Last month, my parents gifted me a pair of wireless earbuds with the intention of helping me to multitask. This small piece of gadget indeed made my life quite easy as I could attend lectures while exercising, could listen to music while making my breakfast and having a chat with a friend. These tiny buds could be placed in their box to get charged. Being a curious creature, I started thinking about the technology being used to power this device. I started researching about this technology and found it quite interesting. I am articulating what I understood from my research.
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In this article, I will cover:
1. What is Wireless Electricity and Wireless Power Transmission ? and how does it work?
2. Types of Wireless Power Transmission
3. Trends in Wireless Power Transmission
4. Challenges of wireless power transmission and the research in progress
5. Application of Wireless Power Transmission
6. The future of wireless power
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Energy is a cornerstone of modern life; it is an enabler and driver that could open infinite possibilities. Energy is an engine for socio-economic growth, driving productivity and prosperity at an unprecedented rate. It fuels the modern economy. Energy resources stand at the heart of our relationship with our planet and communities. The UN’s Sustainable Development Goal 7 (SDG7) calls to “ensure access to affordable, reliable, sustainable, and modern energy for all” by 2030. Yet 770 million people still do not have access to electricity, 75% of which are in sub-Saharan Africa where around half of the local population is impacted. Since 2015, electrification rates have slowed to a 1% annual gain — too slow to meet the SDG7 targets. Progress is plodding among the most vulnerable communities, including the least developed countries, landlocked developing countries, and Small Island Developing States. To overcome this, here is a solution to diminish greenhouse gas emissions into the soil’s atmosphere through an alternative power generation. One sustainable technology leading this charge is WPT (Wireless Power Transmission).
Wireless Energy Transmission (WET)
WET or electromagnetic power transfer is the transmission of electrical energy without wires as an actual connection. In a wireless power transmission system, a transmitter device, driven by electric power from a power source, generates a time-varying electromagnetic field, which transmits power across space to a receiver device, which extracts power from the field and supplies it to an electrical load. This technology is called Wireless Power Transmission (WPT). WPT technology can eliminate the use of the wires and batteries, thus increasing the mobility, convenience, and safety of an electronic device for all users. WPT is valuable to control electrical gadgets where interconnecting wires are badly designed, perilous, or are impractical.
Types of Wireless Power Transmission
WPT techniques are of two types, non-radiative and radiative. In non-radiative techniques, power is transferred by magnetic fields using inductive coupling between coils of wire. The inductive coupling method is the most essential methods that help the experts to transfer energy wirelessly via inductive coupling. It is used for near field power transmission. However, the power transmission takes place between the two conductive materials through mutual inductance.
In radiative far-field techniques, which is also known as power beaming, power is transferred by beams of electromagnetic radiation, like microwaves or laser beams. Microwave Power Transmission consists of two sections. It includes the transmitting section and receiving section. In the transmission section, the microwave power source generates microwave power controlled by the electronic control circuits. The waveguide circulator protects the microwave sourced from the reflecting power which connects through the co-ax waveguide adaptor.
Laser Power Transmission: Laser technology is used to transfer power in the form of light energy, and the power converts to electric energy at the end of the receiver. In addition, it receives power using different sources like sun, electricity generator or high-intensity-focused light. However, the size and shape of the beam decide by a set of optics. The transmitted LASER light receives by the photo-voltaic cells. It converts the light into electrical signals. Usually, it uses optical-fiber cables for transmission.
Trends in Wireless Electricity Transmission
The long-distance high-power wireless transmissions are mainly used for the space solar power satellites and the far-distance remote site power supplies, the short-range low-power wireless transmissions are applied to the power grid system to form a wireless power supply, the wireless charging system and the medical sensor network and imaging systems. The carbon nanotubes will be proved as a boon for the research and industries. Presently it is being used in the solar cell application to improve the efficiency and reduce the weight and cost. by this method we can refine the method of solar power transmission and hence can achieve greater efficiency.
