Yes, but do you think there is likely to be the same level of increase in the next 13 years?
Ususally new technology seems to level off after a while as physical barriers are reached.
Arthur
Electric cars are a pipe dream
- Thread starter Syzygys
- Start date
Yes, but do you think there is likely to be the same level of increase in the next 13 years?
Ususally new technology seems to level off after a while as physical barriers are reached.
Arthur
Yes, something along those lines.
Agreed. But we're not just making those batteries slightly more efficient any more. The old LiCoO2 cathode based batteries were what we got to 2800mah with; they're probably near their max. Nowadays most conversion cars are using LiFePO4 for longevity, with some cars using LiCoNiMn for increased capacity. There's LiNiO2 which is fairly new. They are already close to LiCoO2 in capacity and there's a lot of room for improvement.
Also, as people build more and more capacity, demand for replacement batteries will increase. There's nothing like the potential for making a few billion dollars to spur research into new chemistries, geometries and management systems.
You are surely dead by now, but congratulations DAN: "On July 12, 2011, the Company will host a ceremony to mark the completion and full operation of its first 20-megawatt flywheel energy storage plant in Stephentown, New York. The facility, which provides grid-stabilizing commercial frequency regulation services to the New York State electricity grid, is currently operating at 18 MW and is expected to reach its full 20 MW capacity later this month. " - From: http://phx.corporate-ir.net/phoenix.zhtml?c=123367&p=irol-newsArticle&ID=1569408&highlight=
The Smart Energy 25 flywheel system includes a rotating carbon-fiber composite rim, levitated on hybrid magnetic bearings operating in a near-frictionless vacuum-sealed environment. The rim {light color in above figure's cut away, black at top} itself is fabricated from a patented combination of high-strength, lightweight fiber composites, including graphite and fiberglass combined with resins, which allow the flywheel to rotate at high speeds (16,000 rpm) and store large amounts of energy as compared to flywheels made from metals. To reach its operational speed, the system draws electricity from the grid to power a permanent magnet motor. As the rim spins faster, it stores energy kinetically. The 4th-generation flywheel, the Smart Energy 25, can instantly absorb and inject up to 25 kilowatt-hours of electricity in response to power grid requirements. Our current focus is on grid frequency regulation, whereby flywheels help maintain the necessary balance between energy supply and demand by effectively "recycling" electricity. {BT notes: last two sentences from another beacon power link. Also note: the Leaf EV has 24kwh battery. They are focused there as no other technology can smooth out brief demand changes. Currently a sudden demand is supplied by the generator's "spinning reserve" which drops the frequency from 60 hz}
The flywheel can spin for very extended periods with great efficiency because friction and drag are reduced by the use of magnetic bearings in a vacuum-sealed environment. Because it incurs low friction, little power is required to maintain the flywheel's operating speed.
When a grid operator sends a signal that requests the system to absorb power, the Smart Energy Matrix uses power from the grid to drive the motor/generator, which in turn spins up the flywheel. When a signal is sent for electrical power to be provided, the momentum of the spinning flywheel drives a generator and the kinetic energy is converted into electrical energy for release to the grid. {BT notes: doing this while keeping 60 hz AC output takes considerable electronics, but for use in a bus's DC motor, only a rectifier at any frequency of spin works.}
ADVANTAGES:
• Highly cyclic capability: Smart Energy 25 flywheels are designed for hundreds of thousands of charge-discharge cycles over their 20-year life, making them ideally suited to the frequency regulation function.
• Smart Grid attributes: Smart Energy 25 flywheels and Smart Energy Matrix plants are interactive systems that can be monitored and operated remotely as part of an intelligent grid design.
• 20-year design life: Smart Energy 25 flywheels are designed and built for 20 years of virtually maintenance-free operation.
• Sustainable technology: Smart Energy 25 flywheels are emissions-free, do not require fuel, and contain no hazardous chemical materials, simplifying permitting and avoiding potential ground contamination issues.
