14 Apr 12
Originally posted by KazetNagorraHi speed recharging would be wonderful for electric cars. The main problem there is that getting that much power into a car in a few minutes would require large cables not just quick batteries.
For certain high-performance applications, perhaps. It doesn't seem like there would be much of a cost advantage over ordinary batteries, although that might come over time.
The other factor is the material. Almost all current electric car batteries are heavy and use rare materials - this one uses carbon.
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15 Apr 12
1 edit
Originally posted by twhiteheadThe main problem with trying to charge electric cars fast from an electricity supply point of view
Hi speed recharging would be wonderful for electric cars. The main problem there is that getting that much power into a car in a few minutes would require large cables not just quick batteries.
The other factor is the material. Almost all current electric car batteries are heavy and use rare materials - this one uses carbon.
is that the grid is not designed to take the kind of load millions of fast charging cars would generate.
Actually the grid as it stands couldn't take the energy demands of everyone driving electric cars even
if they charged slowly.
But charging rapidly would make load balancing the grid that much harder.
One solution might be for charging points to slowly build up a stored charge (either in these capacitors or
by doing something like converting water to hydrogen for chemical energy storage) from the grid and then
release that charge rapidly when you park your car to charge up.
That way the grid gets an even predictable load, and you don't need to upgrade the mains electricity cables
to everyone's homes, but you can still charge the car quickly.
EDIT: I would add though that if these can be mass produced and work as described then they wouldn't just
be used in high end specialist products.
They would be used in almost everything we currently stick a battery in.
And more besides, being flexible they would be utilised in the flexible computers/displays currently under
development.
Built into smart clothing and animated cereal boxes.
15 Apr 12
1 edit
note that, if such a thing was developed, a reasonably cheap ultracap ( “ultracap” is short for ultracapacitor which just means supercapacitor ) with high energy density ( although it is really more the specific energy that counts in most situations ) not only would have the advantage over a battery of having higher power input and output but also would be temperature insensitive compared to a battery ( if the battery electrolyte gets too cold or, worse, freezes, it stops working properly ) and also would have unlimited shelf life whether charged up or not ( unlike many batteries ) and should also avoid having to use relatively rare chemical elements such as lithium as well as avoiding toxic elements such as lead and also should charge and discharge with near 100% energy efficiency which would be a level of efficiency unattainable for batteries!
All in all that is a very impressive list of potential advantages! -now if we just figure out how to make the specific energy of a cheap ultracap about the same as for the best lithium batteries....
15 Apr 12
1 edit
Originally posted by twhiteheadIt would take more than just thick cables. Look at the numbers: Suppose you have a battery rated 10 kwhr. So if you feed it one kw it takes 10 hours to charge. You feed it 10 kw it takes 1 hour to charge. So far so good. Suppose now you want to charge it in say 5 minutes, that is 1/12th the time.
Hi speed recharging would be wonderful for electric cars. The main problem there is that getting that much power into a car in a few minutes would require large cables not just quick batteries.
The other factor is the material. Almost all current electric car batteries are heavy and use rare materials - this one uses carbon.
That means for that 1/12th of time you need to have a feed capable of 12 times the energy again, or now it's up to 120 KW. If you were using 120 volts that would require a feed capable of 1000 amperes. 240 volts and half that, 500 amps.
But that's not the end. The power supply capable of delivering that much energy has to come from the mains and now you need a small substation to supply that much energy.
Or you have a power supply that runs on a smaller amount of energy 24/7, and it stored up 10 Kwhr of energy and can give it up faster, say again in 5 minutes. It would take a supercapacitor station to provide that much energy that quickly.
But that is just for one car. You would not have that kind of electronics in your house, it would take up most of the space of a garage, so it would be limited to a charging station. The only problem there is what I described was for one car. Suppose you have 10,000 cars that need that much energy?
One car using a 10 kwhr battery coming from mains at a lower rate 24/7 would require a constant drain of 416 watts 24/7 to give one charge per day of 10 kwhr to a battery. So if you had 10,000 cars and they all worked the same, now you need a substantial power unit capable of over 4 megawatts going 24/7.
