Peak Oil
Donate Bitcoin

Donate Paypal


PeakOil is You

PeakOil is You

The Pressurized Air Car?

Discussions of conventional and alternative energy production technologies.
Post a reply

Re: Compressed air car article - Gizmag

Postby jbeckton » Fri 23 Mar 2007, 08:24:59

$this->bbcode_second_pass_quote('clueless', '')$this->bbcode_second_pass_quote('', 'N')evermind the air car, my point is, and always has been, that if were could develop an infastructure that was dependent on electricity alone, we have a chance to achieve sustainability. Sure there are a lot more pieces to the puzzle.


What you are saying is that we just "Rebuild" what has taken 150 years to build and run it on electricity ?


Most of what we had used 150 years ago runs on electricity anyways, what are you talking about?

Lets just recap some of your posts:

1) A wind farm can’t produce the power of a 3500 rpm turbine.
2) The US dept. of Wind Energy is responsible for the deficit.
3) You are not sure if a nuclear reaction uses air as fuel.
4) Oil and natural gas are not fossil fuels.
5) You believe 33% efficiency is very efficient when carnot is 62%
6) Oil will get cheap post PO effects.
7) Natural gas is a smelly substance found in the earth.

Everyone makes simple mistakes and asks questions about things they don’t understand but for someone working in the energy business you understand incredibly little. You should not use the notion that you hire engineers as any kind of credibility (like you tried to on this thread) in the future because you have absolutely no engineering or power generation knowledge whatsoever.
User avatar
jbeckton
Expert
Expert
 
Posts: 2082
Joined: Fri 05 Jan 2007, 04:00:00
Top

Re: Compressed air car article - Gizmag

Postby kolm » Fri 23 Mar 2007, 08:51:36

$this->bbcode_second_pass_quote('jbeckton', '')$this->bbcode_second_pass_quote('kolm', '
')(a) energies are not all alike,
(b) net energy calculations are not always the only thing that matters,
(c) people won't act 'rational' (maximize energy flow over lifespan of humanity), but what economists call 'rational' (maximize short-time earnings).


Is a wind generated watt different than a coal generated watt as far as the end user is concerned?


The end user will notice the difference on his electricity bill, so yes, they are different for him. For the power generator, they are even more different. The wind generated watthour is generated when the wind blows; the coal generated watthour is generated when the operator wants it to be generated. That is a huge difference in practice. The learning curve on how to deal with this just started; e.g., the theory of pricing intermittend electric power is in its infancy. Power suppliers will learn to deal better with this than today, which will reflect on the bill, but I don't expect miracles.

However, I rather wanted to refer to FF vs. electricity. A heap of coal is something entirely different from a tank of gasoline, which is in turn very different from electric power. They have different applications and values.

If you wanted to maximise the really-long-term energy flow from renewables with FF, it might even make sense to use them for building huge mountains in high-rainfall areas for running water power. Nobody will do this, however, because in a shorter time window the investment would essentially appear as a complete loss.

$this->bbcode_second_pass_quote('', '
')$this->bbcode_second_pass_quote('kolm', '
')The problem is that they are not very reliable. (Ask the danes about it.) People don't want unreliable power supply, so power suppliers need backups, either by call options on power or by back-up plants.

Coal and nuclear provide base load and will for the forseeable future. Wind and solar will supplement.


Well, but you need load balance, and coal and nuclear do not want to be used for load balance. This might be a solvable problem, but the solution does not seem obvious or easy.

$this->bbcode_second_pass_quote('', '
')$this->bbcode_second_pass_quote('kolm', '
')First of all, Parson type steam turbine couples work at about 40%, not 33%, and they are used in the power industry if it pays off economically. In NPP, you usually don't want many things that can jam, because down-time and maintenance costs you dearly, hence you usually accept lower efficiency than theoretically achievable. Second, even 33% is not too far from carnot efficiency, hence I do not understand what you mean by 'not efficient at all'.


Forget Parson. Whats the efficiency of the average steam turbine generator in the US? About 33%.


Well, that could be due to one of three possible causes:

(a) Engineers are stupid idiots in the US.
(b) US Power supply managers do not care about economics of their plants.
(c) This is about the right rate for cost-efficient generation given today's conditions.

Your guess?

