ELECTRICITY ON THE GO: Dynamic electric-vehicle charging would help to eliminate the fear that drivers might have of being stuck on the road with a dead battery, often referred to as "range anxiety." Instead of setting up refueling stations inside garages, chargers should be installed in the road itself.
Image: Courtesy of University of Michigan--Shanghai Jiao Tong University Joint Institute
-
The Best Science Writing Online 2012
Showcasing more than fifty of the most provocative, original, and significant online essays from 2011, The Best Science Writing Online 2012 will change the way...
Read More »
Plug-in electric cars such as the Chevy Volt and the Nissan Leaf have only just begun to penetrate the U.S. consumer market, but already automakers are thinking ahead to the next technological advance: a car that can recharge itself anytime and (almost) anywhere.
Consumers are perfectly happy to plug in phones and game controllers, but many have not yet adapted to the idea of plugging in a car at the end of a commute.
Stationary wireless charging
"Almost universally, all the carmakers have learned...that consumers find plugging in a vehicle is inconvenient, and the carmakers have concluded they need to offer some type of wireless, hands-free charging," says David Schatz, director of business development and marketing for WiTricity Corp. in Watertown, Mass., which makes wireless chargers for phones and cars. With WiTricity's system, a user would not have to park his or her car directly on a charging mat, let alone deal with wires. As long as the car is within range of the charging station, energy begins to flow into the battery.
The process relies on a principle called magnetic resonance coupling (pdf). The charging device, made of a coiled wire with capacitance plates on either end, uses electricity to create a magnetic field that resonates at a specific frequency. Just as an opera singer can shatter a wine glass by singing the right note, the emitting coil transfers energy only to a receiving coil that resonates at the same frequency. Magnetic resonance coupling is thought to be safer than other methods of wireless charging because the intensity of the field can be increased without affecting other, non-resonant objects nearby.
The technology, invented at the Massachusetts Institute of Technology four years ago, may end up in cars soon. WiTricity last year partnered with major automobile component supplier Delphi Electronics on a demo car, and Mitsubishi Motors recently agreed to work with WiTricity on infrastructure research.
Dynamic wireless charging
Other researchers are taking wireless charging to the next step: designing cars that can charge while on the road. Dynamic charging would help to eliminate the fear that drivers might have of being stuck on the road with a dead battery, often referred to as "range anxiety."
A team at the University of Michigan–Shanghai Jiao Tong University Joint Institute in China is testing a prototype electric vehicle (EV) that would use a similar resonant coupling system to charge. Instead of setting up refueling stations inside garages, however, the researchers suggest chargers should be installed in the road itself, so cars could juice up on the go. Because electricity in this scenario would be ubiquitous, cars could eliminate heavy batteries, using supercapacitors to store energy.
Supercapacitors could be an ideal storage device for fast, frequent charging, as opposed to the slow, hours-long process used by many of today's plug-in vehicles. Chengbin Ma, an engineer at the institute, sees this setup as perfect for a fleet of electric buses, because they have guaranteed stops where the energy could be delivered for longer periods of time.
Ma and colleagues have built a coffee can–size prototype vehicle that "can really move and stop for wireless charging automatically," he says. The next steps are to finish a go-kart–size one-seater EV prototype, boost the system's power, and perfect that car's on-the-move recharging.
"Super" capacitors?
On the other hand, supercapacitors still have some technical issues that need to be ironed out. "I don't think there's an enormous expectation for them," says Brett Smith, co-director of manufacturing, engineering, and technology at the Center for Automotive Research, an Ann Arbor, Mich., nonprofit that studies the auto industry. "I think they will potentially be a lesser cost [than batteries], but they aren't robust enough. They don't do what the industry needs them to do yet." Smith says that no matter how far the new advances have taken this technology, it will be a decade before it appears in mass-market cars.
As for implanting chargers in the roadbed, that technology is "fascinating, and very expensive," Smith says. In cities the infrastructure will likely be built sooner because there's "an incredible need for traffic and pollution management," or at least more than in suburban and rural areas. Still, "people are complaining about the infrastructure cost of putting in [just] a charging station," he says. Larger infrastructure improvements will be an even tougher sell.