From: http://www.beaconpower.com/products/smart-energy-25.asp
They have a brief video, but it took half an hour to download in the background as I did other things, at: http://www.beaconpower.com/products/smart-energy-25.asp
Billy T comments on bus application:This 100kw, 25kwh unit is about 2 meters tall*, so would fit in bus but may be too heavy** as made for very rapid energy transfer. It has a large motor/generator and strong shaft, etc. That can dump all the stored energy in 15 minutes- More than a bus would require as they are sized for 100kw peak power which is 134 hp. Thus, a city bus could have the same energy storage but 3 or 4 times lower peak power*** level with smaller motor/generator, less massive shaft, etc. Also it could be half as tall with hemispheric end plates for the vacuum chamber instead of thick flat plates for at least 50% reduction in mass. and still store more than 10kwh, which with recovery of >90% of the energy now lost in the bus's frequent stops**** would probably let the typical bus run for four hours before needing to connect to any electric power source. Unit recharges while driver eats his lunch from a 25kw source (Your house may have that.)? From same source eight buses could recharge in 8 hour night or 32 busses recharge each night at the depot recharge from 100kw source, which is less than most super market chain stores have.
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* Judging from a photo of man standing next to it. Unfortunately, the exact dimensions and weight I could not find.
** But possibly less than current motor, battery, gears, transmission, cooling and exhaust systems it replaces with two 15hp in-wheel electric motors, which could give 40hp for a few seconds every minute as bus accelerates from a stop.
*** Perhaps more than a 100 fold reduction as their text states: "can instantly absorb and inject up to 25 kilowatt-hours" not take 15 minutes to transfer all the stored energy as I conservatively assumed.
**** Even assuming it did not over heat, catch fire, etc. a Li-ion battery being so frequently cycled to store the and return <90% the kinetic energy of a bus stopping would be dead in 20 weeks instead of lasting more than 20 years.
As I have noted in prior posts, some day when they power cars, you will buy your car without any super flywheel and transfer the one from your old car going to the scrap yard into the new car. Instead of a dozen or more sets of batteries for three successive EVs, you will need three or more cars for your one supper flywheel!
The flywheel can spin for very extended periods with great efficiency because friction and drag are reduced by the use of magnetic bearings in a vacuum-sealed environment. Because it incurs low friction, little power is required to maintain the flywheel's operating speed.
When a grid operator sends a signal that requests the system to absorb power, the Smart Energy Matrix uses power from the grid to drive the motor/generator, which in turn spins up the flywheel. When a signal is sent for electrical power to be provided, the momentum of the spinning flywheel drives a generator and the kinetic energy is converted into electrical energy for release to the grid. {BT notes: doing this while keeping 60 hz AC output takes considerable electronics, but for use in a bus's DC motor, only a rectifier at any frequency of spin works.}
ADVANTAGES:
• Highly cyclic capability: Smart Energy 25 flywheels are designed for hundreds of thousands of charge-discharge cycles over their 20-year life, making them ideally suited to the frequency regulation function.
• Smart Grid attributes: Smart Energy 25 flywheels and Smart Energy Matrix plants are interactive systems that can be monitored and operated remotely as part of an intelligent grid design.
• 20-year design life: Smart Energy 25 flywheels are designed and built for 20 years of virtually maintenance-free operation.
• Sustainable technology: Smart Energy 25 flywheels are emissions-free, do not require fuel, and contain no hazardous chemical materials, simplifying permitting and avoiding potential ground contamination issues.
From: http://www.beaconpower.com/products/smart-energy-25.asp
They have a brief video, but it took half an hour to download in the background as I did other things, at: http://www.beaconpower.com/products/smart-energy-25.asp
Billy T comments on bus application:This 100kw, 25kwh unit is about 2 meters tall*, so would fit in bus but may be too heavy** as made for very rapid energy transfer. It has a large motor/generator and strong shaft, etc. That can dump all the stored energy in 15 minutes- More than a bus would require as they are sized for 100kw peak power which is 134 hp. Thus, a city bus could have the same energy storage but 3 or 4 times lower peak power*** level with smaller motor/generator, less massive shaft, etc. Also it could be half as tall with hemispheric end plates for the vacuum chamber instead of thick flat plates for at least 50% reduction in mass. and still store more than 10kwh, which with recovery of >90% of the energy now lost in the bus's frequent stops**** would probably let the typical bus run for four hours before needing to connect to any electric power source. Unit recharges while driver eats his lunch from a 25kw source (Your house may have that.)? From same source eight buses could recharge in 8 hour night or 32 busses recharge each night at the depot recharge from 100kw source, which is less than most super market chain stores have.