$this->bbcode_second_pass_quote('', '
')Not too far off from carnot? Lets see-

TH=1005 degF =813.71K
TL= 95 degF =308.15K


TH is rather 630 K for Boiled Water reactors; in coal plant, you do have 800 Kelvin steam, but the usable range is up to TL = 380 K (steam starts to condense). However, I'm not picky, you can run with those numbers if you like.

$this->bbcode_second_pass_quote('', '
')Yeah, good call 33% is close to 62%


My result is more like 49% carnot, but I'll gladly go with yours:
That's a question of perspective, ain't it? Is 1/2 of the absolute best the universe can offer (no matter what science and technology is used) far off or pretty close? I think it's not that far away; we came from 6% to this with a lot of high-level engineering.

And mind you, the original claim was that NPP/CPP are working with incredibly poor efficiency. I rather think that they are working with amazingly high efficiency, given the challenges involved. You build a better economical plant, you can spit on the 33%.

$this->bbcode_second_pass_quote('', '')$this->bbcode_second_pass_quote('kolm', '')$this->bbcode_second_pass_quote('', '
')Where does nuclear energy suck air out of the atmosphere?

At its ventilation openings. Cool air is used to cool cooling water.


Sure, but where does the steam burn oxygen which was the point I was making?


I did not see that you made this point. This might be my error, but I just saw a question; usually questions are stated because one is interested in the answer.

$this->bbcode_second_pass_quote('', '
')$this->bbcode_second_pass_quote('kolm', '
')$this->bbcode_second_pass_quote('', '
')It uses a nuclear reaction to boil water, the rest is no different from a coal plant.

Hell yes it is. If you have a leakage in the cooling water containment of the coal plant, you can make a guesstimate how long you can run this thing and go on; in the NPP, you have to shut down immediately and file an incident report.

And that happens all the time right?


I know an engineer who rather regularly (every two-three moths) was called into the Coal PP to estimate how many tons of water the newest leakage would lose per second, and if they can run it until 10 pm, when it was cheapest to take it from grid and fix the leakage. This was regular business at a rather high-level and well-maintained Power supplier. So, yes, it happens rather often in a coal plant.

The NPP designs are trying to minimize such coincidences, with consequences for the steam turbine design part.

But of course you're right in stating that the fundamental principle of generation at this point is the same.
User avatar
kolm
Peat
Peat
 
Posts: 80
Joined: Thu 11 May 2006, 03:00:00
Top

Re: Compressed air car article - Gizmag

Postby yesplease » Fri 23 Mar 2007, 09:49:12

$this->bbcode_second_pass_quote('SolarDave', 'W')here is your smiley, and how can you continue to take this vehicle seriously? Do you realize 6 Wh/mile implies THREE DOUBLE-A 2000 mAh NiMH cells, which hold a total of slightly over 6 Wh of energy, would supposedly propel this vehicle for a MILE?

WAKE UP!
Where is your smiley and how can you continue to take those calculations you made based off of another's figures seriously? If a road bicycle uses the same energy with half the aerodynamic friction, and a tenth of the rolling friction, do you really think the air car uses 6wh/mile? More to the point, do you really think the air car only holds 2.5kwh of useful potential energy in it's tank? ;)

From the site. $this->bbcode_second_pass_quote('', ' ') Refilling time obviously depends on the source of electricity used. Here are our initial estimates:

- For CityCAT's :
· 230V : approx 5hrs 30mins
Unless the compressor's only pulling down a few amps, there's probably going to be more than 2.5kwh of energy in that tank.

Going back to the 2.5kwh figure's calculation.$this->bbcode_second_pass_quote('', 'O')K. I found an error in my calculation. The 90 m^3 is probably at STP. So the tank holds 0.3 m^3 at 300 bar.