Other challenges
Besides cost, the big disadvantage of both Ma's and WiTricity's technology is distance. The car's receiving coil still needs to be fairly close to the charger's emitting coil. WiTricity's Schatz says an optimum distance is roughly 12 to 18 centimeters. Ma's system has similar limitations: At about 50 centimeters away from the charging station, power transfer dropped to almost nil. Supporters argue that a trade-off in efficiency is worth it for the advantage of not having to use a physical plug. "It's a small loss compared to when you plug in a vehicle, but a huge gain in ergonomics, or ease of use," Schatz adds.
Despite the challenges that wireless charging poses for both carmakers and drivers, the concept is gaining momentum. Audi introduced a wireless-charge concept car that is half race car and half coupe, dubbed simply the Audi Urban Concept, at the Frankfurt Motor Show in September. Toyota recently announced an agreement to collaborate with WiTricity in developing its resonance wireless charging technology. Likewise, BMW and Siemens are partnering to develop inductive charging stations for eventual use by taxis. If such development continues at this pace, a future with cordless electric cars may not be too far down the road.
See what we're tweeting about
34 Comments
Add CommentAaaahh!!! I can hear all the doomsayers now screaming about the charging mats causing cancer of the toes and two headed cockroaches from the electromagnetic radiation.
Reply | Report Abuse | Link to thisNobody is going to allow the utility to run their $10K battery up and down at its convenience drastically decreasing its lifetime.
Reply | Report Abuse | Link to thisSo what if a friend calls telling you there is free beer, but the utility just finished draining your battery. Your kids needs to go to hospital emergency. There was an earthquake and the utility needs your power a lot more than you.
Using battery for grid scale energy storage is far more expensive than pumped hydro.
There is not mention in this article of using the batteries for grid storage.
Reply | Report Abuse | Link to thisI don't see roads in the future.The internal combustion engine will soon be dead.From emission related complications.
Reply | Report Abuse | Link to thisHow efficient would this be? That is, for every watt that is broadcast into the air, how much power is actually put into the battery? It doesn't seem like this technology can be very efficient at all, since you're just broadcasting EMF.
Reply | Report Abuse | Link to thisIf you could charge 10 cars by connecting them with a cable for the same amount of energy used to charge one car through the air, it would be ridiculously inefficient and irresponsible to build an air charging system.
This technology might be the solution to all our perpetual charging needs. Imagine broadcasting solar energy from large scale desert "solar farms" to satellites that reflect these signals to large cities, thereby powering them without power lines. Brilliant!
Reply | Report Abuse | Link to thisIt boils down to efficiency. Can 200 million vehicles be driven by electricity more efficiently than with a gas engine. Electric motors are over twice as efficient as internal combustion motors but how does the overall 'well-to-wheel' efficiencies compare?
Reply | Report Abuse | Link to thisRegardless of the delivery system (plug-in, wireless etc), providing electricity for a huge number of vehicle will require several more power stations which will, for the next several decades, burn fossil fuel. Energy is energy, burn fuel in a motor or burn it in a power station. Presumably the later is best. An advantage with electricity is that it can be produced from a variety of sources (coal,oil,natural gas,hydro,wind,solar etc) therefore an electric vehicle can take advantage of this whereas an internal combustion engine driven vehicle can only run on oil products. It will be interesting to see how all this pans out.
Or three-fingered, yellow-skinned two dimensional people that live in televisions. Oh, wait....
Reply | Report Abuse | Link to this
Reply | Report Abuse | Link to thisThe things wrong with this is the ineff. It's just not hard to plug EV's in when needed.
They say only 80% eff isn't bad but that equals another 20 coal powerplants in 20 yrs vs a 100% eff plug and almost eliminate coal power using EV's to store or charge on RE. But even on coal power who's US share is dropping fast, 20% in the last few yrs, EV's still put out less pollution because they are far more eff and it's easier to control one powerplant vs 50k ICE's. Plus most EV charging in the future will be done with electricity that would be wasted as spinning reserve, turing chargers on and off to balance power needs so not really adding pollution, even stoping a good amount once V2G is used as the more polluting, less eff peaking power won't be needed. And no EVers won't get stuck with dead batteries as they would just tell the power company when it would be needed and they would only use the top 20-40% of the back pack cap anyway.
