OK, the solar leaf is still using the solar energy. You still cannot exceed 100% of the incoming energy. The one developed at MIT is said to be 10x more efficient than a real leaf.
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OK, the solar leaf is still using the solar energy. You still cannot exceed 100% of the incoming energy. The one developed at MIT is said to be 10x more efficient than a real leaf.
Water can be split into hydrogen and oxygen by running electricity through it. You get energy out by burning the resulting hydrogen (this results in water, completing the cycle).Quote:
Originally Posted by Drachen
In this case you can substitute the word "fuel cell" for "battery" to get the concept.
A fuel cell is, in essence, a battery, albeit storage of energy by slightly different chemical means.
This technology does seem to be a bit different, in that it uses sunlight and catalysts to cause the reaction, as opposed to the electrolysis method. My gut says this is much more energetically efficient than direct electrolysis.
The article is pretty short on details to be able to tell.
The law of conseravation of energy though is still an immutable law of physics and cannot be cheated even so. The 1200 watts/sq ft/day is the upper end, the only thing a catalyst does is get you closer to this theoretical maximum.
My chemistry professor likened reactions to pushing a ball up a hill, and then letting it roll down the other side. (energy of activiation). It requires a certain amount of energy into a reaction before you can get anything out. A gallon of gasoline does not spontaneously combust, but add a little spark or heat via a match and you get a lot out.
........___
...... /....\
....../......\
___/....... \
...............\
................\________
What a catalyst does is makes the top of the hill a lot shorter.
......._____
____/.......\
...............\
................\_________
The net energy you get out (i.e. the difference between the starting elevation and the ending elevation) hasn't changed, but you don't need as much to get the ball rolling.
Hope this helps. It is my understanding of it, and may not be 100% up, but I am pretty good with these things generally, much to mouse's dismay. ;)
The catalyst is made of nickel and colbalt. The chemical is water. It uses the sun to trigger the reaction.Quote:
Originally Posted by Wild Cobra
Once again. Gasoline and oxygen do nothing until heat is added. The resulting reaction releases more energy than the heat alone provides. In this example the sun is the heat and is able to provide X amount of energy, but adding the sun to the catalyst and chemical can release more energy than the sun provides alone.
Quote:
Originally Posted by RandomGuy
Isn't this just Brown's Gas (oxyhydrogen)?
http://en.wikipedia.org/wiki/Oxyhydrogen
By the way "The energy required to generate the oxyhydrogen always exceeds the energy released by combusting it.".
Got that, as shown by my post following that one. I replied before looking it up. When you said chemical reaction, I assumed there was more than just breaking down water. After all, a real leaf does do other chemical reactions which take carbon out of the air.Quote:
Originally Posted by Drachen
An entire post without mention of the VRWC?Quote:
Originally Posted by boutons_deux
(feints)
Bouton's....Quote:
Originally Posted by RandomGuy
Don't do that....
I'm not ready for a heart attack!
Sorry, I was typing when you posted that other one, I am going to go ahead an stop since A) I am outmatched (it seems RG has a better handle on it than I) and B) the articles that I have read a very short on details and therefore most of what I am suggesting are just guesses. Hopefully I guessed right, but I will have to wait for more info. I know they are licensing this tech to TaTa to make it commercially available so I guess when that happens, more info will be made available.Quote:
Originally Posted by Wild Cobra
This is why I don't put anyone on ignore. Boutons does eventually post some things that I consider to be reasonable and thoughful and Jack Sommerset posted something funny once.Quote:
Originally Posted by RandomGuy
Oh and before someone replies to this with "Link?" I don't have a catologous memory of everything I have read here so I don't remember. I just remember it happened. :lol
Are you fencing Boutons now? :) [/snark]Quote:
Originally Posted by RandomGuy
argh. Stupid, silly, pig-dog French words muddying up our nice Germanic-rooted language.Quote:
Originally Posted by LnGrrrR
Feint faint.... whose to say which is falling over and which is a false attack?
Yes, exactly. That is one of the implications of the second law of thermodynamics.Quote:
Originally Posted by DarrinS
Mmmm entropy.
