Wind Energy

Electricity is perhaps the most versatile energy carrier in modern economies, and it is therefore fundamentally linked to human and economic development. Electricity growth has outpaced that of any other fuel, leading to ever-increasing shares in the overall mix. This trend is expected to continue throughout the following decades, with large – especially rural – segments of the world population in developing countries climbing the “energy ladder” and becoming connected to power grids (UNDP 2004). Electricity therefore deserves particular attention with regard to its contribution to global greenhouse gas emissions, which is reflected in the ongoing development of low-carbon technologies for power generation. The main purpose of this chapter is to provide a bridge between detailed technical reports and broad resource and economic assessments on wind power. The following aspects of wind energy are covered: the global potential of the wind resource, technical principles of wind energy converters, capacity and load characteristics, life-cycle characteristics, current scale of deployment, contribution to global electricity supply, cost of electricity output, and future technical challenges. Wind power is the second-strongest-growing of renewable electricity technologies, with recent annual growth rates of about 34%. The technology is mature and simple, and decades of experience exist in a few countries. Due to strong economies of scale, wind turbines have grown to several megawatts per device, and wind farms have now been deployed offshore. The wind energy industry is still small but competitive: 120 GW of installed wind power contributes only about 1.5% or 260 TWh to global electricity generation at average capacity factors of around 25%, and levelised costs between 3 and 7 US¢/kWh, including additional costs brought about by the variability of the wind resource. The technical potential of wind is larger than current global electricity consumption, but the main barrier to widespread wind power deployment is wind variability, which poses limits to grid integration at penetration rates above 20%. Life-cycle emissions for wind power alone are among the lowest for all technologies; however, in order to compare wind energy in a systems view, one needs to consider its low capacity credit: Adding emissions from fossil-fuel balancing and peaking reserves that are required to maintain overall systems reliability places wind power at about 65 g/kWh. Wind power’s contribution to twenty-first century emissions abatement is potentially large at 450–500 Gt CO₂.