PORTLAND, Ore. -- A new type of electric power storage unit that combines the best of supercapacitors and lithium ion batteries, combined with thermoelectric charging from heat of engines, could be the ideal power source for future vehicles -- from cars to industrial trucks to military convoys, according to Peter Harrop, chairman of IDTechEx Ltd. in Cambridge, United Kingdom.
"Supercabatteries have battery and supercapacitor properties, usually intermediate between the two. While there are lead-acid- and nickel-battery-based versions, the main attention is on ones with a lithium-ion battery electrode and a supercapacitor electrode," Harrop told EE Times. "These asymmetric electrochemical double layer capacitors (EDLC) are otherwise known as lithium-ion capacitors. They are a promising option for replacing lithium-ion batteries and supercapacitors in automotive applications because they have faster charge and discharge and some other superior properties."
A supercabattery combines one electrode of a batteries with the other from a supercapacitor, also called 'hybrid capacitors' the double layer is the best of both worlds.
Superabatteries are gaining traction at future-looking automobile makers world wide, according to Harrop, including BMW, Ford, Komatsu and AIST-The Japanese Government Research Center.
Thermoelectrics, which recover energy that would otherwise be lost to heat generation, will also become commonplace in the cars, trucks and convoys of the future, according to Harrop, as well as in many other applications.
Thermoelectric materials can recover heat energy from the exhaust and motors to recharge the supercabatteries.
"Thermoelectric devices will be a separate market over 1 billion dollars in 2025 including automotive," Harrop told us.
Until now there have been very few themoelectric sucess successs stories except for novelty items. EnOcean Alliance, for instance, uses thermoelectric devices attached to radiators to generate tiny UHF pulses to operate wireless building controls and Schneider Electric uses them to power wireless sensors that trigger responses to heat overloads on copper busbars.
But so far thermoelectrics have been a failure in cars -- for instance, after 20 years of research BMW was only able to achieve about one tenth of the theoretical maximum -- about 3 percent, according to Harrop. But in 2014 the Japanese maker of giant construction vehicles, Komatsu KELK, was able to prove that 1.5KW could be recovered with thermoelectric innovations that doubled their efficiency to 7.5 percent. IDTechExj predicts that thermoelectric energy harvesting will become commonplace on commercial busses and hybrid cars by 2018. The largest vehicles will take advantage of the technology first, because they generate enough heat to make thermoelectrics useful.
But by 2020 supercabatteries will become commonplace on nearly all hybrid electric vehicles, according to IDTechEx, with the thermoelectric energy harvesters extending their range, thereby enabling smaller supercabatteries to be used. For instance, the U.S. Military predicts a 70 percent reduction in fuel consumption as a result by 2020. And by 2025 IDTechEx predicts 9 million hybrid electric cars will use thermoelectrics and by 2030 hybrids will continue to outsell pure electric vehicles simply because they do not produce enough heat to take advantage of the advanced thermoelectric materials available by then.
Conventional gas powered cars, which will still be outselling hybrids and pure electrics in 2030, will also be taking advantage of thermoelectrics to power the heater, ventilation motors and other electric-powered accessories in even convention gas guzzlers.
(Video, above) Summary of electric vehicles of the future as chairman of IDTechEx Peter Harrop. (Source: IDTechEx)
— R. Colin Johnson, Advanced Technology Editor, EE Times
IJD: Thanks for sharing your deep knowledge of flywheels and how they are only economical for busses that start-stop alot. I can see the wisdom of your argument, and I guess others can too, because others too predict that busses will be first, they just never told me why before! Thanks for clearing that up.
With flywheels inside the wheels you might have a bit of a problem turning -- have you ever played with a gyroscope?
To avoid gyroscopic effect in cars they need to be mounted with their axis vertical -- and even then may need to be gimbal-mounted to avoid problems if the car tilts left/right or goes up/down a hill. Add this to the cost of vacuum-sealing, magnetic bearings, power transfer and the economics make little sense.
And the energy density of flywheels isn't as high as lithium batteries by the time you've made them out of expensive materials and built a strong (heavy!) enough case to keep all the bits in if they break.
The only real use -- and even then it's marginal because of the cost -- is in vehicles which do a *lot* of rapid start/stop driving like buses, because unlike batteries the cycle lifetime is pretty much infinite and they store a lot more energy than supercapacitors and can get it in and out quickly.
Les_Slater 2/1/2015 11:28:16 AM: The mechanical engineers of today are already designing new flywheel designs, with miniscule friction and less spin-up drag. They may someday be able to put them in the wheels themselves to drastically reduce operating cost of any vehicle switching to "green wheels"!
hm_:After thinking about it, I agree with both your points. First of all flywheels are definitely the greenest solution, and secondly they may be old-school to old-timers, but all the marketing department has to do is rename them something comtemporary like "green energy spinner" or something hip :)
_hm, as far as I can tell the flywheel is being considered as a higher energy density alternative to the battery, current technology is nowhere near approaching chemically stored energy such as in hydrocarbon fuels and their relatively close alternatives.
Not sure how nanotechnology might effect energy density. We can reduce required mass by increasing rotational velocity but still leaves the problem of coupling the energy to and from such a flywheel.
Lithium batteries are being used for all electric vehicles presently. Some examples of such have quite spectacular power at their disposal and some even quite usable range, but not both at the same time. It is possible that flywheel could provide a decent measure of both.
@R_Colin_Jhonson: Yes, I know it is so called old school. But in hindsight, there is nonesuch as old school!. Also, flywheel may be greenest of all. What I was suggesting is that with new nano materials and other new technologies, this simple concept can again be revisited.
The crankshaft has many limitations and problems, the chief among them is the fixed geometric relationship between angular position of the crank and the linear position of the piston within the cylinder. This translates, within engine displacement and weight constraints, to a very large mismatch between combustion energy and shaft output energy, whether that be used directly for propulsion or storage of any sort.
_hm: Yes, there is a lot of talk about flywheels--that's an old school solution. My first job (while still in high school) was a paper bag factory for Purina Chow--did you know there is such a thing as Rat Chow? Anyway, I digress, every machine in that old factory had a flywheel on it that turned sometimes as much as an hour after it was shut down. A lot of energy can be stored in flywheels for stamp dies and such. Its a good solution for cars, but so old-school that people don't want to use them. Thanks for the blast from the past, even though its a good solution even today.
Les_Slater: Yes you are right about the total lifetime energy savings. Also these thermoelectric materials are getting cheaper and cheaper and at the same time more and more efficient. It may soon be a no-brainer to recapture heat energy and turn it into electricity. With approximately one billion cars on the street to day and the two billion mark coming before the end of the decade, it may even contribute to cooling the planet or at least crowded metropolitan areas like New York City.