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Car Of The Future

I actually saw that on a show on the discovery channel called future car, it's an interesting idea, but I doubt it's safety since it's built out of light weight materials so that the weak motor can power it. Also, in order to make it viable it will have to have some type of compressor on the car to refill it's self, otherwise you will only get a very short distance out of the car, and not much speed.
 
The whole idea is completely fucking stupid, and the hype is totally misleading. It is not, in any way, zero emissions. How do you think they compress the air? With a gas or electric powered air compressor. It uses just as much energy, and creates just as much pollution as any other car. Air is just a storage medium, like batteries or fuel tanks. It is not an energy source, because you can't mine compressed air out of the ground. Air, in general, is a very inefficient energy storage medium due to all the heat created when it's compressed. (much of the energy is completely wasted) Much like laser discs, this technology will be totally forgotten before it has a chance to catch on.
 
I agree with Noelie. Windmills are only green when they are correctly sited. I used to install them and we used to do a years data logging of a site to get data to decide if a site would be economically viable, it could also be used to see if it was ecologically viable, the two are not the same!

If you can use the heat generated in the compression of the air to serve a useful purpose if only to heat your local swimming pool, or your home then it is not wasted. If the source of the power to drive the compressor is from a carbon neutral or carbon negative source then you have managed to turn green.

If you can make the car light weight and include braking regeneration you reduce your power input requirement still more.

The engine in the original thread uses the multiple expansion system to get the most out of the compressed air, a technology that revolutionised the steam engine and is used in all base load power stations to this day.

It would be a great mistake to close our minds to the energy efficiency that modern technology can bring and we should remember and make use of the discoveries of the past when energy was a scarce resource and we were striving for efficiency. Back then it was scarce because it was hard to find and hard to transport. Now it is hard to find because we have used it all up with no thought to the environment that the releasing millions of years of laid down, sun fueled, carbon reserves will have in the 200 years we have released the majority of it in.
 
noelie said:
How can three minutes of electricity to fill the tanks with compressed air and driving it for 400km on that tank of air use as much energy and cause as much pollution compared to a petrol engine?
Click to expand...

Physics is physics. It takes the same amount of energy to move that car from one place to another as any other type of car that weighs the same and has the same aerodynamics. It takes more energy to fill those tanks as it does to charge an electric car to drive the same distance. And that electricity was likely generated from a coal or natural gas power plant. So you're losing energy converting from fossil fuel to electricity, then you lose even more when you convert the electricity into compressed air. It is NOT emissions free. It is NOT more efficient than anything we currently have available. Air is a terrible way to store energy.

Yes, it is more efficent than an old car with a big gas engine. So is any new car with a modern gas engine. And hybrids. And electrics. And hydrogen. This technology is worthless, it was outdated before they started working on it.
 
Oh dear I am obviously posting in an invisible font so I am the firstmonkey! I will try to evolve!
 
You guys are completely missing the point. This car is NOT the car of the future. It does not solve any problems. The fact that the emissions don't come directly out of the ass of the car is just stupid semantics. Emissions are created for every single mile you drive, whether they come out of the car or somewhere else is completely irrelivant.

There are two reasons we are developing new propulsion technology.
1. Pollution
2. We are running out of energy

This car solves neither of those problems. It uses the same energy sources we are running out of today. It pollutes. It's also impractical to drive.

Electric, hybrid, and hydrogen cars have all already been invented. They are all much more practical. This car is basically the same as an electric car - it takes one energy source, stores it, and then reproduces the energy without pollution. The difference is, electric motors are nearly 100% efficient, air motors are not. Also, much of the energy is wasted when compressing the air, as opposed to charging a battery. But still, electric cars don't solve any problems either, because you still have to charge them, and that still creates pollution.

The "car of the future" is hydrogen powered. Unlike air, or batteries, hydrogen is actually a fuel, not just a storage medium. Hydrogen cars actually do produce emissions free electricity, which is used to power the car. The only problem is there are no hydrogen fillup stations, and hydrogen cars currently cost several million dollars.

Anything a compressed air powered car can do, an electric car can already do better. And electric cars are quickly becoming obsolete too. Electric cars have been around since the 70s, notice they haven't caught on yet?
 
So where do you get your hydrogen from? It is so reactive that it always combines and needs energy to separate it?
 
noelie said:
You know - I knew a bit about hydrogen and electric cars already but less than an hour of research on the web into compressed air and I'm able to knock back all your points
Click to expand...

No, you most certainly haven't. You haven't "knocked back" a single thing I said. The fact remains, air is not energy, and there are already several more efficent ways to store energy. This car means absolutely nothing. It will never catch on, I guarantee it. And no, you can't buy one right now for 15 grand. :rolleyes:

I have more important things to do than argue with someone who is clueless.
 
It's a pile of Bull Shit.

I don't know which version of thermodynamics those folks used in the development of this thing. One of the first things you learn in thermo is that you DO NOT want to do work (compressing a gas) on a compressible fluid and use it as an energy source (power source, maybe). A huge amount of the work that goes into compressing a gas is lost as heat, as the increased pressure and the ideal gas law cause the temperature of the gas to rise. Anyone have an air compressor? What happens when you turn it on and the tank gets filled? The compressor gets hot. Very hot.

