Great post @clausewitz! It is a basic rule that plants get only a small part of the sunlight they receive. Animals that eats plants receives much smaller part of that energy and when that animal is killed and eaten up, the amount of energy received is very very low. So, it takes a lots of resources and time to raise an animal for food. On the other hand energy received from plants are more in proportion than the energy received from animals.
We can save our earth by adopting vegan diet.