4,000,000 + watts 24/7. That is 100 megawatt hours per day or 36 gigawatt hours of energy per year. And that is for only 10,000 cars. To get rid of fossil fuels you have to do that for literally millions of cars. So where will that kind of energy come from? Dedicated nuke plants? Solar plants covering a hundred square kilometers? Where?
15 Apr 12
1 edit
Originally posted by sonhouse“...One car using a 10 kwhr battery coming from mains at a lower rate 24/7 would require a constant drain of 416 watts 24/7 to give one charge per day of 10 kwhr to a battery.
It would take more than just thick cables. Look at the numbers: Suppose you have a battery rated 10 kwhr. So if you feed it one kw it takes 10 hours to charge. You feed it 10 kw it takes 1 hour to charge. So far so good. Suppose now you want to charge it in say 5 minutes, that is 1/12th the time.
That means for that 1/12th of time you need to have a feed gy come from? Dedicated nuke plants? Solar plants covering a hundred square kilometers? Where?
….
…
...Solar plants covering a hundred square kilometers? Where? ...”
what about solar panels on every roof top of every house and garage and virtually every building ( and the sides of the taller buildings esp the south side -can ignore the north side ) ?
Assuming you use solar panels that are 17% energy efficient ( some are currently that efficient and the efficiency is expected to increase to about 25% in five years time according to some ) and taking into account the fact that the solar radiation reaching the Earth’s surface is on average 198 W/m2, assuming my calculations are correct, you would need about: 416W/m2 / ( 0.17*198W ) = ~12m2 i.e. about 12 square meters of solar panels or 3 by 4 meters to run one car 24/7. The roof area of my small modest house would more than cover that.
16 Apr 12
Originally posted by sonhouseWhere the energy comes from is a different topic altogether. This thread is mostly about the difference between types of batteries. So lets assume power stations are readily available. How does a company like Google that have a fleet of all electric cars currently handle the load? Would faster charging affect them negatively?
4,000,000 + watts 24/7. That is 100 megawatt hours per day or 36 gigawatt hours of energy per year. And that is for only 10,000 cars. To get rid of fossil fuels you have to do that for literally millions of cars. So where will that kind of energy come from? Dedicated nuke plants? Solar plants covering a hundred square kilometers? Where?
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16 Apr 12
Originally posted by twhiteheadParticularly as in this instance the 'batteries' would last much longer than present day batteries do.
I can see enormous benefits to faster charging even for other applications. Most people would love to be able to charge their phones/ laptops/ cameras faster - and would probably happily pay twice the price or more for their batteries.
18 Apr 12
Originally posted by humyOne fly in your oinkment is the fact the sun is only maxed out about 1/3 of the day so you need first, 3 times the area you thought you did and second you have to have a way of storing all that energy overnight so now you need batteries at your house of whatever variety you can afford. But you would probably need an ultracapacitor bank to store that energy so you could discharge it in 5 minutes like our goal. So you still have plenty of engineering and financial problems to overcome to get a system like that running. For instance, getting solar cells down to ten cents US a watt would be one great goal. Now it is more like 1 dollar at best.
“...One car using a 10 kwhr battery coming from mains at a lower rate 24/7 would require a constant drain of 416 watts 24/7 to give one charge per day of 10 kwhr to a battery.
….
…
...Solar plants covering a hundred square kilometers? Where? ...”
what about solar panels on every roof top of every house and garage and virtually every building ( and the si ...[text shortened]... 4 meters to run one car 24/7. The roof area of my small modest house would more than cover that.
18 Apr 12
2 edits
Originally posted by sonhouse“...One fly in your oinkment is the fact the sun is only maxed out about 1/3 of the day ...”
One fly in your oinkment is the fact the sun is only maxed out about 1/3 of the day so you need first, 3 times the area you thought you did and second you have to have a way of storing all that energy overnight so now you need batteries at your house of whatever variety you can afford. But you would probably need an ultracapacitor bank to store that energy ...[text shortened]... cells down to ten cents US a watt would be one great goal. Now it is more like 1 dollar at best.
