GC: n

CT: This analysis reviews and synthesizes the literature on the net energy return for electric power generation by wind turbines. Energy return on investment (EROI) is the ratio of energy delivered to energy costs. We examine 119 wind turbines from 50 different analyses, ranging in publication date from 1977 to 2007. We extend on previous work by including additional and more recent analyses, distinguishing between important assumptions about system boundaries and methodological approaches, and viewing the EROI as function of power rating. Our survey shows an average EROI for all studies (operational and conceptual) of 25.2 (n = 114; std. dev = 22.3). The average EROI for just the operational studies is 19.8 (n = 60; std. dev = 13.7). This places wind in a favorable position relative to fossil fuels, nuclear, and solar power generation technologies in terms of EROI.

S: http://www.sciencedirect.com/science/article/pii/S096014810900055X (last access: 10 December 2014)

N: 1. energy (n): 1590s, “force of expression,” from Middle French énergie (16c.), from Late Latin energia, from Greek energeia “activity, action, operation,” from energos “active, working,” from en “at” + ergon “work, that which is wrought; business; action”.
Used by Aristotle with a sense of “actuality, reality, existence” (opposed to “potential”) but this was misunderstood in Late Latin and afterward as “force of expression,” as the power which calls up realistic mental pictures. Broader meaning of “power” in English is first recorded 1660s. Scientific use is from 1807. Energy crisis first attested 1970.
return (n): late 14c., “act of coming back,” also “official report of election results,” from Anglo-French retorn, Old French retorne, verbal noun from retorner (see return (v.)). In ball games from 1833; specifically in tennis from 1886. Meaning “a yield, a profit” is recorded from 1620s. Meaning “a thing sent back” is from 1875. Many happy returns of the day was used by Addison (1716). Mailing return address attested from 1884.
2. While diesel’s energy density is an undeniable asset, of even greater significance is its energy return. A fuel’s energy return on energy investment ratio, sometimes referred to by the acronyms EROEI or EROI, is a metric used to gauge its production efficiency. It turns out that a fuel’s energy return also has broad social and economic significance, and this essay explains that significance in a way that hopefully makes it accessible.

S: 1. OED – http://www.etymonline.com/index.php?allowed_in_frame=0&search=energy+return&searchmode=none (last access: 10 December 2014). 2. http://www.resilience.org/stories/2013-08-11/the-social-implications-of-energy-return (last access: 10 December 2014).

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CR: energy