The process of collecting energy from sources available in the immediate environment of a device is known as Energy Harvesting. The harvested energy is mostly converted to electrical energy for the device’s use.
This energy can be harvested from radio waves, vibrations, heat, light, and possibly sound. Furthermore, energy harvesting can also be called Power Harvesting or Energy Scavenging.
1. About Energy Harvesting
Accurate wireless technology will allow for the independence of devices from external manipulation. Devices positioned in challenging-to-reach locations will particularly benefit from this. Implementing energy harvesting can eliminate the need for power lines, battery replacement, battery charging, fuel tank filling, and similar tasks.
This is a quest for a more sustainable future since energy harvesting is a more eco-friendly solution to technological advancements.
2. Modes of Energy Harvesting
As discussed in the previous section, many forms of energy can be harvested. Let us look at how some of them work.
2.1. Harvesting Kinetic energy
Kinetic energy can be harvested in two ways. Electricity can be generated by harvesting Kinetic energy in two ways: through electromagnetic induction or piezoelectric generation.
Electromagnetic induction takes place when the coil or a magnet moves about each other. This movement generated electricity in the coil.
The polarization that occurs when pressure is applied to a piezoelectric material causes electricity generation.
These are used to harvest the vibrational energy. This can enable us to draw energy from the floors we walk on or the roads vehicles drive on. Intelligent solutions are already in our hands, empowering us to control and monitor our devices easily. TV remotes and motion-powered watches are just a few examples, inspiring us to imagine new ways of interacting with technology.
2.2. Harvesting Thermal Energy
The ability to capture the heat that is simply available in the environment is known as harvesting thermal energy. This ability takes place through an effect called the Seebeck Effect.
The Seebeck Effect occurs when a temperature difference between two points generates an electric current in conducting materials.
The material has varying temperatures that create a temperature gradient. This gradient is then utilized to generate electric energy using the energy from the sun in the environment.
This piece of tech can be instrumental in automobiles. Our overheating devices could also power themselves if we can efficiently harvest the released heat and convert it to mechanical or electrical energy.
2.3. Harvesting Light Energy
The process of trapping light to convert it to the desired form of energy. This form of harvesting energy is already quite popular, so we are now discussing Solar Panels.
The use of Photovoltaic cells enables the harvesting of Light energy or solar energy. The photovoltaic effect is the process where photons excite electrons, generating electric current. There are different types of solar cells available including single and multi-junction cells, thin-film cells, crystalline Si cells, and emerging PV technologies.
The most efficient Light and heat Energy Harvesters that we know of would be plants . They absorb the energy to convert it into the kind of energy they require to survive, photosynthesis.
2.4. Harvesting Radio Waves
RF harvesting technology can eliminate the need for cords, plugs, and batteries, allowing miniature devices to function continuously. To harvest RF, a dipole antenna (coiled wire) must be positioned on either side of a metal plate, generating a current by sourcing two coils with opposite charges.
Imagine living in homes that don’t have any plugs around the house. That future isn’t here yet due to specific difficulties. A study by Joule cites issues with a lack of optimization of antennas for ambient RF harvesting.
3. Basic Technologies Used in Energy Harvesting
The components used in energy harvesters would entirely depend on the energy that is being captured for use. But we can safely say that every harvester is made of three main components.
This is the central part. It is the component that converts the available energy into usable electrical energy.
This is a choice-based component. Either there are electronic devices such as chips, circuits, etc., that immediately consume the harvested energy or energy storage components such as batteries, capacitors, etc.
3.3. Interface Circuit
The circuit makes sure the maximum extractable energy is, well, extracted from the harvester and conditions it into the desired form.
4. Developments and Possibilities of Energy Harvesting
The generation of electricity through energy harvesting is often characterized by its unreliability, thus restricting its use to devices with low power requirements. Nevertheless, energy harvesting technologies are fundamental in the creation of networks of interconnected IoT and M2M devices.
It becomes crucial to develop more advanced energy harvesting techniques to meet the data needs of smart homes, factories, and cities, which will rely on a diverse array of networked sensors and devices.
The development in this field opens various research areas in the field of Material Science. Developing new materials to increase the efficiency of the discussed applications is one of the goals of researchers. Material science and nano-technology might go hand-in-hand to bring us closer to the future where technology becomes much easier to handle while being cost effective.
Energy harvesting is a promising field with the ability to make our futures greener since it uses renewable resources’ energy and converts it into usable, desired energy. This might either make our batteries last longer or might eradicate the need for batteries. This will reduce electronic waste.
There have been some fascinating developments in Energy harvesting such as a fake leaf that can harvest up to 40 volts of electricity from wind and rain, a brain simulator that harvests energy from our breath, wallpapers that can photosynthesize, and many more. This development might be one of the solutions to the ever-increasing energy demand.
5. What is Energy Storage?
Energy harvesting is essential. But to be of greater use, the harvested energy needs to be stored. A cycle where the supply and demand is maintained. Effective energy storage is crucial for a reliable and flexible grid, delivering power when and where needed for consumers.
High-quality energy storage technologies are essential for the long-term sustainability and stability of our energy systems.