0.3 m^3 at 300 bar is 9 mega joules. That's 0.07 gallons of gasoline.
$this->bbcode_second_pass_quote('MDI', 'T')hese tanks hold 90 cubic metres of air compressed to 300 bars.
$this->bbcode_second_pass_quote('Wikipedia', 'A') Nm3 is a cubic meter of gas volume at normal, i.e. atmospheric pressure conditions. Thus if 1.0 m3 of ambient air is very slowly compressed into a 5-liter bottle at 200 bar, the potential energy stored is 583 kJ (or 0.16 kWh). A highly efficient air motor could transfer this into kinetic energy if it runs very slowly and manages to expand the air from its initial 200 bar pressure completely down to 1 bar (bottle completely "empty" at ambient pressure). This is practically impossible and if the bottle is emptied down to 10 bar, the energy extractable is about 330 kJ.Somehow, 1 cubic meter of ambient air compressed into a container with a pressure of 200 bar has .16kwh of energy, but 90 cubic meters of ambient air compressed into a container with a pressure of 300 bar only has 2.5kwh of energy? Do you think it's more likely that our back of the envelope calculations were off, or that MDI's calculations were off? I'm betting they're both off, but that ours were off more. :P

WAKE UP!

P.s. I should add, that in light of recent posts, I've decided not to questions other poster's figures unless the post is directed (not politely, in your case) at me. If I'm trying to make a point that's not explicitly dependent on the "correct" figures, I figure there's no need to stir up the pot, especially in light of recent reactions. [smilie=eusa_eh.gif]
Last edited by yesplease on Fri 23 Mar 2007, 11:09:00, edited 1 time in total.
$this->bbcode_second_pass_quote('Professor Membrane', ' ')Not now son, I'm making ... TOAST!
User avatar
yesplease
Intermediate Crude
Intermediate Crude
 
Posts: 3765
Joined: Tue 03 Oct 2006, 03:00:00
Top

Re: Compressed air car article - Gizmag

Postby jbeckton » Fri 23 Mar 2007, 10:31:35

$this->bbcode_second_pass_quote('kolm', '
')Well, but you need load balance, and coal and nuclear do not want to be used for load balance. This might be a solvable problem, but the solution does not seem obvious or easy.


Solar power would be most effective at later afternoon, just as load is peaking. Coal and Nuclear will always be base load.

$this->bbcode_second_pass_quote('kolm', '
')
Well, that could be due to one of three possible causes:

(a) Engineers are stupid idiots in the US.
(b) US Power supply managers do not care about economics of their plants.
(c) This is about the right rate for cost-efficient generation given today's conditions.

Your guess?


I'll do you one better and give you an anwser rather than a guess. Materials and GG's. The cycle efficiency inproves with temp difference, so you must ask why not superheat the water even more to improve the cycle? Materials for containing higher temp and pressure steam cost too much money, and the boiler temperature is directly related the the CO2 production rate. The hotter the boiler the more energy transfered to the steam but at the cost of high CO2 production.

$this->bbcode_second_pass_quote('', '
')Not too far off from carnot? Lets see-

TH=1005 degF =813.71K
TL= 95 degF =308.15K


$this->bbcode_second_pass_quote('kolm', '
')TH is rather 630 K for Boiled Water reactors; in coal plant, you do have 800 Kelvin steam, but the usable range is up to TL = 380 K (steam starts to condense). However, I'm not picky, you can run with those numbers if you like.


Those were the current number for my plant at the time. I just wanted to point out that the cycle is not as efficient as it could be and that it was nowhere near carnot as was claimed.

$this->bbcode_second_pass_quote('kolm', '
')I know an engineer who rather regularly (every two-three moths) was called into the Coal PP to estimate how many tons of water the newest leakage would lose per second, and if they can run it until 10 pm, when it was cheapest to take it from grid and fix the leakage. This was regular business at a rather high-level and well-maintained Power supplier. So, yes, it happens rather often in a coal plant.

Every coal plant in the country has at least 1 leak somewhere all the time. You are refering to high pressure boiler leaks that do not happen every 2-3 months at most plants. Sure you have your older units but thats not common. Most leaks are small leaks that never justify a derate or taking the unit off-line.

My original point was that the principal of the nucler plant is the same as coal, its just the method of boiling the water thats different.
User avatar
jbeckton
Expert
Expert
 
Posts: 2082
Joined: Fri 05 Jan 2007, 04:00:00
Top

Re: Compressed air car article - Gizmag

Postby clueless » Fri 23 Mar 2007, 10:47:57

$this->bbcode_second_pass_quote('', '
')
1) A wind farm can’t produce the power of a 3500 rpm turbine.
2) The US dept. of Wind Energy is responsible for the deficit.
3) You are not sure if a nuclear reaction uses air as fuel.
4) Oil and natural gas are not fossil fuels.
5) You believe 33% efficiency is very efficient when carnot is 62%
6) Oil will get cheap post PO effects.
7) Natural gas is a smelly substance found in the earth.