Quote:
Originally Posted by RandomGuy
Would it make more sense to use the solar energy directly, rather than waste some by producing the gas?
On the other hand, the gas can be easily stored and is portable.
This is what kills the "water car" out of the gate, in case anybody ever runs across that pseudo-scientific claptrap. A car that runs on water by using electricity to make this, then burning it. i.e. perpetual motion.Quote:
Originally Posted by DarrinS
"They" are keeping the water car from us, 'cause they want us dependent on oil, or so the conspiracy theory goes.
That might make sense if it didn't defy the very laws of physics.
Sure there are cars that can run on burning hydrogen, but you still need to get the energy to get that hydrogen from *somewhere*. This little fact escapes some people.
Surely, you mean "who's" to say... :DQuote:
Originally Posted by RandomGuy
It would make sense that way, yes.Quote:
Originally Posted by DarrinS
As noted before, you would not get the energy losses in storing/retrieving it from a battery.
Gasoline is an excellent fuel, as the energy content shows.
The problem with gasoline is in producing it. If you start from scratch you get a LOT of energy loss, and an inefficient process.
We have benefitted from not having to produce it from scratch, i.e. producing it from crude oil.
The big systemic problem is that it is taking more and more energy to get the next unit of gasoline, making it less and less efficient over time.
Take a barrel of sour crude and light sweet crude.
Sour crude requires energy up front to heat it to the point where you can extract it. It then requires energy to remove the sulfur, then you have the equivalent of light sweet crude, then you refine it further, and get gasoline.
Light sweet doesn’t require as much coaxing to get it out of the ground, then doesn’t require the extra refining steps (read: energy) to fully concentrate the energy of the oil into gasoline.
If you like a barrel of sour crude is much less “energy dense” than light sweet.
Our problem as a civilization is that the light sweet variety is being used up pretty quickly. This leaves sour crude to fill the gap.
I imagine it is virtually certain that battery/fuel cell technology may one day produce a battery that, volume for volume and pound for pound, stores more useable energy than gasoline, but that is beyond anything that mankind is capable of in my lifetime.
The concept of EROEI is important to think about.
http://en.wikipedia.org/wiki/EROEI
If you have the time, there is a VERY long, but comprehensive look at energy and what it means to our civilization here:
http://www.theoildrum.com/story/2006/8/2/114144/2387
Another one of my more favorite websites:
http://www.abelard.org/briefings/transportable-fuel.php
That depends. You use the energy from your battery to cause a spark which then causes the combustion that fuels your car. But it doesn't make sense to just use the energy from your battery directly to fuel your car, does it?Quote:
Originally Posted by DarrinS
Whether or not what was stated above was valid, that doesn't mean the principle you just stated is always correct.
Take the time to read this bit:Quote:
Originally Posted by MannyIsGod
http://www.theoildrum.com/story/2006/8/2/114144/2387
Fascinating reading.
(some of the bits are referenced from the authors example of "sasquatches" and "mongo nut trees" that makes for some entertaining reading)Quote:
THE BOTTOM LINE:
1) Net energy is more important from a relative basis than absolute. A 3:1 EROI doesn't tell us much unless we know how that compares to what an organism/society has been built on/used to. A 2:1 EROI would have made stone age villagers incredibly rich. A 5:1 EROI may not be enough to power our society. (e.g. as fossil fuels get more expensive they will collapse the economy and no real recovery will ever happen as the high energy gain outputs are already gone)
2) Energy reserves are not as important as energy flow rates. We could have a billion mongo nut trees, but all that matters is the maximum flow that society is able to harvest in real time. (This obviously applies to oil as well)
3) Energy quality depends on the context. High BTU substances, like oil or coal, are clearly very useful to our society, but may not be to others. (the sasquatch colony valued and used Waybread, not oil)
4) Liebigs law of the minimum applies to an energy portfolio. Wind has a high EROI, but our system infrastructure relies on liquid fuels. The net energy of the weakest link matters more than the overall net energy of society. (Adding high EROI wind capacity while net energy of oil dwindles does not solve the problem, unless the energy mix changes from liquid fuels to electricity)
5) Using different boundaries in net energy analysis will lead to different conclusions. A society running at 5:1 EROI would be happy to develop a scalable technology with an 8:1 EROI, however, after environmental externalities are included, it might only be a 3:1 technology. (Coal-to-liquids and climate change comes to mind) The difficulties lie in making meaningful comparisons and valuing important life functions not priced in the market system.
