Bio Gas - Free Gas Fuel

[Triffidtraps]

Hi Everyone

Has anyone ever thought of using composting toilet waste to make "Bio Gas" I have seen that if you ferment human or animal waste you can produce you own free "Bio Gas" Which can then be used as a fuel for cooking, Heating or to make electricity

[Dave Thacker]

I've seen specials where people cook over what looks like a contained cesspool. I think you could do it, however, pressurizing and storing the gas would need to be accomplished to make it really useful. Otherwise, It's probably simpler and safer to cook over wood. And, what would it smell like? If it had any ... um... unfavorably familiar odor.... hmmm.... might not be very appetizing. I have no idea really. It's mostly an issue of how do you contain and store the energy? If you used a pump to force it into bottle, something capable of high pressure like a refrigeration compressor, then you have the issue of being certain your not also capturing oxygen and compressing that with the gas. The absence of oxygen in the compressed fuel is the only reason the flame does not rush into the bottle and make a very big explosion. Sounds pretty tricky.

[Triffidtraps]

Hi dave thank you for your reply i saw last year kevin McCloud - "Man Made Home" tv program. Here is the episodes on youtube below. The biogas is in episode 3

http://www.youtube.com/show/kevinmccloudsmanmadehome

In wales there is a biogas refinery that produces biogas from animal waste & uses it to produce over 80kw of electricity.

kevin McCloud built a what looked like a composting toilet that had a pipe which sent the liquid waste into a large 2nd sewage pipe/waterbarrel combined tank which expanded as the gas was generated. He then piped the gas to a camping stove & the gas was pretty much odorless. He cooked on it just like any other gas stove. His design seems to work extremely well. I guess you could use the gas to run a generator or gas fridge or cook on. The only thing i find scary is storing the gas safely on site. But with a good designed tank i guess it would be made safe.

[Dave Thacker]

Very cool. I hadn't found anything to watch this evening and that should fill up the time quite well. Other issues, if your not containing it in a pressure vessel, then there has to be an overflow for unused gas. Does it rise, settle in low spots? Also, Troy's fridge requires gas under pressure to run. It would be cool if it could be worked out however. I've a funny feeling he'll be switching to a compressor type fridge at some point. They are just too efficient and simple. Maybe one more step in battery and another pair of panels and he's there for all his loads. At the rate he's going, it won't be long.

What is the gas that is produced? I would presume methane?

I'll watch the series and get up to speed.

[Dave Thacker]

Trifftraps, man, that channel is not available in the USA. Dang. Oh well, I'll have to dig around form some other interesting videos.

[Dave Thacker]

Plans:

http://youtu.be/l5e_2W71jMM

[Dave Thacker]

Excellent site explaining propane appliances run on only ounces of pressure:

http://www.motleyrvrepair.com/propane_s ... nd_use.htm

[techman]

I have often considered biogas and have studied it online quite a bit. But the only problem I have is the idea of storing a flammable gas. I know, I use propane all the time, but I do not handle it nor fill the bottles, nor make the appliances myself.

I have seen people run generators and heat their home with it though. You collect the gas in a huge balloon, which gives you the pressure you need to run devices with it.

[Triffidtraps]

Sorry Dave i didn't realise you could not view the programs i forgot about the regional restictions stuff !! Thanks for the links on youtube they was interesting

Yes techman i agree storing the gas can be hazardous but if the container is construced well and placed in the ground and in an are away from harm it should be ok. I am suprised just how much gas can be produced in just a few weeks though

[Dave Thacker]

I'm skeptical if you can get as much energy out of Bio Gas (methane) as it takes to produce it. It's only in the availability of free materials (waste) to make the gas where the economy is to be found. Turning trash into energy. Storage is the problem. It does not liquefy at easily attainable pressures. It takes something like 14 atmospheres which is quite high.

However, a metal tank could be filled with a high pressure 12v pump. I saw one on Ebay that went to 250 psi without too much looking.

Imagine a simple system where when the bladder on the digester gets to a certain height, a switch is triggered and the pump runs until the bladder is level again when a infrared emitter/detector is used to detect time to disable the pump.

In this way, you could build up a storage of fuel in a container not subject to wind damage or requiring a problematic hole in the ground.

If you found an 80 gallon compressor tank that was being discarded, used the tank (would be rated for 200psi) and got it up to capacity, I'm not sure how much gas that would be equivalent to. Not be liquefied, it might only be similar to a few pounds of propane.

Propane tanks typically hold only about 110psi from the short research I did. Some investigation would be required to see if it was safe to run them up to 200psi.

All in all, it's doable but I'm not sure the return would be worth it. It might be less work, energy input and money to just cut a little more wood. Hard to beat wood.

A lot of this stuff comes down to a simple thought. Obviously we want to be self sufficient. However, from an efficiency point of view, every 2 hours you work can fill up a 20 lb propane bottle. Is it less work to get the money to get the propane than it is to make that much fuel on your own? It might be 10x the work to make that fuel.

Time might be better spent drilling for another all natural renewable organic resource, natural gas. There are more and more people with their own natural gas supply every day.

What is the economy of effort here?