Everyone makes simple mistakes and asks questions about things they don’t understand but for someone working in the energy business you understand incredibly little. You should not use the notion that you hire engineers as any kind of credibility (like you tried to on this thread) in the future because you have absolutely no engineering or power generation knowledge whatsoever.


You are a mental case pal.

$this->bbcode_second_pass_quote('', '1')) A wind farm can’t produce the power of a 3500 rpm turbine.


No - I said it will not replace a combustion or steam turbnine -How about answering my question that if it is such a viable alternaive why has it never been done ??? Kolm made my point for me but were unable to draw the conclusion -

$this->bbcode_second_pass_quote('', 'T')he end user will notice the difference on his electricity bill, so yes, they are different for him. For the power generator, they are even more different. The wind generated watthour is generated when the wind blows; the coal generated watthour is generated when the operator wants it to be generated. That is a huge difference in practice. The learning curve on how to deal with this just started; e.g., the theory of pricing intermittend electric power is in its infancy. Power suppliers will learn to deal better with this than today, which will reflect on the bill, but I don't expect miracles.




$this->bbcode_second_pass_quote('', '2')) The US dept. of Wind Energy is responsible for the deficit.


Uhh..Huh - Can you read ? I said general govt incompetence, Want to trust the govt to save you ?? Go ahead - Remember Katrina

$this->bbcode_second_pass_quote('', '3')) You are not sure if a nuclear reaction uses air as fuel.
I asked a question - And i didn't ask you, at least I have the humility to ask something I don't know.

$this->bbcode_second_pass_quote('', '4')) Oil and natural gas are not fossil fuels.

I said they have nothing to do with fossils - It is mainly plant matter.

$this->bbcode_second_pass_quote('', '5')) You believe 33% efficiency is very efficient when carnot is 62%

I said nothing of the sort.

$this->bbcode_second_pass_quote('', '6')) Oil will get cheap post PO effects.

Cheap is a realative term - What happens when demand destruction occurs ?? Prices very well could go down, are you also fortune teller and can see the future ?

$this->bbcode_second_pass_quote('', '7')) Natural gas is a smelly substance found in the earth.

I won't bother responding to this...

$this->bbcode_second_pass_quote('', 'E')veryone makes simple mistakes and asks questions about things they don’t understand but for someone working in the energy business you understand incredibly little. You should not use the notion that you hire engineers as any kind of credibility (like you tried to on this thread) in the future because you have absolutely no engineering or power generation knowledge whatsoever

Big shot engineer with an attitude - My claim was (if you have the abilty to read) is that I was watching where the R&D money was being spent and it is going into coal and nuclear. That was my statment nothing more nothing less.

If I am such a threat and obviously incomptent you sure spent a lot of time trying to discredit me. Enjoy your solar panels and windmills ! It will actually be funny to see people who have no sense of reality and who trust in the God of technology to make a go of it !!

JBeckton - You are a GOD !!!! (in your own eyes)


$this->bbcode_second_pass_quote('', 'W')ell, that could be due to one of three possible causes:

(a) Engineers are stupid idiots in the US.
(b) US Power supply managers do not care about economics of their plants.
(c) This is about the right rate for cost-efficient generation given today's conditions.
User avatar
clueless
Heavy Crude
Heavy Crude
 
Posts: 1001
Joined: Tue 13 Sep 2005, 03:00:00
Location: Just the right place
Top

Re: Compressed air car article - Gizmag

Postby Aaron » Fri 23 Mar 2007, 11:09:04

[stream]http://www.peakoil.com/sample/expectresults.wav[/stream]
The problem is, of course, that not only is economics bankrupt, but it has always been nothing more than politics in disguise... economics is a form of brain damage.

