Renewable energy comes from natural resources like rain, sunlight, wind, tides, and geothermal heat. The conventional fuels are getting replaced by the renewable sources in four different areas like hot water or space heating, rural energy services, electricity generation and motor fuels.

Mainstream forms of renewable energy

The mainstream forms of renewable energy are listed below.

• Wind power
• Hydropower
• Solar energy
• Biomass
• Biofuel
• Geothermal energy

Among these various forms of renewable energy, biofuel is used for transportation.

Biofuels are derived from biomass and it includes a wide variety of fuels like liquid fuels, biomass, biogases, etc. Liquid biofuels include biodiesel and bioethanol. Gaseous biofuels are synthetic gas, landfill gas, and biogas. Bioethanol is an alcohol fermented from the sugar components of plant materials especially from starch and sugar crops. Biodiesel is derived from recycled greases, animal fats, or vegetable oils.

Power generation for automobiles

The term alternative fuel vehicle means any vehicle that runs on fuel other than the conventional petroleum products for instance diesel, gasoline etc. The need of the hour is to design alternative power generating systems across the countries of the globe and leading automobile manufacturers. This need has suddenly come up due to a number of factors including the stern environmental laws, hefty taxes levied on fuel, probability of norms relating to reduction in the emission of greenhouse gases and many more. A number of research and development works are in progress regarding this issue.

The production of vehicles using electric power, internal burning of fuels, GCI, HCCI, fuel cells, energy of stored and compressed air, alcohol, combustible fuel, etc has been stressed upon as it is sustainable. Particularly, use of ethanol and butanol are being much stressed upon.

Ethanol can be produced using petrol or natural gas. It is emerging as the favorite among the researchers as it can be easily made from fermentation of starchy substances derived from agricultural products like sugarcane, grains, etc. Ethanol is considered to be the most renewable one. Ethanol in its pure form can be used as a fuel for vehicles. However, it is generally used as a gasoline additive to raise octane and improve emissions from vehicle. Butanol production is done from natural products. Biodiesel can also be used in its pure form as a fuel for vehicles. Usually, it is used as a diesel additive to decrease levels of particulates, hydrocarbons, and carbon monoxide from vehicles run by diesel.

The discussion will not be complete if hybrid vehicles are not mentioned. A famous model is the gasoline-electric engine where electric batteries help in driving during acceleration and other applications where more power is needed. Hydrogen is used as primary fuel in a hydrogen-car. The solar energy is also harnessed to develop solar cars.

Thus, a gist of the discussion is to point out the growing opportunities that the non conventional energy sources are opening to combat the fuel crisis in near future.