There are several companies into the market with technologies that can safely transmit power through the air. Emrod, a government-backed New Zealand startup is leading the race with their expected consumer rollout of the world’s first long-range, high-power, wireless power transmission to replace existing copper line technology. This technology utilizes electromagnetic waves to transmit energy wirelessly over vast distances. Energy is converted into electromagnetic radiation by a transmitting antenna, picked up by a receiving antenna, and then distributed locally by conventional means. The efficiency of any WPT technology is measured in terms of the power loss in the process of transfer. Emrod’s technology was not so efficient, so to address this challenge They use metamaterials (in the relays) to focus the transmitted radiation more tightly than previous microwave-based wireless power attempts. This helped to increase the efficiency of their system to 70%.
The global wireless power transmission market is expected to grow with a CAGR of 23% from 2021 to 2024. The future of the wireless power transmission market looks very promising with great opportunities in the smartphone, notebook, tablet, wearable electronic, and electric vehicle charging applications. The major drivers for this market are increasing consumer preference for wireless connectivity, growth in electric vehicles, and increasing need for effective charging systems.
Some of the leading companies working with the wireless power transmission technologies include Integrated Device Technology, Qualcomm, Samsung Electronics, TDK Corporation, Texas Instruments, Nucurrent, and Witricity Corporation.
Challenges of wireless electrification and the research in progress
Wireless power transmission has not been as successful as the technology currently faces some limitations. The transmission range of wireless power transmission through electromagnetic induction and or by magnetic resonance technique is limited. This limitation of the range poses a serious challenge for the manufacturers. The efficiency of the power is inversely proportional to the distance between the transmitter and receiver; however, it is predicted to improve over time. Safety issue is also the main concern for the wireless transmission market as strong electromagnetic fields may harm the biological environment.
The performance of WPT systems has been steadily increasing. In 2016, Oak Ridge National Laboratory (ORNL) developed and demonstrated a 20 kW WPT system for a Toyota RAV4 EV. INL, in collaboration with ORNL, quantified the performance and electromagnetic (EM) field safety of the WPT system. Two years later in 2018, ORNL advanced their WPT design to 120 kW, which is now the world’s highest power level WPT system for LDEV.
The development of silicon carbide (SiC) technologies makes it possible to operate at a higher power level and in a higher frequency (up to 100 kHz theoretically) as compared to conventional MOSFET because of the low switching loss and good thermal behavior. The current commercial SiC power modules are mainly available from Wolfspeed, ROHM, Infineon, SEMIKRON, and STMicroelectronics. When the switching frequency increases, high frequency electromagnetic interference (EMI) or frequency electromagnetic compatibility (EMC) becomes a challenge. For high power SiC applications (1200V or above) at the switching frequency of 20 kHz and 50 kHz, the EMI can be reduced to the allowed range in accordance with the standard of DO-160 (Environmental Conditions and Test Procedures for Airborne Equipment).
Electrified transportation technology is unique because it is one of the few technologies that is mobile, publicly accessible, and can be integrated into the electric grid. These unique aspects result in potential cybersecurity risks as well. With advancements in electric vehicle charging infrastructure towards higher power levels and increased sophistication, such as wireless power transfer, potential negative impacts from cybersecurity vulnerabilities are also increasing, especially for those of high power WPT and wired extreme fast charging (XFC) installed in public places. Cybersecurity vulnerabilities in physical systems may result in even greater impacts to public safety and electric grid security, in addition to denial of service, hardware damage, or theft/alteration of data. Cybersecurity should be considered early on during the design phase to incorporate solutions to reduce the risk of nefarious access, safeguard data and information, and enable a safe minimum state of operation during a cyber-event.
As for commercially available WPT systems, WiTricity develops a variety of WPT ranging from 3 to 11 kW with an efficiency of 90–93% operating at 85 kHz. Qualcomm presented 20 kW dynamic WPT with an efficiency of 90%. Efacec Electric Mobility in Portugal has developed their WPT system with a maximum power of 22 kW.
