Increasing the amount renewable energy sources will indirectly cause less fossil fuels to be burned. Since the burning of non-renewable sources emit various greenhouse gases such as carbon dioxide (CO2) and nitrogen oxides, the decrease in fossil fuel usage will indirectly reduce global warming. Cleaner, renewable forms of energy can be very efficiently used in automobiles - which makes it the best substitute for fuel cars; however the biggest hindrance to the complete replacement of traditional fuels is the much higher price of electric cars. If the price barrier can somehow be broken down, renewable energy vehicles will overtake traditional cars and the world will be much safer.