Hazel Henderson
User avatar
Aaron
Resting in Peace
 
Posts: 5998
Joined: Thu 15 Apr 2004, 03:00:00
Location: Houston
Top

Re: Compressed air car article - Gizmag

Postby clueless » Fri 23 Mar 2007, 11:14:20

$this->bbcode_second_pass_quote('', 'h')ttp://www.innovative-ehs.com


Nice webiste - That your work ? I thought you were going to kick me off for flaming...
User avatar
clueless
Heavy Crude
Heavy Crude
 
Posts: 1001
Joined: Tue 13 Sep 2005, 03:00:00
Location: Just the right place
Top

Re: Compressed air car article - Gizmag

Postby jbeckton » Fri 23 Mar 2007, 11:14:25

$this->bbcode_second_pass_quote('', ' ')The US dept. of Wind Energy is responsible for the deficit.

$this->bbcode_second_pass_quote('Clueless', '
')Uhh..Huh - Can you read ? I said general govt incompetence, Want to trust the govt to save you ?? Go ahead - Remember Katrina


I can read, I just wanted to verifty that you were are dumb as I thought you were.

Confirmation recieved!
User avatar
jbeckton
Expert
Expert
 
Posts: 2082
Joined: Fri 05 Jan 2007, 04:00:00
Top

Re: Compressed air car article - Gizmag

Postby Aaron » Fri 23 Mar 2007, 11:16:55

$this->bbcode_second_pass_quote('clueless', '')$this->bbcode_second_pass_quote('', 'h')ttp://www.innovative-ehs.com


Nice webiste - That your work ? I thought you were going to kick me off for flaming...


Yeah it is... thanks.

Here's a more recent "Under Construction" effort for my friends at FlexCad.

http://www.flexcad.com/index.php

Kick you?

lol

You're one of the good ones guy.
The problem is, of course, that not only is economics bankrupt, but it has always been nothing more than politics in disguise... economics is a form of brain damage.

Hazel Henderson
User avatar
Aaron
Resting in Peace
 
Posts: 5998
Joined: Thu 15 Apr 2004, 03:00:00
Location: Houston
Top

Re: Compressed air car article - Gizmag

Postby smallpoxgirl » Fri 23 Mar 2007, 14:20:44

$this->bbcode_second_pass_quote('yesplease', ' ')Do you think it's more likely that our back of the envelope calculations were off, or that MDI's calculations were off? I'm betting they're both off, but that ours were off more. :P


Fair enough. How much does energy does MDI say is stored in the tanks? I can't find it on their website.
"We were standing on the edges
Of a thousand burning bridges
Sifting through the ashes every day
What we thought would never end
Now is nothing more than a memory
The way things were before
I lost my way" - OCMS
User avatar
smallpoxgirl
Expert
Expert
 
Posts: 7258
Joined: Mon 08 Nov 2004, 04:00:00
Top

Re: Compressed air car article - Gizmag

Postby yesplease » Fri 23 Mar 2007, 14:51:22

$this->bbcode_second_pass_quote('smallpoxgirl', 'F')air enough. How much does energy does MDI say is stored in the tanks? I can't find it on their website.


I don't think it says, in English anyway. I found this on another forum
$this->bbcode_second_pass_quote('', 'S')omeone raised the question of the true energy cost required to recharge the 200bar tanks in the air car so I did some armchair calculations. According to MDI it takes 5.5 hrs to recharge the tank off a home 230V circuit and they claim a 125 mile range minimum. My experience has shown that these manufacturers overinflate their claims, but if we use their own numbers we get 303 watt/hours per mile.


Which seems pretty reasonable. If we assume 1 cubic meter of ambient air at 200 bar has .16kwh, then 90 cubic meters of ambient air at 300 bar probably has greater than 15kwh of energy. Over 125 miles, this would result in energy use of ~120wh/mile (or ~300wh/mile if including the efficiency (likely ~30-40%) of the small home compressor to relate it to the previous quote).

Considering that a RAV-4 EV uses ~200wh/mile at 45mph, this vehicle using 120wh/mile in much slower urban driving seems reasonable. The advantage of an EV being better energy efficiency, and the advantage of this being no periodic battery replacement. Both are much more energy efficient for most dense urban/city driving compared to almost any ICE powered car. Then again, so is a bike, but I doubt most people would use a bike instead of a car.
$this->bbcode_second_pass_quote('Professor Membrane', ' ')Not now son, I'm making ... TOAST!
User avatar
yesplease
Intermediate Crude
Intermediate Crude
 
Posts: 3765
Joined: Tue 03 Oct 2006, 03:00:00
Top

Re: Compressed air car article - Gizmag

Postby smallpoxgirl » Fri 23 Mar 2007, 19:28:02

$this->bbcode_second_pass_quote('yesplease', 'S')omeone raised the question of the true energy cost required to recharge the 200bar tanks in the air car so I did some armchair calculations. According to MDI it takes 5.5 hrs to recharge the tank off a home 230V circuit and they claim a 125 mile range minimum. My experience has shown that these manufacturers overinflate their claims, but if we use their own numbers we get 303 watt/hours per mile.


