Rain Energy Research Articles

Are Triboelectric Nanogenerators More Efficient Than Piezoelectric Transducers in Generating Energy from Precipitation?

This review examines two primary methods for harvesting energy from precipitation: triboelectric nanogenerators (TENGs) and piezoelectric transducers, which are leading technologies in converting mechanical energy from rain into electrical energy. The comparison between TENGs and piezoelectric transducers focuses on their operational mechanisms, material characteristics, and environmental factors such as water pH and temperature. The review highlights that TENGs offer greater design flexibility, efficiency in low-intensity rain, and cost-effectiveness, while piezoelectric transducers excel in high-frequency environments. The development of hybrid systems combining both technologies presents a more efficient and sustainable solution for rain energy harvesting.

Estimation of energy available in rain droplets from meteorological rainfall data

Abstract Even though the amount of rainfall is well documented in the reports of the India Meteorological Department (IMD), the rainfall energy available in different parts of India is unknown to the best of our knowledge. This paper reports a theoretical framework to convert the meteorological rainfall data to rainfall energy. The amount of rainfall over the south-west Monsoon period of 2022 is first converted to an average rainfall rate. Using the information on rain droplet size distribution for a rainfall of a given rainfall rate, the total energy contained in the rainfall is derived. In this, both the kinetic and surface energies of rain droplets of different sizes are considered. Based on the developed theoretical framework, rainfall map of India is converted to rainfall energy map showing states/union territories with maximum and minimum rainfall energy. Furthermore, for selected states in India, the districts showing maximum and minimum rainfall energy are also highlighted. The framework developed in the present study would help attempts to develop efficient rain energy harvesting systems.

Proposal and design a comprehensive framework to provide water and energy from rain and precipitation

In this paper a new renewable energy source was proposed based on rain power. Rain energy was not used as an energy source up to now; so, in this research its applicability was investigated as a green large scale power source. Hence, three innovative mechanisms were presented to harvest the energy of rain. Firstly, the kinetic energy of rain drops was converted to electricity using piezoelectric harvesters designed and named as Pizo-panel collectors. Secondly, potential energy of collected rainwater was enhanced by utilizing designed towers and converted to electricity using a water turbine. Thirdly, collected water was used in osmotic power units to generate electricity from the salinity gradient of that rain water and brine. The results show that generated power in the presented power plant named as rain power plant, was considerable and can be used for diversifying of energy basket. In addition to power generation, collected water in the rain power plant can be used for supplying urban and agricultural need for water. The presented power source not only does not have destructive impacts on the environment, but also helps the soil to prevent it from splash and crusting erosion. The results showed that total global annual rain energy potential amount was estimated to be 3.44×108 GWh which is comparable with global potential of solar energy. Also, the results showed that for rainy areas with an annual rainfall of 200 cm, 2.59 kWh/m2 could be produced, which is equal to 51.7 MWh for an area of 200,000 m2.

A hybrid wind and raindrop energy harvesting operating on Savonius turbine

In offshore environments, abundant wind and rainfall resources await development, representing significant untapped energy potential for powering Internet of Things (IoT) devices. Triboelectric Nanogenerators (TENGs) are particularly suited for capturing continuous motion in offshore environments, presenting a reliable solution for sustainable energy generation in IoT applications. Herein, we propose a wind-droplet hybrid generator (WDHG) tailored for adaptive environmental energy harvesting, explicitly targeting the demanding conditions prevalent in offshore environments. The WDHG combines the efficiency of a helical Savonius TENG with the versatility of an interdigitated electrode TENG, enabling simultaneous wind and rain energy harvesting. The helical Savonius TENG exhibits superior aerodynamic performance, producing an output power ranging from 0.39 to 2.10 mW with wind speeds increasing from 0.75 to 6.84 m/s. Additionally, the droplet TENG generates a power output of 35.90 mW/m2 under rainfall at 70 mm/min. Optimizations include not only the comparative analysis of helical Savonius turbines and the variation in pole-pair numbers but also adjustments in fluorinated ethylene propylene (FEP) film thickness and electrode gap length for interdigitated electrode, alongside the development of a tailored power management circuit (PMC) featuring dual bridge rectifiers, a buck circuit module, and a smart load switch. The PMC enables continuous operation of a low-powered digital thermohygrometer under conditions of 4.5 m/s wind speed, and drives a 20-second wake BLE server under 7.2 m/s wind speeds. Integration of the WDHG with offshore wind and raindrop extends energy harvesting capabilities, exhibiting a great potential of providing reliable power source for IoT devices.

