How N. Dakota Became Saudi Arabia

Since I recently switched to gas from oil heat, I don't want to see more CNG vehicles. In large numbers they will drive up heating costs, as heating oil drives up diesel costs during the winter currently does.

Personal concerns aside, I think CNG is a great fuel in large vehicles with a set, local route, such as buses, deliverly, and garbage trucks. For long distance shipping, I think the reduced range and refueling pumps will increase times, and thus costs.

Converting a personal vehicle to it is straight forward. I believe the costs and headaches involved have more to do with local regulations.

The tanks likely wouldn't make it practical for push and walk behinds, but I'd love to have a CNG of LP riding mower or lawn tractor.

 

i wonder how long a 15 hp engine would run on a propane grill tank? we use the big ones on the forklifts at work, but i don't know how much bigger they are, or the hp of the forklifts.

 

You can figure about 0.5 to 0.7 lbs/hp hour for a simple gas engine like that. If it's putting out 15 hp, 7.5+ lbs/hour. At 7hp 3.5+ lbs/hr.

A really efficient engine will use less fuel per hp-hr.

20 lb capacity is a fairly standard propane grill tank.

 

that doesn't sound much more efficient than gasoline, is it cleaner? plus the tank swap that often would be a hassle. i think a 5 gallon gas can lasts me about 4-5 hours.

 

Short version, if you can run 4 to 5 hours on 5 gallons of gas, you will be able to run about 75% to 80% as long on 20 lb of LPG
All else being equal LPG would be cleaner.

Efficiency is about the same in lbs/hp-hr. Brake Specific Fuel Consumption (BSFC). BSFC of an engine is measured in terms of lbs (or grams) of fuel per hp (or kW) hr consumed, not volume so you will use more gallons of LPG for the same power x time.

But yes, it would require a bigger heavier tank. a 20 lb propane tank hold about 5 gallons of LPG but LPG isn't as dense as gasoline so it only has the energy content of about 3.5 gallons of gasoline. 3.5 is from memory but close. It's definitely less than 4.

 

LEHR makes line trimmers and walk behind mowers that run on disposable 1LB propane tanks. LEHR - Environmentally Friendly Technology

I dislike the idea of a disposable propane tank, but they can be reused. 1 LB tanks are very easy to fill from a 20LB tank.
http://www.google.com/products/cata...=X&ei=v7CkTqeqJMu9tge1hYWfBQ&ved=0CJcBEPMCMAk

 

There is no reason to expect better efficiency. Both are petroleum burning internal combustion engines operating on the same cycle.

Tom

 

One would think that a propane mower would be cleaner than gaso. A modern car e.g. Prius has a lot of thought and cat converters given to how to burn cleanly, but these features missing on a mower for sure.

 

A grill tank wouldn't work. It takes the fumes off the top. The tanks for forklifts and other engines have a dip tube to take up the liquid.

It burns much cleaner than gasoline, and would be a big improvement over the little emission controls on a lawnmower.

 

A couple of points about Propane.

Propane contains fewer BTUs per gallon than either gasoline, or fuel oil.

As a result, fuel mileage per gallon ( all else staying the same) is going to go down.

Propane has ~80-90,000 BTUs/gallon, gasoline 125,000, fuel oil, ~ 135,000 per gallon.

http://www.hrt.msu.edu/energy/pdf/heating value of common fuels.pdf

Icarus