EROEI [energy returned on energy invested, or net energy] is to a civilization what gross profit is to a business, the source of the surplus that supports the entire enterprise.
![EROEI [energy returned on energy invested, or net energy] is to a civilization what gross profit is to a business, the source of the surplus that supports the entire enterprise.](http://cdn.quoteddaily.com/images/john-michael-greer/eroei-energy-returned-on-energy-invested-or-net-energy-is-to-a-civilization-what-gross-profit-is-to-a-business.jpg)
EROEI [energy returned on energy invested, or net energy] is to a civilization what gross profit is to a business, the source of the surplus that supports the entire enterprise.