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#11
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Behold the CityCAT air car, powered by compressed air.
Michael Pardee wrote: > In a time when efficiency is seen as more important than ever, the inherent > inefficiency of compressed air makes this a tough sell. A *non-sell* for general road use. Graham |
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#12
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Behold the CityCAT air car, powered by compressed air.
"Michael Pardee" > wrote in message .. . > > > > > The physics of the technology pretty much cap the energy storage efficiency > at 50% max, and it's going to be hard to break the 35% barrier. The ratio of > specific heats problem (the same thing that makes a basketball "deader" than > a superball) won't go away as long as this universe is in existence. > Adaptive air motors are possible but always tricky. Using only the "top > half" of the pressure charge means hauling around a lot of dead weight. > > Batteries don't have to be bad for the environment at all. The heavy metals > that are most to blame for batteries' bad rep are completely recyclable. The > larger batteries get the less likely they will escape the recycling stream; > even standard car batteries are rarely dumped any more. > > Air powered cars have been around longer than electric cars - there are > reasons they haven't caught on. In a time when efficiency is seen as more > important than ever, the inherent inefficiency of compressed air makes this > a tough sell. > > Mike > > All true, but batteries are every bit as heavy as air tanks, in their current state of development. Air is as good an alternative source of energy as any other, and it's the combination of various technologies that will save us, not one specific one. Air is perfectly clean and endlessly renewable, so efficiency can take a back seat till better options come along. Lord knows it's better than alcohol. It's "alternative thinking" that's important, not necessarily relative efficiency. In other words, don't shoot it down cause it's not perfect. What's most important at this point in time is that it's CLEAN. Unless you're off the grid on solar and wind, electricity is anything BUT clean. |
#13
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Behold the CityCAT air car, powered by compressed air.
"Dan G" > wrote in message
. .. > > > All true, but batteries are every bit as heavy as air tanks, in their > current state of development. Air is as good an alternative source of > energy > as any other, and it's the combination of various technologies that will > save us, not one specific one. Air is perfectly clean and endlessly > renewable, so efficiency can take a back seat till better options come > along. Lord knows it's better than alcohol. It's "alternative thinking" > that's important, not necessarily relative efficiency. In other words, > don't > shoot it down cause it's not perfect. What's most important at this point > in > time is that it's CLEAN. Unless you're off the grid on solar and wind, > electricity is anything BUT clean. > > > Compressed air is only a storage medium, just as batteries, hydrogen or flywheels are. According to the Wikipedia entry on energy density, http://en.wikipedia.org/wiki/Energy_density, it competes poorly in that category. Even excluding the weight of the tanks, just the weight of the air itself, it weighs 2-3 times as much as the equivalent capacity of Li-Ion batteries and has at least 7 times the loss. (The practical recovery efficiency of compressed air is given as 64%, which is the efficiency if the driven device is 100% efficient over the entire range of pressure. This requires the air pressure used not drop much below the 20 bar pressure they cite; darned Second Law of Thermodynamics!) It fares even worse in energy density against compressed hydrogen powering a fuel cell, which offers about 250 times the energy density of compressed air. Mike |
#14
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Behold the CityCAT air car, powered by compressed air.
Michael Pardee said the following on 5/26/2007 8:23 PM:
> "Dan G" > wrote in message > . .. >> >> All true, but batteries are every bit as heavy as air tanks, in their >> current state of development. Air is as good an alternative source of >> energy >> as any other, and it's the combination of various technologies that will >> save us, not one specific one. Air is perfectly clean and endlessly >> renewable, so efficiency can take a back seat till better options come >> along. Lord knows it's better than alcohol. It's "alternative thinking" >> that's important, not necessarily relative efficiency. In other words, >> don't >> shoot it down cause it's not perfect. What's most important at this point >> in >> time is that it's CLEAN. Unless you're off the grid on solar and wind, >> electricity is anything BUT clean. >> >> >> > Compressed air is only a storage medium, just as batteries, hydrogen or > flywheels are. According to the Wikipedia entry on energy density, > http://en.wikipedia.org/wiki/Energy_density, it competes poorly in that > category. Even excluding the weight of the tanks, just the weight of the air > itself, it weighs 2-3 times as much as the equivalent capacity of Li-Ion > batteries and has at least 7 times the loss. (The practical recovery > efficiency of compressed air is given as 64%, which is the efficiency if the > driven device is 100% efficient over the entire range of pressure. This > requires the air pressure used not drop much below the 20 bar pressure they > cite; darned Second Law of Thermodynamics!) It fares even worse in energy > density against compressed hydrogen powering a fuel cell, which offers about > 250 times the energy density of compressed air. > > Mike > > > Entropy just ain't what it used to be. |
#15
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Behold the CityCAT air car, powered by compressed air.
