That was kind of my point. You're always going to put more energy into making hydrogen than you get out of it. Every time you do an energy conversion, you lose some. Now you could get around this, if you had an electrolysis plant with a 40 acre array of solar collectors out back powering it.

 

That's well (?!) known, and irrelevant since with the exception of fossil fuels and derivatives, one always need to put in more energy in one way or another, even though some of those energy might be free, thanks to our mighty Sun.
Obviously, the hydrogen won't be generated onboard in the vehicle by electrolysis ( see: "Water as a fuel" ) since an electric vehicle would be a lot more efficient. Although it would be possible to generate H2 on-board, for instance: LiH + H2O = H2 + LiOH. but I don't think this would be suitable for various reasons.

One could use nucler, wind, or solar energy to generate electricity (no greenhouse gases for either one!) that is used for the electrolysis of water either in a plant, or right in the gas-station.

 

I see that no one mentioned digester gas yet. I see that some cities are starting to collect and use it off of their waste water treatment plants.

Heck, us country folk almost all have septic tanks that we could harvest from. Most propane carbs I've looked at are listed as exceptable for use with digester gas, so maybe you could even run the household apliances on it.

 

Eat beans, America needs the gas!

Sorry, I couldn't help but add a little levity to the disucssion. You really are on to a good idea there Cap'n. It's probably better to do something with all that garbage, and, um, other unutilized resources.

 

Maybe even hook up the seat to the carb for occasional shots...

Digester gas, I believe is nostly methane (CH4) with some C2H6, NH3, H2S, etc. added, so it's somewhat close to CNG that ddn't fare too well in the past. I'm not sure if a small-scale, home operation can make a good enough gas (H2S is bad!!) at a reasonable cost in sufficient quantity. It would definitely be good enough for heating to augment natural gas, for instance.

 

I am a strong advocate of biofuels. I am coming from a political view on the subject which I won't go into here, but I am trying to learn more about the technical aspects of gasoline substitutes so I keep reading.

One question, what exactly does this statement mean?

Also, I found an article on making butanol which I sent to my best friend who is a phd chemist, and he thought it sounded better than ethanol and very easy to make. So what's the difference?

 

The latent heat of vaporization, or really, the standard enthalpy change of vaporization, is the amount of heat that needs to be added to a substance to change it from a liquid to a gas once the substance is at its boiling point. It is usually expressed as energy per amount of substance, such as kilo-Joules/mol (kJ/mol). Imagine heating a pot of water on your stove. Once the water gets to 212degF (or so depending on the air pressure at your location), you will need to add an additional 40.65 kJ/mol of water molecules to turn that water from a liquid at 212degF to a gas at 212degF. Temperature is constant through a phase change.

http://en.wikipedia.org/wiki/Latent_...f_vaporization

I think having a higher heat of vaporization will mean that the fuel will be less likely to turn into a gaseous state where it would be more likely to detonate (causing pinging/knocking).

Range of flammability I think refers to the air-to-fuel (A/F) ratios that a fuel can be safely run at without misfires or detonation. If you run too lean for the fuel (high A/F), you are in danger of detonation instead of combustion. If you run too rich (low A/F), you are in danger of a misfire because you effectively flooded the cylinder with too much fuel.

-Jim

 

I'm with everything you said except this. We WANT the fuel to vaporize. Liquid doesn't burn. Even with gasoline, liquid does not burn. How easily the fuel vaporizes shouldn't be an indicator of its propensity for detonation. Even if it is, you control that by controlling the mixture. IE have enough vapor (gas) in the air/fuel mixture to prevent detonation.

I question that a fuel requiring more engergy to be put into it to vaporize is a good thing toward our goal of better mileage or power output. The energy to heat the fuel to vaporize has to come from somewhere. If you introduce hot air to the intake to vaporize the fuel, then the charge is less dense and power output dropps. If the energy comes from the heat of compression then that's work that the engine has to do to vaporize the fuel. If the heat comes from the actual combustion process, then that is energy absorbed by the fuel to turn to vapor without giving anything to the work being done by the engine.

I think it is true about the higher heat of vaporization. I also think it is one of the factors involved when people who use E-85 observe drops in fuel efficiency.

Kind of like back when cereal was advertized to be "Sugar Fortified!!!" or seeing infomercials for "GENUINE!! Faux (false) Pearls!!!!"

 

It seems to me that whatever the fuel, if it's not fully vaporized by the time it passes the intake valve you are going to have a problem with imcomplete combustion.

 

I thought about that more after posting and wished I had corrected it. I'm stilll thinking about why that would be a good thing. Thanks for catching it.

Butanol

-Jim

 

If it where legal I would be making my own ethanol fule...That particuar law needs to be removed. For more than one reason. People could make their own fule and make their home made ferminted drinks less toxic (lower methanol content).

Just my two pennies, good post too.

 

To put it in laymens terms,..

BTU is a measurement of energy/heat out of an amount of fuel. That measurement equates to work. So,...the more btu you have the more work you can do out of that amount of fuel.

Example,...

If you was to take an amount of diesel fuel from Iraq and burn it then take an amount of fuel from mexico and burn it in the same fashion, the Iraq fuel would show a greater efficiency because of the btu count being slightly higher in that crude than the mexican crude, which means you would use less of the Iraq fuel than you would of the mexican fuel over the same period of time.

 

It is legal in the US. You just have to fill out a permit to be an alcohol fuel distiller. The site below that is mentioned very often has the permit application, plans, and can even sell you a still.

www.ethanolstill.com

Or see what the Alcohol and Tobacco Tax and Trade Bureau (under the Dept. of the Treasury) has to say:
http://www.ttb.gov/industrial/alcohol_fuel.shtml

-Jim

 

76, yes, we want fuel to vapourize. But many of the components in gasoline vapourize too easily. This means some of your fuel evapourates before you can use it, and the EPA thinks of it as pollution. Butanol has similar vapourization to ethanol. That means that both of these alcohols will have greater difficulty starting in the cold. The extra heat needed is provided during the compression stroke, it is part of the reason that alcohols do very well in higher compression engines. The reason many E85 and ethanol vehicles experience a mileage drop is from gasoline use is because they don't have enough compression to utilize alcohols benefits. Butanol, a three carbon alcohol is closer to gasoline in performance in a low compression engine. But it suffers thesame reluctance to start in cool weather. And making butanol frequently is quite odiferous. There is a farmer someplace who is making cheese whey into butanol, ethanol, and acetone. I don't recall the exact proportions you get of each, but his method gives off all three. Most of your harder to start issues can be solved by blending some gasoline into the mix, 15% or so, like is done with E85. Higher power ignitions help as well, like electronics instead of points. DF, on lunch at work

 

I wouldn't read too much into small BTU differences betwwen crudes of different origin. While it's more complicated than the ratio of carbon vs. hydrogen, by an large, the fuel with higher carbon content has more BTU. Which looks nice on paper, but higher carbon fuels may not work as well in an internal combustion engine, and they may not burn as clean as a lighter fuel either. And the latter is getting more and more important, that's why we have oxygenated gasoline now.