How can we send energy wirelessly?

New Zealand: Startup transmits electricity wirelessly

Peter Müller

Sending data through the "air" - almost old hat. But it gets interesting when it works with electricity.

The dream of the electrical pioneer Nikola Tesla could come true and electrical power could be transmitted wirelessly. The New Zealand startup Emrod has finished a prototype that initially wants to transmit 2 kilowatts of electrical power over a distance of 40 meters and also wants to implement the technical principle on a large industrial scale with the help of cooperation partner Powervo, New Zealand's second largest electricity supplier.

The wireless transmission of energy relies on directed microwaves, transmitters and receivers consist of so-called electromagnetic metamaterials, which the military, for example, is also researching with regard to cloaking devices. These materials are characterized by a negative refractive index (more precisely, the real part of the complex refractive index can be negative) and are therefore also able to convert absorbed microwaves back into electricity.

So far the attempt to transport energy over significant distances has failed because of this. Nikola Tesla is said to have caused a major power outage in Colorado Springs during such an attempt with a Tesla transformer. With their high voltage and high-frequency alternating fields, the Tesla transformers are also not entirely harmless.

Emrod, on the other hand, wants to exclude dangers through the targeted transmission from transmitter to receiver, a kind of safety field of low-energy beams around the actual transport beam should also help stop the transmission immediately if an obstacle (bird) or an energy thief enters the area of ​​the beam. Even if you put your hand in the beam, it takes a while before you can even feel anything, explains Emrod founder Greg Kushnir in an interview with It is not a matter of a laser that penetrates everything, but of bundled microwave radiation with a significantly lower frequency and thus energy. In contrast to 5G radio, which has to radiate in all directions (with very little power in comparison), the power transmission from Emrod only travels over precisely defined routes.

Renewable energies make sense of wireless energy transmission, which is often converted into electricity in rough terrain or offshore and where the transmission poses a technical and logistical challenge. Kushnir estimates the overall efficiency of the system at 70 percent, most of the losses arise during transmission. Copper cable is still more efficient, but mainly because the classic overland line works with high voltage.

Electricity transmission through the "air" (electromagnetic waves do not need a carrier medium, neither air nor the ominous ether) is not a completely new technology, some drones can be "refueled" in this way in flight. So far, however, only low performance with high losses has been the rule.