Electricity Through The Air?
In 1901 Nikola Tesla created a 57-metre tower at Wardenclyffe on Long Island, New York. He intended for it to transmit information and electricity wirelessly over long distances. It half worked and a pioneer who, among other things, developed the generation and transmission of alternating current became mostly forgotten. Until Elon Musk revived it by making Tesla the name of his electric-car company and became one of the richest men in the world.
Emrod and Powerco have collaborated to develop a prototype system that in a separate project will beam energy from a solar farm on the North Island to a client several kilometres away as Tesla himself prepared to do so many years ago. The aim is to transmit the power as a narrow beam of microwaves. Power-beaming, as Emrod’s process is known, has been tried before, but mainly for military applications, or for use in outer space (in 1975 Nasa used microwaves to send 34kw of electricity a distance of 1.6km).
Emrod’s operation will begin cautiously. Starting by sending “a few kilowatts” over 1.8km and gradually increasing both power and distance. Emrod unlike others will employ relays and upgraded receivers with so-called metamaterials. The relays work like lenses refocusing the microwave beam and sending it on its way with minimal transmission losses and could even steer it in a new direction.
Metamaterials are composites containing tiny amounts of conductive metals and insulating plastics arrayed in a manner that causes them to interact with electromagnetic radiation such as microwaves in particular ways (already used in cloaking devices like warships and military aircraft that hide from radar). But they can also be used in a receiving antenna, to convert electromagnetic waves into electricity more efficiently.
If Emrod can make this work they will have competitors like TransferFi, based in Singapore. TransferFi is developing a system that shapes beams of radio waves, which generally have a lower frequency than microwaves, to transmit power to specific receiving devices.
PowerLight Technologies, an American firm, has been working with that country’s armed forces on using lasers to transmit power to remote bases and also to power drones while they are in the air.
Mitsubishi Heavy Industries, a Japanese engineering firm, is exploring how the technology might be used to send power to the ground from geostationary satellites fitted with solar panels (this transmission is more than 35,000km).