6) Rather than pursuing the highest and most promising energy technologies, it might be prudent to pursue ones that are certain, and meet the net energy decline half-way by reducing energy footprints. As we decline in aggregate societal energy surplus, a great deal of remaining energy is going to be wasted, ostensibly going after 'more oil and gas', which will likely be unprofitable both monetarily and from energy perspective.
7) Since evolution has favored organisms that have the highest energy output energy input ratios, it will be a cognitive challenge for us (as organisms) to willingly reduce the numerator.
8) Consumption, in the sasquatch example, continued very high until late in the game, and was subsidized from borrowing from other aspects of society. Lack of energy gain was a phantom concept until the situation was much deteriorated. Similarly, in our current fiat based civilization, we might 'replace' the lower energy gain by printing money or relaxing financial requirements, but these measures will not be based on anything biophysical and make the eventual crash much steeper. In the end, it's not about how much energy we have but how much societies can afford via real inputs.
New technology makes hydrogen more viable car fuel
There is a fairly steady drumbeat of news like this. Money is flooding into research at the moment, and while there are no doubt some technologies that will never reach widespread use or full production, something is bound to be a game changer.
http://www-formal.stanford.edu/jmc/p.../hydrogen.htmlQuote:
Hydrogen is often advocated as an energy medium. Here are some relevant facts.
Hydrogen is the lightest of the elements with an atomic weight of 1.0. Liquid hydrogen has a density of 0.07 grams per cubic centimeter, whereas water has a density of 1.0 g/cc and gasoline about 0.75 g/cc. These facts give hydrogen both advantages and disadvantages. The advantage is that it stores approximately 2.6 times the energy per unit mass as gasoline, and the disadvantage is that it needs about 4 times the volume for a given amount of energy. A 15 gallon automobile gasoline tank contains 90 pounds of gasoline. The corresponding hydrogen tank would be 60 gallons, but the hydrogen would weigh only 34 pounds.
Interesting. the new tech from the article posted above might change the volume requirements, if so, that would give gasoline a serious run for it's money.
By the by, even if you don't read this, there are two rather obvious implications:Quote:
Originally Posted by RandomGuy
Standards of living will fall and more people will have to be devoted to energy production.
Both are unavoidable over time.
Game changer of course would be energy sources. As noted in the article though, wind energy seems to have the potential to match oil in terms of invested energy/return on investment.
Any good economist will tell you that energy will be a mix of sources, and I would bet on wind followed by solar, after we get a lot more energy efficient.
Spanish scientists search for fuel of the future
:wowQuote:
US oil giant ExxonMobil plans to invest up to $600 million in research on oil produced from algae.
Interesting. Even algae are still limited by the 2nd law of thermodynamics, as to how much energy you can capture.
Even so, once you start getting a few hundred square miles of bio-reactors, you are talking about some serious amounts of fuel.
Quote:
Originally Posted by RandomGuy
Doesn't surprise me... long shot of getting it to work, good PR.
Just skimmed this... but why even talk about approaching a theoretical 100% conversion for solar?? That isn't possible.
I don't think anyone actually said it was possible but rather people brought it up to show that even that impossible figure isn't enough to power today's vehicles or replace gasoline.
It represents a useful "upper limit" to the amount of energy possible, a starting point, if you will.Quote:
Originally Posted by Sec24Row7
As for whether the technology is feasible, I don't know enough about the technical aspects to pronounce anything a "long shot", but as I have said before, given the sheer number of promising technology that is attracting some pretty heavy R & D dollars, it is virtually certain that at least one or two will pan out.
May not be this one specifically, but sooner or later something will change the way we get/use energy, and that change will be greater than you would seem to think, in all due respect.