Basically, a company could offer to install small household methane digesters to provide people with gas for cooking. The only thing one would have to do is call the company when the gas pressure is getting low, the company would come to recharge the digester and haul away the composted material, which could then be sold. Such a business could use food that would otherwise end up in landfills and make use out of it.
Given the amount of gas present, it can probably be much safer or at least as safe as the big propane tanks people have beside their houses. Maybe some sort of rubber bladder would be more acceptable for the regulatory bodies than the two barrels and bricks.
Here's a video of a more polished version of the barrel in barrel style:
An explanation of the telescoping design:
Setting aside the standard propane containers for a moment, how about a bladder inside of a tank, to be filled with water, thus creating pressure in the gas?
Or simply adding water to a tank filled with biogas.
The other thing about that design is that it is a flow-through system, so a little feedstock is added each day and a little effluent is removed each day. It seems to fit the daily routine of most folks.
Here's what they look like: http://www.afrigadget.com/2010/06/09/solving-the-flexible-biogas-digester-problems/
Here's another low tech option, using tire tubes. They use kitchen waste, instead of manure, and 3 kg of waste produces 1 m3 of biogas: https://energypedia.info/index.php/TyreTube_Biogas_Plant
but the double barrel, piston-like design seems really simple and just great to me, like its just what i'd like to persue eventually.
anyone have figures on approximately how much this type of system costs to construct?
also, it seems like the top barrell is loosly placed, which means a lot of methane would escape via the sides rather than going into the barrel, im sure soem ruber could solve this, but is it nessacary to make a good seal or is it good enough to just leave the barrel there and allow it to capture what gas is created directly beneath it
also, what about putting a 50lb weight on top to pressurize it more? such as one used on a weightlifting bar so that it could go around your gas exit...
also, is 50lbs too much from anyones experience?
On a guess, since these systems are actively in use and obviously working the benefit that might be gained by a gasket on the floating barrel is not worth the effort involved. I suspect that the "feed tube" needs to be set at a sufficient height to prevent methane from escaping by that outlet too easily.
I don't know how much air the bacteria involved need in order to do their digesting - that might be another reason not to have the system sealed too well...
Interesting. I had not understood how profoundly simple one of these systems could be.
It's so simple, I'm surprised it wasn't done hundreds of years ago. Or maybe it was and I just haven't heard about it yet
Peter Ellis wrote:We're looking at methane, so it's a heavier than air gas that is not going to go up and out of the barrel just on its own
Methane is lighter than air, I believe.
Peter Ellis wrote:I don't know how much air the bacteria involved need in order to do their digesting - that might be another reason not to have the system sealed too well...
it needs to be sealed from outside air, they are anaerobic bacteria.
Still, they look inexpensive to build, especially if repurposing scrap barrels. Seems a shame to not make methane just because it can't power an entire house by itself. I'd really like to know what the production rate is vs the amount required to meet all a home's energy needs. I'm curious as to how many would be needed for that.
Also, what feedstock would you all use to feed it, keeping in mind you need to add some each day.
Don't know if that's correct or not.
They say the ones in India produce enough gas for cooking, no problem. But, it's supposed to be difficult to produce enough methane to run a generator often enough to consistently charge a battery bank.
Then again, perhaps if it made enough to charge a battery bank 5 times per month, that would be 5 fewer days per month of grid electricity used.
As you can see, I'm clear as mud on methane production & use.
I know digesters aren't consistent producers, varying in output depending on several factors. I figure the methane might be able to reduce the amount of NG one has to supply.
Anyone know what size digester would be needed to meet that demand each day?
Refrigeration is one of the difficult ones to meet off the grid without patrolium fuel. It might be possible with solar panels, though, and perhaps a generator run off homemade methane as a backup for cloudy/rainy stretches.