Alireza Ghasemi Ghodrat - B.S. Student, Department of Chemical Engineering, Isfahan University of Technology,
Hamid Zilouei - Associate Professor, Department of Chemical Engineering, Isfahan University of Technology

Attraction for renewable energies has been raised, in the recent decades, in order to prevent and control the environmental pollutions and greenhouse gas emissions.Global warning for depletion of fossil fuels together with fluctuation in price and accessibility of them have been increased the tendency of consumers for renewable energies. Consumption of hydroelectricity and other renewable energies has been grown 16% and 96%, respectively, in 2013 relative to 2009. It has been shown that only one fifth of the wind energy potential in the world can generate lectricity which is seven times greater than its global consumption. Moreover, 45% annual growth in photovoltaic power which means doubling every two years, makes it one of the renewables with the highest growth capacity. The amount of energy that stores in 10 km upper part of the earth’s crust is fifty thousand times greater than the energy stores in whole fossil fuel sources. Absorption of 1.83 kg CO2 by generation of 1 kg microalgal dry biomass gives power to third generation of biofuels to supply some part of energy demands in both economical and environmental standpoint. However, high prices technology, difficulties in geographical accessibility, and proper environmental conditions are the limitations of renewable energies. In this paper, some data and information is presented about fossil fuel production and consumption and their longevity, renewable position and projections, adopted policies and barriers to the use of renewable energies and the recommends for the world.

energy, renewable, fossil fuel, policy