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Encore un cas ou les skeptos ont des prémonitions ? :-) Ça vient tout juste de sortir.
But there's a very simple and fundamental reason why you cannot power a car by burning water in the engine.
The reason is that the water has already been burnt, and the chemical energy has been taken out!
PODCAST et article ici.
http://www.abc.net.au/science/articles/2009/06/23/2604574.htm
Rien de nouveau, juste une façon simple de l'expliquer.
Water-powered engine theories need hosing down
Once you get a bunch of hot rod motorheads together, sooner or later, the talk will turn to the invention of the car powered by tap water.
Apparently, in the recent or distant past, a poorly defined consortium of evil politicians and/or car manufacturers and/or oil companies suppressed this marvellous invention to protect their own interests.
Even conspiracy theorists who don't drive believe this one.
Yes, the word was that all you had to do was to make some cheap modifications to the engine or carburettor or fuel injection system, and you could run your internal combustion engine by pouring water into the fuel tank.
But there's a very simple and fundamental reason why you cannot power a car by burning water in the engine.
The reason is that the water has already been burnt, and the chemical energy has been taken out!
Let me explain. When you burn coal in a furnace, the chemical reaction gives you carbon dioxide and heat. You can use the heat from the combustion to turn water into high pressure steam, and then use that steam to push the blades of a turbine to make electricity.
If you go back to the coal furnace, you will find some ashes there. These ashes are the leftovers from burning the coal. You cannot burn those ashes again. They have already been burnt.
The situation is the same for water because the water has already been burnt.
When you burn hydrogen and oxygen in a chemical reaction, you get water and heat.
When each NASA space shuttle thunders upward into space, its external tank carries some 617 tonnes of liquid oxygen and about 103 tonnes of liquid hydrogen.
They are burnt together to make about 720 tonnes of water, which is instantaneously turned into steam by the heat of the chemical reaction.
This steam builds up inside the rocket engine with enormous pressure, and comes out through the nozzle of the rocket engine. This nozzle is pointing down to the ground.
And so, thanks to the rule that for every action there is an equal and opposite reaction, the space shuttle is pushed upward.
Once it comes out of the nozzle, the steam coming out of the space shuttle engines cools down and turns into droplets of liquid water, which appear as a long skinny vertical cloud behind the rising space shuttle.
So you start with hydrogen and oxygen, and combine them to give you water and heat. Water might be wet like petrol, but it has also been burnt, like coal ashes.
Water is just wet ashes. It has already been burnt. It can't be burnt again! This is the same for the coal ashes. They have been burnt, so they can't be burnt again.
So you can't get any more chemical energy out of that water, because it has already been burnt.
But there is a roundabout way that you can get energy out of that wet liquid water. All you have to do is place the water in a tank that has a metal electrode at each end and shove some electricity into those electrodes.
The energy in the electricity will split the liquid water (H2O) into bubbles of hydrogen gas at one electrode, and bubbles of oxygen gas at the other electrode.
Then you can combine the hydrogen gas and oxygen gas to make water, and heat energy. Surely that will work?
Yes, it will work. That is one way to get energy out of water. But the laws of thermodynamics stop you from getting energy for nothing.
By the way, the casual or layman's form of the three laws of thermodynamics are:
1. you cannot win;
2. you cannot break even; and
3. you will always lose.
So yes, you can get energy from the hydrogen and oxygen you get by splitting water with electricity. But, you have to put more energy in than you get out.
For example, if you put in 100 units of energy to split the water into hydrogen and oxygen, you will get back only 80 units of energy when you recombine that hydrogen and oxygen.
Luckily for the conspiracy theorists, there are other sources of energy besides chemical energy. These include gravitational energy, kinetic energy, heat energy, electrical energy, magnetic energy and nuclear energy.
However, nobody has yet succeeded in using any of these kinds of energy with water to propel a car with an internal combustion engine.
So maybe it's time to hose down such far-fetched ideas.
But there's a very simple and fundamental reason why you cannot power a car by burning water in the engine.
The reason is that the water has already been burnt, and the chemical energy has been taken out!
PODCAST et article ici.
http://www.abc.net.au/science/articles/2009/06/23/2604574.htm
Rien de nouveau, juste une façon simple de l'expliquer.
Water-powered engine theories need hosing down
Once you get a bunch of hot rod motorheads together, sooner or later, the talk will turn to the invention of the car powered by tap water.
Apparently, in the recent or distant past, a poorly defined consortium of evil politicians and/or car manufacturers and/or oil companies suppressed this marvellous invention to protect their own interests.
Even conspiracy theorists who don't drive believe this one.
Yes, the word was that all you had to do was to make some cheap modifications to the engine or carburettor or fuel injection system, and you could run your internal combustion engine by pouring water into the fuel tank.
But there's a very simple and fundamental reason why you cannot power a car by burning water in the engine.
The reason is that the water has already been burnt, and the chemical energy has been taken out!
Let me explain. When you burn coal in a furnace, the chemical reaction gives you carbon dioxide and heat. You can use the heat from the combustion to turn water into high pressure steam, and then use that steam to push the blades of a turbine to make electricity.
If you go back to the coal furnace, you will find some ashes there. These ashes are the leftovers from burning the coal. You cannot burn those ashes again. They have already been burnt.
The situation is the same for water because the water has already been burnt.
When you burn hydrogen and oxygen in a chemical reaction, you get water and heat.
When each NASA space shuttle thunders upward into space, its external tank carries some 617 tonnes of liquid oxygen and about 103 tonnes of liquid hydrogen.
They are burnt together to make about 720 tonnes of water, which is instantaneously turned into steam by the heat of the chemical reaction.
This steam builds up inside the rocket engine with enormous pressure, and comes out through the nozzle of the rocket engine. This nozzle is pointing down to the ground.
And so, thanks to the rule that for every action there is an equal and opposite reaction, the space shuttle is pushed upward.
Once it comes out of the nozzle, the steam coming out of the space shuttle engines cools down and turns into droplets of liquid water, which appear as a long skinny vertical cloud behind the rising space shuttle.
So you start with hydrogen and oxygen, and combine them to give you water and heat. Water might be wet like petrol, but it has also been burnt, like coal ashes.
Water is just wet ashes. It has already been burnt. It can't be burnt again! This is the same for the coal ashes. They have been burnt, so they can't be burnt again.
So you can't get any more chemical energy out of that water, because it has already been burnt.
But there is a roundabout way that you can get energy out of that wet liquid water. All you have to do is place the water in a tank that has a metal electrode at each end and shove some electricity into those electrodes.
The energy in the electricity will split the liquid water (H2O) into bubbles of hydrogen gas at one electrode, and bubbles of oxygen gas at the other electrode.
Then you can combine the hydrogen gas and oxygen gas to make water, and heat energy. Surely that will work?
Yes, it will work. That is one way to get energy out of water. But the laws of thermodynamics stop you from getting energy for nothing.
By the way, the casual or layman's form of the three laws of thermodynamics are:
1. you cannot win;
2. you cannot break even; and
3. you will always lose.
So yes, you can get energy from the hydrogen and oxygen you get by splitting water with electricity. But, you have to put more energy in than you get out.
For example, if you put in 100 units of energy to split the water into hydrogen and oxygen, you will get back only 80 units of energy when you recombine that hydrogen and oxygen.
Luckily for the conspiracy theorists, there are other sources of energy besides chemical energy. These include gravitational energy, kinetic energy, heat energy, electrical energy, magnetic energy and nuclear energy.
However, nobody has yet succeeded in using any of these kinds of energy with water to propel a car with an internal combustion engine.
So maybe it's time to hose down such far-fetched ideas.