Wireless Electricity Update Summer 2009

This is an update on recent developments in wireless electricity. I’ve been writing about wireless electricity for several years now and have corresponded with Marin Soljacic at MIT on one occassion regarding his progress as well.

The MIT Technology Review is doing a good job of following along with the race between their team (now operating within the independant VC funded startup WiTricity) and Intel (who appears to be building on top of some of their own technology) to bring a wireless electricity product to market first . Thanks to my buddy Jim for pointing me to this article last week. The article talks pretty much all about Intel and their June 18th presentation at the Computer History Museum in Mountain View, California. At the event they showed a wireless electricity prototype which charged an iPod speaker at a distance of one meter using a 60 cm diameter loop transmitter and a 30 cm diameter loop receiver both tuned to a frequency (electrical current oscillation) of seven megahertz. Electrical power was transmitted with 80% efficiency through the specific arrangement they demonstrated.

This display is similar to one they showed in the Fall of 2008 which lit a lightbulb over a similar distance with only slightly less (75%) efficiency. Because of the small improvement in efficiency (5% increase in 10 months) I wonder if they are approaching a unique design limitation or a fundamental limitation with the transfer of a magnetic field through the air. It’s also worth wondering whether the 20% of energy lost is falling out as the magnetic field passes through the air (currently a distance of one meter) or through the process in which electric energy is converted into magnetic energy and back within the wire loops that comprise the transmitter and receiver. I figure the magnetic field transfer through the air is to blame for most of the energy lost in this model. Does anyone know?

I also haven’t heard anyone talking about efficiency gained or lost when a single transmitter is used in combination with multiple transmitters. If a transmitter is able to send a magnetic field out in multiple directions (which I don’t know if it does) then it seems to me that a receiver in a location far away from another receiver would not reduce the ability of the other receiver to be driven by the magnetic field. Could this technique be used to increase efficiency to a level that the current energy losses would be more than compensated for? I don’t see why this wouldn’t work… but my physics knowledge is based mostly on Physics 26 and 27 in the undergrad program at UNC from eight years ago 🙂 At least the classes did include sections on electricity and magnetism.

Another note about WiTricity, the company pushing MIT’s research forward that I mentioned earlier, their website contained a few things I found interesting:

1) It mentions that WiTricity has an exclusive license to the wireless electricity prototype intellectual property developed by Marin Soljacic and his team at MIT. There are also some other interesting details on the about us page of the WiTricity website as well.

2) It contains a nice illustrated description about how wireless electricity works which is a great read for a wireless electricity novice and probably great content for a lesson plan if you are a teacher.

Wireless Electricity

Intel recently announced a display of some new technology which looks like another step along the way to a good proof of concept of efficient wireless electricity. Building on Marin Soljacic’s work at MIT (it’s unclear to me whether Intel is actually building on top of the work of Marin’s group or if they’re working in parallel) the group from Intel is displaying the transfer of energy without wires from a transmitter to a receiver separated only by air which in result lights a light bulb. Intel’s demonstration was covered by Gizmodo and has a nice description and some great pictures.

Two years ago Marin Soljacic’s group out of MIT made their first announcements of their plans to use electromagnetic induction (the transfer of energy through the conversion of electric charge to magnetism and vice-versa) to transfer energy through the air from a sending device to a receiving device. The trick to keeping everything safe for humans and electronic devices sharing the air in between was to use a very low power signal and to then use the principle of resonant energy transfer. This is essentially pushing on a wave at a frequency that in result magnifies the strength of the wave. In plain English, think about pushing someone swinging on a playground swing. If you push them at the right time during their swing you will increase the speed at which they swing and the distance they cover. Push at the wrong time and you slow them down. The same concept allows your standard AM/FM radio to tune into a radio wave frequency.

Shortly after Marin’s announcement of the concept for a system to efficiently provide for wireless electricity in the fall of 2006 I contacted him via email. I requested a meeting to introduce myself and my ideas on how important wireless electricity is for our world and also asked for the opportunity to invest in his research. Hey, never chance never dance. Within a few weeks he responded with a short but polite message with an apology for the delay in his reply because he was having difficulty responding to his email volume with the 200+ media outlets that picked up on his recent announcement. He mentioned that he was currently not considering investment or commercialization options for his research. I figure that at some point he’s going to have to consider transferring some of the intellectual property he’s created at MIT out to a private corporation to seek the type of investment required to take it to the next level. Maybe he’s taken another route already and has licensed his technology to Intel in support of their current exploration into wireless electricity. I wish I had some better information on this. Since late 2006 his name has been a continued topic of discussion as the progress on his work has remained on the fringe of media hot topics.

