A famous, iconic image of the great inventor Nikola Tesla casually shows him sitting in a chair, cross-legged, taking notes, oblivious to the plethora of artificial lightning that pierces the air a few meters away from him. Free wireless energy transmission. Today we talk about this.
Decades before Emrod, Tesla and electricity were like an old married couple. His experiments in Colorado with the Wardenclyffe tower inspired him with one of the boldest proposals: power the world with wireless power transmission. Tesla's antenna made headlines with its plans for a "world-wide wireless power system" and obtained funding from JP Morgan to build the first of several huge transmission towers, and transmit electricity wirelessly.
And then nothing more
Until JP Morgan realized that Tesla wanted to make this wireless energy available completely free of charge. Tesla's tower was not just about wireless power transfer. He aimed for free energy for the planet.
At that point, Tesla's dream of wireless energy was smothered in the cradle. JP Morgan canceled further funding. The Wardenclyffe Tower was demolished. When Tesla died, the mystery and doubts about the success of the wireless energy transmission did the rest. Goodbye electricity from the earth.
Meanwhile, another inventor, Guglielmo Marconi, pursued a parallel dream and perhaps anticipated by Tesla himself. A dream that achieved much greater success: the wireless transmission of information over radio waves. The world today is, of course, awash with wireless information, and the word "wireless" is on the agenda.
Today, if the New Zealand startup Emrod will do good things, Tesla and Marconi's dreams could merge.
The company is building a system to transmit energy wirelessly over long distances. Earlier this month (I talked about it here) Emrod has received funding from Powerco, New Zealand's second largest utility, to conduct a test of its system at a grid-connected commercial power plant.
The company hopes to bring energy to communities off the grid or to transmit power from remote renewable sources, such as offshore wind farms. Wireless and green electricity.
How Emrod's wireless energy works
The system consists of four components: a power source, a transmitting antenna, several (or more) transmitting relays and a rectenna.
First, the transmitting antenna transforms electricity into microwave energy. An electromagnetic wave just like Marconi's radio waves, only a little more energetic, and focuses it in a cylindrical beam.
The microwave beam is sent through a series of relays until it hits the rectenna, which converts it back to electricity.
What if you get this ray?
To ensure safety, Emrod uses energy in the industrial, scientific and medical (ISM) band and keeps the power density low. "It's not just how much power you supply, but how much power you supply per square meter", says the founder of Emrod, Greg Kushnir. "The density levels we're using are relatively low. Right now, it's roughly the equivalent of being out in the sun at noon, about 1 kW per square meter."
But if it works as intended, the beam will never come into contact with anything other than air.
The beam stops if it encounters obstacles
The system uses a network of lasers surrounding the beam to detect obstacles, such as a bird or a person, and automatically stops transmitting until the obstruction has moved.
The technology (wireless energy transmission via microwaves) has been around for decades. But to make it commercially viable, energy losses need to be minimized. Kushnir said the metamaterials developed in recent years have made the difference.
The advantage of metamaterials
The company uses metamaterials to more efficiently convert the microwave beam back into electricity. The relays, which are like "lenses" that extend the beam beyond the line of sight refocusing it, are almost lossless. According to Kushnir, most of the losses occur on the other side, where the electricity is converted into microwave energy. Overall, he says,
the system efficiency is about 70%, which is economically sustainable in some areas, the ones the company is aiming at for now.
We do not foresee a situation in the near future where we could say that all copper wire can be replaced by wireless. The system will have lower efficiency levels. It is not a question of replacing the entire infrastructure, but of increasing it where it makes senseGreg Kushnir
A test in the real world
The company's prototype can currently send a few watts of power over a distance of around 130 feet (40 meters). Emrod is currently working on a larger version capable of transmitting a few kilowatts. The plan is to deliver the new system to Powerco in October, test it in the lab for a few months and then, if all goes as planned, test it in the field.
The tests will aim to validate how much wireless power the system can transmit, and over what distance.
Although the current model is modest, Kushnir is certain it will improve. "We can use the exact same technology to transmit 100 times more wireless energy over much longer distances," he said in a press release. "Systems using Emrod technology can transmit any amount of current."
Ray Simpkin, Emrod's chief scientific officer, said the company is also looking into the possibility of transmitting energy through 30 kilometers of water from the New Zealand mainland to Stewart Island. He said the system could cost up to 60 percent of a submarine cable.
Ultimately, the technology can help deliver wireless power to rural areas or transmit power from offshore wind farms. In both cases, it is expensive to build physical infrastructure to power the grid.
In other cases, such as in national parks, a wireless transmission mode may have less impact on the environment and require less maintenance. Or it could be used to provide power after natural disasters where the physical infrastructure has been damaged.
Ultimately, Emrod's is not Tesla's "worldwide wireless system", also because it will cost money.