GEOLOGY

Detailed explanation-1: -Most non-renewable energy sources are fossil fuels: coal, petroleum, and natural gas.

Detailed explanation-2: -As incomes continued to rise, however, coal was slowly replaced with more efficient, convenient, and less polluting fuels such as oil, nuclear energy, natural gas, and, more recently, renewable energy.

Detailed explanation-3: -Some well-known alternative fuels include bio-diesel, bio-alcohol (methanol, ethanol, butane), refuse-derived fuel, chemically stored electricity (batteries and fuel cells), hydrogen, non-fossil methane, non-fossil natural gas, vegetable oil, propane and other biomass sources.

Detailed explanation-4: -Hydrogen. Hydrogen is a potentially emissions-free alternative fuel that can be produced from domestic resources for use in fuel cell vehicles. Natural Gas. Natural gas is a domestically abundant fuel that can have significant cost advantages over gasoline and diesel fuels. Propane.