backyard methane generators

treecarp,

I'm not sure how they make them in China but I have first hand experience with one here in the States.

Back in the '70s I knew some pig farmers near Klickitat, WA. They ran their entire operation off the methane the pigs (and themselves) produced.

All the waste was funneled into a large two-compartment septic tank. The heavy concrete lid was 'floating' on a water gasket. A hole in the lid was covered by a steel dome. A hose ran from the dome to the intake of a six cylinder ford engine. The engine drove a generator (don't remember the size but it

Sorry treecarp,

My keyboard quit in the middle of that last post.

As I was saying, however; I don't know the exact size of the generator but it looked like one of those old 'torpedo' welders.

The cooling hoses from the engine were attached to stainless tubing that lined the bottom of the septic tank.

Asside from the methane the only other product of that process was water.

You also have a build up of sludge.

After disinfection, this makes a good soil structure conditioner and provides some fertilizer. I think it is potassium deficient, but am not sure.

We are in the process of building one right now which we hope to utilizes as many natural means, with the least amount of external energy to extract through design. We utilize parabolic heating of scavenged water to heat the septic system and help it maintain an optimum temperature. The water is used for other things including to motivate a generator during optimum sunlight. The methane is stored however and it's intended use is for both an automobile (occasionally) and the house primarily in unproductive days or night time use. In your case as in ours, a separate generator will run off the methane but only in emergencies as the house uses battery through inverters, primarily in bad weather and at night. Heat energy is stored for nighttime use as well. Methane converters (I'm taking the term in the sense of breaking it out of the "solid" state and converting it into methane through the collection process, also known as methane digester's) Are not difficult and with some work and a little expense made fairly efficient. However with the right design can have a good ROI depending on what your source is to derive the methane gas. What part of the country are you in? Where you live is important to design and if your trying to utilize a home septic or design one utilizing animal waste. Developing a ceptic system or a collection bed for animal or human waste may get expensive. Also, if you're talking about hooking it up to a spark ignition engine, that may require different metering devices such as an Enco converter. There are much less expensive means in which to meter primarily for a constant RPM. Simple needle valves or ball valves are all you need for that. If your interested provide a bit more information and I'll post what has worked for us. Also, of course, there are sites that have gobs of information related. Here are a couple to peruse for starters: http://www.motherearthnews.com/Renewable-Energy/1973-03-01/Modest-Experiment-in-Methane-Gas-Production.aspx http://www.fao.org/docrep/W7241E/w7241e0f.htm http://www.habmigern2003.info/biogas/methane-digester.html Again good ol' google. So read, learn, implement if it's within your abilities and the idea will provide a reasonable return for the money, time and energy spent to utilize.

Hi treecarp

What is the volume and the nature of your intended input?

To give you an indication (from 40 years ago = plus minus 50%), 1 cow can produce about 8 l of diluted dung mixture per day, That need to stay in there for at least 2 months, The size of your fermentation tank therefore needs to be at least 500 liter per cow. Everything working ok you may expect about 50 l of biogas per day.