Fuel of the Future: Water, is it a myth or legend?

studiot

Joined Nov 9, 2007
4,998
Perhaps I can add a safety note here

HYDROGEN is EXPLOSIVE

I say this because I see on tonight's news that someone in Nottingham has blown himself up, succumbing to the latest UK craze for making your own diesel fuel from waste cooking oil and methanol.

In terms of the twaddle about using water as a fuel, it is a simple thermodynamic fact that you have to put more energy in than you get back separating the constitutents of water and recombining them.

However the attractiveness of the scheme is the 'clean burn' of the hydrogen, no nasty pollutants.

But wait - water vapour is approximately 500 times as 'powerful' a greenhouse gas as carbon dioxide.

But some of us don't see an 'energy crisis', just a lack of political will to adopt sensible engineering strategies, using known and proven technologies.

There is more energy in an average atlantic storm than Man has ever used on this planet in his whole collective existance. All that is lacking is the will to collect it.
 

Wendy

Joined Mar 24, 2008
22,428
Learning costs money, consider these kits an educational experience. I've been a bit depressed how hardware seems to be going away, 20 years ago you could get parts everywhere, there were electronics outlets for parts everywhere. Now I know of 2 good ones, and about 5 not so good in the entire city of Dallas and the metroplex.

Experimenting for ones self is good, no matter what the motive. I seriously doubt the numbers will add to any pollution, it keeps people occupied, and occasionally, if rarely, something new is discovered.

Harvesting the energy in storms isn't a matter of will, they aren't predictable enough to use. Wind, sun, and waves now, they are being pursued actively.
 

jpanhalt

Joined Jan 18, 2008
11,088
Hi Bill,

I share your pain about the loss of hardware stores. If you are not aware of McMaster-Carr, it has the most complete line of virtually 100% "in stock" items I have seen. It's a little more expensive than you can find on the open market (for example, its cut metal prices and machine tools), but it is a great time saver, ultra-fast shipper, and no minimum. Its SS and metric hardware is usually much cheaper than the big box stores. It is hard to get a catalog (you have to be an established business or customer), but I find its web site easy to use.

John

BTW, for me it's a local store, only about 30 minutes away. I order and by the time I get there, it is ready for pickup.
 

Wendy

Joined Mar 24, 2008
22,428
I used McMaster-Carr back when I was machine maintainance, they were a favorite. I was thinking more of electronic stuff. I have a Lowe's and Home Depot within stones throw, several actually. Their are other hardware shops around, I like Harbor Freight, they have a local outlet, though Lord help you if you need customer service online. Grainger was OK, but a bit expensive.
 

studiot

Joined Nov 9, 2007
4,998
Harvesting the energy in storms isn't a matter of will, they aren't predictable enough to use. Wind, sun, and waves now, they are being pursued actively.
I was no more suggesting that we harvest storm energy than B J Franklin suggested we harvest lightning through keys touching our knucKles .

I really wanted to show how puny Man's power is when contrasted to Nature.

I do observe that the largest tidal rise in the world is in the Bay of Fundy in Canada, the second largest is the Bristol Channel. It has been estimated that proposed Severn Barrage could supply 20% of UK energy requirements.

I further observe that the stretch of water between Ireland and Scotland, where the Atlantic meets the Irish Sea is 12 miles across. Twice a day enough weight of water moves through the narrows here to power the whole of Europe.

The best we can offer is one measly horizontal flow turbine, installed on the bed of Strangford Loch

http://www.autobloggreen.com/2007/06/16/1-2-mw-tidal-turbine-to-be-installed-off-northern-ireland/

Near one of the main European oil terminals at Milford Haven, lies Pembroke power station.
This power station was built expressly to burn the waste sludge, scraped out from the botoms of supertankers.

Of course these systems are less efficient than burning premium grade fuel. So our cock-eyed 'market system' dictates that these sources remain underused.

We have to do something with the tanker waste - once it was just dumped.

Natural energy is low grade, but can be very clean and green. We need the political will to, for instance, use it indirectly to power pumped storage systems.
 

jpanhalt

Joined Jan 18, 2008
11,088
studiot said:
I do observe that the largest tidal rise in the world is in the Bay of Fundy in Canada, the second largest is the Bristol Channel. It has been estimated that proposed Severn Barrage could supply 20% of UK energy requirements.

