Turning wasted heat and good vibrations into green energy
Whenever we walk or run, we create energy. “With every step we take, we put pressure on both the ground and the soles of our shoes, which in turn creates tiny vibrations – vibrations that produce energy,” says Cintia Mateo Mateo, a senior researcher in advanced materials at the AIMEN Technology Centre. According to Mateo, this phenomenon is called piezoelectricity and could be used to generate electricity. Unfortunately, all this energy is lost. Likewise, the temperature difference created by the body when we exercise could be transformed into electrical energy. But again, lacking the right thermoelectric materials, this energy is wasted. However, this could soon change, thanks in part to the energy harvesting systems AIMEN is developing with the support of the EU-funded InComEss project.
Generating green energy from mechanical vibrations and thermal waste heat
The project set out to demonstrate how piezoelectric and thermoelectric devices can be used to harvest available mechanical vibrations or temperature differences and use them to generate green energy for feeding wireless sensor networks (WSNs). But don’t fret – the project has no intention of connecting such devices to humans and turning us into energy-producing hamsters. “Our focus was on harvesting and storing energy from the vibrations and wasted heat produced within the auto and aerospace sectors,” explains Mateo, who served as the project coordinator. For example, in one case study, a thermoelectric generator was attached to a vehicle’s exhaust system, where it could generate electricity from the difference in temperature caused when the car begins to drive. “Using harvested energy, we were able to monitor the fuel level of a vehicle every 1.5-2 minutes depending on the driving conditions and exhaust gas flow,” adds Mateo. As for the aerospace scenario, the project attached a combined piezo- and thermoelectric generator to an aircraft’s wings. The system transforms both the vibrations and temperature differences that occur in the wing into electrical energy that can be used to transmit data to an internet of things (IoT) platform every couple of minutes.
Not enough energy to power wireless sensor nodes
Although the prototypes were able to generate electricity from mechanical vibration or thermal waste heat, it was not enough to fully power WSNs. “Intent on not wasting an opportunity, we decided to use the case studies to prove the functioning of the conditioner circuit, storage supercapacitors, wireless sensor communications, and IoT platforms, amongst other components,” remarks Mateo. Here, researchers demonstrated that, when integrated with the conditioner circuit and generators, the supercapacitors can store harvested energy. They also proved the developed power conditioning circuit’s capacity for increasing energy transfer efficiency between the generators and the end-use electronics.
A cornerstone for the energy harvesting systems of tomorrow
Although more work needs to be done, the InComEss project serves as a cornerstone from which the energy harvesting systems of the future will be built. “By successfully demonstrating the possibility of using energy harvesting systems to power wireless sensor nodes, we’ve not only helped advance the sensor and IoT markets, we’re also supporting the green energy transition,” concludes Mateo. In addition to continuing to improve the energy generators, project researchers are looking at using the generators to power a range of low-energy sensors.
Keywords
InComEss, heat, green energy, green electricity, energy, energy harvesting, mechanical vibrations, thermal waste heat, piezoelectric, devices, thermoelectric devices, wireless sensor networks