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* Judging from a photo of man standing next to it. Unfortunately, the exact dimensions and weight I could not find.
** But possibly less than current motor, battery, gears, transmission, cooling and exhaust systems it replaces with two 15hp in-wheel electric motors, which could give 40hp for a few seconds every minute as bus accelerates from a stop.
*** Perhaps more than a 100 fold reduction as their text states: "can instantly absorb and inject up to 25 kilowatt-hours" not take 15 minutes to transfer all the stored energy as I conservatively assumed.
**** Even assuming it did not over heat, catch fire, etc. a Li-ion battery being so frequently cycled to store the and return <90% the kinetic energy of a bus stopping would be dead in 20 weeks instead of lasting more than 20 years.
As I have noted in prior posts, some day when they power cars, you will buy your car without any super flywheel and transfer the one from your old car going to the scrap yard into the new car. Instead of a dozen or more sets of batteries for three successive EVs, you will need three or more cars for your one supper flywheel!
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taichitarot
Registered Senior Member
You can't go anywhere. You don't have to & don't want to. You have the World Wide Inter-What at your fingernib.
not sure why you comment, but it is not true if you have a tooth ache, etc. I do agree it would be better to order your groceries, clothes, etc. via internet and have them delivered by a super flywheel powered van than everybody going to the store in their car.
This is an excellent application for flywheels. Weight is a non issue, and a large flywheel, connected as a synchronous motor/generator, is a great frequency stabilizer.
Billy T comments on bus application:This 100kw, 25kwh unit is about 2 meters tall*, so would fit in bus but may be too heavy** as made for very rapid energy transfer. It has a large motor/generator and strong shaft, etc. That can dump all the stored energy in 15 minutes- More than a bus would require as they are sized for 100kw peak power which is 134 hp.[/quote]
A typical Volvo intercity bus has a 360hp (270kW) engine.
Even in the same traffic (stop and go city traffic with frequent stops) a typical hybrid taxi only recovers about 20% of its energy via regen braking.
If a bus takes a peak of 270kW, and averages 1/4 of that (70kW) then he'd have to eat lunch for 3 hours for every hour he drives.
However, some cities (like San Francisco) use catenary power to power their buses. A flywheel would allow short stints away from the catenary power source; this would allow extension of routes with only partial coverage from overhead lines,.
If such things were that easy I would have transferred the engine from my old Datsun 610 (which was fine even after 250,000 miles) to my new car. However, it was a lot easier to buy a new car than to do the work to replace the engine. Same with the wheel bearings, differential, suspension parts etc.
I agree, super flywheel (or electric batteries) are not suitable for intercity bus. I have made it clear in post that I am advocating it only for urban buses. My point is that it frees the bus from trolley lines, so it can go around car wrecks, fire trucks, etc. and still be all electric (in city zero pollution) and batteries cannot efficiently recover braking energy due to the high “over volting” (Recharge terminal voltage much great than open circuit battery voltage) if you did put all of the bus’s kinetic energy into the battery. I.e. say you note:
~80% of the energy is converted into heat if you try to dump rapidly into a battery due to the over voltage required. In contrast, there is very little heat produce by a very rapid transfer of the braking energy into a super flywheel – only a little IR^2 loss in the copper wire of the motor re-spinning the flywheel.
one hour of driving at ave power of 70kW is 70kWh of energy. If three hours were used to put back it back that is ~24kW recharge source assuming about 95% efficiency.
You must still be thinking of the intercity bus as 270kW is 362hp, nearly ten times more than city bus must have if you are willing to let it take two seconds more than typical now for re-acceleration to city traffic traveling speed. Also as bus will be frequent stopping for at least 10 second to take on and discharge passengers, so the generators of the super flywheel can supply (into the non spinning at start or low speed rotation in-wheel bus motors) much more current than it is rated for a couple of seconds and cool later. – I.e. overload it and use generator’s heat capacity. This is not possible if it must climb many block-long steep hills with full passenger load, so I am really speaking of basically level cities, like NYC or any city in a river ancient flood plain, as many are or cities in the flat Midwest of USA. I admit some bus routes may require fuel tanks (ETOH or natural gas, I hope) and IC motors. I am thinking of rated peak power generator of about 30kW (40.2hp) which is occasionally overloaded. (BTW, my first VW only had 36hp and would do 70mph on the level.)
