Posted on 02/08/2007 12:58:09 PM PST by aculeus
That is, if reducing CO2 emmissions really is the goal and not world socialism.
I'm impressed. I did not know the difference was that high. I didn't believe it either, but looked it up here just for a quick resource.
EPA/DOE 2005 Fuel Economy Guide
Initially I thought "why are we not all driving diesels?" But it is the primary reason people buy fuel efficent vehicles in the first place: money. In 2005, the price adder the diesel engine was ~$3,500. (2005 Volkswagen Jetta, TestDrive.com) A seven year investment to break even, longer when you consider time/value of money. Do you think an "ethanol tuned" engine would carry this type of premium? (I recognize, that is a hard question to answer, but critical to the success of a producer of such engines.)
I appreciate the links on the Miller engine. Good reading for me later. And "engineering gobblegook" is what pays my bills. Thanks. A while back a read an article by a Saab Automotive Engineer talking about a new line of engine built specifically from ethanol. He was stating the lower energy content was going to produce a lower MPG but expected people to break even because of the lower price of ethanol. If I can find it again, I'll ping you to it.
You believe there is a way to separate the molecular bond of Hydrogen and Oxygen using less energy than is received by recombining them in a fuel cell or a combustion process?
If this was true, you could mount them both on a vehicle, give it some water and it would run forever. Do you believe in perpetual motion machines?
This hasn't risen to the level of an argument and it's obvious you aren't a scientist.
but I have faith in Man's ability to overcome any obstacle. Obviously you do not.
I have faith in mankind and I also understand what efficiency and heat loss and entropy are. If you can come up with a way to create hydrogen that gives as much energy output as input then you'll be very wealthy. You might want to look up thermodynamics before you try.
I'll never change your way of thinking and you'll never change mine.
How can I change your mind when you don't understand what we're discussing?
Sooner or later someone will figure out a way to make it work
Maybe I'm jumping too quickly to a conclusion. Make what work?
The Saab article isn't the same thing you are talking about. They were adjusting timing and Turbo to better use E85 with a 104 Octane. Ping to you none-the-less.
http://www.edmunds.com/insideline/do/AutoshowArticles/articleId=108748
Can you explain in terms that are specific why it takes more energy than it creates to extract hydrogen from water?
If you can, would you, I will try to follow your logic. Give me enough information so I can research your logic. If you can be math specific, I would appreciate.
I am curious.
Continuing this conversation is pointless.
I believe there is a way that we haven't discovered yet.
That is what I said. If you are out to prove your intellectual and scientific superiority, let me save you the trouble.
I don't know, I'm not trying to develop anything that does this. I have no idea how it works.
Happy?
That being said, I still believe there is a way for this to happen, we just haven't discovered it yet.
I believe we will continue to find "better" ways. We will increase efficiency. I do not believe we will overturn the basic laws of physics to do so.
Thermodynamics is hard.
Because of inefficiencies at every step. It could be theoretically equal, if you could do everything with pure superconductors that have no resistance, every calorie of heat released or required had zero movement in or out of the system, all products and reactants could be moved in and out without energy being spent. But there is some inefficiency in every step of the process, consequently each step requires some additional energy from somewhere.
Good writeup.
Too bad 99% of the MSM (and almost all Americans) can't follow (nor even understand!) his logic.
First, burn fuel to create steam and drive a turbine to create electricity. How much energy is lost in this process? Now push that electricity thru a wire to the site where you're creating the hydrogen fuel. How much energy lost thru electrical resistance? Convert the current from A/C to D/C, more loss. Now use the energy that's left to split hydrogen from water. More energy lost to heat.
Take the H2 and run it thru a fuel cell, more loss.
If you can be math specific, I would appreciate.
I might have a link with specific numbers. If I get a chance, I'll look around.
Thanks.
What we need is a multi-tiered approach.
1. Nuclear Power for 100% the nation's power grid.
2. Develop Bio-fuels, alcohol, methanol, bio-diesel, etc.... City Buses, school buses, garbage trucks, big vehicles with diesel engines but geographically locked to a specific area, convert to biodeisels or biofuels or other alternate fuels.
