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:
“Reckoned physiologically, everything ugly weakens and afflicts man. It recalls decay, danger, impotence; he actually suffers a loss of energy in its presence. The effect of the ugly can be measured with a dynamometer. Whenever man feels in any way depressed, he senses the proximity of something “ugly.” His feeling of power, his will to power, his courage, his pride—they decline with the ugly, they increase with the beautiful.”
—Friedrich Nietzsche (1844–1900)
“I cannot trust myself to put in words what I feel at this time. Every kind thought that is in your minds and every good wish that is in your hearts for me finds its responsive wish and thought in my mind and heart for each of you. I love this city. It has been my own cherished home. Twice before I have left it to discharge public duties and returned to it with gladness, as I hope to do again.”
—Benjamin Harrison (1833–1901)
“Young women especially have something invested in being nice people, and it’s only when you have children that you realise you’re not a nice person at all, but generally a selfish bully.”
—Fay Weldon (b. 1933)