectric generator is probably the Powerpot. It harnesses the heat from a camping stove to create enough energy to power a phone. The first marketed and wearable device was Seiko’s thermic watch from 1998. Other examples of these devices come from Ruud J. M. Vullers and Vladimir Leonov in Belgium. In 2006 they made a blood oxygen sensor that was powered by body heat. Later, they made a thermoelectric device that monitored brain activity. Their most amazing device though was a washable shirt which could be used to monitor heart activity.
There are problems with wearable thermoelectric devices, namely that we can harness power only in the milliwatts from them. Nanotechnology has plenty of untapped potential. Soon we will apply new nanotechnology to these devices and they will become an effective product.
Statistics came from Osman Can Ozcanli, “Turning Body Heat Into Electricity,” Forbes Magazine 8 June 2010
Photo courtesy of thewatchsite.com
Tag(s) : thermoelectric, body heat, Seebeck, Peltier, watts, energy, natural energy, heat,