Yes. It is not practical to transfer IC motor to new car as it is attached to a drive shaft, and water radiator, accelerator mechanical linkage, battery cables, heating ducts, fuel line, etc.
In contrast I am speaking of ONLY unplugging a standardized electrical connector. The way I would envision the gimbals is very simple (and might not work).* As is suggested in prior post comment the end caps of the super flywheel vacuum chamber could be hemisphere. The bottom one just sits in a hemispherical cup and when your car goes around a curve with 5 degree of road bank it tilts 5 degrees in that cup. So transfer to new car, if all has been standardized, is unplug the cable, two strong men gab the two handles on the top hemisphere and lift supper flywheel out of old car’s support cup / gimbal cup. (Four men, two on each side of the tilted back unit, is OK if they have not been eating their wheaties.)
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* Will not work if you roll the car over, but that is not advised for other reasons.
BTW, the gimbal cup and bottom hemisphere would have many very small axis-concentric circular ripples so there is no sliding as unit tilts for curves or hills. We don't want sliding friction to wear it out before its fourth car.
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That's entirely dependent upon the battery/motor system. If you tried that with a low rate high ESR battery, and used a over-rev'd brushed DC motor, it would be very inefficient. If you used something like the A123 18700 cells with a vector driven AC motor efficiency would be in the 90's.
And the loss in the switching elements in the inverter driving the flywheel. In general I^2R (not IR^2) losses in motor/generator systems are comparable to the ESR losses in the battery pack.
Are you seriously suggesting that a city bus that is power limited to 36 hp would be drivable on city streets? Bus manufacturers put the smallest engines in buses they can get away with; a 36hp bus would take minutes to get up to speed and could not climb even moderate grades. It would be nearly unusable.
If "occasionally overloaded" means peak powers of around 362hp then I'd agree. However, if you rated both engines similarly (since IC engines are rated for peak power) you'd need similar power in both cases.
Yep. Now imagine adding ten times the drag and twenty times the weight. You'd need ten times the power to drive the same speed and accelerate only half as fast as your VW.
Yes if you have an economically unaffordable number of batteries you can store even rapidly deliver kWh of energy efficiently in them. This is because the energy stored in a unit of time is IxVb were Vb is the open circuit voltage of the battery. The energy sent into the battery (I am always speaking of a unit of time so can drop the time factor on these power levels) is IxVt where Vt is the terminal voltage charging the battery. The fraction of the applied energy that is converted to heat is (Vt -Vb)/ Vt or 1 -(Vb/Vt) so you want little "over voltage" (Vt - Vb). This can always be kept small if the total I is divided among many batteries.
If you are familiar with the charge rate / Capacity C, POV, batteries need to charge at a fraction of C, but lets assume you can repeatedly (bus stops ~1000 times or more per day) charge at C and you stop from 35mph in one second. Assume 100 pasangers of average weight 150lbs and bus weight is at least twice that of the passengers. Then Calculate C.
I am quite sure buying that much C (kWh storage) is not affordable. I.e. with an affordable C you would need to charge at least at 10C or greater and that would destroy the battery. – That was my point. ONLY the super flywheel can absorb and store energy at high C rates without destruction. That is why the super flywheel company made their focus on the frequency regulation market – a job that is impossible for affordable batteries to do, impossible even for a battery bank that cost 10 times more! (My comment on motor in reply to next part of your post.)
BTW, there are 18,700 tiny batteries used in that sports car precisely because they have high surface to volume ratio and can get rid of the thermal heating with rapid stop and regenerative breaking. This approach can avoid destruction of the battery but that thrown away heat makes the regeneration cycle less efficient still than storage in a super flywheel with very little heating.
Thanks for catching my RI^2 typo. I normally write it as R I^2 to reduce confusion of I^2R being read as I^(2R)and this time failed to switch I & R from the typical order most use.
