Fig a is the schematic diagram of DEG: an ITO glass slide is coated with a thin film of PTFE and an aluminium electrode is put on top of it. Drops of water act as the gate of the transistor and complete the circuit when they hit the surface of the glass. Fig b is the optical image showing four parallel DEG devices fabricated on the glass substrate.
A research team led by scientists from City University of Hong Kong (CityU) has recently developed a new form of droplet-based electricity generator (DEG).
It features a field-effect transistor (FET)-like structure that allows for high energy-conversion efficiency, and its instantaneous power density is increased by thousands of times compared to its counterparts without FET-like structure.
This groundbreaking achievement can help to advance scientific research into water energy generation and tackle the energy crisis.
The research was led by Professor Wang Zuankai from CityU’s Department of Mechanical Engineering; Professor Zeng Xiaocheng from the University of Nebraska-Lincoln, US; and Professor Wang Zhonglin, Founding Director and Chief Scientist at the Beijing Institute of Nanoenergy and Nanosystems of Chinese Academy of Sciences.
Their findings were published in the latest issue of the highly prestigious scientific journal Nature under the title “A droplet-based electricity generator with high instantaneous power density”.
A conventional droplet energy generator based on the triboelectric effect can generate electricity induced by contact electrification and electrostatic induction when a droplet hits a surface. However, the amount of charge generated on the surface is limited by the interfacial effect, and as a result, the energy conversion efficiency is quite low.
In order to improve the conversion efficiency, the research team has spent two years developing the DEG. Its instantaneous power density can reach up to 50.1 W/m2, thousands of times higher than similar devices without the use of the FET-like design. The energy conversion efficiency is also markedly higher.
Professor Wang pointed out that there are two crucial factors for the invention. First, the team found that the continuous droplets impinging on PTFE, an electret material with a quasi-permanent electric charge, provides a new route for the accumulation and storage of high-density surface charges. They found that when water droplets continuously hit the surface of PTFE, the surface charge generated will accumulate and gradually reach saturation. This new discovery has helped to overcome the bottleneck of the low-charge density encountered in previous work.
Research shows that a drop of water released from a height of 15cm can generate a voltage of over 140V, which can light up 100 small LED lights.
Another key feature is a unique set of structures similar to the FET that won the Nobel Prize in Physics in 1956 and has become the basic building block for modern electronic devices. The device consists of an aluminium electrode and an indium tin oxide (ITO) electrode with a film of PTFE deposited on it. The PTFE/ITO electrode is responsible for the charge generation, storage, and induction. When a falling water droplet hits and spreads on the PTFE/ITO surface, it naturally “bridges” the aluminium electrode and the PTFE/ITO electrode, translating the original system into a closed-loop electric circuit.
With this special design, a high density of surface charge can be accumulated on the PTFE through continuous droplet impinging. Meanwhile, when the spreading water connects the two electrodes, all the stored charges on the PTFE can be fully released for the generation of electric current. As a result, both the instantaneous power density and energy conversion efficiency are much higher.
“Our research shows that a drop of 100 microlitres [1 microlitre = one-millionth litre] of water released from a height of 15 cm can generate a voltage of over 140V, and the power generated can light up 100 small LED lights,” said Professor Wang.
Professor Wang said he hoped that the outcome of this research would help to harvest water energy to respond to the global problem of renewable energy shortage. He believed that in the long run, the new design could be applied and installed on different surfaces, where liquid is in contact with a solid, to fully utilise the low-frequency kinetic energy in water. This can range from the hull surface of a ferry to the surface of umbrellas or even inside water bottles.
The Latest Updates from Bing News & Google News
Go deeper with Bing News on:
Droplet-based electricity generator
- Tuning the Superhydrophobic Properties of Hierarchical Nano-microstructural Silica Biomorph Arrays Grown at Triphasic Interfaceson March 12, 2020 at 3:11 am
High resolution transmission electron microscope (HRTEM) imaging and energy dispersion X-Ray spectroscopy (EDS) were employed to further characterize the crystalline structure and chemical ...
- Explained: Why water droplets 'bounce off the walls'on February 26, 2020 at 10:22 am
The new modelling approach we've developed will now have applications to droplet-based phenomena ranging from cloud physics for climate science through to spray cooling for next generation ...
- An unusual source of renewable energyon February 14, 2020 at 2:35 pm
Researchers at the City University of Hong Kong have developed a new device called droplet-based electricity generator (DEG), that can convert a single rain droplet to generate 140 volts ...
- Scientists create new method of extracting electricity from rain dropletson February 13, 2020 at 4:00 pm
This water-centric investigative team was headed up by researchers from City University of Hong Kong (CityU) who have discovered a new type of H2O droplet-based electricity generator that carries the ...
- News by Subject Technology & Engineeringon February 11, 2020 at 4:00 pm
A research team led by scientists from the City University of Hong Kong (CityU) has recently developed a droplet-based electricity generator (DEG), featured with a field-effect transistor (FET ...
Go deeper with Google Headlines on:
Droplet-based electricity generator
Go deeper with Bing News on:
- Water security a priority for Abu Dhabi, projects to ensure sustainability underway: DOE Under-Secretaryon March 22, 2020 at 1:07 am
... security is a priority for Abu Dhabi and the emirate is committed to determining the best ways to make optimal use of natural and desalinated water resources, an Abu Dhabi Department of Energy ...
- World Water Development Report 2020: Water and Climate Changeon March 22, 2020 at 12:10 am
The hydrological changes induced by climate change will add challenges to the sustainable management of water resources, which are already under severe pressure in many regions of the world. Food ...
- Water 'weapon' to fight climate change: UNon March 21, 2020 at 7:31 pm
"If you save water, you're saving energy and reducing the greenhouse gases to produce that energy to bring the water," said Richard Connor, the report's editor. Using less energy cuts down further on ...
- Water is an under-used weapon in climate change fight, UN sayson March 21, 2020 at 5:02 pm
Using water more efficiently in everything from daily life to agriculture and industry would help reduce planet-warming emissions and curb climate change - a potential benefit that has yet to be ...
- SAVVY SHOPPER: Energy saving tips for your gardenon March 21, 2020 at 3:57 pm
You may not realize it but having a garden can increase your energy costs. The reality is that anything can increase energy costs in your home. From having to water your garden to dealing with ...