Oil refineries... (1 Viewer)

[Mike Voigt]

Ajay - here's the issue:

Oil has a tremendous amount of energy already stored in it. It is also combustible, i.e. provide it with a heat source (even if just instantanoeus) and an oxidizer (does not have to be oxygen, but usually is), and it will burn - merrily. For a really harsh example, look at the lit oil wells left behind by the Iraqis in the first Gulf War.

You can do the same with coal, paper, wood, etc. The energy density varies - the amount, per cubic inch, that is stored in the material. So, per cubic inch, hard coal/black coal/anthracite has the highest, and wood has much less. You don't get as much heat out of one cubic inch of wood as you do out of one cubic inch of coal. Ditto with oil - it gives up much more energy than wood.

In water, you have no such thing. You cannot burn it; it is largely inert matter. The waater molecule is very difficult to pry apart; you need energy to do so. You have to introduce and store that energy - in the case of water, separation of water into hydrogen and oxygen, then storign those gases - before you can use it. Using it is essentially "burning" the hydrogen with oxygen. Result - you get water. And start over - except it took more energy to separate the water into gases than you got out of the hydrogen "burn"... moreover, you have to get that energy from somewhere.

Int eh case of oil, it is much easier to use - you don't have to make it, nature already has it ready for you. You don't have to stick nearly as much energy into retrieving it (although that cost goes up and up over time) as you would into having to split water into hydrogen and oxygen.

I like Cees' analogy of a battery. You are storing up energy to use later. In the case of oil, that's done for you. In the case of hydrogen, it isn't, and you have to provide the means (read: energy) to "make" the battery in the form of two substances: hydrogen and oxygen.

Now, we've talked about water, but there are other sources of hydrogen. For example, we could take ethane (C2H6) and change it into ethene (C2H4) - this would gain us two hydrogen atoms. Unfortunately, this also takes energy to do.

In all instances, though, you will have to add energy to gain the hydrogen. Only then can you use it.

The trick is to find a process using the absolute minimum amount of energy and resources to do this. Then, designing a process such that the energy required to generate hydrogen is as smallishly greater than the energy you get back out, i.e. optimize the energy returned (from the burn) on the energy invested (to make the hydrogen). Better yet, the process is easily reversible so you don't have to go through lots of extra steps.

Mike

 

[AjayM]

The battery analogy doesn't work because no matter what you do at the end of the day it takes more energy to fill it than you get in the end. That will never change, you can't apply 75% of a charge and get 100% out of it.

And Hydrogen is one of the most volital elements that we know of with the best example being the Hindenburg (well and the sun). There is plenty of energy in Hydrogen. As opposed to Oxygen or Nitrogen, which has limited energy potential in any form that we can make use of (well other than say wind power, but I'm speaking at a much different level here).

These guys keeping going on and on about how to make usable hydrogen which is a completely seperate part of the puzzle. If you can create a cheap and easy way to "refine" hydrogen then you have a new source of energy (which is part of where all these corporate research projects are going), this was quoted from Wikipedia;

In the laboratory, hydrogen is prepared by reaction of acids on metals such as zinc. For production in large scale commercial bulk hydrogen is usually manufactured by steam reforming natural gas. Electrolysis of water is a simple method, but it is still economically inefficient for mass production. Scientists are now researching new methods for hydrogen production. One of them involves use of green algae. Another promising method involves the conversion of biomass derivatives such as glucose or sorbitol, which can be done at low temperatures through the use of a new catalyst.

I mean if this conversation were happening 100+ years ago we could substitute the word oil for hydrogen here, people didn't just dig an oil well and immediatly knew how to process and refine the stuff like we do today.

Andrew

 

[mark alan]

Andrew,

From the Dept of Energy website:



The energy released in burning 1 lb of hydrogen is 60,000 btu, or 17.6 kw-hr. In other words, you lose 21.3-17.6 = 3.67 kw-hr of energy for each lb of hydrogen you product and consume. That is assuming that the fuel cell is 100% efficient. In reality, it is only 50%.

What I am getting at is that hydrogen is a losing proposition. The more hydrogen you produce, the worse the situation is. A hydrogen economy works only if you have essentially free energy to produce the hydrogen. That doesn't exist (except in Iceland). Even if we had free electricity, we would be better off using the electricity to directly charge batteries and using electric cars. That would be much more efficient, safer, cleaner and cheaper.

Research into hydrogen is a waste of time. I would get into the politics of why the Fed government is promoting fuel cell technology, but that might get this thread closed.

 

[AjayM]

Again, proving my point. You guys keep talking about processing hydrogen but you lock yourself into the technology that is available today without looking towards what will be possible in the future. 100+ years ago I'm going to bet that oil refining wasn't exactly as efficient as it is today.

