Second-generation Bioethanol (2G), also referred to as next-generation biofuels, are fuels that are manufactured from various types of non-food biomass. It is produced from lignocellulosic biomass such as agricultural residues comprising stocks and stems from cereal crops like rice, maize etc. and uses industrial by-products such as crude glycerol as feedstock. Lignocellulose is considered a renewable and inexpensive carbon source, and its availability depends on crops grown in specific regions. Various types of plant biomass like dedicated energy crops have also been used in the production of such biofuels. Maximum potential sources of lignocellulosic biomass include an agricultural waste (wheat straw, corn cob, rice husk, cereal straw, and bagasse), industrial wastes (brewer’s spent grains and grains from distilleries), municipal solid wastes (food waste, kraft paper, and paper sludge containing cellulose). Forest-based woody wastes are the other potential sources of lignocellulosic biomass.
The most striking difference between first-generation and second-generation biofuels is that the former is produced directly from edible portion of crops like rice and other cereals, maize, sugar beet and cane whereas the latter is produced from industrial and household wastes and residuals.