"Don in San Antonio" > wrote in message
... > Entropy just ain't what it used to be. > But we have more of it than ever! |
#16
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Behold the 'Snake oil.'
Back in the day they called the cure-all products, 'Snake oil.' If somebody
could actually come up with an alternated fuel that would not cost any more to produce, deliver, sell, meet all the governmeant regulations as good as crude oil, that was cleaner, they would be doing so. If any manufacture could build a vehicle that would be as powerful, as roomy and salable, meet all the governmeant regulations, that would get 20 miles more per gallon they would be doing so. Nobody could stop them, and in either example they would make that person billions of dollars. mike "Michael Pardee" > wrote in message .. . > "Dan G" > wrote in message > . .. >> >> >> All true, but batteries are every bit as heavy as air tanks, in their >> current state of development. Air is as good an alternative source of >> energy >> as any other, and it's the combination of various technologies that will >> save us, not one specific one. Air is perfectly clean and endlessly >> renewable, so efficiency can take a back seat till better options come >> along. Lord knows it's better than alcohol. It's "alternative thinking" >> that's important, not necessarily relative efficiency. In other words, >> don't >> shoot it down cause it's not perfect. What's most important at this point >> in >> time is that it's CLEAN. Unless you're off the grid on solar and wind, >> electricity is anything BUT clean. >> >> >> > Compressed air is only a storage medium, just as batteries, hydrogen or > flywheels are. According to the Wikipedia entry on energy density, > http://en.wikipedia.org/wiki/Energy_density, it competes poorly in that > category. Even excluding the weight of the tanks, just the weight of the > air itself, it weighs 2-3 times as much as the equivalent capacity of > Li-Ion batteries and has at least 7 times the loss. (The practical > recovery efficiency of compressed air is given as 64%, which is the > efficiency if the driven device is 100% efficient over the entire range of > pressure. This requires the air pressure used not drop much below the 20 > bar pressure they cite; darned Second Law of Thermodynamics!) It fares > even worse in energy density against compressed hydrogen powering a fuel > cell, which offers about 250 times the energy density of compressed air. > > Mike > > |
#17
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Behold the CityCAT air car, powered by compressed air.
Dan G wrote:
> "Michael Pardee" > wrote in message > .. . >>> >> The physics of the technology pretty much cap the energy storage > efficiency >> at 50% max, and it's going to be hard to break the 35% barrier. The ratio > of >> specific heats problem (the same thing that makes a basketball "deader" > than >> a superball) won't go away as long as this universe is in existence. >> Adaptive air motors are possible but always tricky. Using only the "top >> half" of the pressure charge means hauling around a lot of dead weight. >> >> Batteries don't have to be bad for the environment at all. The heavy > metals >> that are most to blame for batteries' bad rep are completely recyclable. > The >> larger batteries get the less likely they will escape the recycling > stream; >> even standard car batteries are rarely dumped any more. >> >> Air powered cars have been around longer than electric cars - there are >> reasons they haven't caught on. In a time when efficiency is seen as more >> important than ever, the inherent inefficiency of compressed air makes > this >> a tough sell. >> >> Mike >> >> > > All true, but batteries are every bit as heavy as air tanks, in their > current state of development. Air tanks are pretty well developed. They are not complicated. They just have a lot of space and a valve. > Air is as good an alternative source of energy > as any other, and it's the combination of various technologies that will > save us, not one specific one. Air is perfectly clean and endlessly > renewable, so efficiency can take a back seat till better options come > along. Lord knows it's better than alcohol. Wrong. Air is not a source of energy. The air has to be compressed. That takes energy, whether it's electricity, gasoline or someone compressing the air with a hand pump. > It's "alternative thinking" > that's important, not necessarily relative efficiency. In other words, don't > shoot it down cause it's not perfect. What's most important at this point in > time is that it's CLEAN. Unless you're off the grid on solar and wind, > electricity is anything BUT clean. yet this is not more than a storage form of electricity. It is really no different than if you charge a battery in the car. Air doesn't compress itself. Jeff |
#18
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Behold the CityCAT air car, powered by compressed air.