Then you go on to talk about an electric car? The technology there is not anywhere where it needs to be either, driving 200 miles then stopping for an 8hr recharge is hardly what I would call the model of efficiency.

 

[mark alan]

you cannot change the laws of thermodynamics. It will always take more energy to produce 1 lb of hydrogen than you will get from burning 1 lb of hydrogen. No magic new technology is going to change that.

The electric car was mentioned because they are now looking at combination hybrid/electic vehicles. It would have more batteries than a standard hybrid, and would be charged at home. For short trips (20-30 miles) the car would run entirely on electric. For longer trips, the internal combustion engine would kick in. The estimate are that this type of vehicle would get 100-200 mpg. Granted, it would also use electricity, but it would use it much more efficiently than an fuel cell car.

If we are going to use electricity to power our cars (which is what a hydrogen car does (inefficiently)), I would rather go straight to an electric car.

 

[CharlesD]

Its important to understand that the chemical energy is not an inherent property of the atoms per se, but is contained in the bonds between atoms. It takes energy to form bonds, and certain types of bonds need less energy to create than others. It follows that lower energy bonds are easier to form than higher energy bonds. In an energy producing chemical reaction the resulting molecules will be in a lower state than the starting ones, and energy is released as a result (burn gasoline in air and the energy is in the form of heat).

Oxygen easily combines with many other elements, almost always in forms that contain less energy than the oxygen by itself. (Uncombined oxygen consists of two oxygen atoms joined together with a relatively high energy bond.) When Oxygen combines with other elements, the reaction can take place very quickly and release energy quite rapidly (aka fire ).

Like O2, H2 molecules contain quite a bit of energy. hydrogen will also combine quite easily with other elements including oxygen. Hydrogen and oxygen combine to form water, they can do this through rapid burning, or through other chemical processes. When they combine they release some of the energy of the hydrogen/hydrogen and oxygen/oxygen bonds.

To get hydrogen from water you must put energy into the system, first to break the bonds between the hydrogen and oxygen atoms and then to bump up the energy state so the hydrogen atoms will bond with each other (as opposed to recombining with the oxygen). So making hydrogen out of water is storing energy, not releasing energy inherent in the hydrogen atoms themselves.

The sun gets its energy from the nuclear fusion of hydrogen atoms to create helium which is an entirely different process.

 

[AjayM]

This says it best;

Challenges
Researchers must overcome several obstacles if hydrogen is to become a major energy resource. Hydrogen is currently more expensive than traditional energy sources; the production efficiency (the amount of energy or feedstock used to produce hydrogen) must improve; and an infrastructure to efficiently transport and distribute hydrogen must be developed. NREL's research is directed towards resolving these issues.


And this is different from a big chunk of fission material how?

How about things like this;

http://www.sciencedaily.com/releases...0422165917.htm

Or reading little tid-bits such as this

http://www.eere.energy.gov/consumeri...eets/a109.html
Hydrogen is the simplest and most common element in the universe. It has the highest energy content per unit of weight—52,000 British Thermal Units (Btu) per pound (or 120.7 kilojoules per gram)—of any known fuel.

So again, the energy is there. Finding a way to get/use it efficiently is the issue (in case I haven't mentioned that one or two dozen times already).

 

[CharlesD]

Fission is a completely different process than releasing chemical energy and has nothing to do with hydrogen.

Fission is very large atoms spontaneously breaking up into other elements (radioactivity) and releasing energy in the process. Nuclear power harnesses this energy by causing radioactive material to decay faster than it would naturally in a controlled chain reaction (neutrons from radioactive decay impact other nearby atoms, causing them to decay and release neutrons...)

 

[Jeff Gatie]

I suggest you and Steeve from Montreal get together and travel to Steeve's mysterious part of the universe in which the laws of physics break down and things like transporters (and a net positive E from 2H2O -> 2H2 + O2 -> 2H2O) are possible. In short it violates the Law of Thermodynamics, an inviolable law of nature (unless you catch a ride on the giant space spider to Steeve's "special" pocket of the universe). See the "Transporters are not possible" thread for details.

P.S. Be very careful, you are amongst a lot of engineers here. Funny facts like physics and the laws of nature tend to creep into the converstation.

 

[mark alan]

Either Andrew is having some fun stringing us along, or he needs to take a basic chemistry class.

 

[Jeff Gatie]

If the "Transporters are not possible" thread is any indication of the type, he's dead serious. To paraphrase the sentiments of that thread - A non-scientis gets to think of the "maybes", scientists just worry about silly laws and math. This lack of "thinking outside the box" is why scientists are so arrogant and think they know everything.