Next supercaps are a scam. They cost 100x's/wthr of what lithium batteries do.
You can't charge while driving from coils in the road because it would put drag on the EV, slowing it by the same amount of energy. Now coils at stop signs, traffic lights could work. Also the copper needed for many full roadways would cost too much.
These are not really needed as several things means they are not needed. Lithium batteries are dropping in price quickly so 100 mile range EV's will cost less than ICE's and run at 25% of an ICE's running cost.
This means 90% of driving needs could be met with that range. If one needs more range even as we speak 1,000's of EV charge stations that can recharge EV's in 15 minutes to 1 hr. Or one could rent a generator mounted on a trailer hitch. Nissan Leaf's are equiped with swapable battery packs and A Better Place is putting in pack swapping, fast charging stations In Cal, other places. While a little light at the moment, soon many EV charging, range extending soltulions will be available.
My present EV's proves this costing only $2/week for everything, electricity, batteries, etc for a Harley Service car size EV trike vs a similar ICE trike. Same for my EV sportwagon VS ICE ones
You all can pi-- and moan about Ev's all you want but I'm laughing all the way to the bank.
I know people are excited by new technologies and in urban areas I might even be convinced, but... If I live in Casper, Wy and I want to get my family to Yellowstone in a car how will this work without oil? The whole state has slightly more than 500,000 people and it is 350 miles through very lightly populated areas. Infrastructure costs per person would have to be enormous for re-charging stations enough to cover the 97,800 square miles. What am I missing? And please, don't say use the "high speed rail". :>)
Reply | Report Abuse | Link to thisReality check. In the month of September General Motors sold 723 Chevy Volts. For all of 2011 to date, they have sold a total of just 3,875 Chevy Volts. That is despite generous government subsidies.
Reply | Report Abuse | Link to thisFor the month of September Nissan sold a whopping total of 1,031 all electric Leaf cars, a decline of 331 from August. Sales of the all electric Leaf are actually declining.
Just for comparison, Chevy sold 18,097 gasoline powered Chevy Cruz cars and Honda sold 13,724 gasoline powered Civics. The entire auto industry sold 13.1 million cars in the month of September.
Now you can draw your own conclusions from these sales numbers. But they are the real numbers.
MIT claims to have invented this method of charging a car battery, but they did NOT. What they have done is modify a patent granted to Nicola Tesla. HE invented the concept and HE invented the technology that provided a prototype used by MIT to develop a variant form of the device designed by N.Tesla. I consider it criminal and unethical for anyone to borrow the intellectual property of another researcher and claim it as their own. Even if the inventor is dead. Attribution means something among people who demonstrate ethics, or their value/reputation as professionals means NOTHING.
Reply | Report Abuse | Link to thisIt takes 8kWhrs to refine a gallon of gasoline. A Nissan Leaf can go around 30 miles on 8kWhrs. Just the ELECTRICITY used to refine gasoline can more than make up for the load that electric cars will put on the grid.
Reply | Report Abuse | Link to thisHave an EV for your daily commute if it's feasible and keep the ICE car for long trips. You can also rent an ICE car for the 1 or 2 times a year you go to Yellowstone.
Reply | Report Abuse | Link to thisThere are ZERO plug-in cars sitting on dealer lots that aren't demonstrator vehicles. ALL plug-ins up for sale have been spoken for and GM & Nissan can't even keep up with demand. Hopefully, the Mitsubishi iMIEV, Tesla Model S, Ford Focus EV, CODA & others entering the market over the next few years will begin to satisfy some of the pent-up demand for plug-in cars. FYI, the Nissan Leaf is outselling a lot of popular cars like the Infiniti FX and Audi A6:
Reply | Report Abuse | Link to thishttp://green.autoblog.com/2011/10/17/nissan-leaf-outselling-15-plus-vehicles-in-u-s/
Should they stop selling all the cars on the list too? Does that make sense? And if you want to talk about subsidies, what about the 4B / year that goes straight from Gov't hands and into the Oil Companies' bank accounts, or the money we spend defending oil supply lines, or the negative externalities (damages to health and property that fuel emissions cause) that are not accounted for in the price of motor fuel? Add those up and you'll see that $7,500 per Electric Vehicle is a bargain!