Michael Pardee wrote:
> "Dan G" > wrote in message > . .. >> >> All true, but batteries are every bit as heavy as air tanks, in their >> current state of development. Air is as good an alternative source of >> energy >> as any other, and it's the combination of various technologies that will >> save us, not one specific one. Air is perfectly clean and endlessly >> renewable, so efficiency can take a back seat till better options come >> along. Lord knows it's better than alcohol. It's "alternative thinking" >> that's important, not necessarily relative efficiency. In other words, >> don't >> shoot it down cause it's not perfect. What's most important at this point >> in >> time is that it's CLEAN. Unless you're off the grid on solar and wind, >> electricity is anything BUT clean. >> >> >> > Compressed air is only a storage medium, just as batteries, hydrogen or > flywheels are. According to the Wikipedia entry on energy density, > http://en.wikipedia.org/wiki/Energy_density, it competes poorly in that > category. Even excluding the weight of the tanks, just the weight of the air > itself, it weighs 2-3 times as much as the equivalent capacity of Li-Ion > batteries and has at least 7 times the loss. (The practical recovery > efficiency of compressed air is given as 64%, which is the efficiency if the > driven device is 100% efficient over the entire range of pressure. This > requires the air pressure used not drop much below the 20 bar pressure they > cite; darned Second Law of Thermodynamics!) It fares even worse in energy > density against compressed hydrogen powering a fuel cell, which offers about > 250 times the energy density of compressed air. > > Mike I could see compressed air powering lawnmowers, go carts, golf carts, and fork lifts. In theory, you could have quick-connect bottles, making it all practical (the bottles could be refilled by a compressor). That would certainly be cleaner than using small internal combustion engines. Other than those sorts of uses, I don't see many possible markets for compressed air. Jeff |
#19
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Behold the CityCAT air car, powered by compressed air.
As long as they are still viable, it doesn't matter that they're less
efficient than EV's, because the environmental impact is far less than fuel burning cars, and even EV's. I personally think that if it is a viable technology, then it is far more attractive than EV's even if they require more refills. Although EV's are potentially a safer alternative to fuel burning cars they still have a large environmental impact. The problem is that it is far down the road and not as visible to the public. Has anyone ever thought of what kind of negative impact the manufacturing of fuel cells has, or what the impact of disposal will have? What will be done with all the chemicals? I think EV's are a short term solution, but in the long term it's a dangerous technology. "Eeyore" > wrote in message ... > > > Dan G wrote: > >> Nevertheless, this type of thinking is what will save us from fossil >> fuels. > > No it won't. > > They are *less* efficient that EVs, so need MORE energy to keep them > running. > > >> The compressed air cars are doing pretty well, > > Where exactly ? Except in your fantasies ? > > >> and if you use solar power to charge them up, it's free energy. > > Damn you're an ignorant prick of the first order. Use the same cutesy > 'solar > energy' in EVs and you'll easily go *TWICE* as far - probably more since > EVs can > reclaim energy by regenerative braking. > > Graham > |
#20
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Behold the CityCAT air car, powered by compressed air.
"Jeremy" > wrote in message
news:FG37i.237824$aG1.12783@pd7urf3no... > As long as they are still viable, it doesn't matter that they're less > efficient than EV's, because the environmental impact is far less than > fuel burning cars, and even EV's. I personally think that if it is a > viable technology, then it is far more attractive than EV's even if they > require more refills. Although EV's are potentially a safer alternative > to fuel burning cars they still have a large environmental impact. The > problem is that it is far down the road and not as visible to the public. > Has anyone ever thought of what kind of negative impact the manufacturing > of fuel cells has, or what the impact of disposal will have? What will be > done with all the chemicals? I think EV's are a short term solution, but > in the long term it's a dangerous technology. > > I disagree about ignoring the inefficiency. Worse, even a simple requirement like passenger heat is not presently in TheAirCar design. The manufacturer claims TheAirCar is quieter than conventional combustion engines (listen to the low speed demo and you may doubt even that) but admits it lacks the silence of EVs. EVs have so many advantages and are well enough proven that competing technologies can't just say, "We can do half that stuff at half the efficiency!" and expect a following. The manufacturer's promo material shows lift trucks powered by air, but battery powered lift trucks have been popular for many decades. The company doesn't even speculate when production will begin. In the meantime, production EVs have actually been on the road. Compressed air is way too little, too late. Do you have any particular reason for concern about battery disposal (recycling) as currently carried out? In the US we go through roughly a hundred million lead-acid car and truck batteries every year, and those are about as toxic as batteries come. I think if it were a problem we'd be hearing about it. Mike |
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