With power transfer levels increasing beyond 100 kW, many technical and risk management challenges emerge. The high-power wireless charging for light-duty electric vehicles, which are aiming at 200 kW or higher wireless power transfer, also face future challenges and risks in the area of electromagnetic safety, resonant frequency determination, and cybersecurity risks. Electromagnetic shielding by using an aluminum or ferrite plane is a typical solution to limit the electromagnetic emission level and ensure the safety of WPT. Department of Energy has a stated goal to reduce the charging time for electric vehicle to 15 min or less, which requires the charging system to deliver 350–400 kW. If WPT power levels continue to increase, electromagnetic safety for WPT with the constraints of LDEV space limitation becomes a critical challenge.
Hence, in order to reach the power level higher than 100 kW, increasing angular resonant frequency (w) will be the main challenge (currently 22 kHz for 120 kW WPT). Given the need for a higher resonant frequency, higher power converters operated at a higher switching frequency are required. Insulated-Gate Bipolar Transistors (IGBTs) are widely used for high power applications, such as the ones for the integration of renewable energy in the power grid or driving high power motors. However, owing to the physical limitations of IGBT, it is normally difficult to operate at a frequency higher than 20 kHz (e.g., the typical operation frequency of IGBT converters in the power grid is 10 kHz). On the other hand, conventional Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET) can work at a high frequency, but the power level is typically low.
To reach its maximum potential and meet the demands of tomorrow’s wireless war fighter, next-generation components, systems, and devices must also be designed and developed with WPT in mind to optimize form, fit, and function and to ensure that the systems are efficient, safe, and accurate.
Applications of wireless power transmission
- Transmission of power to the portable devices wirelessly
Figure 3 show the overall system is made using charger pad and the battery. To transfer energy from the charging pad to the battery each part has planar coils. The charging pad and battery can communicate with each other because the electrical energy is modulated. Before transmitting full power to the battery, the charging pad verify that a valid battery is in place or not. This communication continues throughout the entire charging process to confirm the battery is still in place.
2. Wirelessly charging of electric vehicle
According to Figure 4 a charging pad sits on the ground, connected to a wall-mounted power adapter. All the car parks over it. On the backside of the car there is a receiver when charger detects the receiver within range, it automatically starts charging.
3. Wirelessly charging of public transport
Every electric bus has a wireless charging receiver. According to Figure 5 Wireless chargers are embedded in the hard surface of a road or under the road surface at regular intervals. When the bus is stopped no need to plug in or no need to connect with wireless chargers. It will automatically have charged. It’s a motion bus. These kinds of buses are already tested in the UK, Italy, the Netherlands, and South Korea.
4. Wirelessly charging lane for Self-driving electrical vehicle
In the Figure 6 defines vehicles can simply return and park for a while to charge by using wireless charging pads in parking Garages, curbs, lanes, and for self-driving.
The largest application of the WPT is the production of power by placing satellites with giant solar arrays in Geosynchronous Earth Orbit. However, it transmits the power as microwaves to the earth known as Solar Power Satellites.
The future of wireless power
In future we can use electric appliances by using electricity without wire. A coil in the bottom of the vehicle could receive electricity from a series of coils connected to an electric current embedded in the road. With coils embedded in the roads, we could eventually enjoy a totally automated highway system. Self-driving electric vehicles could be wirelessly charged enroute, and GPS and other navigation systems would also be powered wirelessly. Following are some potential scopes of using wireless power transfer technology:
- An IoT Revolution
The ability of the WattUp far-field transmitter and the Cota Tile to transmit data along with power makes them particularly compelling for the Internet of Things. Wireless power is going to go hand-in-hand with the evolution of this entire market. The best example of this is Ossia’s Cota Forever Battery. It can be placed in smoke alarms, sparing you from charging them and allowing for the transfer of data by giving you the Cota Cloud: cloud-based software that allows for power management of various devices. Myant’s Skiin fitness- and health-tracking clothes, are the first WattUp-enabled products.
Ossia is working on getting the Tile into a smaller, more efficient form-factor. The future system that they are working on will achieve the 10 meters and 20 meters. They are focused at scales, so that their system could cover 80 or 100 meters. The first place you might see the larger Tile is in your local Walmart. In this case, you’d have several Cota Tiles providing power to thousands of low-power RFID tags. And the tags, which could show prices, discounts, and bar codes, could all be managed by software.
