This article provides a short note on biodiesel.
Biodiesels are diesel like liquid fuels obtained from renewable biological substances. Any vegetable oil (edible or non-edible) and/or animal fats (lard or tallow) can be converted to biodiesel by methyl esterification and can be used in diesel engine vehicles.
Biodiesels therefore are called vegetable oil methyl esters (VOME). Biodiesels are biodegradable and nontoxic. On combustion they produce 60% less net carbon dioxide emission than petro-diesel. As it is produced from atmospheric CO2via photosynthesis no fresh CO2 is emitted, as it is the case with fossil fuels (Table 29.2).
Diesel engines are a type of combustion engine. Rudolf Diesel (1858-1913) originally designed the diesel engine to use vegetable oil as fuel to help agrarian society to compete with large petroleum industry in 1883 (patented). But American petroleum industry soon developed petro-diesel and developed modified diesel engines using petro-diesel, which was cheap and the first biodiesel was developed from groundnut oil.
Profuse petrol supply from Middle East and cheap petro diesel led to suppressions of biodiesel research and development. With gradual exhaustion of the petrol resources worldwide and because of environmental problems of CO2 and NxO gas emission from petrol or petro-diesel the possibility of alternative renewable biofuel searching started since 1970s.
Biodiesel is distinctly different from petro diesel, petroleum and many synthetic diesels produced in recent time. Biodiesels have characters, which are significantly eco-friendly. Most vegetable oils can be converted into biodiesels.
Biodiesels crops and their relative efficiencies are shown in Table 29.2 and relative efficiency of petrol diesel and biodiesels are shown in Table 29.3. It may be noted that biodiesel production potential is again more in USA with their discovery of the algae (trade secret) for commercial production of biodiesel (Table 29.3).
Environmentally biodiesels are quite eco-friendly but several other aspects are to be considered seriously.
The scarcity of edible vegetable oils and conversion of cereal crop able lands to vegetable oil cultivation may lead to shortage of vegetable oil and food plants. Already Indonesia and the Philippines have cut down 10 million acres of tropical forests for Palm oil cultivation. Environmentalist and Statesmen must be careful about this.