I don't think so. The statistic I got from the net from http://home.iprimus.com.au/nielsens/solrad.html basically said:
“...the solar radiation reaching the Earth’s surface is on AVERAGE 198 W/m2, ...” (my quote and emphasis)
( it actually said "...The radiation reaching the Earth's surface is therefore on average 198 W/m2, i.e. 58% of the radiation intercepted by the Earth...." )
unless I am missing something here, the operative word here is “AVERAGE” which I take as meaning over the 24 hour period that includes the darkness of night and also when the sun is set low in the sky so doesn't that implicitly takes full account of the fact that “ the sun is only maxed out about 1/3 of the day” ?
Unless that statistic was referring to the solar radiation reaching the Earth’s surface during the daytime only? -You suddenly make be not too sure so I want either conformation or refutation of this.
18 Apr 12
Originally posted by twhiteheadI assume we are talking about producing enough power to give one electric car one full charge of 10 kwhr into its battery/ultracap. But I do not know how many km that could realistically make it run for.
So are we talking about producing enough power to drive 24 hours a day, or enough to give one car one full charge (about 300km)?
I got the “416 watts” figure from sonhouse and just trusted that figure to be correct.
But I decided to do some checking:
1 kwhr = 3600 kJ
so 10 kwhr is 36000 kJ which is what is required to fully charge a 10 kwhr battery/ultracap.
The solar radiation reaching the Earth’s surface is on average 198 W/m2 ( I am assuming here that figure is for the 24 hour period but I would like conformation of this )
so, assuming a solar panel has an efficiency of 17%, the amount of energy generated by one square solar panel ( if approximately laid horizontal ) would be about:
0.17 efficiency * 198 W/m2 * 60 * 60 * 24 = 2908224 joules
which is about 2908 kJ . Lets call that 2900 kJ
then that would mean I would need about 36000 kJ / 2900 kJ = 12.4 square meters of solar panel on the roof to charge one 10 kwhr battery/ultracap just once each 24 hour period.
( note that I have well over 12.4 square meters of roof space on my smallish house )
19 Apr 12
Originally posted by humyThat is what I mean, the sun is too low in the sky to do much power collecting in the morning and twilight hours so you get from say 9 am to 4 pm ish to gather the most power. So that combined with the fact you can't get ANY power after sundown unless you can convert the ten percent of solar energy in the form of neutrino's which isn't happening any time in THIS century, you have at most 50% of the day to collect power and the most efficient light gathering time will be less than 50% because of low in the sky sun, which will lose you at least another 15% so you are now down to about 35%, close enough to one third. Which means if you need 2000 watts 24/7 for whatever, you better have 6000 watts of solar so you get 2000 watt/days over that 24 hour period.
“...One fly in your oinkment is the fact the sun is only maxed out about 1/3 of the day ...”
I don't think so. The statistic I got from the net from http://home.iprimus.com.au/nielsens/solrad.html basically said:
“...the solar radiation reaching the Earth’s surface is on AVERAGE 198 W/m2, ...” (my quote and emphasis)
( it actually said "...The radiatio ...[text shortened]... ly? -You suddenly make be not too sure so I want either conformation or refutation of this.
Stick those same cells up in geosynchronous orbit and now you are talking more like 99% sunlit time and full 1030 odd watts per square meter of collection potential, I hear noises like maybe 40% cells are coming around in the next few years so that would be about 600 watts per square meter collected, of course then you have the shipping problem, getting that energy to earth.....
So on Earth you have about 1000 watts per square meter hitting the TOP of the atmosphere, and you have to lose at least half of that maybe 2/3 so that leaves you with only 3 or 400 watts collectible per square meter, and even with 40% cells you are now at 160 ish watts per square meter out the door. So 20 square meters for 3200 watts, then divide that by 3, now you are down to about 1000 watt days collected for 24/7 use with about 20 square meters of cells. Even if you had 100% cells you would only get 8000 watts from that same 20 square meters, divide that by 3, you get 2600 watts for 24/7 use, which isn't also going to happen THIS century. So to power a house which takes 2kw 24/7 means you need about 40 square meters of cells and the ability to store the energy generated by the cells to make use of it 24/7. Not that that could not be done, it is just very expensive at this stage of the game both for PV cells and for storage.