methane from a septic tank can this be practical to use as fuel?

 

You won't get much from a septic tank, but if you have access to lots of waste cow or chicken manure it is a source of methane that can be used for fuel.

FABMANDELUX.

 

I do not know if a diesel engine can be converted to run on methane or not. I do know that gasoline engines can.
It is not dissimilar to conversion for using Propane.

I think the downside to using methane recovered from animal waste is collection, purification, and compression. While it is possible to do these things doing them on anything less than a large comercial scale is not practical. It may not even be economically practical on that scale, I say that because I believe someone would be doing it already if it was practical.

 

I would be remiss if I didn't say I think it is a crappy idea.... ...he he he.

 

Yes, you can use Methane in a diesel engine! The injector pump is set to the idle setting and "wired" shut, then Methane is introduced into the intake and controlled by a "butterfly" valve for throttle control.


The regonal land fill near where I live recovers the methane generated by the rotting garbage and compresses it for later use. There are 6 large dairys near here and they all are building metane digesters fed by the cow poop and use it to fire their boilers.

It can also work in a small scale too. In 1979 when I lived in Ark, we used a 55 gallon drum digester to fuel our gas hot water tank, and gas cook stove. We used grass clippings, moldy hay, etc.

There are lots of people using it to stay "off-grid" today!

FABMANDELUX.

 

ok guys by now you should know how hardheaded i am. i need better answer than those.

lets say we modifed a septic tank that could collect all the methane and we had alcohol gas trap that we could monitor it and we added stuff to the tank such as wilted cabbage from super market trash, beans, sawdust, leaves what ever so we could get this thing realy brewing

remember this thing will be brewing 24 7

just think about the last time you ate cabbage or beans now that just a small portion and maybe half of what its capable of.

and we had a GO metro converted to run methane.

how many miles do you think we could go on a week worth of methane?

 

Try these:
http://www.energyjustice.net/digesters/
http://www.habmigern2003.info/biogas/methane-digester.html
http://news.surfwax.com/energy/files..._Digester.html


FABMANDELUX.

 

Yes a diesel engine can be ran off of Methane, which is more commonly refered to as Natural Gas. The conversion ratio is now up to 70% nat gas 30% diesel. Really increases stationary engine runtimes in times of natural disasters. Altronic Inc. bought the company that invented it and is really expanding its business line.

As for pullonthis21, you would need a pressure tank to store the methane in, and a compressor to compress it. The tank is really not the problem, the compressor able to pick the gas up in ounces or even at a vacuum rated for Nat Gas is going to cost you more than 2 brand new PowerStroke Diesel trucks.

Ryan

 

Compression is the issue, that's for sure.

I deal with natural gas pipelines every day at work, and the smallest compressor I've ever heard of costs around $150,000 for 90 hp. There must be ones smaller than that, but it's starting to be a pretty specialty item. Certainly that's oversized for the home septic system you are talking about. you would need less than a single hp I would imagine.
I have heard a little about people using "microturbines" as electrical generators. Could be another alternative to burning it in your truck.
Our company burns natural gas in some old ford 400 engines to make electricity in one location.

 

There are home-use NG compressors for use with CNG vehicles. YOu connect it to your service, hook it up to your CNG vehicle and it fills your tank overnight. I believe the compressors are under $5000.00.

 

furball69, that sounds perfect. Anyone out there actually have one of these? Are they reciprocating, turbine or screw compressors?

 

Couldn't find any specifics on the pump but I'd guess reciprocating.

found some interesting reads.

http://www.myphill.com/

http://www.mpt.org/motorweek/afv/cng_hr.shtml

http://uk.dgc.dk/pdf/altener.pdf

http://www.greencarcongress.com/natural_gas/index.html

 

When I was making it in 1979 we used a "york" AC compressor with a 2 hp elect motor to compress it enough to put it in "old" propane bottles. We never got it to compress to a liquid tho, that takes 900 psi!


FABMANDELUX.

 

I thought methane had to be cryogenically cooled to -260F to liquify it. Those home pumps do 3600 PSI and they still call it a CNG system, as opposed to LNG. LNG tanks are double walled, super insulated, with a vacuum separating the two walls - to keep the product cold... same as liquid hydrogen fuel cells.

 

CNG stands for Compressed Natural Gas. LNG= Liquified Natural Gas. Gas to your home appliances is regulated in ounces. Only because it comes from a pipeline that has a very big volume and pressure differential. Average pipeline is 20 inch Dia, and runs 990 PSI. City Gates take it to around 60psi in 4, 2 or 1" lines. Factoring that Natural gas has less BTU content than Gasoline you are already at a disadvantage. Pipeline quality Natural Gas is between 970-1130 BTU. Digester or Landfill methane is usually around 500-600 BTU. Effectively you would need to compress the methane to 2000 psi to get enough btu content to make an average trip feasable. (500-600BTU would go half as far as 1000 BTU fuel) Or double the size of the tank. Then you need a much better ignition system to ignite the lower BTU content fuel. Not that I don't appreciate your thinking, or telling you that it couldn't be done, but by the time you do all the above, you could get you a older Ford diesel truck and make quite a Bio Diesel still and be driving for around $.47 per gallon.

Ryan