Transferring energy through space has been around for a while. This process has been used by the sun for over 4.5 billion years. The losses are huge. Most solar energy is lost to space, and only a small fraction reaches celestial bodies orbiting around it. Only a fraction can be harnessed. This is true for wireless energy transmissions over distances greater than a few millimetres. Their efficiency, which measures the ratio of usable energy and total energy expenditure, drops rapidly with distance.
Bundling electromagnetic energy is one solution.
Emerald is a New Zealand-based cleantech company that relies on a beamforming method to convert electricity into an electromagnetic beam. This beamforming technique sends the beam from one antenna directly. Emrod demonstrated proof-of-concept wireless power transmission at a greater than 97% beamforming efficiency one year after its foundation. Greg Kushnir, CEO and founder of Emrod, explains the key innovation. “We achieve high efficiency using electromagnetic metamaterials. They can be used to bundle electromagnetic energy in the transmitting radio antenna. We believe that we can achieve an efficiency of more than 80 per cent by improving the transmitting and receiving sides, which are the most vulnerable. Depending on where you are located, and the losses that may be incurred due to power theft, power transmission over high voltage lines have an efficiency of 60-95 per cent. Metamaterials such as those made of composites of metal or plastic have “unnatural” optical and electrical properties. If the structures are not smaller than the wavelength, they can interact with electromagnetic waves unexpectedly. Metamaterial, for example, can direct radar beams around it in a way that is invisible to radar.
Field tests are currently being conducted.
Kushnir says: “The metamaterials we design and construct are distinguished by their smart property such as their precise shape, geometry and size, orientation, and arrangement which allow us to block, reduce, amplify, redirect or amplify electromagnetic energy.” Emrod Wireless power transmission uses a frequency of 5.8 gigahertz. This frequency is used for wireless power transmission and is independent of weather conditions. Emrod developed beamforming technology. The energy is transmitted via relay antennas from the transmitting antenna to the receiving antenna as a tightly bundled “rod”. This technology is also used to name the company: Em stands for electromagnetic and rod for the rod. With the New Zealand power supply Powerco, Emrod, A larger indoor prototype has been developed, and a wireless system is being planned to be built to allow further expansion. Powerco’s Supply network. The system is expected to provide power to remote areas and reduce the need to install copper cables in difficult terrain. The wireless system will also reduce maintenance costs and impact the environment. Kushnir says that wireless power transmission is a key technology to transport energy to consumers sustainably, especially for renewable electricity generation. Transport by cable is difficult because of the many substations and transmission towers. It also requires many materials, such as copper, and extensive maintenance and repair.
Where conventional wired connections are too expensive, complicated to install, or difficult to maintain, permanent Emrod units may be used.
Photo illustration of an antenna truck used for power supply in disaster zones.
It is now a part of everyday life to transmit energy wirelessly over short distances. Wireless energy transport over long distances is a complex task to keep losses low. This is why Emrod’s highly-specialized antenna design is so important. Low-loss energy transport through the air is possible if the receiver and transmitter are just a few centimetres apart. This is state of the art. The transmitter and receiver are simply two coils that face each other at a short distance.
Inductive coupling is a well-established principle.
An alternating current can be sent through the transmitter coil to induce an alternating voltage in its receiver coil. Wireless charging stations already use this principle of inductive coupling for smartphones and electric toothbrushes. These advanced systems transmit electricity wirelessly up to two meters with high efficiency. Passive RFID transponders (RFID = radiofrequency identification) are also widely used. They don’t require external power supplies or batteries. These tiny transponders can be used as smart cards for access control, car immobilizers and radio tags to mark goods. The beams also transmit the transponder’s energy from the reading device. The Transrapid is a German-developed high-speed monorail train that uses magnetic levitation. It can also be supplied with wireless power through inductive coupling. This technology will be especially important for electric cars. The future could see car batteries being recharged while driving along a charging lane on the road with embedded coils or plates. This would allow for an extended battery range of thousands of kilometres. The challenge for e-mobility, industrial applications and RFIDs is much greater than it is for small devices and RFIDs. A smartphone battery can be recharged quickly with a power consumption of just 5 watts. For electric vehicles, such as autonomous mobile robots, floor conveyors, and industrial equipment, you will need 1,000 times more wireless power. These systems are still in the infancy stages. A team from the University of Colorado Boulder presented recently a test setup that can transmit 1 kilowatt over 12 centimetres.
Jun Yao, a physicist, and Derek Lovely, a microbiologist, have created an air-powered generator to connect electrodes to protein nanowires. This generates electricity from water vapour naturally found in the atmosphere.