I further observe that the stretch of water between Ireland and Scotland, where the Atlantic meets the Irish Sea is 12 miles across. Twice a day enough weight of water moves through the narrows here to power the whole of Europe.
Does changing (retarding) the tides affect the earth's rotation? Are there any environmental studies you might be able to give links to?
John
 

studiot

Joined Nov 9, 2007
4,998
Hi John,

If you get the chance to see the series of 6 programs, presented by Professor Ian Stewart I would thoroughly recommend them.

http://www.plymouth.ac.uk/PlanetEarth

Once you have penetrated the good proff's bighead style, the content is superb and totally modern.

He refers to the last NASA ongoing moon experiment, connected with this. I don't readily have figures, (perhaps Dave can help?) but the tidal energy derives from the gravitational interaction between the Earth and the Moon. It is collossal. I am sure that any energy we could extract would be a mere bagatelle in comparison.

Of greater concern is the NASA confirmation that the moon is receeding a few centimetres a year.
 

Dave

Joined Nov 17, 2003
6,970
Does changing (retarding) the tides affect the earth's rotation? Are there any environmental studies you might be able to give links to?
John
This reminds me of the "fact/myth" of the effect the Three Gorges Dam has on the earth rotational axis - that is the weigh of water concentrating behind the dam is so significant that it will have a negligibly small but real effect. Obviously this gets blown into the conspiratory idea that the Three Gorges Dam will change the length of days and eventually blow the Earth out of its orbit of the Sun! All this is a speculative idea, but when considering the effect the water mass would have on the centre of balance of the Earth, then I suppose this is more fact than myth - however it is pretty insignificant.

Changes in tides might have the same effect, however it is cumulative and dynamic. That is changes around the world would play against each other in a time varying fashion; therefore statistically speaking the effect would probably be (even more) insignificant than the case for the Three Gorges.

This, of course, is just a thought exercise.

Dave
 

jpanhalt

Joined Jan 18, 2008
11,088
Dave and studiot,

Thanks for the replies. Both of you got right to the issue. We are extracting energy from a system and using it somewhere else. That system is therefore being perturbed. To what extent? I don't know. We all agree there is no such thing as free energy.

As for the gravitational energy source being large, that is true, but there are numerous examples where a small force over time can significantly change a much larger system that is in resonance or equilibrium. Anyone who has ever docked a large boat knows it doesn't take much force on the line to do it, if the timing is right, and you have a sufficiently strong dock/fulcrum to work against.

At the root of it all, I am a bit skeptical of forward looking documents that predict negligible consequences from disruptions of nature. As an example, I would point to the effects of freons on the upper atmosphere, which were certainly not anticipated. We could stop production of R12 and R22, but what can we do about a perturbed orbit? (No, I don't have nightmares about black holes generated in the LHC at Cern devouring the earth next year.)

As for my gut bias, I am more concerned about disruption of winds and tides -- something for we have no historical record on which to base predictions -- than I am on adding more CO2 to the atmosphere. At least we know the earth has survived high CO2 concentrations in the past.

I will take a look at Prof. Stewart's programs later today. Thanks for the link.

John
 

studiot

Joined Nov 9, 2007
4,998
John, you are right to observe that carbon dioxide levels have varied in the past and that the Earth is still here - That is part of the thesis in both Prof Stewart's TV programmes and the book by Fred Hoyle I referenced in a previous thread - ICE.

Now consider this.

Sea levels have also varied considerably over past history. this means that the gravitational field has been lugging significantly larger and smaller amounts of water about, and dragging it across significantly different terrain over the millenia. The different terrain has different resistance to motion. So the net result is huge natural variations in the energy system, but the Earth is still here!

My point is that in both these cases and many others, the natural variations dwarf any man made input or output.
 

thingmaker3

Joined May 16, 2005
5,084
What about tectonic plate movement? I suspect the shifting of a continent might have somewhat more effect on the planet's moment of inertia than would some (realatively) tiny lake.
 

thingmaker3

Joined May 16, 2005
5,084
What happened to the post I just typed in about the fuel efficiency in vehicles?
Nothing is showing up on search, so it wasn't put in the wrong thread by accident. I know how frustrating it can be to compose a post and have a browser or server glitch interfere at the last minute.
 