Supercapacitors and high capacity batteries sound great. Enough energy to run coast to coast in a cubic foot.
Reply | Report Abuse | Link to thisIs anybody dealing with the issue that energy concentrated that highly makes a weapon?
Whatever happened to hydrogen fuel cell powered cars? Weren't they supposed to be the next big thing?
Reply | Report Abuse | Link to thisWeird. I own a Leaf and plug it in most every night. It takes about 5 or 10 seconds. How can people find that inconvenient? It's about as easy as any imaginable activity and has the advantage of being incredibly satisfying. It charges at night when demand is down but the power companies turbines are still spinning. Has it really come to this? Plugging in a plug is inconvenient?
Reply | Report Abuse | Link to thisIMO:
Reply | Report Abuse | Link to this#1. If it is touted as "the next big thing", it usually isn't.
#2. My guess that the reality of creating a safe infrastructure of hydrogen refueling stations to replace the tens of thousands of corner gas stations crushed it.
#3. Special feature of #2: how would you safely send thousands of shipments H2 via bomb - I mean tanker - through cities? Maybe there are ways but a quick calculation of the potential energy in a tanker sized vehicle filled with H2 ...frightening.
Good point but my guess is that it is not the plug-in at night which is the issue, it's the limited range (real / imagined) of the vehicle on a single charge that they are trying deal with.
Reply | Report Abuse | Link to thisFrankly, I am not a fan because it doesn't fit a lot of of us out here in the West but I can see where urban customers, especially in the densely concentrated East might benefit. I just think that a lot of the "paranoia" of those who are so strongly against EVs is based on being afraid some "Greenie" in NY, NY or DC will decide to do to the gas car what they are doing to the incandescent light bulb - ie. take away the choice. Can't we all just get along? (Rhetorical: Is it paranoia if the threat is real?)
and peeing in the corner if the room, you can do it, but it stinks
Reply | Report Abuse | Link to thisSounds like a great breakthru.... BUT, I have a pace-maker installed. What problems would I have with this new charging methods....
Reply | Report Abuse | Link to thisCan I be close to the charging stations, in the car, etc.???/
Thanks....
An additional caveat: Did you read the pdf on this? There are distance limits, in addition to the losses, even if the magnetic resonance is *more* efficient than normal coupling. But did you also notice that it would induce power, albeit at a much lower percentage, into anything metal? Like the car body (or parts if you have a plastic body), your watch, cell phone, pacemaker (do I recall something about microwave oven warnings????). My glasses would turn me into a hot-head!!! I am sure there would be practical applications, but recharghing everything on the go in public areas wouldn't work. It might work with mag-lev trains so that there would be no power contacts needed, and where the transmitters would be away from the general public.
Reply | Report Abuse | Link to thisAs I have said, It's all a matter of how to use the available energy most efficiently. If we could make a battery that gave a 300 mile range which could be recharged in 5 mins with 90% efficiency the nation would flock to electric cars. But at the moment cars like the Volt can get about 50 miles out of its battery and then has to start up its gas engine to feed the battery. Of course there may be an overall efficiency gain but I doubt that it is much better than the less complicated 'Clean' Diesel which is very popular in Europe.
Reply | Report Abuse | Link to thisBy the way, the 16kwhr battery in the Volt is equivalent to half a gallon of gas which costs 4kwhr to make therefore the Grid has to come up with another 12 kwhr to be equivalent. I don't know how many kwhrs is required to put one kwhr into the Volts battery but I suspect it's at least 1.5
Supercapacitors are fascinating and impractical. They can only store 2.5 KJ of energy per kg. Lithium ion batteries can store 720 KJ per kg.
Reply | Report Abuse | Link to thisI wonder if imbedding permanent magnets in the road surface on hills and induction coils in the car would provide permanent charging of the car batteries but not strong enough to provide too much dynamic braking. Charging capacitors during the induction period and discharging during non induction periods could even out the battery charging. Permanent magnets do not emit oscillating magnet fields, the cause of concern for alot of people.