This strikes me as a pretty useless calculation. How on earth can you calculate the stored energy based on voltage alone. Without having some estimate of amperage, voltage doesn't help you.

$this->bbcode_second_pass_quote('', 'I')f we assume 1 cubic meter of ambient air at 200 bar has .16kwh, then 90 cubic meters of ambient air at 300 bar probably has greater than 15kwh of energy.


You quoted that smidgen from wikipedia. Can you give us the derivation? Or at least link the rest of the article?

So I found this: link

I thought that potential energy from a compressed gas was calculated as just PV. They say that the formula for air is 110*ln(Pa/Pb)*Nm where Nm is the number of cubic feet of air at STP and the result is in kJ. For 300 bar and 90 m^3, that's 56 megajoules or 15 kWH.

Does that number make you happier? :-D That would jive with your wikipedia numbers. It would also jive pretty well with their quote of a couple of dollars in electricity to fill the tank.
"We were standing on the edges
Of a thousand burning bridges
Sifting through the ashes every day
What we thought would never end
Now is nothing more than a memory
The way things were before
I lost my way" - OCMS
User avatar
smallpoxgirl
Expert
Expert
 
Posts: 7258
Joined: Mon 08 Nov 2004, 04:00:00
Top

Re: Compressed air car article - Gizmag

Postby yesplease » Sat 24 Mar 2007, 00:04:57

$this->bbcode_second_pass_quote('smallpoxgirl', '')$this->bbcode_second_pass_quote('', 'S')omeone raised the question of the true energy cost required to recharge the 200bar tanks in the air car so I did some armchair calculations. According to MDI it takes 5.5 hrs to recharge the tank off a home 230V circuit and they claim a 125 mile range minimum. My experience has shown that these manufacturers overinflate their claims, but if we use their own numbers we get 303 watt/hours per mile.
This strikes me as a pretty useless calculation. How on earth can you calculate the stored energy based on voltage alone. Without having some estimate of amperage, voltage doesn't help you.
It's simple and elegant imo. We're not going to charge it using a couple amps, that would take 4ever. We'll try to get it done quickly. Take a look at your circuit breaker (Or a common circuit breaker?). Factor in a safety margin for a current spike, and a rough guestimation of compressor efficiency. You should see where it came from. ;)

$this->bbcode_second_pass_quote('smallpoxgirl', 'O')r at least link the rest of the article?
I can do you one better. The article I quoted was using a specific case. There's probably a derivation of it out there if you really want that too.

$this->bbcode_second_pass_quote('smallpoxgirl', 'D')oes that number make you happier? :-D That would jive with your wikipedia numbers. It would also jive pretty well with their quote of a couple of dollars in electricity to fill the tank.
Numbers are numbers. Competent use of them is what's really nice. I also suppose I'm not a big fan of using them to further a belief or agenda, they should be able to stand on their own imo. The only problem once we realize that is, where can we find accurate figures, or at least decent approximations. [smilie=icon_thumleft.gif]
$this->bbcode_second_pass_quote('Professor Membrane', ' ')Not now son, I'm making ... TOAST!
User avatar
yesplease
Intermediate Crude
Intermediate Crude
 
Posts: 3765
Joined: Tue 03 Oct 2006, 03:00:00
Top

Re: Compressed air car article - Gizmag

Postby smallpoxgirl » Sat 24 Mar 2007, 01:01:05

$this->bbcode_second_pass_quote('yesplease', 'T')ake a look at your circuit breaker (Or a common circuit breaker?

WTF!?!?! You must be kidding. You can draw anywhere from less than a watt up to maybe 50 kilowatts off a 230v line.

