Every time you chew through one of those energy bars you are feeding your body’s power plant. By metabolizing glucose and other nutrients, you are providing energy to your muscles, heart or the millions of neurons in your nervous system. Your heart alone beats around forty million times a year. However, all the energy that isn’t used up by your body is lost in the atmosphere. Paradoxically, we also rush from one place to the other perpetually concerned over the battery life of our smartphones and other portable devices. The same can be said about all kinds of wearables, which are embedded in our clothes or bodies and have their own energy requirements.
What if we could channel the energy of our bodies to charge the latest smartphone we just purchased? In a way, it resembles those classic wristwatches that drew their energy from the pulse and movements of our hands, only far more sophisticated.
Last year, Canan Dagdeviren (MIT) and two other pieces of research from the Chinese Academy of Science published an article in the journal Annual Reviews where they investigated the potential of the human body as a source of energy. Now they have moved to the practical side of things.
Piezoelectric mechanisms are one of their main research focuses. This is the kind of electricity generated by the pressure applied to a material, such as quartz. Thus, they have developed a series of slim and unobtrusive materials that can be placed on the heart or the muscles to harvest electricity through the torsion forced by the organ. One of the most obvious applications would be an “infinite” pacemaker powered by the renewable energy of the heart itself. Vanderbilt University (Tennessee, USA) is also working on similar materials, as can be seen on this video.
Dagdeviren is also working on the possibilities provided by the thermal energy released by the human body. This could be used to power wearables such as smartwatches or even cochlear implants.
One of the most interesting applications would be triboelectricity, the static-electricity charges generated by contact and motion between surfaces from two different materials. There is a wide range of materials with triboelectric behaviors, although some are more efficient than others. In this case, the researchers are studying the most adequate surfaces, by working on different nanoscale configurations (cubes, pyramids or threads). So far, they have proved that a pyramidal mesh can generate up to five times more electricity than a flat surface. Their latest prototype is a triboelectric fabric that can charge Li-Ion batteries fitted into a belt. Besides charging such devices, triboelectricity can also be used to stimulate the growth of body tissues and speed up the healing of wounds.
Finally, the University of Fudan (Shanghai, China) has applied the principles of hydroelectricity to blood circulation. They envision nanoelectronic generators composed of carbon tubes that harness electricity from the bloodstream.
Students that power their own campus
Leaving the nanoscopic scale behind, we could be using our own physical exercise and movements to cover our daily electricity requirements with renewable and clean energy. That’s the idea behind the Human Power Plant project, a case study presented at Utrecht University that is researching the potential for a building powered by the exercise of its own residents. According to their numbers, one or two hour-long workouts every day, mainly on treadmills and exercise bikes, but also with machines installed in the students’ bedrooms, would be enough to cover their lighting needs, as well as the charging of laptops or smartphones. For instance, an exercise bike could deliver between 75 and 100 watts. The goal would be to attain a net zero-carbon footprint while keeping students fit in the process.
Sources: The Atlantic