good example silage piles. you can make your own with wood chips and grass or straw/hay easily mother earth magazine has good articles about it. can get well over 100 deg C can use it for cooking or hot water.
a larger powerplant could consist of a hybrid car converted into a generator.
might come in handy for running a hottub for free. Have not tested this myself for how it cooks things or smell but some already use such technology for daily living so it must be comparable.
who would be interested in this
restaurants – turn food scraps into refridgerated type dogfood and use the rest like breadscraps and leftover things to make gas. half a 5 gallon pail of scraps should make 1000+ L of gas.
could use a simple water displacement system aswell using 2 barrels or concrete containers. another lady used sandbags on a bag to push the gas out.
https://sciencing.com/compress-methane-gas-liquid-7398367.html not sure how this is stored yet i would really doubt propane bottle would be suited for it using -150 deg c temps and high pressure to make it.
funny way to get poop from cows would be to devise a way to train them somehow or wait untill they fill up with water and startle them somehow ?