Hydrophobic sisal cellulose paper-based TENG for collecting rain energy and raindrop-based sensor

Hydrophobic Sisal cellulose paper (SCP) was obtained by surface modification of SCP via physical adsorbing polymer and chemical grafting monomer, respectively. The influence of surface modification conditioning on the hydrophobicity, dielectric constant and dipole moment of the SCP was investigated. The results showed that the hydrophobicity and dielectric constant of the modified SCP increased with the concentration and amount of the modifiers. The output electrical performance of the TENGs assembled by the two types of hydrophobic SCP for rain energy collection was compared. The output electrical performance of the chemically modified hydrophobic SCP-TENG is higher than that of the physical modified. The maximum power density of the former reaches 8.2 mW/m2. Furthermore, based on the linear relationship between the output performance (output voltage intensity and output current intensity) of hydrophobic SCP-TENG and the droplet velocity, a raindrop-based sensor based on hydrophobic SCP-TENG was successfully constructed and estimated.

Study and fabrication of rain triboelectric nanogenerator based on laser-induced graphene interdigital electrode

In this work, a rain triboelectric nanogenerator (R-TENG) based on a laser-induced graphene (LIG) interdigital electrode was developed to harvest rain energy. The R-TENG comprises a LIG interdigital electrode on a polymer substrate with a hydrophobic Polydimethylsiloxane (PDMS) layer as a protective layer. When raindrops fall onto the surface of the PDMS layer and move between two adjacent interdigital electrodes, the accumulated charges move back and forth, resulting in the generation of alternating current. The LIG pattern design and the energy collection efficiency were studied by altering the production parameters of the LIG electrode and measuring the droplet diameter on the PDMS surface. A R-TENG with an electrode width of 3 mm produces a laser power of 2.1 W, and an output voltage of 2.46 V is generated. The R-TENG could be applied as an additional energy source to harvest rain energy for agricultural IoT sensors.

Self-powered graphene-based composites for rain energy harvesting

Rain-responsive G-CB/PVC composite films are made to generate electricity.

Electron Aurora and Polar Rain Dependencies on Solar Wind Parameters

AbstractData analysis was performed using 17 years of Defense Meteorological Satellite Program SSJ/4/5 data to characterize the relations between the solar wind parameters and the electron low‐energy fluxes measured on both magnetic poles (magnetic latitude above 55°). Inputs are solar wind velocity, density, dynamic pressure, and Bz of the interplanetary magnetic field. The median of electron energy flux for each MLAT‐MLT pair has been computed for given values of solar wind condition parameters. Results highlight that high velocity, density or pressure implies higher energy flux overall, higher polar rain energy fluxes, and wider nightside oval. There seems to be a positive correlation between polar rain and solar wind density, contrary to a previous study. As a function of Bz, the oval width has a “U” shape and the polar cap activity a “V” shape, with their minimum at Bz around zero.

Self-powered siphon rain gauge based on triboelectric nanogenerators

Rainfall measurement is of great significance to agriculture, weather forecasting and water resource management, while rain energy harvesting is a desirable solution to energy demand of wireless sensor networks of rainfall information. In this work, a novel self-powered siphon rain gauge (SR) integrating with a siphon unit, a sensing unit and an energy harvesting unit is proposed, which can simultaneously measure rainfall information and capture rain energy. In the siphon unit, a siphon structure is used to periodically automatically trigger and stop siphon events. In the sensing unit, a liquid–solid multi-tube triboelectric nanogenerator (TENG) is proposed for the first time to detect rainfall information by a multi-tube synergistic sensing strategy. In the energy harvesting unit, a rotary TENG excited by the siphon emptying event is utilized to generate electricity by a rainwater potential energy collection-based generation strategy. After optimization design, the water level resolution of the multi-tube TENG is around 2.5 times higher than that of traditional single-tube TENG, resulting in a rainfall resolution of 20.45 μm of SR. Besides, the rotary TENG successfully converts random, disordered, high-entropy raindrops energy into regular, ordered, low-entropy fluid mechanical energy. It can finally help the SR achieve a power density of 97.2 µW/m2, which is nearly 2.5 times higher than that of liquid–solid contact TENG using the traditional instantaneous impact-based generation strategy. The proposed self-powered SR not only obtains an excellent real-time rainfall sensing capability, but also has remarkable rain energy harvesting ability. Therefore, this SR has great potential for extensive applications in the hydrology and meteorology fields.

