I am busy building a bio-digester to produce biogas for cooking/water heating in a cold climate.
I am using the 3 IBC tank solution. Tank 1 is the digester itself. Tank 2 is the gas storage unit. Tank 3 is the pressure for the gas outlet.
Tanks 2 & 3 will be linked. As tank 2 fills with gas, water overflows into a container with sump pump and is then pumped up to tank 3. When cooking, etc, the return valve is opened, allowing water pressure from tank 3 to push the gas in tank 2 towards the house.
I will be keeping tank 1 warm via a combination of insulation and surrounding the tank with decomposing matter from tree cutting & autumn leaves. I will also be running a hot water line through it from a compost heater.
Tanks 2 & 3 pose a bigger logistical challenge.
I brew beer for a living and use ethylene glycol to keep our fermentors & chillers from freezing over. I was wondering if it could also be used in this sort of set up. Aside from the gas outlet from tank 2 to the house, it is a closed system as far as the water is concerned.
However, I am unsure of how the ethylene glycol would react with the biogas. Is it safe?
The biogas will be produced from a mixture of food waste, cooked malts, and animal manure. It will be run through a water filter to prevent blowback (between the house and tank 2) and a steel wool filter (to remove hydrogen sulfates).
Other than pollution issues, should I be aware of anything else? I am worried about the glycol evaporating into the biogas causing an explosion.