Posted on 02/08/2007 12:58:09 PM PST by aculeus
I was following all this pretty good until they had to throw in the numbers 205 kcal/mole, via the following reaction: CH4 + 2O2 => CO2 + 2H2O ÄH = 205 kcal/mole . They lost me there.......
Sorry if it sounded like I was singling you out; but I have noticed lately, even in MSM publications that there is a great tendency to use loose for lose and to use lead for led and I can't figure out why.
I'm a natural speed reader and it brings me up short every time I encounter one of these potholes in the language.
Have a good day.
Apparently there was a memo that the rest of us never received. It also included exchanging I and Me ;o)
I would like to add a few items to your totally correct list.
1. Petroleum hydrocarbons are the second most abundant source of hydrogen on Earth, after the oceans.
2. Gasoline is a mixture of hydrocarbons - chemically similar molecules, all with a straight or branched chain of carbon atoms, plus a number of attached hydrogen atoms. Collectively, all can be represented by the generic formula:
H - (CH2)n - H
where "n" can be any number up to perhaps 40 or so. The lightest is Methane (CH4), the major component of natural gas. Carbon has an atomic weight of 12 and Hydrogen 1, so Methane has a molecular weight of 12 + 4 = 16, 25% of which (by weight) is Hydrogen.
3. Propane, which can be liquefied at ambient temperatures and relatively low pressure, is C3H8, with a molecular weight of 12 x 3 + 8 = 44, and is 18% Hydrogen by weight.
4. Gasoline is a mixture of medium weight liquid hydrocarbons, but can reasonably be represented (on average) by Octane, C8H18, which has a molecular weight of 8 x 12 + 18 = 114, and is 15.8% Hydrogen by weight.
5. One "mole" of Hydrogen gas at Standard Temperature and Pressure (STP = 68F, 14.7PSI) has a volume of 22.4 liters (6 gallons) and weighs 2 grams. Liquid Hydrogen has a specific gravity of 0.070. This means 1 liter would weigh 70 grams, and 22.4 liters would weigh 1568 grams.
6. Six gallons of gasoline would weigh approximately 6 x 8 x .75 = 36 pounds, x 16 oz/lb x 25.4 grams/oz = 14,360 grams. 14,360 x .158 = 2269 grams of Hydrogen, in the same space, without compression.
7. 2269 / 2 = 1135, x 14.7 = 16,677 PSI pressure required to achieve the same density of Hydrogen in the same size tank. This would be 2269 / 1568 = 1.45 times as dense as LIQUID Hydrogen, and beyond current production technology.
8. Low molecular weight hydrocarbons are the most efficient way to store Hydrogen that God ever designed, and if you want something better, you should ask Him to do it. According to His rules, the fuel of the future will not be much different from what we use today, whether we continue to find and refine it, or manufacture it from other sources of Carbon and Hydrogen.
NOTE: I realize that I used a mixture of units, but I wanted to use familiar terms and measures where possible for clarity, while using constants and characteristics that would be easy to verify.
from February, Robert Zubrin (that’s why I pinged AntiKev).
Jupiter is surrounded by radiation belts so intense that they are deadly to humans and electronics. It also has a massive gravity field that would severely impair hydrogen export operations. These would also be complicated by the 2.5-year Jupiter-to-Earth flight transit time (during which any liquid hydrogen launched would probably boil away), and the fact that upon re-entry at Earth, the imagined hydrogen shipping capsule would face heat loads about eight times higher than those withstood by a space shuttle returning from orbit.
It seems like Zubrin, who I respect very much, has (like most engineers) hardened with age. He was the champion of neglecting the radiation issue on the Mars journey (rightfully). But he says that Jupiter's radiation is too much to overcome. Why can't we aero-brake the capsules into orbit? I'm not arguing his points (yet) I don't have time. But as far as I'm concerned that is just and engineering problem, as Zubrin used to be fond of pointing out.
I'll read the whole thing and post a more detailed analysis later.
Okay, after having read the whole thing. Bob has a hard-on for Methane. And I don’t blame him. I agree 100% that methane and methanol are much better logistically than hydrogen. But hydrogen is the holy grail. Much like self-sustaining fusion. That’s why we will always see research money pumped into hydrogen technologies. As long as the glimmer of hope is there...someone will fund it.
That being said. Bob’s numbers are sound, there’s no doubt about that. And sometimes chemistry and physics win out. Well...the fundamental laws always win out. But I’ve learned to take even the most learned scientists with a grain of salt when they say that something is impossible.
“When an old and esteemed scientist says something is possible, he is most probably right. When that same scientist says something is impossible, he is most probably wrong.”
Long read, I’ll finish it later.
Unless and until the Laws of Thermodynamics are repealed, that is true of every energy source. The relevant question is how much the production of this energy source costs.
Ethanol also costs more energy to produce than it can provide. Although ethanol is much less costly to produce than hydrogen, it is still costlier than oil, which is why it is only produced due to mandates, subsidies and high tariffs against imports, and it now appears also at the cost of distorted grain and foodstuffs markets.
Rather than a government solution of mandates, subsidies and tariffs, we ought to look at market-based solutions, such as replacing oil and gas power generation with nuclear and taking the government restrictions off oil production in ANWR and the Outer Continental Shelf and domestic gas. Sensibly done, ethanol will be part of the mix, but not the sole answer.
Hydrogen, absent a technology breakthrough, is likely a long-term solution, when (and if) demand for oil, supplemented by ethanol, drives its price so high as to begin to make hydrogen an attractive alternative.
Please check with me before you use my punch line please. But if we work at night, that means we will have to use lights on the sun. This could confuse animals that hunt at night. Since you made the suggestion before I had a chance to, you get to write the enviromental impact statement.
I hate those methane hard-ons. Just one person lights a match...
...and the whole thing goes up in flames. Talk about a party trick.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.