Synthetic Leaves Generate Electricity from Wind and Rain
The World Health Organization projects that climate change will cause over 250,000 additional deaths annually (Climate Change, 2023). Consequently, the issue tends to draw attention from people across the United States who demand immediate action. The most popular forms of renewable energy are solar power, wind power, and hydropower. Unfortunately, all of these methods of generating electricity have downsides, including cost and harm to the environment. However, there are new innovative forms of renewable energy that do not have the same downsides as the traditional green technology. An example of this is the multi-source energy harvester that can harness energy from a triboelectric nanogenerator (TENG) and a droplet-based electricity generator (DEG).
Most current forms of renewable energy utilize only one source, such as the sun or wind. However, the multi-source energy harvester harnesses energy fom both the rain and the wind, which maximizes efficiency and potential output of energy. The technology consists of tiny, leaf-shaped devices, which are placed on an artificial plant. These are commonly referred to as “power plants,” which harness the energy from the wind and rain (Min et al., 2024). The engineering and design of these power plants creates a unique structure which causes the motion from the wind and rain to make the internal parts of the metallic leaves touch, generating a current.
The first of the two parts of the multi-source energy harvester is the triboelectric nanogenerator, or TENG, which harnesses energy from the wind. TENG consists of nylon nanofibers between polytetrafluoroethylene, also known as Teflon, and copper electrodes (Artificial ‘power plants’, 2024). When it is windy, the layers of the TENG press together, generate static charges, and convert those charges into a current, which creates usable electricity. The TENG works well for this leaf-based technology because of its innate characteristics: flexibility, simplistic design, and wide structural choices (Kim et al., 2021). Furthermore, the material of the TENG is biodegradable and recyclable, which decreases its environmental costs.
The second part of this technology is the droplet-based electricity generator (DEG), which harvests energy from the rain. This technology consists of Teflon, which is waterproofed and covered in conductive fabric that acts as electrodes. The DEG generates electricity when the raindrops hit the electrodes, which causes an imbalance of charges, and results in a small current and high voltage, which is converted to electricity (Artificial ‘power plants’, 2024). The DEG is key to the power plantes because it combines the triboelectric charging and the hydrophobic effect. Triboelectric charging describes the process of transferring electrons, or charging, through rubbing or friction (Triboelectric Charging, n.d.). The hydrophobic effect is a phenomena observed in lotus leaves where the leaves repel water, and this technology mimics that. Studies have found that the coupling of these two processes leads to significantly high and rapid energy outputs (Min et al., 2024).
Recently a new development was made in finding the optimal water droplet height to obtain maximum energy. Optimal conditions for these technologies take into account the water droplet height, wind speed, force applied, and orientation. Optimal conditions result in a maximum of 113 volts and 67 μA from the DEG and 252 volts and 57.6 μA from the TENG, but only for short periods of time (Min et al., 2024). Scientists implemented four of these synthetic leaves in a commercial artificial plant and measured the output energy of wind and rain from the synthetic leaves. The resulting maximum voltage and short circuit current was 67.5 V and 10 μA and 12 V and 1.75 μA for the DEG and TENG respectively (Min et al., 2024).
There are several applications of this technology in an increasingly digitized world such as digital agriculture, smart homes, and the Internet of Things. Researchers have stated that this “power plant” technology has the potential to expand into larger networks of plants to produce clean energy from natural and renewable sources (Emir, 2024). This would mean that the plants have the capability to replace electricity sources such as fossil fuels or even solar energy. Scientists have found that this multi-source harvesting technology represents a significant advancement in the field of green energy and could work to supply the high demand for sustainable and eco-friendly energy (Emir, 2024).
Furthermore, these “power plants” are better than other renewable alternatives when it comes to environmental effects. The materials that make up the TENG and DEG are environmentally friendly, durable, lightweight, but most importantly biodegradable and recyclable (Min et al., 2024). Other renewable energy sources such as solar power, contain heavy metals, such as lead, which leads them to be classified as “hazardous waste” by some governments, including the U.S. (Atasu et al., 2021). Solar technologies, and other green technologies, are often difficult to dispose of and there is little incentive for innovation in the manufacturing process because the technologies are so expensive. However the “power plant” technology does not have a large negative impact on the environment because it is sustainably sourced and has a clean disposal process.
Ultimately, more research needs to be done to increase the energy output from wind and rain.The leaves could also be made more accessible by decreasing the cost and producing them on a larger scale. Although this technology is very new, scientists have articulated its potential as a key mechanism in the transition away from fossil fuel energy sources towards renewable energy sources.