the science behind stripping methane requires some extremely complex engineering.
Read that sentence five times.
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The science itself is not terribly hard. As Joel said, the process is the bitch.
Ok, now then. Lets be clear, I'm not turning anything into a big know-it-all. I've probably got a few details incorrect, and mini-setups on Mythbusters don't work int he long-term. Just because you can create a cubic foot of methane doesn't mean you can do it consistently and run machines with it.
Methane, in and of itself, is a viable source of BTUs. Methane is a BY-PRODUCT of decomposition. Other gasses are released as well. It can come from animal waste, compost of garbage, all sorts of sources.
This is where the term
stripping comes into play. Methane must be isolated from the total release of gasses. Production of propane and butane are similar processes.
All of these gasses have a different specific gravity. Under conditions of temperature and pressure they will separate. Trapped within the raw vapor is a whole bunch of undesirable chemicals. Carbon, water vapor, and anything else that is capable of evaporation, depending on the source.
I'm sure a few of you are familiar with the concept of a gas chromatograph. A few probably even use them in laboratory settings.
As you selectively create the mechanical environment prime for isolation of methane (meaning the pipe-works), the other shit will drop out in condensate, and create a wet toxic sludge. These undesirable condensate particles are known as "heavies". The remaining gas is raw methane, and anything lighter can be flamed off as it rises above the optimum gravity, as it passes through a process of gas scrubbing.
You must pass the gas through cooling pressure drops to make this happen, which means compression and pressurization must occur, in order to - in turn - reduce pressure in the separation processing. To make that pressure, you have to run compressors. To run the compressors, you have to run engines.
Trap raw material, pressurize, drop drop drop, separate separate separate. Result is raw methane and heavies. Scrub scrub scrub, discard garbage, flame other shit, chromatograph, and finally a finished product that is in a BTU range of 1.01 to 1.05
The BTUs must be relatively consistent to burn properly, and any orifice through which the burning tip creates a flame has to be drilled to deliver the gas at a pressure/burn rate. If the BTU quality fluctuates, it'll flame out the appliance.
The whole picture I'm trying to deliver is, all the machinery in the process is extensive. To run one generator, you're gonna have to run at least four engines. Its totally inefficient. It only becomes efficient when you have a very large source of gas, like a thousand acre farm with thousands of animals to produce all that waste. Its like buying a huge fucking wheat combine to farm a tiny little back yard. Not practical.
The little examples you see on YouTube science projects are done by people to show that it can be done, but that doesn't mean the process is efficient for the amount of energy produced in relation to the BTU requirements of any given situation. In a small place where five people live, the ratio is totally ridiculous. If a hundred people were dependent on that delivery of energy, maybe it would be worth it.