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Long-range wireless power transmission, also known as wireless power transfer (WPT), involves the transmission of electrical power from a power source to a remote device without the use of any physical connections. This technology is rapidly gaining popularity as it enables individuals and businesses to power their electronic devices without using cords, cables or batteries. 

Long-range WPT has many practical applications ranging from charging smartphones and smartwatches to enabling electric vehicles (EVs) to travel greater distances without the need for frequent charging. To fully grasp the benefits of long-range WPT, it is important to explore how long-range WPT works, its practical applications and the challenges encountered in implementing this technology.

It all started with Tesla

While developing his “Tesla coil” transformer circuit in the 1890s, which generated alternating current electricity, Nikola Tesla started to think about wireless energy. 

In Colorado Springs, Tesla conducted his first significant wireless electricity experiment in 1899 at the “Experimental Station”. He constructed a robust oscillator inside of a barn-like building with a wooden tower and a 40-meter metal pole topped with a copper sphere (Figure 1). With this device, a light bulb could be powered more than three kilometers (two miles) away. 

His Tesla coil worked flawlessly, but the experiment destroyed the dynamo of the Colorado Springs electricity company, putting the entire neighborhood in the dark. 

Through his research, Tesla developed the theory and technology behind WPT, as well as the first experimental devices for transmitting electrical energy through the air without the use of wires. Tesla envisioned a world where energy could be transmitted wirelessly, without the need for physical connections or power cords, and he laid the foundation for modern WPT technology.

The principle behind long-range WPT

Long-range WPT is mainly based on two technologies: magnetic resonance and electromagnetic radiation. Magnetic resonance uses magnetic fields to transmit electricity between two electronic devices that share the same frequency. Electromagnetic radiation, on the other hand, relies on the principle of inductive coupling that involves the creation of an alternating current in a receiver coil situated near the power source. The power source generates an electromagnetic field, which the receiver coil captures and converts into a current.

Magnetic resonance is considered the most effective technology for long-range WPT because it can transmit power over greater distances without much loss. The power source and receiver must be tuned to the same frequency to ensure effective power transfer. This technology is often used in consumer electronics, such as laptops, smartphones and smartwatches, where the distance between the power source and the device is relatively small. 

However, for long-range WPT used in industrial applications, such as charging electric cars, electromagnetic radiation technology is used.

Emrod’s approach to WPT

Emrod, a New Zealand-based startup, has developed a method to transmit energy via electromagnetic waves over long distances using proprietary beam-forming technology, metamaterials and rectennas.

The company uses two technologies to produce a beam that is kept narrow and focused, in contrast to Tesla’s original concept that transmitted energy in an omnidirectional way. The first has to do with transmission that uses single wave patterns and tiny radio components to produce a collimated beam that is parallel. The second has to do with special metamaterials that work well with certain radio waves. Emrod’s technique (Figure 2) sends power in a focussed, unidirectional beam from one antenna to another.

The goal of Emrod’s technology is to provide a new method of delivering electricity to rural communities, which frequently have the largest electrification gaps and cannot afford the kind of infrastructure needed to sustain the electrical grid. 

For the purpose of supplying power to its consumers, Emrod’s antennas serve as the cable. All of the windy and sunny locations where renewable energy can be used will have these antennas. The only thing limiting the transmission distance is a line of sight between each antenna, and the system operates in all weather.

Practical applications of long-range WPT

The most obvious application for long-range WPT is in EVs, where the ability to charge EVs wirelessly while driving could revolutionize the automotive industry. Wireless charging would mean that EV owners would not need to frequently stop for charging, and they would be able to travel greater distances without worrying about battery life. This would have a major impact in reducing carbon emissions, making electric cars more practical for use in industries where long-distance travel is necessary.

Long-range WPT is also used in the medical industry where implantable medical devices, such as pacemakers, are powered wirelessly. This technology eliminates the need for invasive surgery to replace batteries in implantable devices, reducing the risk of complications during surgery. Similarly, WPT technology could be used to power other medical devices, such as insulin pumps and hearing aids.

Another practical application of long-range WPT is in corporate and residential environments, where the charging of smart devices can be done wirelessly. This technology has significant energy-saving benefits as it eliminates the need for chargers and cords, which are often left plugged in when no longer used.

The future of long-range WPT

Like any new technology, long-range WPT comes with its own set of challenges. The most significant challenge is efficiency. WPT systems are not 100% efficient, meaning that energy is lost during the transmission process. The power lost during the transmission process results in less power being available to the receiver, which reduces the effectiveness and efficiency of the system. So, improving the efficiency of WPT systems is critical to the development of this technology.

Another challenge is the need for standardization. The technology is still relatively new, and many companies use different power transmission technologies, leading to incompatibility issues among devices. To ensure the widespread adoption of this technology, standards must be established to ensure interoperability among different devices.

The future of long-range WPT looks promising, with major technology companies investing heavily in this technology. Major companies operating in the consumer electronics sector have already released devices that support WPT. Furthermore, the EV industry is heavily investing in wireless charging technologies, with several companies already offering wireless charging stations for EVs. It is evident that this technology has significant economic, environmental and practical benefits, and hence, it is essential to continue investing in its development.