Life-cycle green-house gas emissions of onshore and offshore wind turbines

Onshore and offshore wind turbines may have different environmental sustainability due to their own characteristics, and this information is important for future growth of wind power. The paper uses life cycle assessment (LCA) to estimate the life-cycle greenhouse gas (GHG) emissions of onshore and offshore wind turbines with the nominal capacity of 2 MW, to advance our understanding of onshore and offshore wind energy and to inform policy, planning, and investment decisions for future growth of wind power. Results show that the life-cycle GHG emission intensity is 0.082 kg CO₂-equivalent (eq)/Megajoule (MJ) for onshore wind turbine and is 0.130 kg CO₂-eq/MJ for offshore wind turbine, respectively. Offshore wind turbine has larger life-cycle GHG emissions than onshore wind turbine, owing to the floating platform fixed in sea. Onshore and offshore wind turbines have much smaller life-cycle GHG emission intensity than coal power plants. If the installed wind turbines in 2014 displace coal, the saved GHG emissions can roughly reach 5.08 × 10⁷ t CO₂-eq, accounting for 0.09% of global GHG emissions in 2012. The sensitive analysis shows that the lifetime and energy production of wind turbine have large influences on the GHG emission intensity of both onshore and offshore wind turbines, implying that it is an effective way to prolong the lifetime of wind turbine and increase the energy production of wind turbine to reduce the GHG emission intensity of wind turbine. The sensitivity analysis further shows that the distance from wind turbine factory to wind farm site has more significant influence on the life-cycle GHG emission intensities of both onshore and offshore wind turbines than that from wind farm site to the recycling and landfill locations, suggesting that the wind farm site and the wind turbine factory should be as close as possible.