The line graph shows the increasing consumption of renewable energy and the major sources in the United States of America from 1949 to 2008. Overall, it is noticeable that renewable energy use more than doubled over the period, led by substantial growth in biofuels, which emerged as a significant opponent against wood and hydroelectric power in the 2000s.
Wood saw steady growth from 1975 to 1985 but reverted to its original level, less than 2 quadrillions British Thermal Unit. Hydroelectric power initially matched wood’s level but experienced more advancement, then declined sharply in the late 1990s. Towards the end of the period, wind power started to become more noticeable, slowly rising to around 0.5 quadrillion Btu.
This suggests that wind power, along with biofuels, is getting ready to replace wood and hydroelectricity as the main sources of renewable energy in the future in order to save the environment and the ozone layer.