Simulation of a Pumped Stormwater System and Evaluation of the Solar Potential for Pumping

Renewable energy investments are increasing in countries that want to reduce their dependence on foreign energy and prevent damage to nature. As the request for green vitality generation is emerging, specialists over the globe have been attempting to generate power with better approaches. Rainwater harvesting can also be a non-conventional energy source, just like wind and solar energy. Generating energy, even on a small scale, can reduce environmentally harmful and costly methods of energy production. Various endeavours have been made so far to generate electricity using rain, one of the world's most abundant resources; however, this may be one of the most compelling studies. The goal of this study is to provide electricity from rainwater in areas with a lot of rainfall but minimal electricity. In terms of power generated, raindrops will never be able to compete with a hydroelectric power station. However, they have one significant advantage – they are free. With the increasing energy prices and developing new technology, the commercial use of rain energy does not seem far away. Energy generated from solar cells and a pump power-stormwater system reduced variable electricity costs by $ 572. In the energy storage dimension represented by a pumped stormwater reservoir in the study, the economic benefit potential is very low. Minimizing operating costs, maximizing storage capacity and efficiencies, as well as filling and unloading times of approximately one hour are recommended.

Perovskite quantum dot-based tandem triboelectric-solar cell for boosting the efficiency and rain energy harvesting

Silicon (Si) solar cell efficiently convert solar energy into electricity under the sun illumination, but its inherent intermittent power generation due to diurnal and seasonal cycle has usually allowed for the requirement for alternative power sources. Owing to the abundance, diversity and availability, rain drop energy is one of the most promising green energy sources. Hence, hybrid energy harvesting could be a promising strategy of achieving preferential hybrid performances without sacrificing the advantages in individual devices. Herein, we proposed a hybrid solar and rain energy harvesting device featuring the integration of triboelectric nanogenerator (TENG) top-cell and a crystalline Si solar cell bottom-cell by laminating perovskite quantum dots-embedded polydimethylsiloxane composite film (PQDP) onto the Si solar cell, which endows enhanced electrical output performances under rainy days. To overcome the limitation of low external quantum efficiency (EQE) in the ultraviolet region of the Si solar cell, the PCE of the hybrid solar cell is significantly enhanced from 18.47% of bare Si solar cell to 20.16% owing to the anti-reflection effect of PQDP film and the down-conversion property of CsPbBr3 QDs doped with Ce3+ ions. Meanwhile, this hybrid solar cell presents excellent durability after continuous measurement over 7 days. This tandem hybrid solar cell provides a promising strategy to simultaneously scavenging the solar and rain energy and boosting the power conversion efficiency by introducing the perovskite QDs without affecting the efficiency of bare Si solar cell.

Self‐Feedback Sensing Properties of Self‐Powered Multi‐Parameter Meteorological Sensor with Omnidirectional Array Structure

AbstractFrequent meteorological disasters pose more and more extensive threats to human life and property. However, the traditional meteorological sensors based on external power supply, for natural disaster monitoring and early warning, are severely limited in remote and unattended areas. Herein, a self‐powered multi‐parameter meteorological sensor (SMPM‐sensor) for various weather monitoring is proposed, which can monitor the weather through the feedback of electrical energy output while collecting natural energy. The designed 360° omnidirectional array structure facilitates efficient collection of all‐weather solar energy and rain energy in different directions and monitoring the light intensity without the influence of solar azimuth. Based on the four‐segmented disc‐shaped structure and the introduced Ecoflex transition layer, the frequency and amplitude of the wind electrical output can be effectively improved. Owing to structure and material optimizations, a good linearity of 0.9746 between the current and the solar illuminance is exhibited, a wide monitoring range of rainfall intensity changes from 0.1 to 11.9 mm min−1, and the linearity between wind speed and voltage frequency can be as high as 0.9986. Therefore, based on excellent sensing performances, good stability, and real‐time characteristic, the fabricated SMPM sensor provides a potential technological strategy for the field of meteorological disaster monitoring.