30HP Air Compressor - 230v, 76 amps: link

3/4HP Air Compressor - 230V, 2.5 amps: link
"We were standing on the edges
Of a thousand burning bridges
Sifting through the ashes every day
What we thought would never end
Now is nothing more than a memory
The way things were before
I lost my way" - OCMS
User avatar
smallpoxgirl
Expert
Expert
 
Posts: 7258
Joined: Mon 08 Nov 2004, 04:00:00
Top

Re: Compressed air car article - Gizmag

Postby yesplease » Sat 24 Mar 2007, 08:46:43

$this->bbcode_second_pass_quote('smallpoxgirl', 'W')TF!?!?! You must be kidding. You can draw anywhere from less than a watt up to maybe 50 kilowatts off a 230v line.


Maybe you can, but it seems to be a common current limit imle. For example, the most current I can run here w/o tripping a fuse is 30A, and I'm guessing every house on the block is similar, unless modified. I can buy a 3 phase 240V compressor, but just because it's available doesn't mean I can run it at my home. :lol:
$this->bbcode_second_pass_quote('Professor Membrane', ' ')Not now son, I'm making ... TOAST!
User avatar
yesplease
Intermediate Crude
Intermediate Crude
 
Posts: 3765
Joined: Tue 03 Oct 2006, 03:00:00
Top

Re: Compressed air car article - Gizmag

Postby smallpoxgirl » Sat 24 Mar 2007, 09:49:54

The only thing that CDI says about the compressor is that it runs off 230v. Single phase? Three phase? 2 amps? 70 amps? they don't say. I think you'd probably get an equally accurate estimate of the power usage by averaging the winning numbers in the last power ball lottery as by trying to guess based on how big your breakers are.

If we did take your assumption that it draws 30 A. Lets say 25amps so you're not tripping the breaker every few seconds. They say it takes 5:30 to fill the tank that way. So 25amps x 230 volts X5.5 hours = 38 kwh. Where did you come up with 15 kwh?
"We were standing on the edges
Of a thousand burning bridges
Sifting through the ashes every day
What we thought would never end
Now is nothing more than a memory
The way things were before
I lost my way" - OCMS
User avatar
smallpoxgirl
Expert
Expert
 
Posts: 7258
Joined: Mon 08 Nov 2004, 04:00:00
Top

Re: Compressed air car article - Gizmag

Postby yesplease » Sun 25 Mar 2007, 13:35:12

25A(230V)=5750W, over 5.5 hours is 31.63kwh. The compressor isn't a perfect mechanism, and 50% seems like a nice round number for efficiency. Which results in ~15kwh of potential energy in the tank. Granted, there may be some households w/ 70A (very, very few w/ 3 phase, if any), but I would bet that most have lower breakers. In fact, I would go so far as to say that the common low end garage breaker value is 30A, meaning that when MDI uses the 5.5h value, they're looking at the most common lower value. They also don't have to worry about voltage since it seems that 230V is the standard over there, as opposed to 115V here.
$this->bbcode_second_pass_quote('Wikipedia', 'N')orth American and European power distribution systems also differ in that North American systems tend to have a greater number of low-voltage, step-down transformers located close to customers' premises. For example, in the US a pole-mounted transformer in a suburban setting may supply 1-3 houses, whereas in the UK a typical urban or suburban low-voltage substation might be rated at 2 MW and supply a whole neighbourhood. This is because the higher voltage used in Europe (380 V vs 230 V) may be carried over a greater distance with acceptable power loss. An advantage of the North American setup is that failure or maintenance on a single transformer will only affect a few customers. Advantages of the UK setup are that the transformers may be fewer, larger and more efficient, and due to diversity there need be less spare capacity in the transformers, reducing power wastage.

You can also arrive at the ~15kwh number via 110ln(300). Or include temperature and pressure.
$this->bbcode_second_pass_quote('Professor Membrane', ' ')Not now son, I'm making ... TOAST!
User avatar
yesplease
Intermediate Crude
Intermediate Crude
 
Posts: 3765
Joined: Tue 03 Oct 2006, 03:00:00
Top

Re: Compressed air car article - Gizmag

Postby smallpoxgirl » Sun 25 Mar 2007, 13:53:42

$this->bbcode_second_pass_quote('yesplease', ' ')Granted, there may be some households w/ 70A (very, very few w/ 3 phase, if any), but I would bet that most have lower breakers.


I would way rather rewire my house for three-phase, than to drive around at 12 mph.