Reply | Report Abuse | Link to thisascott
The magnet idea would act like regenerative braking. You could convert the potential energy from the hill to electrical energy but this would not be as efficient as using the braking system for the same job.
Reply | Report Abuse | Link to thisIts extremely inefficient and would require vast amounts of unsustainable copper. Think about what you are doing to the environment, people!! Its past time for us to force republican evniro-haters into green and sustainability classes and if they don't pass the exams then they take the class again. Its not enough to just educate the kids with these earth-haters on the loose!!! Should include climate change in the classes too for the unenlightened.
Reply | Report Abuse | Link to thisRunning low on power, pull into a "Battery station" and swap batteries.
Reply | Report Abuse | Link to thisIn order for this to work, we'll need to retro fit Battery producing companies to produce a standard, one size fits all, electric car battery. Global standardisation of battery size and connection is absolutely necessary.
Recycling of Battery parts, to build new ones is a must to curb pollution
Retro fit Gas/ Petrol stations to include Battery Swap. Pull up, swap a battery and move on.
This is an efficient and realistic solution, for the world to adopt now.
Things will use power more efficiently over time.
Pro's
- Easy
- Quick
- Petrol Companies already have 3 Phase power and could charge multiple batteries at once, ready for people to pull up and swap the car battery.
- Allow Petrol Companies to own this process, and we'll move quickly to electricity without the current hinderance on policy changes that effect their core petrol based business
- Battery development will become less pollutant than putting cables and power charging stations in roads, etc.
- The Battery can then be used to hold Hydrogen gels, at a later stage
Cheers
Perhaps it would be just more enviro friendly to shoot all of us "republican enviro-haters" (sorry but I just had to correct your spelling) and grind us up in to Soilent Green. Think how Green that would be! :>)
Reply | Report Abuse | Link to thisLook, why are you here in "Scientific American" if you don't share the scientific concept that honest differences are discussed, in a civil manner, based on rational, fact based discourse rather than personal, ad hominem rants at one another? (....heavy sigh.)
The suggestion that this technology is better suited to urban areas seems backward to me. In a high-use area, the chargers would need to be arrayed in a grid and on almost all the time, which raises challenges for supplying and distributing the power to run them. In a rural setting, where there will presumably be less frequent use, small solar panels could maintain batteries that supply a charger that comes on when a vehicle approaches. In fact, maybe these cars could be designed with a small transmitter that triggers the charger to come on when needed. Rural areas typically have fewer, longer roads, which would make it possible to locate the charger, or a long string of chargers, in fewer areas where the majority of the traffic could be served. Further, rural areas typically have less traffic congestion and, therefore, less incentive for drivers to seek out alternate routes to avoid traffic. Urban areas, on the other hand, would need to have a grid of chargers, some of which would see high use during rush hour and then declining use similar to a rural road during nonrush hours. Lower population density results in more predictable driving patterns, which makes technology such as this easier to implement. To my thinking this concept seems easily adaptable to many rural areas.
Reply | Report Abuse | Link to thisPoint well taken. How does the inconvenience of plugging in compare to the inconvenience of driving to a gas station, completing a financial transaction, and then pumping the gas?
Reply | Report Abuse | Link to thisIf you were refering to my comments on the use of this type of technology (and EV's in general) in urban areas:
Reply | Report Abuse | Link to thisIn Denver, some streets have traffic in the 100,000's / day passing any given point. In our rural areas (with it's thousands of miles of gravel county roads) some have a traffic density of a few per day. I feel that your points are well taken but would be overshadowed by the extremely high cost per vehicle charged to install the infrastructure needed by the technology in this article in rural areas vs. urban.
With regard to EV's in general, there are many here who have to drive 15 miles on county road just to get to the blacktop - then another 20 - 30 to town to pick up 100 lb bags of feed. I was not saying that EV's can't work here but I just don't feel that they are well suited as they exist today. I just hope that the large % of our population which is now urban, doesn't forget the needs of the farmers & ranchers out here in the west and mandate what, for us, are ill suited solutions.
That's a great point - it's a solution to a non-existent problem.
Reply | Report Abuse | Link to this