What are the impact of wind turbine?
Net energy gain
Modern wind turbine systems have a net energy gain, in other words during their service life they produce more energy than is used to build the system. Any practical large-scale energy source must produce more energy than is used in its construction. The energy return on investment (EROI) for wind energy is equal to the cumulative electricity generated divided by the cumulative primary energy required to build and maintain a turbine. According to a meta study, in which all existing studies from 1977 to 2007 were reviewed, the EROI for wind ranges from 5 to 35,[15] with the most common turbines in the range of 2 MW nameplate capacity-rotor diameters of 66 meters, the EROI is on average 16.[16][17] EROI is strongly proportional to turbine size, and larger late-generation turbines average at the high end of this range, at or above 35.[better source needed] Since energy produced is several times energy consumed in construction, there is a net energy gain.[15] Wind turbine manufacturer Vestas claims that initial energy "pay back" is within about 7-9 months of operation for a 1.65-2.0MW wind power plant under low wind conditions,[18][19] whereas Siemens Wind Power calculates 5-10 months depending on circumstances