Confirmed through experiments, researchers have developed a way to generate electricity, through simple fluctuations in temperature, that may one day allow us to harness the simple movement of trees as a renewable source of energy.
News of this recent development in energy research came in an academic press release today from Linköping University in Sweden, where researchers from the Laboratory of Organic Electronics have been inspired by photosynthesis in creating a “tiny optical generator” that produces electricity through fluctuations in lighting and heat, like with the change from sunshine to shade.
Magnus Jonsson, a lead investigator in the lab who was involved with the project, said in a statement that “the research is at an early stage, but we may in the future be able to use the natural fluctuations between sunshine and shade in trees to harvest energy”.
The biggest drawback of current solar-powered systems is that they require constant sunlight to draw energy at optimal capacity – unlike plants, which continue to harvest energy through photosynthesis despite changes in weather and sunlight. With this in mind, researchers from Linköping University have built a system that depends on such changes to function.
The new system incorporates materials from a previous project done in collaboration between researchers from Linköping University and the University of Gothenburg, in which Jonsson and colleagues were involved in the development of nanoanttenas, extremely small antennas constructed from metal discs that measure only 160 nanometres across. These nanoanttenas are able to generate heat energy from sources of infrared light.
Jonsson and his team at Linköping University, as part of a new project led by PhD Student Mina Shiran Chaharsoughi, have been able to build these antennas into an optical generator. The nano-sized discs are distributed along a surface, about 0.3 micrometres apart, and a thin polymeric film is layered on top. This results in a pyroelectric system, where changes in temperature translate to an electric charge. That is, when the system is heated or cooled, it generates an electric current. The polymeric film converts heat energy produced by the antennas into electricity.
The only catch is that the polymeric film must be polarized first – one end must be positively charged, and the other negatively charged. Although once the film is polarized, researchers say “it remains polarized for a long time.” As for the nanoantennas, the team used gold and silver as materials for the metal discs, although they say cheaper materials can be used instead, like copper or aluminum. Billions of these discs can be spread across a surface to generate electricity from temperature fluctuations as part of a pyroelectric system.
The temperature fluctuations do not need to be great for the system to work. Chaharsoughi demonstrated that energy can be produced through the simple change from sun to shade and back. Holding a twig with leaves over the optical generator, the fluttering of the leaves (caused by air flow from a nearby fan), resulted in fluctuations in sunlight that were enough to generate a small amount of electricity in the system, successfully powering an external circuit.
The new technology is described in Advanced Optical Materials.