Wind turbines 32 m blade of a 1.5 MW turbine Hub height: 80 to 100 m Rated power: 1-5 MW
Global simulations GATOR-GCMOM model, a one-way- nested global-to-regional Gas, Aerosol, Transport, Radiation, General Circulation, Mesoscale, and Ocean Model; 47 vertical layers (5 intersecting rotor swept area); Coarse resolution (4 o x5 o ); 4-years simulations (2006-2009).
Global simulations – continued Power curve of REPower 5 MW turbine inserted directly in code
100-m winds, no extraction of energy by wind turbines Mean wind speed ~ 8.1 m/s
Equations for extracting energy from wind via turbines Kinetic energy E extracted from a wind turbine over time step t: E(t) = P EXTR (V(t)) x t New wind speed v at (t+ t): P EXTR =instantaneous power extracted from wind via turbine power curve M=mass of air in layer
Wind power and speed with turbines everywhere on Earth Number of turbines = 1,200 Millions Total extractable power = 253 TW Mean wind speed ~ 4 m/s
Wind power and speed with turbines over land only Number of turbines = 300 Millions Total extractable power = 80 TW Mean wind speed ~ 7 m/s
Wind power from 4 million turbines in three selected configurations 7.4 TW 2 TW4 TW
Global/Land saturation wind potentials Jacobson and Archer (PNAS, 2012)
Global/Land saturation wind potentials Jacobson and Archer (PNAS, 2012) Theoretical wind power potential Practical wind power potential 70
Wind turbine parameterization Our turbine parameterization reduces winds at hub height and accounts for correct momentum extraction; Roughness parameterization incorrectly reduces winds most at the surface. Jacobson and Archer (PNAS, 2012)
Wind turbines reduce evaporation and surface temperature Turbines slow surface winds, reducing evaporation, warming ground at first but reducing latent heat release, cooling the air. The reduction in water vapor, a greenhouse gas, cools the air and ground further.
The Cape Wind met tower today Cost estimate to replace arms: <$300K
Conclusions Renewable energy is the only way to stop pollution, global warming, and ocean acidification and to provide endless energy; Wind power potential is >250 TW (colossal); Wind power extraction can potentially impact global climate, but only at colossal extraction rates; At scale of global energy demand (~10 TW), wind power extraction does not cause climatic effects; Cape Wind could become unique met/ocean research platform for <$300K. HELP!!!