In physics, energy economics and ecological energetics, energy returned on energy invested (EROEI or ERoEI); or energy return on investment (EROI), is the ratio of the amount of usable energy acquired from a particular energy resource to the amount of energy expended to obtain that energy resource. When the EROEI of a resource is less than or equal to one, that energy source becomes an "energy sink", and can no longer be used as a primary source of energy.
Read more about Energy Returned On Energy Invested: Non-manmade Energy Inputs, Relationship To Net Energy Gain, Economic Influence of EROEI, Criticism of EROEI, EROEI Under Rapid Growth
Famous quotes containing the words energy, returned and/or invested:
“The tendencies of the times favor the idea of self-government, and leave the individual, for all code, to the rewards and penalties of his own constitution, which work with more energy than we believe, whilst we depend on artificial restraints.”
—Ralph Waldo Emerson (1803–1882)
“A steam ran small and terrible and shrill;
it was so still;
the stream ran from the oak-copse
and returned and ran
back into shadow.”
—Hilda Doolittle (1886–1961)
“Whenever parents become overly invested in a particular skill or accomplishment, a child’s fear of failure multiplies. This is why some children refuse to get into the pool for a swimming lesson, or turn their back on Daddy’s favorite sport.”
—Cathy Rindner Tempelsman (20th century)