3. Use wind power, solar power, hydro-power to crack hydrogen from water to power fuel cells.
4. Start using the higher-efficiency diesel engines in Vans, SUVs and small cars.
5. Pass federal legislation that any vehicle getting 50 mpg or better can be purchased tax free (no city, county, state or federal taxes).
The left will still whine about something else. It's in their nature. Bunch of cry-babies!
OK, I now recognize from reading more closely that several of us here on this thread are engineers, and several are not.
We engineers are making references to thermodynamics, but we're not doing well at explaining the thermo issues to the non-engineers here. Therefore, without the engineering/physics lingo, here are the three laws of thermodynamics which constrain all issues of energy creation, conversion and use, in the joking manner that engineers use to remember them.
1. "You can't win."
This is the law that states that you cannot pull out of a system more energy than you put into it. This is the law that is used to negate all sorts of various quack perpetual motion schemes, as well as claims for things like hydrogen that it is a "fuel" instead of an "energy transfer mechanism."
2. "You can't even break even!"
This is where engineering starts sounding like the Dismal Science of Economics. If "winning" is doing better than breaking even, then breaking even would be simply achieving 100% energy efficiency as we change the form of energy; eg, if we could break even, we could convert electricity to mechanical power without any loss due to heat in the conductors, or we could convert electricity into hydrogen into mechanical energy without the evaporative losses of liquid H2 going to gas and floating away.
Mind you, "you can't break even" doesn't mean that we shouldn't try. At all levels in the engineering game now, the quest is on to eliminate or minimize as many inefficiencies and losses as we possibly can. The hybrid car, or super-efficient electric motors, superconductors -- these are all ways we're trying to get closer to breaking even. But we all know that we will never, ever achieve a "no loss" situation in energy conversions. All we can do is minimize waste and loss.
There is one caveat: you can break even, if and only if you cool the universe down to absolute zero, ie, zero Kelvins. Since most things assume a rather solid, steady and uninteresting state of being at this (lack of) temperature, it is a rather academic break-even point.
3. "You can't quit the game."
This means that if you live in this universe, laws 1 and 2 apply, and without inventing a whole new universe with whole new physical laws, and then moving you and your invention there, you can't get around laws 1 and 2. Just ain't no way.
With respect to hydrogen:
Let's say we have some wonderful new way to create massive quantities of H2 cheaply. It is a given that there is no "free" pool of H2 just sitting around on earth. We all agree that hydrogen is plentiful on this planet, but it is all bound up into some other matter: water, hydrocarbons, organic matter, metal hydrates, etc, etc, etc. It does not exist in a free, unbound form.
OK, so we all agree on that. Now to get H2, this means we must unbind it from where ever/whatever is holding it - let's assume water.
So, let's assume (for the sake of argument) electrolysis of water, which gives us 2H2 + O2 as a result, yes?
We have to use some type of power to generate the electricity. We have "X" electricity we generate.
Now we must conduct that power to the plant where we do the electrolysis. We lose some there. We do the electrolysis. In the process, some H2 is going to be leaked away. More loss. Now we want to liquid H2 to make it dense for transportation. Now we're stuffing in an incredible amount of power into this process to compress/chill the H2, and we're bleeding off the waste as heat in the compressed gas, which is mostly lost.
Anyone who has been around an air compressor can tell you that when you compress a gas, it gets hot. That heat is power being wasted, which we then have to cool off. That's energy loss. And we have more energy loss in the motor(s) to run the compressors, we have losses in friction in pipelines for the gas to be put into the compressor, friction coming out of the compressor, etc.
Now comes the monster losses in an H2 system. SO we have liquid H2. It is a cryogenic liquid, with rather interesting properties. Let's put aside the interesting properties and just deal with the fact that liquid H2 is very, very cold and the surrounding environment on earth is much, much warmer, even if you're located in Siberia:
All cryo liquids absorb heat from the outside environment. As they do this, the pressures become untenable in the storage system, so you have to bleed off the excess pressure -- ie, release gaseous H2. Big losses right there. And you have to do this in every cryo tank along the distribution path, so you have a compound effect of losses.
