Man has always used natural resources . Today we are destroying the environment. The exploitation of natural resources makes necessary to find new alternative , less polluting resources. The evolution of scientific research has developed renewable energy sources including wind and solar energies. Wind farms use the power of the wind, transforming it into energy . They transform fossil fuels into electricity. But gas, oil and coal create air pollution. One effect of this pollution is higher global warming. Many people believe that this causes modifications on the climate called climate change; they say we need to use cleaner forms of energy for example solar power, hydroelectric power, and wind power from wind farms.