They are circular though and with that should count as zero-emission:
1: steer calf is born from cow
2: calf gets his goolies cut off turning him into an ox
3: ox eats grass, burps and farts and shits it out on both ends. Some of his shit ends up as fertiliser for the grass he or one of his fellow bovines eat
4: eventually ox gets eaten
The input: grass -> cow -> oxen
The output: oxen -> shit -> grass
From grass they came, to grass they return. If someone were to be so kind as to shrink bovines down to, say, bumblebee-size it would be easy to do an experiment with that in one of those glass-sphere closed ecosystems. I'm pretty sure they'd thrive.
They are circular though and with that should count as zero-emission:
1: steer calf is born from cow
2: calf gets his goolies cut off turning him into an ox
3: ox eats grass, burps and farts and shits it out on both ends. Some of his shit ends up as fertiliser for the grass he or one of his fellow bovines eat
4: eventually ox gets eaten
The input: grass -> cow -> oxen
The output: oxen -> shit -> grass
From grass they came, to grass they return. If someone were to be so kind as to shrink bovines down to, say, bumblebee-size it would be easy to do an experiment with that in one of those glass-sphere closed ecosystems. I'm pretty sure they'd thrive.