2. Solar Power Satellite
Satellite with solar panel is used to capture maximum amount of solar energy from the sun in the space. Satellite consists of microwave transmitter which is used to convert power into microwave for transmission. According to Figure 7 transmitting microwave from the satellite present in space received by the microwave receiving antenna situated into the earth. This microwave receives antenna then convert microwave into electricity. Then this electricity can be used to power home and office etc.
3. Wirelessly powered home appliances
In future there will be a transmitting device inside home that will transmit power to all the home appliances such as Television, Laptop, Lamp, Iron, Sound Box, Fridge, Mobile etc. shown in Figure 8. Transmitting device transmit power and all the appliances will receive that power through receiving devices set up inside into all appliances.
4. Wirelessly charging of electric vehicle on the way
According to Figure 9 in future there will be no need to stop and charge the electrical vehicles. On the way charging can be done. In this concept power beam transmitter will be connected to highways, busy traffic areas with power source. which converts electricity into power beam and then that beam will be transmitted to the electrical vehicle which consist power beam receiver that convert power beam into electrical power for the charging of battery inside the vehicle.
5. Universal power source in emergency
In an emergency or disaster situation where all the communication medium and power system has broken down. Communication immediately after a disaster situation is an important component of response and recovery; it connects affected people, families and communities with support system and other family members.
In this situation an emergency power source may help to provide necessary power source to power their communication devices so that they can easily connect with their family and rescue services as show in Figure 10. A universal power source consists of an airship built in power transmitter which act as power source and drones, which consists of power receiving and transmitting device which provide basic communication as well basic wireless power to the affected people.
6. Wirelessly powered train
According to Figure 11 in future train may get power wirelessly. There will be no need to connects the train with wire. In this system a dual mode power receiver and transmitter will connect to the pole. Each station will have a pole with the dual mode transmitter and receiver. Power come from the power station that dual mode transmitter captures the power and transmit the power. By using dual mode transmitter power receive and transmit happen simultaneously. These powers will be received by the receiver that fixed in the roof of the train. In this process there is no need to use wire.
7. Wirelessly power supply to house from power station
In future clean and green power generation may be done using the renewable source of energy. Figure 12 defines power may be supplied to our houses wirelessly. Power transmitting antenna connected with the power supply providing station then power transmitting antenna convert electric power into microwave then transmit it to the nearest dual mode power receiving and transmitting antenna which transmit this microwave to nearest antenna which is connected nearest to the house. The house has its power receiving antenna which converts this microwave into electrical power. This electric power than utilize by the house.
8. Wirelessly controlling drone to extinguish the fire
In future drone may be used to extinguish the fire. Drone may carry the water pipe and set the pipe to exact location that will be controlling by the people using remote control system.
Figure 13 defines drone may get the power from transmitter establish in the fire down car. Transmitter transmits power and drone will have a receiver device that will receive the power and work properly until the power has stopped. Drone is very useful because where people cannot reach drone can reach there and can capture pictures, videos of that area situation. In emergency, it is not possible to connect the drone with wire, so this process will be very useful.
9. Wireless power applies to medical devices
In future wireless power supply in medical devices can be possible. There will be a transmitter that will be directly connected with power station. Figure 14 defines transmitter receives the signal from power station and transmit the signal continuously. The transmitting power receives by the receiver establishes in hospital and generates wireless electricity. By using this electricity medical devices will be performed simultaneously. There will be some electrical devices in patients hand these devices show the status of that patient. Their physical status will show in monitor. So, doctors can easily understand their condition and can take measurable step quickly.
10. Wirelessly powered smart city
According to Figure 15 a city can be a smart city using wireless technology. We can use power from power station without wire through transmitter and receiver. Transmitter transmit electricity from power station and a receiver receive the power and supply the power between houses, cars, trains, offices even emergency areas where wired technology is impossible to set up. By using wireless technology our environment will be carbon dioxide gas free. We get benefited because our environment will be clean and harmful gas free that emits from car, train or other vehicles.
