Sustainability aspects of biofuels
number of reasons.
2.2. Biofuels' feedstock and future projections
There are mainly two types of liquid biofuels, which have significantly grown in the last
decade: that is bioethanol and biodiesel. Bioethanol is based on sugar, extracted from
sugarcane and beet, or starch, which mainly comes from maize, wheat or cassava. Starch-
based crops must be first converted into sugars in the saccarification process, which requires
substantial volumes of enzymes to turn starch into sugars (Soetaert, W. 2008). The starchy
products represent only a small percentage of the total plant mass. Other plants' building
blocks like cellulose and lignin are currently not being used to make biofuels as there is not a
commercial viable production method for making ethanol form cellulosic biomass (FAO,
2008).
Biodiesel is based on the oil crops, such as rapeseed in Europe and soybean in the USA and
Brazil. In tropical regions, biodiesel feedstock can also be sourced from palm, coconut and
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