A famous, iconic image of the great inventor Nikola Tesla shows him casually sitting in a chair, cross-legged, taking notes, unaware of the plethora of artificial lightning piercing the air just 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 one of his boldest proposals: power the world with wireless power transmission. Tesla's antenna made headlines with its plans for a "worldwide wireless energy system" and secured funding from JP Morgan to build the first of several massive transmission towers, and transmit electrical power 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 wireless energy dream was stifled in the cradle. JP Morgan canceled further financing. Wardenclyffe Tower was demolished. Upon Tesla's death, the mystery and doubts about the success of wireless energy transmission did the rest. Goodbye electricity from the earth.
Meanwhile, another inventor, Guglielmo Marconi, pursued a dream parallel to and perhaps anticipated by Tesla himself. A dream that achieved much greater success: the wireless transmission of information over radio waves. Today's world is, of course, awash in wireless information, and the word “wireless” is commonplace.
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 power 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 power to communities far from the grid or transmit power from remote renewable sources, such as offshore wind farms. Wireless and green electricity.
How Emrod 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 turns electricity into microwave energy. An electromagnetic wave just like Marconi's radio waves, only a little more energetic, and focuses it into 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 provide, but how much power you provide per square meter,” says the founder of Emrod, Greg Kushnir. “The density levels we are using are relatively low. At the moment, it's roughly the equivalent of standing outside at midday in the sun, 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 transmission 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 difference was made by metamaterials developed in recent years.
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 by refocusing it, are almost loss-free. According to Kushnir, most of the losses occur on the other side, where the electricity is converted into microwave energy. Overall, he says, system efficiency is approximately 70%, which is economically sustainable in some areas, the ones the company is aiming for for now.
We don't 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's not about replacing the entire infrastructure, but augmenting it where it makes sense
Greg Kushnir
A test in the real world
The company's prototype can currently send a few watts of energy a distance of about 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.
While the current model is modest, Kushnir is certain it will improve. “We can use the exact same technology to transmit 100 times more wireless power 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 examining the possibility of transmitting power across 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 physical infrastructure has been damaged.
Ultimately, Emrod's is not Tesla's "global wireless system", also because it will have a cost.