6. Methods of Energy Storage
There are many kinds of batteries. The most popular one is the Lithium-Ion battery. A flow battery stores energy through two chemicals dissolved in liquids and held in tanks, making it ideal for longer storage periods.
A battery is a device that consists of an anode, a cathode, and an electrolyte. The reaction here produces the necessary electrical energy. Between the cathode and anode, an electrical charge can travel via the electrolyte, a chemical medium. When a device, such as a lightbulb or an electric circuit, is connected to a battery, chemical processes take place on the electrodes and provide a flow of electrical energy to the device.
A capacitor is an electronic component that stores electrical energy in an electrostatic field. It consists of two metal plates separated by a dielectric material, and its ability to store energy is referred to as capacitance.
A supercapacitor or an ultracapacitor works like a capacitor but with greater storage ability. The supercapacitor electrodes are coated with activated carbon, and separated by an ion-permeable membrane to exchange electrolyte ions.
6.2 Mechanical Systems
Although longer-duration systems are being developed, flywheels can normally absorb and release high power for just 15 minutes or less. Energy is stored in a rapidly spinning mechanical rotor. These systems, which react to a control signal that is altered every few seconds, can balance variations in electricity supply and demand.
These are useful even in the concept of a regenerative braking system and prove effective in an electric train.
To explain the regenerative braking system, let us take a look at how our cars work. While driving, we come to a stop by applying the brakes. This application makes the vehicle slow down by applying pressure on the wheel rotors. This causes friction and heat loss, energy loss. Hybrid vehicles harness this energy and either use it or store it in batteries.
Over 95% of the storage in use today is provided by pumped hydroelectric plants, making them the most prevalent type of energy storage on the grid. Excess electricity is used to power turbines to pump water to a raised reservoir during off-peak times.
6.3. Thermal Storage
Utilizing mirrors or lenses to gather solar radiation, concentrated solar power (CSP) systems employ the heated fluid to turn a turbine and produce electricity. The heat may either be utilized right away to produce energy or it can be thermally stored for later use.
7. Why Do We Need Energy Storage
Energy storage enhances grid operational flexibility, provides several services, and has a variety of uses. Storage technologies offer enormous promise for smoothing out the power supply from renewable energy sources and ensuring that the supply of generation matches the demand since certain renewable energy technologies—such as wind and solar—have unpredictable outputs.
Storage can supply power in reaction to variations or decreases in power, regulate electricity’s frequency and voltage, and postpone or eliminate the need for expensive transmission and distribution upgrades to ease congestion.
Battery storage can start releasing electricity to the grid extremely rapidly, in less than a second, whereas traditional thermal power plants require hours to restart. This quick reaction makes energy storage highly desired.
One effective way to mitigate demand spikes and potentially save customers money is through the use of energy storage. By storing excess energy during off-peak hours and releasing it during peak demand times, energy storage can help lower peak demand and ultimately lead to a more stable and cost-effective energy supply.
In both rural and urban contexts, community resilience is crucial. In highly populated cities, energy storage can assist in meeting peak energy needs, relieving system pressure, and limiting increases in power prices.
In times of extreme heat or cold, energy storage can assist in averting power outages, hence preserving public safety. Storage can be used to develop community-level microgrids or resiliency hubs, either alone or in conjunction with community solar, aggregated rooftop solar projects on homes or businesses, or both.
8. Interesting and Notable Advancements in Energy Harvesting and Storage
Revolutionizing the medical industry, the new innovative and significant bioelectronics invention led to a patch creation using completely rubbery materials that are friendly to heart tissue.
The new patch, which is entirely comprised of rubbery electronics, can simultaneously gather data on electrophysiological activity, body temperature, pulse, and other cardiac health markers. Since the patch draws electricity from the heart’s beating, it may function without an external power source.
A space-based solar power plant would be put into a geostationary orbit, which would place it in a permanent location over the Earth and expose it to the Sun’s radiation constantly. Consequently, if all goes according to plan, the technology might one day gather enormous amounts of energy from space, sufficient to power millions of homes.
This could be the Dyson sphere that has been conceptualized but never really existed. Freeman Dyson conceptualized a megastructure that encompasses a star to harness its solar energy output.
Metal-free water-based battery electrodes might eventually replace the widely used lithium-ion batteries for a variety of purposes. The distinction is that instead of using metal electrodes, polymer electrodes are employed, and water and organic salts are used as the electrolyte.
A water-based electrolyte plays a crucial role in conducting ions and energy storage in such a configuration, keeping the battery from catching fire. The electrodes may swell up as a result of their interactions with them, which would reduce performance.
The notion of capturing energy from the surrounding environment and preserving it for future utilization is a truly groundbreaking concept. Thanks to these remarkable technological advancements, we have established a highly durable and sustainable energy ecosystem.
We must accept and implement these cutting-edge ideas going ahead to promote cooperation between businesses, decision-makers, and researchers. In doing so, we can hasten the adoption of energy harvesting and storage technologies, laying the foundation for a sustainable future with clean, dependable, and affordable energy for everyone.