Just wanted to see what the concensus is around here. Do you consider propane a green alternative? Burns with better emmisions so is enviromentally friendly? Or is it only a little better than gas as it is still a net release of carbon into the air etc etc? Same with CNG? I used to think it was a greener alternative but nowadays I'm not so sure. Oh, and I certainly don't want to confuse alternative fuels with being automatically green.

 

Well, no one else will venture into this topic, so I will stab at it. If propane proved to be an alternitive fuel that made us less dependent on oil, then I would say yes, and consider a change. But the house is out on that, and I will be damned if I will spend a fortune to do a study. How about you?

 

Well, being it's a hydro-carbon, I'd say it can't be anything other than a net release of carbon to the atmosphere. Thing is it is a much cleaner burning alternative so I'd have to say it's better than gasoline for cleanliness.

 

No "fossil fuel" is green...

 

I've read about 25% 'cleaner' emissions with dedicated propane. Does this ring true with FTE users? Anyone put a sniffer on their propane powered engine versus gas?

Hear you on the hydrocarbon portion. I'm under the impression we have a greater domestic supply of propane/light hydrocarbons than other petroleum. I also think it tends to lag behind gasoline in price - espescially if you can home deliver and home pump. That doesn't necesssarily make it green but it does become easier on the green in my wallet. Is it a significant lesser of two evils or would I be splitting hairs by calling it green?

 

Actually propane is a colorless gas.

Seriously though, propane is a petroleum byproduct, meaning that as long as we're refining petroleum, we should have easy, cheap access to propane. I know some people with a lot of propane vehicles in their fleet and they do have a sniffer. I vaguely recall over 300 PPM CO from a 350 at idle.

 

Propane comes from crude oil and is a very similar hydocarbon to those in gasoline. If retrofitted to an old, carburated gasoline engine, it can reduce some emissions, but not much CO2, by definition. Compared to a modern computerized EFI gasoline engine, no.

CNG and LNG are another story. Most natural gas is domestic and because CH4 (methane) contains for hydrogen atoms for each carbon, CO2 and other emissions are lower. A CNG Crown Vic, for instance, runs so much cleaner than the gasoline version, that California allows them special status, such as single occupant in carpool lanes.

Jim

 

Thanks for the info jimandmandy - didn't appreciate those differences between these fuels. Because of those extra Hydrogens is there more water produced?

 

Every two hydrogen atoms combines with an oxygen atom from the air and makes a water molecule (H2O) and heat that expands the gases and drives the piston.

All of the hydrocarbon fuels produce CO2 which is a greenhouse gas.

Alcohol made from growing things is the only green hydrocarbon fuel because all of the CO2 produced when it burns was originally absorbed by growing plants from the air.

Unfortunately any combustion process can also produce NOx (a pollutant) from the high temperatures involved. That is why we have EGR systems to reduce combustion temps during some engine operating conditions.

 

Yes, there is more water vapor and less CO2.

I should state that LPG usually contains a mixture of propane C3H8 and butane C4H10. Gasoline is a mixture of mostly seven and eight carbon molecules. So, although LPG still comes from crude oil, it does produce proportionally less CO2 and more water than gasoline. Propane, in this regard, is "greener" than gasoline.

Jim

 

Alcohol is not a hydrocarbon, it is a carbohydrate.

Good for beer.

 

Very funny!

 

When you ferment a sugar into alcohol, the sugar is converted into CO2 and ethanol in equal parts by weight. One ton of sugar, fermented, will produce a half ton of CO2 and a half ton of alcohol, roughly. Not sure how much CO2 is left to be released during the actual combustion process; probably not a lot.

 

C2H5OH + (3) O2 = (3) H2O + (2) CO2

You dont get that much CO2 release from combustion, but how much extra is released in order to boil the femented sugar for distillation into pure ethanol? What these simple chemical formulas dont show is how much heat energy is released, in other words, how much useful work you get for the amount of CO2 produced. That is where a supposedly "dirty" fuel, like diesel, may actually be "greener" in some cases.

Jim

 

I'd like to see more CNG usage. It's burned off as waste in other parts of the world, correct?