In this day and age, we all want and prefer wireless systems and devices for instance; Bluetooth headsets, WiFi/ wireless internet connection on our computers and devices, wireless and seamless transfer of information and media, wireless or cloud backup storage. The list is simply endless. This quest for wireless systems is because of the simplicity, convenience and smartness attributed to wireless systems.
The one that catches my attention the most is wireless electricity/power transfer that in itself has found application in battery charging for phones and electric vehicles. In a Ted talk in 2009 Eric Giler now the CEO at MIT inspired WiTricity Corp presented one of the first wireless electricity transfer demonstrations to turn on a tv and charge a phone.
This wireless power transfer concept was first introduced by Nikola Tesla. Having built a 187 feet tall tower intended for wireless communication, he wanted to extend it for transmitting wireless power.“…More important than all of this, however, will be the transmission of power, without wires, which will be shown on a scale large enough to carry conviction” quoted in a magazine, Nicola Tesla made known his intentions for wireless power transfer. Unfortunately his funding for the project was cut off before he could realise this. It’s from re-visiting some of his work that interest in wireless power has developed again.
So how does this work?
The general idea is to have power transmitted from one circuit to the other using electromagnetic fields at specific frequencies and resonance. This idea is borrowed from the working of a transformer that transfers power from one circuit to another by magnetically coupling the two circuits through iron. A wireless system, however, achieves the same effect without a medium.
As with other wireless systems, one therefore needs a transmitter(transmitting coils in this case) and a receiver(receiving coils) setup to communicate with each other(in this case at the same frequency and resonance) so that the power exchange can occur.
Where is this being applied?
It goes without saying, electric vehicles. Early this year Korea Advanced institute of Science and Technology(KAIST) developed and showcased a wireless power transfer technology for commuter vehicles, railways and harbor freight. The On-line Electric Vehicle(OLEV) has receiver coils at the bottom of the bus and transmitter coils installed under the road surface. Reading this, questions of efficiency arise. In their press release this bus is claimed to have 85% transmission efficiency for a 20 cm gap between the vehicle and road surface. Other companies like Primove are also adopting wireless charging for commuter buses, except that they have specific charging stations along the bus route stops. This obviously reduces the setup and operating cost.
Another application as you have already heard is the wireless phone charging. Phones like the Nexus 4, Nokia Lumia 920, HTC Droid DNA among others have this capability and come with wireless charging mats. Of course the idea of only having your phone charge when it’s only on the mat has its pros and cons that can make another post. A more interesting wireless phone charging idea being envisioned by QI Wireless Power Consortium is snack charging on-the-go. The idea is basically like the way you receive internet connection with wi-fi, with on-the-go, you’ll be able to receive charge on your battery just by being around the “charging hotspot”. As long as your phone is QI standard compatible you will have the ability to charge your phone anywhere with a QI transmitter. This promises to do away with the cumbersome and messy chargers and USB cables — something am personally looking forward to.
What are some of the biggest concerns for wireless charging?
Is it safe : When you hear electromagnetic fields, you think of the danger of cancer from over exposure. However because wireless technology uses electromagnetic fields at specific frequencies and resonance not radiation, the danger in radiation fields is therefore eliminated.
Standards for safety levels of exposure to radio frequency are available to manufacturers by IEEE and other bodies. Fact sheets regarding electromagnetic fields and public health have also been made available by World Health organisation(WHO). These provide guidelines on product safety that manufactures ensure their products abide by.
Is it efficient and available: To extend this technology and keep it efficient enough goes back to the question of standardization. IP(Intellectual Property) and patents are being written by different companies to have this covered and have general standards that all device manufacturing companies can live up to.
Cost: As with new technologies no cost speculation has been made yet for this except the promise that with high demand and production, the cost will not be an issue.
So the biggest question is not whether we shall get there, it’s more about when are we going to have this technology readily available worldwide. I don’t have an answer to that but i know we shall get there – A world of complete wireless systems.
Editor’s Note: This is a guest post by Jemimah C. Akiror. She is as a research assistant at Concordia university Canada where her research is mainly in energy efficiency and electrical machine design. She also takes interest in power systems, renewable energy technologies and power electronics. You can follow her via @JemyConnie or on Linkedin.