Working windmills in the suburbs of Amsterdam, North Holland, The Netherlands

Combine harvester in a wheat field, Herefordshire, England, United Kingdom

Military helicopter hovers in clearing in Ulu Temburong National Park, Brunei

Military helicopter hovers in clearing in Ulu Temburong National Park, Brunei

Combine harvester in a wheat field, Herefordshire, England, United Kingdom

Combine harvester in a wheat field, Herefordshire, England, United Kingdom

Helicopter from aircraft carrier USS Nimitz, Los Angeles, United States.

Helicopter from USS Nimitz, Los Angeles, United States.

Presidential helicopter leaves London with George W Bush on board after his official visit to Britain

Revolving blades of a 2.3 megawatt wind turbine, Blacklaw Windfarm, South Lanarkshire, Scotland

Revolving blades of a 2.3 megawatt wind turbine, Blacklaw Windfarm, South Lanarkshire, Scotland

Alternative energy source: wind turbines and a canola field