Proc. Natl Acad. Sci. USA http://doi.org/cd6c (2017)

Credit: TOMASZ KOZAL/ALAMY STOCK PHOTO

Energy transition requires a growth in green power, and wind energy is one such growing industry. Turbines extract kinetic energy from wind and convert it to electricity, but without downward transport of kinetic energy from higher in the atmosphere to replace the extracted energy, the size of wind farms and spacing of turbines contribute to limit the rate of electricity generation.

Most wind farms are located on land with generation limits of ∼1.5 W per m2 for large farms; however wind speeds are often greater over the ocean. There are now a number of offshore wind farms, predominantly in shallow coastal areas, whereas the strongest winds are further offshore. To understand the potential of an open ocean location, Anna Possner and Ken Caldeira of the Carnegie Institution for Science, Stanford USA, investigate where wind speeds are greater and if there is downward replacement of energy. They show that the North Atlantic is a region where transport of energy from above may be greater than that on land. Potential limitations are the seasonality of winds and the lack of technology suitable to withstand the open ocean environment. However giant wind farms in this location could, theoretically, provide energy to meet current world demand.