Page 195 - Advances in Eco-Fuels for a Sustainable Environment

Anaerobic digestion of various feedstocks for second-generation biofuel production 159

worldwide, leading to the generation of an enormous amount of kitchen waste [9].
Kitchen waste has high organic nutrient content and rapidly decomposes due to the
microbial action. This causes bad smells and diseases that make kitchen waste man-
agement a serious problem all over the world. As kitchen waste is mostly organic in
nature, it is an ideal feedstock for biogas production and therefore the potential of food
and kitchen waste as a substrate for biogas production has been studied widely [10].
Most of the research and development efforts worldwide focus on methods to produce
so-called second-generation biofuels that are identified as having excellent environ-
mental performance as well as high biomass feedstock flexibility [11].
Producing syngas from biowaste is a vital step in the making of most second-
generation biofuels. Several countries of the Organization for Economic Cooperation
and Development (OECD) have established their own biofuel industries for local use
[12]. The annual worldwide production of syngas mainly from fossil energy sources
such as natural gas, oil, and coal is approximately 6EJ, which corresponds to about 2%
of total primary energy consumption [6]. The major producers and consumers of bio-
ethanol (around 95% of the worldwide total) are Brazil and the United States; simi-
larly, for biodiesel the primary ones are Germany, Austria, and France. The preferred
feedstock includes materials that are woody as well as grassy in nature as well as agri-
cultural, municipal, and industrial wastes [13]. The synthetic transportation fuels such
as biomethanol, bioethanol, di-methyl-ether (DME), synthetic natural gas, FT
(Fischer-Tropsch) fuel, and hydrogen, which are produced as well as commercialized
by Sasol (South Africa) and Mobil (United States), are some examples [14] that can be
converted into syngas by a steam reforming process. The syngas derived from biogas
might be used for higher alcohol production.
When biogas development across the world is reviewed, India and China stand no
less than the other countries, even if the thrust is coming from Western Europe. India is
known all over the world for having built the first-ever anaerobic digester in 1897
when human waste was used to generate gas for lighting streets in the Matunga Leper
Asylum in Mumbai [15]. Intensive research in the years 1950, when several designs of
plants were developed. Most remarkable of them, known as “Grama Laxmi III” was
developed by Joshbai Patel (a Gandhian worker from Gujarat). It became the proto-
type for the later day’s Khadi and Village Industry Commission (KVIC) floating-
dome model. After a lull, interest for biogas was renewed at the beginning of the years
1960 when KVIC set up and developed standard biogas plants. It was thus decided to
create a million installations of family size and many other Community installations of
the government, during the sixth plan for five years. It has sustained itself until now
without breakage and has reached 4 million plants (MNRE 2011). The national biogas
and manure management program had planned to set up 150,000 “family-type” biogas
plants during 2009 and 2010 [16].
Biomass is one of the most focused fields in India for renewable energy programs
due to the large quantity of residues generated from crops as well as the energy
demand. About 26 crops from a total of 39 residue crops are considered for the case
study [10]. Overall, India produces 686 MT gross crop residue biomass on annual
basis, of which 234 MT (34% of gross) are estimated as surplus for bioenergy gener-
ation. Rural areas mostly use crops and animal wastes for energy production as well as
to meet cooking energy needs. These two are the primary sources contributing to a