BIOFUELS FOR TRANSPORT SECTOR

Hydrocarbon fuels - also called fossil fuels - have been the main source of energy for the transportation and other sectors for more than a century. However, their rapidly increasing consumption and consequent depletion of reserves clearly show that the end of the ‘Fossil fuel age’ is not very far off. Besides, these fuels are the chief contributors to urban air pollution and a major source of green house gases - considered to be the prime cause behind the global climate change.
Biofuels are renewable hence they can supplement hydrocarbon fuels, assist in their conservation, reduce GHGs as well as mitigate their adverse effects on the climate resulting from global warming. The term biofuels is usually intended to imply fuels sourced from biomass that are used for transportation purposes.
Biofuel include methane, producer gas, alcohols, esters and other chemicals made from cellulose biomass. Biofuels such as bio-ethanol and biodiesel have their own specific advantages.
Bio-ethanol, produced from substrates containing sugar, starches and cellulosic biomass, is an established oxygenate and transport fuel with many advantages:O It is an octane boosterO Being an oxygenate, it improves the combustion characteristics of gasolineO Reduces harmful emissions such as carbon monoxide, hydrocarbons and particulate matterO Readily blends with gasolineO Readily biodegradable, while a oxygenate such as MTBE is not
Biodiesel is produced mainly from vegetable oils and fats. Biodiesel, is commercially available in several countries from the esterification of vegetable oils including rape seed, soybean, sun flower and Jatropha oils as well as from tallow and waste cooking oils. O It can be used for greening waste landsO It is produced using a proven and low-capital-cost technology, hence can be readily implementedO It is biodegradable, non-toxic and free from sulfur.O It has properties that help reduce carbon monoxide, hydrocarbons, particulate matter and O It readily blends with diesel
Biofuels offer many benefits. They are beneficial for the environment because they add fewer emissions to the atmosphere than petroleum fuels on a per kilometer traveled basis, and they often utilize waste biomass resources that currently have no value and require disposal. Unlike petroleum, which is a non renewable natural resource, biofuels are renewable and inexhaustible sources of fuel, assuming the feedstock is produced in a sustainable fashion. Where energy crops are grown domestically, or other biomass sources are readily available for conversion, biofuels can reduce a country’s dependence on the vagaries of imported oil price fluctuations and uncertain supplies. The use of biofuels could therefore help to strengthen the energy security and boost a nation’s economy should crude oil prices reach and maintain levels above around $50/barrel.
All petroleum-derived fuels suitable for transport vehicles are compounds containing predominantly carbon and hydrogen atoms. Other constituent elements generally regarded as undesirable contaminants such as tetraethyl lead have been added in the past to modify fuel properties so as to reduce the tendency of the fuel to ‘knock’ during combustion in an internal combustion engine. Other chemical additives such as nitro methane have been added to specialty fuels to improve power output.
Liquid biofuels differ chemically from fossil fuels in that they contain oxygen in addition to the carbon and hydrogen atoms. As with fossil fuels, they may also contain other elements, notably nitrogen and once again this is generally regarded as an undesirable impurity.
For biofuels there is some discrepancy between their specifications and the measured octane or cetane number since the tests were originally developed for hydrocarbon fuels. A direct comparison between the octane and cetane numbers for fossil fuels and biofuels may therefore be misleading when compared in terms of engine performance. However, the measures can be used indicatively to show the suitability of the fuels for various applications.
Bioethanol and biodiesel are the two most common types of biofuel currently used around the world. This is due to good availability of suitable feed stocks, a relatively good understanding of conversion technologies and the opportunity for practical implementation by being able to blend the biofuels with petroleum-based gasoline or diesel.
The potential for biomass-derived products as lubricants is also gaining interest. Good varieties of oil seed rape have been bred for the good lubricity characteristics of the oils and have long been used in aircraft. They are also biodegradable, have low toxicity and therefore tend to be more environmentally acceptable than mineral oil, which can cause adverse effects on soils and plants when poorly disposed of.
With rising world prices of crude oil and petroleum products and increasing dependence on imports, developing countries is becoming more and more vulnerable in the matter of energy security. Biofuels will mitigate this vulnerability and other adverse effects of use of fossil fuels. In addition, harnessing of large areas of arable land resources for plantation of suitable energy crops will promote sustainable development and employment, mainly in rural areas.