Self-powered PtNi-polyaniline films for converting rain energy into electricity.

Developing novel rainwater energy harvesting beyond conventional electricity is a promising strategy to address the problems of the energy crisis and environmental pollution. In this current work, a class of self-powered PtNi and optimal PtNi-polyaniline (PANI) films are successfully developed to convert rainwater into electricity for power generation. The maximized current, voltage and power of the self-powered PtNi-PANI films are 4.95 μA per droplet, 69.85 μV per droplet and 416.54 pW per droplet, respectively, which are attributed to the charging/discharging electrical signals between the cations provided by the rainwater and the electrons offered by the films. These results indicate that the optimized signal values are highly dependent on the elevated electron concentration of films, as well as the concentration, radius and charge of ions in rainwater. This work provides fresh insights into rain energy and enriches our knowledge of how to convert renewable energy into electricity generation.

Smart Solar‐Panel Umbrella toward High‐Efficient Hybrid Solar and Rain Energy Harvesting

Solar photovoltaic power generation technology is the top priority of the global energy development strategy. Although the photoelectric conversion efficiency of crystalline silicon solar cells is as high as 33.7%, the power generation efficiency is relatively low or even unable to generate power normally under low‐light environments such as rainy weather and a cloudy day. Herein, a smart solar panel umbrella system with an auto open and close function is realized by integrating a polysilicon solar cell module and an interdigitated electrode structure triboelectric nanogenerator (IDE–TENG) toward hybrid solar and rain energy harvesting. The output performances of the IDE–TENG are systematically investigated and optimized by regulating the dielectric thickness, inclination angle of IDE–TENG, and various drip types. On this basis, combined with the solar module, the function of auto open and close for the smart solar panel system is realized by a 32‐bit microcontroller and a raindrop sensor, which can be automatically switched as the weather changes and maintain high power conversion efficiency of 19.61% of the solar cell. This smart solar panel umbrella system can be used as a self‐powered supply for all‐weather landscape lighting to save the utilization of fossil energy and contribute in the realization of carbon neutrality.

Rain Energy Harvesting Using Atomically Thin Gadolinium Telluride Decorated 3D Printed Nanogenerator

AbstractThe 3D printing (3DP) technology offers an innovative approach to developing energy storage devices to create facile and low‐cost customized electrodes for modern electronics. Generating electric potential by moving a droplet of ionic solution over 2D materials is a novel method for rain energy harvesting. This work demonstrates a liquid‐solid contact electrification‐based 3DP nanogenerator where raindrop passes through the positively charged ultrathin gadolinium telluride (Gd2Te3) sheets. The output efficiency of the nanogenerator is increased to ≈400% by enhancing the surface area of copious 3D‐printed porous structures. The density functional theory (DFT) calculations reveal that the high electrical conductivity of (112) surface of Gd2Te3 is due to the p‐type charge carriers, which help to generate electricity by interacting with the ionic solution. This work can open up a new avenue to advance scientific research on blue energy harvesting and tackle the energy crisis.

All-aerosol-sprayed high-performance transparent triboelectric nanogenerator with embedded charge-storage layer for self-powered invisible security IoT system and raindrop-solar hybrid energy harvester

Practical utilization of the triboelectric nanogenerators (TENGs), which have unique advantageous aspects of a simple operation mechanism, material selection diversity, and high energy conversion efficiency, requires high functionality as well as a scalable fabrication to broaden the applicable fields. Here, we report the concept of all-aerosol-sprayed transparent TENG (ST-TENG) by sequentially spraying total three layers of a silver nanowire conductive layer, transparent polystyrene charge-storage layer, and fluoropolymer contact layer. All layers were achieved by aerosol spray process, thereby exhibiting high design flexibility enough to fabricate ST-TENGs on various pre-made commercial devices. The presence of the transparent polystyrene layer as a charge storing interlayer significantly enhances the power density of the ST-TENG up to 818 mW/m2. As proof-of-concept applications, a self-powered invisible security internet-of-things system, which could blend with the surroundings, exploited biomechanical energy from foot-step for energy harvesting and invasion sensing. Furthermore, by exploiting the all-aerosol-spray process and high light transmittance of the ST-TENG, a hybrid energy harvester to simultaneously generate electricity from solar and rain energy was directly fabricated on a commercial solar panel. This work provides the brand-new concept of TENG with a scalable in-situ fabrication process, enhanced performance, and outstanding light transmittance.