 

[AjayM]

I what?

I posted some information above that talks about energy from "gotten" from oil being 80-90% efficient, it then mentions hydrogen being 60-70% efficient. It also mentions coal burning elctrical plants only being 15-20%, these are all from source to consumer numbers.

I'm sure you have some information that refutes those statements that I can read, right?

Andrew

 

[AjayM]

Ok, if this is the kind of crap you guys are going to post then I'll just stop posting. I've asked for technical papers explaining all the stuff you guys mention, yet how many links to such information have been provided? ZIP - ZILCH - NOTHING, I guess you "scientist" types (and I'll use that term lightly in refernce to the BS above) just believe everything somebody tells you on a forum on the net', right?

Considering this whole thread fart came about by somebodies assertion that oil companies don't spend any money on researching other methods of "getting" energy, info which was pulled straight out of their backside might I add, I'll take what you guys say with a grain of salt until you can prove otherwise. Mmmm'kay?

 

[mark alan]

The difference is that with oil and coal you are releasing energy that is already stored in the oil and coal. With hydrogen, you are adding energy, and then getting out less than you added. It is an entirely different thing.

 

[Jeff Gatie]

Well to wheel study of the efficiency of hydrogen

Seems the numbers are not so good when you actually put the H2 into a car and drive it.

 

[CharlesD]

Ajay,

hydrogen research is not about replacing conventional energy as such, but about getting an energy storage medium that does not rely on hydrocarbons being used at the point of energy consumption (e.g. a car).

The biggest advantage of hydrogen fuel in a car would be non polluting exhaust (H2 combines with O2 to produce energy + water). Its easier to scrub the output of 100 big oil burning power plants than of 100 million gasoline burning cars. Also the hydrogen could be produced from non-oil based energy sources, but somehow I doubt that any oil companies researching hydrogen fuel cells are interested in that angle as much as they are from not being hamstrung by emissions standards.

 

[AjayM]

Finally...a link. Which says the same thing I've said now more than a couple of times;

Although it is possible that future research may some day provide solutions to these and other problems for using hydrogen as a transportation fuel, the technology is not ready for commercialization and funding for an infrastructure isn't available today.

hmmm

Posted by me
So again, the energy is there. Finding a way to get/use it efficiently is the issue (in case I haven't mentioned that one or two dozen times already).

and

Posted by me again
You guys keep talking about processing hydrogen but you lock yourself into the technology that is available today without looking towards what will be possible in the future. 100+ years ago I'm going to bet that oil refining wasn't exactly as efficient as it is today.

and

Posted by me yet again
These guys keeping going on and on about how to make usable hydrogen which is a completely seperate part of the puzzle. If you can create a cheap and easy way to "refine" hydrogen then you have a new source of energy (which is part of where all these corporate research projects are going)

Where do you think all that R&D money is going?

Isn't the point of looking at alternative fuels is the understanding that one day in the future there will be no more oil? Nobody is saying that oil isn't a better option than hydrogen or any other alternative fuel, otherwise oil wouldn't be at the top of the heap, but again without oil you have to look at the next one down the list, and the next one down from that, etc.

Andrew

 

[Jeff Gatie]

Again, the methods of creating hydrogen are well know and very, very simple. "Refining" them is out of the question, because it does not matter how much you refine it, it is limited by the Laws of Thermodynamics (see marc alans DOE quotes above) - the fact is you always get less out than you put in (not so with oil, coal, etc.). It takes energy to make hydrogen and unless you are Iceland, or have a massive changeover to wind, wave, hydro etc., the net result is a loss. All anyone is saying is that without other replenishable, non-polluting sources of power with which to produce the hydrogen, hydrogen does nothing for the environment except cost more money and burn more fossil fuels. Similar to recycling paper, the net result is more money spent and more pollution added to the environment.

 

[AjayM]

So you're saying here that "oil, coal, etc." all break the laws of thermodynamics? We both know that's not the case. The DOE quotes mention one method of "refining" hydrogen. As the links I posted above show people are "discovering" new ways to "ease" the process as well. Will those discoveries lead to anything? Who knows, maybe they will maybe they won't.

 

[Jeff Gatie]

Nope, coal and oil get their energy from millions of years of compression and chemical changes within the earth's crust, not to mention the original plants received energy from the sun millions and millions of years ago. When we burn it, we release those millions of years of stored up energy. Water starts off inert and we must extract the hydrogen from it in order to get something to burn. The fact that hydrogen is such a good releaser of energy is why you almost never find it in it's "pure" H2 form in nature. Hydrocarbons are another story.