Solar and wind or water power energies are the substitutes to fossil fuels (e.g. petroleum). In the 21st century, with environmental concerns, the environmental advocates emphasize the consumption of ‘clean’ energy to save our planet. In the assumption that solar/wind/water energies are in their efficient production which leads to an affordable market price, what would such result impact the equilibrium condition (e.g. equilibrium price vs. quantity) of the world petroleum market?