$this->bbcode_second_pass_quote('', 'I')n fact, I would go so far as to say that the common low end garage breaker value is 30A, meaning that when MDI uses the 5.5h value, they're looking at the most common lower value. They also don't have to worry about voltage since it seems that 230V is the standard over there, as opposed to 115V here.


Hmm. So even though Europeans use 230v electricity, they still use 30A breakers? You know this or are you just pulling it out of your butt?

I say average the winning powerball numbers. It's just as scientific a methodology, and just as likely to give an accurate results.

BTW, the breakers on my panel all seem to be 20A.
"We were standing on the edges
Of a thousand burning bridges
Sifting through the ashes every day
What we thought would never end
Now is nothing more than a memory
The way things were before
I lost my way" - OCMS
User avatar
smallpoxgirl
Expert
Expert
 
Posts: 7258
Joined: Mon 08 Nov 2004, 04:00:00
Top

Re: Compressed air car article - Gizmag

Postby yesplease » Sun 25 Mar 2007, 14:57:47

$this->bbcode_second_pass_quote('smallpoxgirl', 'I') would way rather rewire my house for three-phase, than to drive around at 12 mph.
If used in the proper context, i.e. dense urban commuting, we would have to drive around at an average of 12mph regardless of what we did it in. But anyhoo... The point of these isn't to hop in and drive a hundred or so miles at 70mph, it's to have lower cost, lower local pollution urban transportation. Gl on "rewiring" your house for three phase, my uncle's pretty handy, and even he said it's not worth it given the cost and complexity. Of course, you can "rewire" your house for three phase (keeping in mind, the power limit via the power company will probably still be the same) or drive around at 12mph if you like. No one here is holding you back. :-D


$this->bbcode_second_pass_quote('smallpoxgirl', 'H')mm. So even though Europeans use 230v electricity, they still use 30A breakers? You know this or are you just pulling it out of your butt?

I say average the winning powerball numbers. It's just as scientific a methodology, and just as likely to give an accurate results.
Lemme put it this way. If MDI uses that figure, there is probably a reason for it. They aren't going to look at the high end case, they're going to look at the likely low end case. Sure, everyone in Europe could use 115V and have 10A breakers, but if that was the case I doubt MDI would've given those figures. I don't have to explicitly know what the average voltage/breaker value is, because they probably do, and their figure is probably based on what the likely power transfer limit in Europe is. All I, and the poster I quoted earlier, have to do is go backwards using reasonable figures. If you consider powerball numbers to be reasonable figures, feel free to use them. But I would advise against "rewiring" your house for three phase if this is the case, you may not get an accurate results. :P

$this->bbcode_second_pass_quote('smallpoxgirl', 'B')TW, the breakers on my panel all seem to be 20A.
What's the voltage? ;)
$this->bbcode_second_pass_quote('Professor Membrane', ' ')Not now son, I'm making ... TOAST!
User avatar
yesplease
Intermediate Crude
Intermediate Crude
 
Posts: 3765
Joined: Tue 03 Oct 2006, 03:00:00
Top

Re: Compressed air car article - Gizmag

Postby smallpoxgirl » Sun 25 Mar 2007, 15:48:18

$this->bbcode_second_pass_quote('yesplease', 'I')f MDI uses that figure, there is probably a reason for it. They aren't going to look at the high end case, they're going to look at the likely low end case. Sure, everyone in Europe could use 115V and have 10A breakers, but if that was the case I doubt MDI would've given those figures.


Where did they give those numbers? They gave voltage. They gave time. I haven't found amperage anywhere on their site. That's a problem since energy=volts*amps*time

$this->bbcode_second_pass_quote('', '')$this->bbcode_second_pass_quote('smallpoxgirl', 'B')TW, the breakers on my panel all seem to be 20A.
What's the voltage? ;)


120V.

Guess the aircar's only going to go 3mph at my house.
"We were standing on the edges
Of a thousand burning bridges
Sifting through the ashes every day
What we thought would never end
Now is nothing more than a memory
The way things were before
I lost my way" - OCMS
User avatar
smallpoxgirl
Expert
Expert
 
Posts: 7258
Joined: Mon 08 Nov 2004, 04:00:00
Top
PreviousNext
Post a reply

Return to Energy Technology

Who is online

Users browsing this forum: No registered users and 1 guest



cron