Imagine the possibilities if we could reach power anywhere without cables. Nikola Tesla himself tried to dream long-range wireless power transmission into existence. Where Tesla once failed, developments in radar and advanced materials technology are making this technology possible. Emrod is preparing to transmit energy via electromagnetic waves over long distances using proprietary beam-forming technology, metamaterials, and rectennas.
The New Zealand start-up is partnering with Powerco, a power distribution company also based in New Zealand, to develop a prototype system, and will be testing the technology this year.
In an interview with EE Times, Greg Kushnir, CEO at Emrod, explained how Emrod’s wireless system works by converting electricity into microwave energy, which is then shaped into a collimated beam and sent directly through the air from a transmitting antenna to a receiving one. When reaching the receiving antenna, the electromagnetic energy is converted back into electricity for consumers’ use. According to the company, this technology can be upgraded to carry kWs of electricity wirelessly over very large distances.
“Emrod incorporated as a company in 2019 after successfully completing a feasibility study to confirm the viability of the technology. The company subsequently demonstrated a proof-of-concept system, and is currently undergoing testing in an indoor facility, ahead of a planned field trial. Emrod is a team of 10, but has plans to grow significantly over the coming 12 months to support the implementation of infield pilot projects, ongoing R&D and commercialization,” said Kushnir.
In the 1890s, Nikola Tesla began considering wireless energy while working on his “Tesla coil” transformer circuit that generated alternating current electricity. Tesla’s first real experiment with wireless electricity took place in 1899 in Colorado Springs. He built a powerful oscillator inside a barn-like structure with a wooden tower topped by a 40-meter metal pole with a copper sphere on top. The inventor demonstrated that he could power light bulbs from more than 3 kilometres (two miles) away. His Tesla coil succeeded perfectly, but the experiment burned out the Colorado Springs power company’s dynamo, leaving the whole community in the dark.
“I think anyone who is interested in wireless technology has a deep appreciation for the work of Nikola Tesla. His work was instrumental for much of the wireless communication technology we enjoy today,” said Kushnir.
Kushnir pointed out that the science (and technology) behind Emrod’s wireless system is considerably different from what Tesla was proposing. Emrod can keep the beam tight and focused with two technologies. The first is related to transmission consisting of small radio elements and single wave patterns to create a collimated beam aligned in parallel. The second is related to proprietary metamaterials that effectively interact with those radio waves.
“It has had to be in order to achieve the power levels and efficiency levels that make it viable for the use cases we are focusing on. For example, Tesla’s system transmitted energy in a way that is described as omnidirectional, meaning it emits power in all directions. Emrod’s system uses a focused, unidirectional beam, sending power directly from one antenna to another. We have also developed passive relays to extend the range of our system and built-in new safety systems (see below),” said Kushnir.
He added, “the antenna design, metamaterials, and relay technology we use are critical as they allow us to achieve a certain level of performance, i.e. efficiency levels, reliability and distance. The safety considerations that are built into the system are also necessary for the system to be used for commercial purposes.”
The technology (wireless energy transmission via microwaves) has been around for decades. But to make it commercially viable, it was necessary to minimize energy losses. Kushnir highlighted how the use of metamaterials developed in recent years has made a difference.
Emrod’s technology aims to offer a new way to bring electricity to places that often have the biggest electrification gap in rural areas, and which cannot afford the kind of infrastructure that supports the electricity grid. Their antennas act as the cable that provides electricity to their customers. These antennas will be located in all those windy and sunny places where renewable energy can be used. The system works in all weather conditions, and the transmission distance is limited only by a line of sight between each antenna.
Transmitting energy wirelessly over difficult terrain eliminates the need for traditional poles and lines, as in the case of cellular base stations. Emrod’s system provides a wireless point-to-point connection between the power point and the base station using a pair of antennas. Kushnir points out that in the Pacific islands, electricity costs are very expensive and the use of renewable energy has to challenge infrastructure cost issues. Using Emrod’s wireless Tele-energy technology, it is possible to reduce dependence on diesel generators, bring electricity to remote communities, and thus lower the cost.
“Currently, the use cases where Emrod’s system is economically viable is where it would otherwise be difficult and expensive to lay and maintain powerline infrastructure, for example across waterways, forest or contentious sites. We are planning our first infield pilot project, which will be deployed in New Zealand, for the purpose of transmitting power from a new solar farm to service the needs of a commercial customer in the area,” said Kushnir.
Emrod’s technology uses a transmitting antenna, a series of repeaters, and a receiving rectenna (a rectifying antenna capable of converting microwave energy into electricity). Each of these components appears as a square panel mounted on an appropriate structure. The greater the surface area of the panel, the greater the transmission power and the greater the distance it can cover.
“Using Emrod’s system, wireless transmission distance in a typical use case ranges up to 40km, as long as there is line of sight between the transmitting and receiving antenna. This can be extended using passive relays. Currently, available semiconductor technology for the amplifiers places an upper limit on the antenna power density of around 10kW per square metre.”
The startup also considers the possibility of having wireless electricity in emergency situations, such as unexpected power outages. A truck could be equipped with a rectenna and then driven into the visual range of a repeater to create a temporary wireless power connection. Emrod worked with New Zealand’s spectrum management authorities throughout the development process and will ensure that the entire technology meets safety standards. Emrod uses power in the industrial, scientific, and medical (ISM) band and keeps power density low.
Emrod’s point-to-point transmission means that power is radiated directly between two points. There is no radiation around the beam, as is the case with high-voltage cable transmission. The low-power safety laser ensures that the transmission beam turns off immediately before any transient object (such as a bird or helicopter) can reach the main beam, ensuring that it never touches anything but clean air.