Electric generation by wind turbine is growing very strongly. However, the environmental impact of
wind energy is still a matter of controversy. This paper uses Life Cycle Assessment, comparing two
systems: a 4.5MWand a 250Wwind turbines, to evaluate their environmental impact. All stages of life
cycle (manufacturing, transports, installation, maintenance, disassembly and disposal) have been
analysed and sensitivity tests have been performed. According to the indexes (PEPBT (primary energy
pay back time), CO2 emissions, etc.), the results show that wind energy is an excellent environmental
solution provided first, the turbines are high efficiency ones and implemented on sites where the wind
resource is good, second, components transportation should not spend too much energy and, third,
recycling during decommissioning should be performed correctly. This study proves that wind energy
should become one of the best ways to mitigate climate change and to provide electricity in rural zones
not connected to the grid.