jsohn

I have been working on engines my entire life and I thought that making a tractor run on poo would be an awesome project but i had never heard of it being done so i set out to try to engineer a solution. This is what i came up with. On dairy farms, cows produce a lot of manure. Storing manure creates methane. Digesters are used by dairy farmers to reduce odors of manure and to capture methane gas. A digester holds manure in an air-tight tank and heats it to about 100 degrees. Bacteria in the manure thrive in these conditions and they consume solids in the manure while releasing methane gas. Ordinarily, the methane would be burned off but why cant you run an engine on it? I have made a tractor run on natural gas and don't see why i should not be able to pipe methane gas out of a dairy farmers digester and send it through an engine that has been outfitted to run on natural gas. What i am asking is will this work and should i pursue this idea? Also correct me on any information that i have presented that is incorrect, i am not a dairy farmer and do not know much of methane.

nikdfish

I've heard of this being done to run a stationary generator, but the problem with using it to run a tractor would be in making it managably portable. I don't know what would be needed to liquify it, but it would probably not be insignificant....

Nick

rsmith335

I think ground up politications would put off more gas.

Mickey

How practical is one thing but is it doable, yes. During WW II in Europe it was not that unusual. Think they used chicken and pig manure. I've seen pictures with digester on the back of the car.

L.A.'s main sewage treatment plant has been running their operation for more than 60 yrs off the methane produced on-site. At the time I visited the site they had 4-5 large engines of about 800 HP each running generators using the methane. Back then the operation was almost self sufficient, costing tax payers $.75/yr per household.

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RRICVV

It's been going on for years with stationary engines so why not tractors?
Here is just one example of an stationary engine running on gas.

YouTube - 1887 Crossley Brothers "Otto Silent"

Whether it be natural gas or methane gas, it will run. As "nikdfish" said, making it portable might be the limiting factor for a tractor...

jsohn

Can't you just mount a propane tank on the tractor and then send the methane into the propane tank under extreme pressure?

nikdfish

Propane tanks don't hold extreme pressure (like that in a scuba tank). Propane is a liquified gas w/ the pressure being that of the vapor pressure of the liquid at the ambient temp, typically less than 150 psi (although the tank is probably rated to 300 psi).

Methane is pretty much what you find in natural gas. Liquid natural gas is typically maintained in cryogenic containers to keep the pressure down. Compressed natural gas, like you find for CNG vehicles, is in tanks with extreme pressure ( 3K psi ?) like a scuba tank...

Nick

snowman17

How do they liquefy the gas to make LP? Can it be done to the methane from manure digesters?

nikdfish

Propane & methane/natural gas are two very different critters.

Propane, is kinda like butane (i.e. whats in lighters) in that it can be held liquid at room temperature under reasonable pressures.

Methane/natural gas - is only liquid at really low temperatures, like minus 260 degrees farenheit low. I believe the liquification process includes generation of tempertures significantly below that to actually condense the gas into a liquid.
Probably not a viable DIY project.

Nick

snowman17

So running engines off of methane works for stationary setups (my local landfill does this with generators), but is not practical for portable engines (tractor, car, ect.)

Mickey had mentioned about digesters being mounted to cars during WWII. Can a portable digester produce a high enough volume to run an engine under load? I'm not sure one could.

nikdfish

I've seen pictures and descriptions of wood gasification generators used to fuel civilian vehicles in wwII, but can't recall ever having seen a methane digester being used...

Gasification generators used heat (usually from burning wood or coal) to release combustable vapors from wood (or other fuel) that could be routed to the vehicle carburetor .

Nick

Larry in OK

Take a look over on Mother Earth News web site. I think there are some articles in the archives about running a pickup on wood gas/methane. It's been a while since I looked at it but I seem to remember the generator pretty well took up the bed of the truck.

urednecku

About 35 years ago there was a local feed-lot that I was told was using the methane to operate their equipment, including tractors. No idea how they did it. (But that company went outta business due to bad management years ago.)
Yea, I think it's do-able, but don't know how practical. Might depend on how much you'll be running it.