Page 124 - Biofuels Refining and Performance

Chapter
4

Raw Materials to Produce

Low-Cost Biodiesel

M. P. Dorado

4.1 Introduction
The present energy scenario is undergoing a period of transition, as
more and more energy consumers understand the inevitability of
exhaustion of fossil fuel. The era of fossil fuel of nonrenewable resources
is gradually coming to an end, where oil and natural gas will be depleted
first, followed eventually by depletion of coal. In developing countries,
the energy problem is rather critical. The price paid for petrol, diesel,
and petroleum products now dominates over all other expenditures
and forms a major part of a country’s import bill. In view of the prob-
lems stated, there is a need for developing alternative energy sources.
Alternative fuel options are mainly biogas, producer gas, methanol,
ethanol, and vegetable oils. But biogas and producer gas have low
energy contents per unit mass and can substitute for diesel fuel only
up to 80%. Moreover, there are problems of storage because of their
gaseous nature. Methanol and ethanol have very poor calorific value
per unit mass, apart from having a low Cetane number. Therefore,
these are rather unsuitable as substitutes for high-compression diesel
engines. Experimental evidence indicates that methanol and ethanol
can be substituted up to only 20–40%. There exists a number of plant
species that produce oils and hydrocarbon substances as a part of their
metabolism. These products can be used with other fuels in diesel
engines with various degrees of processing. The development of veg-
etable oils as liquid fuels have several advantages over other alterna-
tive fuel options, such as

107
Copyright © 2008 by The McGraw-Hill Companies, Inc. Click here for terms of use.