Before Intel’s August 2008 announcement of their demonstration Marin has completed his own presentation of a working device built to the specifications of his plans announced in late 2006. News of his prototype built at MIT was released mid year 2007 and once again was widely covered by the media. Marin’s faculty homepage at MIT tells a bit of his story through links to news stories and published research. Intel took another 14 months and has claimed that they’re able to transfer power the same distance as Marin (a couple of feet) with greater efficiency (75% over the previously achieved 50%), essentially losing less power through the air.

Efficiency is of course the name of the game with wireless electricity now and that’s why everyone’s measuring it and talking about it. The first challenge was creating a way to transmit power through the air in a way that is safe for humans and everything else in between the sending and receiving devices. Wireless electricity has existed for many years in the form of lightening in nature and arcing among high power circuits. I remember as a kid enjoying the night sky going from black to bright white during a major snow storm as a nearby power exchange station shot huge arcs of electricity into the air. Our house was probably two miles from the station and we could clearly see the strings of electricity that must have been launched several hundred feet into the air to have been visible to us. Severe storms, the kind that produce the biggest lightening, have always been one of my most favorite things to see. For some reason seeing nature at work creating electricity in the sky is incredibly calming to me and I’ve been known to wanter outside in big storms just to get a chance to take it all in.

In concept, radio and TV waves are already electromagnetic waves, containing a wave component of electricity and another of magnetism that mirror each other and repeat over very long distances. But they are very low power and require a powered device on the receiving end to interpret their signal and boost it. As another example in about 2001 I bought an induction charged electric shaver which charged by simply sitting in a cradle (no metal connections existed on the charger or the shaver). The charger which plugged in to the wall outlet alternated current within a coil which created an alternating magnetic field which because of its immediate proximity (about 5 millimeters in distance) was sensed by the shaver which itself had a coil of wires on which the current alternated in result of alternating magnetic field. This process moved the alternating electric current from the wall outlet into the shaver which could then charge its internal battery as if it were also plugged into the wall. I was probably the person most excited in the world to be charging my shaver for the time I used that model. In the radio/TV and the induction charging shaver examples we have both a long distance and short distance solution for electromagnetic signal transfer. The long distance solution being too weak to transfer any type of meaningful power to the receiving device and the short distance solution not being able to cover any meaningful distance. As an entrepreneur this void is what got me excited about a mainstream wireless electricity solution that fell somewhere in the middle. A model that was both powerful enough to charge a receiving device but weak enough to be sent over long distances without disrupting everything in between.

In both Intel’s and Marin’s prototypes they’ve started with a distance of a couple of feet (enough to allow them to stick some things in between to see what effects are realized) and they’re entirely focused on trying to get as much power as possible from the sending device to the receiving device. There may also be a parallel advantage here in that 100% power reception on the receiving side may also mean that since no power is lost along the way that it couldn’t have affected anything in between because otherwise it would have lost intensity but I don’t know enough about electromagnetic signals to know if this is true. I guess a device in between could have been affected by the signal even if passes along an identical signal but something about the law of the conversation of mass and energy seems impossible there. I’ll defer to a physicist on this one. Regardless, efficiency is the goal and the improvement from 50% to 75% efficiency within just 14 months is really exciting.

I envision a go-to-market solution here where 15-20 feet is considered good enough for the first round of devices because it accommodates the size of a standard private office, cubicle, or room of a residential house. Since all of these are already hard-wired from an external source to the outlet the big advantage here in the short term is from the wall outlet to the end device: the cell phone, laptop computer, monitor, projector, digital camera, etc. I think the first company that moves in this space will establish a brand name with builders who will install the wireless electricity sending devices into each room they build alongside traditional plug-in devices. These relationships will then later be leveraged as a product with the required efficiency at longer distances and through more obstacles (walls being the important ones to consider) becomes available and they go into production as the infrastructure that moves power from an external source to every outlet or end device within a building. I haven’t done the math but my gut (Steven Colbert reference) tells me the first opportunity is at least a $50 billion annual market with the latter being 3-5x that annually. Then of course the opportunity that remains is for long distance regional power distribution through the air. Even as optimistic as I am now I really don’t see this being utilized as the primary source of power distribution any time within the next 25 years even if it were to exist now but the model for its adoption exists in the transition from wired home phone service to cellular phone service. Personally, although there is absolutely no good reason for me to have a wired phone line at home I do have one. Even early adopters like my wife and I are still clinging to the ways of old I guess because if just feels wrong to abandon it. I guess our monthly stipend to AT&T for wired phone service helps us sleep better at night. I do have a number of friends that don’t have wired home phone service but I don’t know of any of our parents that have done completely without. Time will change this of course.

