Make Your Own Biogas
October 24, 2008
By Jeff Hoard
The filled drums are kept in a sunroom or solar collector to maintain the proper temperature.
courtesy Jeff Hoard
There is a real possibility that many readers of GRIT have the makings of a methane gas supply right in their backyards and could reduce – or eliminate – their household gas bill each month.
Just a couple of horses or cows, a few goats or pigs, or a couple hundred chickens can supply enough manure to make a substantial amount of biogas that can be used anywhere natural gas is used, or propane with a few adjustments.
Biogas, in simple terms, is the methane/carbon dioxide combination (approximately 70 percent methane and 30 percent CO2) made naturally when organic material decays without oxygen and in a temperature of 85 to 105 degrees.
Digesters are used. A continuous load digester is fed a little organic material each day for continuous operation, while a batch load digester is filled all at once and, as production declines, is emptied and refilled. We use a series of 55-gallon drums, and combine the two methods. We dump and refill one drum every couple of weeks for an uninterrupted and continuous supply of gas.
We keep the drums in a simple, south-facing, solar collector to reach and regulate the proper temperature.
To collect the gas, poly tubing is run from each barrel into a main line that runs through two simple PVC manifolds. These have the proper shut-offs and moisture drains. They also have the ability to scrub the gas. From there, the gas is piped and stored in a bank of inner tubes. Yes, regular ol’ inner tubes.
The inner tubes store a significant volume of gas while still keeping the pressure fairly steady. These are housed in a storage shed, away from everything, and the gas is pied to the house.
Obviously, the number of drums used determines the amount of gas produced and how much of the house it can power, from a couple of burners on the stove to the whole house (this is more possible in warmer climates, but still doable in cold areas).
The manure used is not wasted, as it is actually better fertilizer after this process than before and with very little odor. The process is simple.
The best part about our system in our situation (being off the grid) is that it is non-electric (the natural pressure produced by the organisms runs the system). I’ve built and installed our water pumping windmills and installed our solar power system, and the biogas system was easier and cheaper to build by far.
There is a lot of information out there on biogas. What I’ve described here is our system in general terms. We sell a booklet that describes the system in detail, with diagrams and photographs plus simple production procedures. It also includes little tricks we’ve learned to avoid problems and keep things running smoothly and trouble free.
Send $5 to HM Ranch, HC 61 Box 6108, Austin, NV 89310. For more information, e-mail me at HMRanch@Hughes.net.