Unlike you, I assumed a Brushless DC system. I.e. the existing super flywheels are AC as they are for AC line frequency application. I am not an expert in this area so a Brushless DC motor may not work well as a generator when reversed. If that is the case there would be inverters. I think a Brush Less DC, BLDC, motor can be as efficient as the vectored AC system and BLDC motor may have better low speed torque, and tolerates overloading better. Here are a few extracts from wiki at: http://en.wikipedia.org/wiki/Brushless_DC_electric_motor
“…The maximum power that can be applied to a BLDC motor is exceptionally high, limited almost exclusively by heat, which can weaken the magnets. .” Recall my comments about greatly overloading them for a few seconds and letting them cool later, especially while bus is stopped and letting riders off and picking up passengers.
“…BLDC motors are often more efficient at converting electricity into mechanical power than brushed DC motors. … AC induction motors require induction of magnetic field in the rotor by the rotating field of the stator; this results in the magnetic and electric fields being out of phase. The phase difference requires greater current and current losses to achieve power. BLDC motors are microprocessor-controlled to keep the stator current in phase with the permanent magnets of the rotor, requiring less current for the same effect and therefore resulting in greater efficiency.…” I might add that there is R I^2 loss in the AC rotor but none in the BLDC’s permanent magnet rotor.
No I said “about 30kW” (40.2hp) and that for a few seconds when first starting to move again after a 10+ second no-power applied bus stop it could be over loaded to be like an 80hp motor as it is thermally limited. I also suggested that one could take a few seconds more to come up to the traffic speed with decreasing to rating power applied. Idea is that it needs relatively little power to roll at steady speed and the overload energy applied is thermally off set, compared to steady rated power level, by the zero thermal heating during the next bus stop’s 10+ seconds. (Again I am assuming city is basically on flat ground.)
There would not be 10times the drag as my 36hp VW traveling at 70mph on a bus going at average speed of 20mph or less with stops and traffic. Yes it would be slower to accerate during the ~80hp overloaded seconds pulling away from the bus stop due to the much greater weight but once up to speed 40hp should be adequate and the extra weight has very little effect – Perhaps slightly more heating of the flexing tires, but the bus has more of them and they are much bigger with higher internal pressure, so perhaps fully loaded bus’s tire heating is not much different from my VW’s tires with each section of the VW's tread flexing more than three as often. (Diameter & speed difference make >3 factor.) Certainly the extra weight is only significant when acceleration (breaking included), not when just rolling along.
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Nissan’s all electric Leaf is pulling ahead GM’s plug-in Volt in 2011’s first half. Sold 3,875 vs. 2,745.
From: http://www.bloomberg.com/news/2011-...d-of-gm-s-volt-in-rechargeable-car-sales.html
From: http://www.bloomberg.com/news/2011-...d-of-gm-s-volt-in-rechargeable-car-sales.html
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Glad you commented. I pasted in the wrong number for Volt. I've now corrected it to 2,745
Boost converter full bridge
Hi , i need to help .
I want to do an dc/dc converter 25-40V to 400V .
I think to use UC3825 to control an full bridge + tansformer 1:20 with e401028 (4/80sp).
I don't have some good result ...
Someone suggest me to use UC3875 .
Can you help ?
Hi , i need to help .
I want to do an dc/dc converter 25-40V to 400V .
I think to use UC3825 to control an full bridge + tansformer 1:20 with e401028 (4/80sp).
I don't have some good result ...
Someone suggest me to use UC3875 .
Can you help ?
Hi , i need to help .
I want to do an dc/dc converter 25-40V to 400V .
I think to use UC3825 to control an full bridge + tansformer 1:20 with e401028 (4/80sp).
I don't have some good result ...
Someone suggest me to use UC3875 .
Can you help ?
cristix
Try the site Endless-sphere for your question,this site deals with all versions
of vehicles that deal in electrical propulsion.Many experienced members at
the forum.Good luck.
http://tinyurl.com/3f8dgec
Electric cars are the most efficient cars on the market, with a storage to wheels efficiency of 85-90%. The problem is solely the batteries; there are no cheap, long range, small and lightweight options available yet.
The UC3875 is a pretty sophisticated controller, intended for a very specific kind of resonant converter. I suspect you'd be happier with a regular flyback converter. Google "flashlamp power supply" - that's a common application for a low voltage (5-12v) to 400 volt supply.