I do wonder what the required efficiency for widespread market adoption will be, it seems like 75% is getting really close. For instance if I pay 10 cents to charge my laptop over night (I have no clue what it costs me to do this now but it can’t be much) I would gladly pay 15 cents to charge it over night without a plug. Since the devices that consume the majority of power in my house are large or don’t ever move (water heater, air conditioner, oven, lights, etc) it seems like the efficiency lost will maybe apply to 10% of my power consumption in total but will benefit 100% of the devices I move around and that need their batteries recharged at least once per week (laptop, cell phone, digital camera). That seems like a trade off that most people would be willing to make. So, what are you waiting for Intel? Other than the obvious requirements of bringing a product to the mass consumer market which I don’t begin to claim to know it seems likely that the remaining obstacle will be in terms of power intensity. Current prototypes are lighting a light bulb. I’m not sure how that equates to the power required by my laptop’s power chord but it seems likely to be less.

Of high concern will also be authentication and access control. Since wireless electricity when originated like in current prototypes is turned on literally any device that is in reach of the signal can charge from it. I’m not sure whether multiple devices receiving the signal will cause additional usage of power from the source. They may also reduce the strength of the signal for all other receivers which if true means that your immediate neighbors could easily leach off of your power. Although wireless Internet signals went mainstream without any decent type of encryption in place they were typically associated with sources that allowed unlimited data transfer which meant wireless Internet theft really only drew resources away from the source device but didn’t cause any associated additional unit cost to the owner of the wireless access point. Of course in aggregate a unit cost to upgrade to a higher speed service existed but this didn’t affect the vast majority people. If additional users of broadcast wireless electricity cause the source device to increase its power throughput in a similar fashion there may be a direct unit cost to the owner who will experience a higher power bill in the following month. If this is the case finding a way to limit usage to a controlled group of receivers will be critical before a solution can go into mainstream production. This doesn’t seem easy considering the broadcast model and no apparent need for communication from the receiving device back to the source device (unlike in the wireless Internet signal model) with wireless power.

In terms of social benefit (since I’ve spent my focus so far considering commercial applications and strategy) I see several opportunities that we must hold high in our list of intentions for the technology that enables whatever solution we end of reaching:

Emergencies: Wireless power over long distances should remove many of the break points in power service that are caused by natural disasters that take down physical transmission lines. Using wireless power as an alternative power source just for emergencies might allow a central power source to bring local power sub-stations back on line instantly when major trunk lines are disabled.

Safety: Countless accidents caused by the necessity of power transmission lines could be eliminated. Physical power chords are some of the last things we have running all over our houses and offices these days and they spend a lot of their time among our feet and near our water sources where they are most likely to cause problems.

Beauty: Power lines are most frequently run through the air where they serve little other purpose other than being a great resting place for shoes whose laces have been tied together and for birds who intend to poop on us from a fixed vantage point. Among our houses and offices the wire managers and conduits that move wires around are constantly being adjusted in an attempt to make them more discrete already.

Poverty: Moving power through the air may make it more cost efficient than the current implementation which requires a lot of resources of wood, metal, rubber, and land to get it from point a to point b. Areas of the world that it has been just too difficult to get reliable power to previously may be easily powered without the need for wires. Historically we know that the access to a reliable power infrastructure is a key component in stimulating developing countries’ economies.

Political Power & War: Moving power through the air may make it more difficult for military targeting of key power distribution resources as they won’t be as visible as they are now and they won’t follow any key distribution lines. After an attack power could be restored more quickly from an alternative source station that re-powered the air from a different point whether provided by the country affected or by emergency relief efforts from allies.

My Peace of Mind: Power chords are so 1800s and they’re cramping my style. Everything else I do today is free from wires, except my tightrope walking habit (my fake tightrope walking habit that is), so it sure would be nice to cut that electric wire away without worry of being shocked back to the century that invented it. Set me free!

Update 1/13/2009: Last week Palm announced wireless electricity as part of their new charging base for the Palm Pre to be released around March of 2009. The device’s Touchstone base will be sold separately and uses the basic process of induction to turn electric current into magnetism then back into electric current. The Touchstone base (like a shaver I bought back in 2001) claims to charge “wirelessly through the air” when in fact the charging base and the device actually touch directly. Having the two components touch isn’t required as part of the transfer of energy but it is required to minimize the distance between the sending and the receiving devices. As I’ve mentioned above, new developments focus primarily on using this same principle over a more helpful distance (larger than two millimeters :)) of five to twenty-five feet where the challenge becomes focus, sensitivity, and tuning to preserve the energy in the transfer and prevent damage to anything along the way.