Research has shown that a modern wind turbine will recover all of the energy expended in its manufacture, operation and decommissioning within approximately three months. This figure is similar for onshore and offshore wind turbines. Exact figures for energy costs vary depending on the type of turbine, location, etc. However, a reasonable estimate in the construction of an onshore turbine is that (a) foundation energy costs account for up to 5 per cent. of the total and (b) support infrastructure accounts for less than 20 per cent. The rest is primarily accounted for in the manufacture of the turbine itself.
Over an operating lifetime of 20 years, an onshore turbine is expected to recover over 80 times the input energy required. This figure also includes maintenance energy requirements and transmission losses of 6 to 9 per cent. Carbon savings are dependent on the emissions from electricity that would otherwise have been produced from conventional power stations, but it is reasonable to assume that the lifetime savings will be of a similar multiple. The energy recovery for an offshore turbine is expected to be higher due to higher energy outputs over a longer lifetime.