Getting the picture yet? The first law of thermo tell us that H2, because it has to be extracted from some compound to liberate it, as opposed to just "mined" in a usable form the way we do with coal, oil, natural gas, etc, we'll never get above unity on power creation. We're putting energy into the process of breaking hydrogen away from something. We can never get more energy potential into H2 than we put into breaking the atomic bonds that allowed us to liberate the H2. Got that?
The second law of thermo tells us that we're going to be losing power all along the way from the point where we created H2 from an injection of outside power -- in effect, we're using a very lossy piece of wire to transmit the electrical power we used to liberate the H2 in the first place. We would be better off using conventional electrical vehicles and batteries than using liquid H2.
And the third law tells us that no matter how inflated their egos, the Congress, the POTUS and all the bureaucrats in the US will never be able to mandate that the situation ever becomes any better.
Yes, diesel engines cost more. But there is also a marketing component WRT diesels in passenger cars in the US.
In the EU now, over 40% of all new cars sold are diesels -- small, highly-efficient turbo'ed, common rail or "Pump Duese" (pump injector -- aka 'piezo injectors'), getting mileage like those VW products I'm using for illustration. So customers like the performance. So customers in the EU like diesels and they like the performance they're seeing from tiny little diesel engines (1.8 to 2.2 liter displacement).
In the US, however, GM and others have made such a hash of diesel engine products for the consumer in the late 70's that an entire generation of consumers instantly says "Oh, not this crap again!" when you tell them about diesels. To sell these people on diesel cars, you need to bodily grab them, sit them down in the driver's seat of a prospective car, and force them to drive it.
The fault for this is GM's. GM had some atrocious products in the late 70's -- in particular, a 350-cid engine that they made into a diesel by changing the crank, pistons, heads, etc -- and the result was a roaring piece of crap. It was unreliable, trouble-prone, smoked like it was burning soft coal, you name it.
The second perception of diesels in US consumer's minds comes again from GM, or rather, the Detroit Engine division, who used to make these smoke-belching two-stroke diesels that used to be used in muni bus fleets all over the US. People saw how these things belched smoke, knew they were diesels and it is implanted in their minds that "diesel means thick black smoke."
The first thing we US consumers need to do is start pressuring Detroit to make modern products - and by "modern" I mean "Look at the European engine manufactures, particularly in Germany, and use that as a starting point. Don't try to cheap out of this."
The second thing we US consumers need to do is become informed about what is possible with diesels. With today's computerized fuel injection systems, they no longer smoke -- either at idle or under hard acceleration. They're highly fuel efficient. And they're not slow. The problem of perceived "lack of get up and go" again comes from the 70's -- GM didn't put a turbo on that piece of crap 350-cid V-8 morphadite diesel, which means that until it got up in RPM and "breathing", the performance just sucked the chrome off a bumper hitch.
Today, there are no diesels in cars without a turbo. Period. It is just naturally assumed that "diesel needs a turbo" and that's the truth. They do, to get the highest efficiency and performance out of them.
Next thing diesel cars need: better transmissions. Diesels have a characteristic of developing their torque at low RPM's, and in a narrow band of RPM's. This is why big diesel trucks have 9 to 18 gears in them -- to keep the engine in the RPM range where it is most efficient and developing the best torque. If you can do that, a diesel engined car can fly off the starting line.
You're starting to see ads for 8-speed trannies on luxury cars now, even with gasoline engines. The recent turbodiesel cars being released by MBZ and others are up to six speeds. Want to see the optimum efficiency from a diesel? Get a 10 to 14 speed transmission in the car, and keep that engine within a narrow 200 RPM "power band" and not only will you see your fuel mileage go up, up, up, but the car will fly off the starting line.
Diesels do get much better miliage in similar vehicles.
Increased compression increases temperature increasing effiency. Look up the the Carnot limit. If you understand that, you will understand why.
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