Mean Green

Most of the cars in the world are run by internal combustion engines using gasoline or diesel fuels for propulsion. However, there is massive concern regarding the air pollution caused by the usage of such vehicles hence alternative fuel technologies are being looked into. Other factors that might lead to its decline are the increasing prices of oil-based products and stricter environmental laws. Global warming is finally being recognized as a global issue hence the emission of the greenhouse gases by these automobiles has to be looked into. Other than gasoline and diesel, petroleum products such as Liquefied Petroleum Gas (LPG) and Compressed Natural Gas (CNG) are also used in some internal combustion engines.

Diesel was first used as a fuel in automobiles in the 1930s, introduced by Mercedes Benz and Citroen. Diesel has much higher fuel burn efficiency as compared to petrol. However, they require better filters to handle exhaust gases of fine soot particles which are called diesel particulate matter. Cars that run on gasoline are generally lighter and can work at higher rotational speeds. Sports cars are normally fitted with gasoline engines due to this reason. A catalytic converter may be used to clean up exhaust gases released. Biofuels are also used in some automobiles to increase octane, improve emissions or simply as an alternative to petroleum fuels. Ethanol is used popularly as fuel in Brazil; it caters to almost 20% of the automotive fuel need of the nation.

Electric cars and stream driven engines were produced way before gas powered engines. Steam powered engines could not run until the boiler pressure was available; additionally they tended to be very heavy so they never achieved mass popularity as a road vehicle. Initially, the electric cars had an advantage as they were silent as compared to the loud gas powered engines, a problem which was later rectified. However, there are many reasons which led to their downfall. The batteries of these cards needed to be recharged regularly so they were not fit to travel on for a long range. The extra weight these batteries occupied was another disadvantage. Henry Ford struck the greatest blow in their popularity by mass producing gas powered engines at affordable rates. In the 1950s there was some interest in gas turbine engines but no cars reached production due to high fuel consumption, delay in throttle response and a lack of engine braking. Cars which use compressed air like the Tata/MDI OneCAT Air Car are being developed as an alternative. There are several prototypes available. These cars either use solely air or air combined with diesel/ethanol/gasoline.

Rocket and jet cars are another alternative to the normal road automobiles. These cars are propelled by propulsive jets which are emitted from rocket, turbojet or turbofan engines. In 1997, the ThrustSSC used two turbofans with reheat and was able to go beyond the speed of sound at ground level. It is safe to say, however, these cars will probably never go into mass production for the general audience. The major asset of rocket and jet cars is their ability to reach great speeds.