Creation of commercializable solar power-generating windows using exponential technologies
In the past few years, several research teams have pioneered silicon nanoparticles to capture everyday light flowing through our windows. Little solar cells at the edges of windows then harvest this energy for ready use.
Scientists at Michigan State, for instance, have developed novel “solar concentrators.” Capable of being layered over any window, these solar concentrators leverage non-visible wavelengths of light — near infrared and ultraviolet — pushing them to those solar cells embedded at the edge of each window panel. Rendered entirely invisible, such solar cells could generate energy on almost any sun-facing screen, from electronic gadgets to glass patio doors to reflective skyscrapers. And beyond self-charging windows, countless future city pilots have staked ambitious goals for solar panel farms and renewable energy targets.
11. Dubai’s “Strategic Plan 2021”
Touting a multi-decade Dubai Clean Energy Strategy, Dubai aims to gradually derive 75 percent of its energy from clean sources by 2050. With plans to launch the largest single-site solar project on the planet by 2030, boasting a projected capacity of 5,000 megawatts, Dubai further aims to derive 25 percent of its energy needs from solar power in the next decade.
And in the city’s “Strategic Plan 2021,” Dubai aims to soon:
· 3D-print 25 percent of its buildings.
· Make 25 percent of transit automated and driverless.
· Install hundreds of artificial “trees,” all leveraging solar power and providing the city with free WiFi, info-mapping screens, and charging ports.
· Integrate passenger drones capable of carrying individuals to public transit systems.
· And drive forward countless designs of everything from underwater bio-desalination plants to smart meters and grids.
12. Self-Powering Cities
As new materials forge ahead to create pliable and self-healing structures, green infrastructure technologies are exploding into a competitive marketplace. Aided by plummeting costs, future cities will soon surround us with self-charging buildings, green city ecosystems, and urban residences that generate far more than they consume. And as 5G communications networks, proliferating sensors, and centralized AI (Artificial Intelligence) hubs monitor and analyze every aspect of our urban environments, cities are fast becoming intelligent organisms, capable of seeing and responding to our data in real time.
For example, Toyota is building a futuristic prototype city powered by hydrogen. Toyota has partnered with Japanese petroleum company ENEOS to build a hydrogen fuel cell system that will be the city’s source of power. ENEOS will install a hydrogen refueling station near Woven City and produce “green hydrogen” there, which will supply fuel cell generators in the city. They’ll also build a supply and demand management system and do research on hydrogen supply. Solar panels will also supply part of the city’s energy needs. The city’s smart homes will reportedly be able to automatically take out residents’ trash and restock their refrigerators (using grocery-shopping robots?), and sensor-based AI will even monitor residents’ health. Sensors embedded in all manner of infrastructure will send data to cars to raise their “awareness” of surroundings and road conditions.
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Thank you for reading this article — hope you enjoyed it so far! As the research progresses and we keep on addressing challenges of WPT technology, it will continue to make our life easier day by day. As exponential technologies across energy and water burst onto the scene, self-charging cities are becoming today’s testing ground for a slew of green infrastructure pilots, promising a future of self-sufficient societies. For example, A global leader in green technologies and renewable energy, Dubai stands as a gleaming example that any environmental context can give rise to thriving and self-sufficient eco-powerhouses. But Dubai is not alone, and others are quickly following suit. Leading the pack of China’s 500 smart city pilots, Xiong’an New Area (near Beijing) aims to become a thriving economic zone powered by 100 percent clean electricity. Also 100 U.S. cities are committed and on their way to the same goal.
I’m delighted to pan out with Tesla’s (WPT Inventor) vision, a great source of inspiration for budding scientist world-over:
“Power can be, and at no distant date will be, transmitted without wires, for all commercial uses, such as the lighting of homes and the driving of aeroplanes. I have discovered the essential principles, and it only remains to develop them commercially. When this is done, you will be able to go anywhere in the world — to the mountain top overlooking your farm, to the arctic, or to the desert — and set up a little equipment that will give you heat to cook with, and light to read by.” — Nikola Tesla.