New cambered-surface based drip generator: A drop of water generates 50 µA current without pre-charging

Triboelectricity has demonstrated bright application prospects in the field of blue energy harvesting. However, the low output efficiency of solid-liquid triboelectricity hinders its practical application. This paper proposed a high-efficiency drip nanogenerator with a cambered surface based on the brachistochrone curve principle. In this nanogenerator, a drop of water can achieve an output current of 50 µA and an output voltage of 137 V without pre-charging. The cambered-surface structured triboelectric nanogenerator (C-TENG) enhances the short-circuit current by 30 times compared to the traditional TENG based on flat-surface structure (F-TENG). The output power of C-TENG reaches up to 1.875 mW at the central angle of 60°. The Simcenter STAR-CCM+ Viewer software is utilized to simulate the falling process of water droplets and the dynamics to explain the difference in the falling process of central angle structures at different central angles. The C-TENG characteristics ensure improved energy collection efficiency. Therefore, it is used to design a new droplet energy collection structure for rain energy harvesting. C-TENG has a more significant lighting effect than F-TENG. This new drip generator demonstrates remarkable efficiency in collecting various water energies in nature and has potential applications in device power supply and self-powered sensing.

Green self-propelling swimmer driven by rain droplets

The existing self-propelling methods have the limitations of chemical reaction, emission of toxics and additional auxiliary devices, high cost, low durability, and low propelling force and velocity, making them difficult for apply in practice. To overcome these limitations, we develop a green self-propelling swimmer composed of a superhydrophobic plate with a superhydrophilic slit on its sidewall. Water droplet touched with the slit easily and quickly pass through the slit and generate a water jet to propel the swimmer to spontaneously move. The propelling velocity, propelling time, propelling distance, and movement direction of the swimmer are programmable by adjusting the slit width, water droplet volume and the shape of the swimmer. Since the developed swimmer can easily capture the water droplet from rain as the fuel, our self-propelling method can also make full use of rain energy, effectively transfer the surface energy of rain droplets into mechanical energy, and easily realize the continuous movement in the rainy environment, showing remarkable application prospect in the collection and application of rain energy.

Tipping-bucket self-powered rain gauge based on triboelectric nanogenerators for rainfall measurement

The traditional tipping-bucket rain gauge (TBR) has the problems of low measurement accuracy and severe abrasion under heavy rainfall conditions, and cannot realize the real-time rainfall monitoring and rain energy harvesting. In this work, a TBR based on manifold triboelectric nanogenerator (TENG) units is proposed to solve the above problems. The significant parameters affecting the electrical output performances of freestanding TENG (F-TENG) and contact-separation mode TENG (CS-TENG) units are comprehensively explored and then optimized from the theoretical and experimental perspectives. Based on the optimized structure of TENG units, a series of experiments for sensing and power generation performances and demonstrations of the TENGs-based TBR are carried out. The experimental results indicate that the proposed TBR can detect the real-time and average rainfall intensities ranging from 0 to 288 mm/d with a minimum rainfall amount resolution of 5.5 µm. Besides, the frequency of the output electrical signal varies linearly with the rainfall intensity but invariant as the humidity changes. More importantly, the rain gauge can obtain the peak output power of 7.63 mW by the CS-TENG unit with a multilayered structure at 250 mm/d. Therefore, the proposed TENGs-based TBR as a rainfall sensor has real-time measurement ability, high resolution, excellent anti-humidity interference ability, as well as rainwater energy harvesting function. The presented multi-functional TBR has great potential to achieve monitoring and data delivery of rainfall information in extreme environments, contributing to the further development of self-powered wireless sensor networks of rainfall information.

Rain Energy Harvesting Using Atomically Thin Gadolinium Telluride Decorated 3d Printed Nanogenerator

Rain Energy Harvesting Using Atomically Thin Gadolinium Telluride Decorated 3d Printed Nanogenerator