As for the weird connecting rod design...exactly how long will this engine last? And how much will it cost? There really isn't reason to have the piston at TDC for that long. That little trick will not solve the burning time loss. Believe it or not, the flame does not advance across the cylinder "instantly". It actually takes between 30 and 60 crank angle degrees from the start to end of combustion. The burning time loss is responsible for a whopping 6% of the 15%age points that separate the real engine from its theoretical maximum described below.

As my IC Engines professor, David Kittelson says, hydrogen...the fuel of the future, and always will be.

Like it or not, we're going to be stuck with the IC Engine (Both spark ignition and diesel) for a long, long, long, long, long, long time. The reliability and cost advantages of the IC engine are impossible to beat.

The current state of the IC engine is such that its efficiency is about 85% of what it could thermodynamically be from the fuel-air cycle. Getting the last 15% is going to be impossible. The losses just can't be eliminated.

Our best bet? Diesels running on dimethyl ether, made from paper mill by-products.
 
noelie said:
A hydrogen vehicle is a vehicle, such as an automobile or aircraft, which uses hydrogen as its primary source of power for locomotion. These vehicles generally use the hydrogen in one of two methods: combustion or fuel-cell conversion:

* In combustion, the hydrogen is "burned" in engines in fundamentally the same method as traditional gasoline cars.
* In fuel-cell conversion, the hydrogen is turned into electricity through fuel cells which then power electric motors.

Hydrogen does not come as a pre-existing source of energy like fossil fuels, but a carrier, much like a battery.
Click to expand...

Ummm....it's not quite that simple...

Yes, a standard spark-ignition engine can burn hydrogen, if it's also getting a touch of gasoline to ignite the mixture. But...there's a big catch with burning hydrogen. With fluid fuels (gasoline, diesel...), the volume of the fuel itself going into the engine is negligible--basically all of the cylinder volume can be filled with fresh air. But with hydrogen, the fuel is a gas that takes up volume just as the fresh air does. SO for the same size engine, you get about 50-75% of the power with burning hydrogen as you do when you burn gasoline, despite hydrogen having 3x the fuel energy of gasoline.

Fuel cells...There's a long, long, string of component efficiencies that when put together cripple the fuel cell when compared even to burning hydrogen. There's the production of hydrogen, the compression of hydrogen (for storage), fuel cell efficiency, battery efficiency (fuel cells have horrible power density), electrical system efficiency, and finally motor efficiency. The best brushless DC motors are 90-93% efficient, but they're quite small--not enough power. Most conventional/brushless DC motors are somewhere around 85%
 
You still haven't come up with a remotely reasonable reason why an air powered car would be better than anything else.
 
If all people went round dismissing technological innovation based on myths and fallacies without considering the possibilities and benefits, we would never have "progressed" as a species. The compressed air technology can have benefits in specific circumstances. Think of a city taxi. The benefit over electric is that the power to weight ratio is much greater so you are not constantly accelerating a heavy battery. Maintenance is minimal, recharging is fast, no battery to maintain / replace / recycle. While it is true that the compression of the air produces heat, this is only inefficient if you don't use that heat to do useful work. It shouldn't take much imagination to come up with ideas. I thank the original poster for stirring my interest.
 
The losses when dealing with compressed air are something around 50%, whereas today's DOHC 4-valve/cyl SI/CI engines only lose about 15%.

The heat that's rejected when you compress air is low-grade junk heat. Not more than 200degF--can't even make steam with it. Anything under 200degF is junk heat that we can't do anything with.

What is possible with compressed air, and all forms of fluid power (hydraulic, compressed air...), is implementation as a hybrid vehicle in series with an IC engine. Here, the engine is running as the energy source with gasoline/ethanol/pick-your-favorite-hydrocarbon-fuel, and the fluid power system (compressed air or nitrogen, hydraulics) acting as the power source. We've got a big grant from the NSF here at the U of MN ME Dept to do research on this type of thing. The power density of fluid power is fantastic compared with electric motors or IC Engines. It's got the potential to blow electric hybrids out of the water.

Power density/Energy density. A big and important difference.
 
From research on wikipedia link it would seem that the energy density of compressed air at 300 bar, the proposed storage pressure of the car, would be 4.05 MJ/Kg 18 times greater than a NiMH battery and similar to that of TNT. Using an efficient expansion engine, as is proposed, should enable the majority of that to be recovered to do useful work.

I think the Tesla car is great but I wouldn't like to replace the battery. I have looked into this before and the battery pack is actually fault tolerant in that it will bypass faulty cells without allowing them to compromise the rest. Compressed air bypasses these problems but I worry about what would happen in a crash. Although gasoline has ten times the energy density of compressed air @ 300 bar, it can only release it slowly as it needs to vapourise and have enough oxygen and a source of ignition. If an air tank failed it would be like a bomb going off. Best safety precaution would be to fit all cars with a spike sticking out of the steering wheel, not a nice, peace of mind inducing airbag ;)

Almost forgot 200 F is above the central heating temperature of most boilers unless you use steam heat. It can also be used to preheat water for other systems, you just have to use your imagination not just quote that heat below a certain temperature is junk heat. It is only junk if you are unable to come up with an idea as to how to use it.
 
Yeah, 200degF heat---you can do something with it if the thing that's going to use it is close by (and you're using it as heat)--it can't be converted into shaft work.

I thought about the whole air tank thing too. If it were punctured...goodbye. And how heavy would it be??

I'll explain power/energy density when I have some more time.
 
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