Dave

Joined Nov 17, 2003
6,970
What about tectonic plate movement? I suspect the shifting of a continent might have somewhat more effect on the planet's moment of inertia than would some (realatively) tiny lake.
Absolutely, reason would agree with you. Although they may argue the distributed nature of tectonic movement which "spreads" the impact. The Three Gorges Dam lake (I can't recall its name) is a focal point of "pressure" which will have a (more direct?) impact on the centre of balance. I would be more inclined to look at the mass released from something like the Mount St Helens volcano eruption (obviously that had other major environmental considerations).

It's speculative stuff.

Dave
 

studiot

Joined Nov 9, 2007
4,998
OK I'm low level formatting someone's hard drive at the moment so I'll have nothing better to do for the next 14,000 years so I'll try to type it in again.

Incidentally about techtonics, I'd feel a mite constipated if I had India ramming up my backside, like the Himalayas. I think the impacts are spread over time so produce a low 'impulse'?
 

studiot

Joined Nov 9, 2007
4,998
Since this thread is about automotive fuel efficiency, let’s examine the subject.

Firstly somewhere between 30% and 70 % of the bond energy output by the combustion process is lost in mechanical losses in the system.

Secondly the amount of energy required to complete a particular journey depends upon: the weight of the car and its occupants, the style of driving, and the road conditions (leading to the amount of braking/acceleration cycles needed).

Modern vehicles have improved their efficiency by reducing the weight component of the vehicle. This trend has brought about substantial improvements in fuel efficiencies.

Now to consider the efficiency of the combustion process itself. Modern internal combustion engines operate at greater than 80% combustion efficiency.

Also you cannot extract all the bond energy from the combustion process, simply because if you did you could not remove the exhaust products. These need to remain in the gaseous (more energetic) state.

Therefore to get more energy out you have to put more energy in.

One way to do this is to dilute the fuel with (add) a substance of greater calorific value. However water certainly is not such a fuel, in fact it has negative calorific value.

The only other way is to introduce the water in a higher energy state by separately adding energy to it. I do not see any sign of the significant amounts needed being introduced by the alchemical processes proposed.

It is, of course, possible that adding the ‘activated’ water somehow compensates for a poorly adjusted carburetion/injection system or timing. Surely it is better in this instance to tune you car properly? It is, of course, impossible to maximise both performance and economy at the same time. The user has to choose a balance between - the addition of the water will change this balance.

I have noticed that driving in Fog takes more fuel than in clear air. In fact the density of the air is another important variable, and your car is only tuned for one value.

Alternatively you can simply drive with a lighter foot on the accelerator.
 

studiot

Joined Nov 9, 2007
4,998
I suppose that if you injected enough water and some of the waste heat converted it to steam this would increase the pressure in the cylinder since water expands 1700 times when it converts to steam.

But this would have to be achieved without quenching the combustion.

Tricky
 
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Dave

Joined Nov 17, 2003
6,970
Now to consider the efficiency of the combustion process itself. Modern internal combustion engines operate at greater than 80% combustion efficiency.
studiot, where are you getting the 80% from?

I was always under the impression that due to the heat loss mechanisms that the internal combustion engines run at less than 50% efficiency.

(Btw, I'm still try to catch up with all the matter in this thread!)

Dave
 

studiot

Joined Nov 9, 2007
4,998
When I state that the combustion process is over 80% efficient I mean that process of converting the hydrocarbon/air mixture to carbon dioxide and water vapour etc is over 80% complete in a modern engine.

Thus 80% + of the available bond energy is released.

Some of this energy appears as pressure energy, in the product gasses, some as heat.
The pressure energy is available to do work on the pistons, during the expansion stroke.
Not all the pressure energy is recovered as the expansion is never fully to atmospheric pressure, always somewhat above.
More of this mechanical energy is lost at each part of the crank, through the transmission, to flexing and heating of the tyres.

I have lumped all these losses together for this purpose.

So in summary

During combustion you are down to 80% of max.
During work production and transmission you are down to 30% to 70% of this

So your overall efficiency is between .3*.8 and .7*.8

i.e between 24% an 56% efficient.
 
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