Multiwalled Carbon Nanotube Yarn Thermoelectric Energy Generating Candle

Abstract

Carbon nanotubes (CNTs) possess extraordinary properties and were only introduced to the world three decades ago. New applications and models of CNTs continue to surface both in the micro and macroscopic world. CNTs’ high electric conductivity properties qualify them for thermoelectric energy harvesting materials. The Seebeck Effect is the phenomena behind thermoelectric energy harvesting, which entails a flow of electrical current caused by a temperature difference between two conductors in contact with each other. By forming a junction between an average 5μm diameter multiwalled carbon nanotube (MWNT) yarn and 25μm diameter platinum line, we were able to produce a thermoelectric energy harvesting system in the fashion of a liquid fuel candle. The tea-sized candle consisted of a CNT yarn acting as a wick, where majority of the yarn was submerged in liquid fuel - the heatsink. CNT yarn is an attractive wick candidate due to its high porosity, capabilities of conveying fuel vertically, and thermoelectric properties. The exposed portion of the CNT yarn was connected orthogonally to a platinum line and their junction was the point of combustion. With the aid of a microcapillary tube, liquid fuel traveled vertically up the CNT yarn to provide a stable flow of fuel. Our thermoelectric candle produced a maximum power of 301nW, but when doubling the amount of CNT and platinum the candle’s power increased to 963nW. The voltage was dependent on both the material properties and flame relation to the junction but remained constant for a long duration. Longer duration tests were administered to monitor the circuit’s voltage over time. Maximizing an output voltage to a more efficient degree could be possible by quantifying the capillary force of CNT yarn in order to better supply the ideal amount of a specific fuel for the desired flame size. These results demonstrate candles can produce harvestable energy in an environmentally friendly fashion, even though there might not be a current use or storage procedure for the limited amount of energy harvested from a single candle.