I would like to ask why you're using anaerobic composting instead of aerobic to get compost for your garden. Aerobic composting is certainly something that requires some more effort than the old compost heap, but it is going to produce less methane and also the heat of aerobic composting discourages insects and possibly other critters, whereas an anaerobic compost heap is warm enough that some insects and animals prefer to lay eggs and have burrows in them, especially when the weather turns cold or they are raising babies...