Page 154 - Lignocellulosic Biomass to Liquid Biofuels

Lignocellulosic biomass to biodiesel 129

emission, as well as they are generated from available atmospheric CO 2 ,
water and sunlight, and obtained by using biological processes, such as
photosynthesis [6,7]. The biomass contributes to around 10% of global
primary energy, about 55 EJ in 2013, and the technical potential derived
from available annual supplies of residues and wastes has been estimated in
energy terms above 100 EJ/year at delivered costs in the range of US
$2 3/GJ [8]. However, in many regions because of limiting supplies of
these biomass feedstocks, the growth of vegetative grasses or short rotation
crops may be necessary to meet the demand for biofuels. Local field trials
to determine the levels of productivity under a range of growth condi-
tions is required to identify potential energy crops able to grow in mar-
ginal and degraded lands and avoid the direct competition with food
chain and fiber crops, which require better quality of arable lands.
In recent decades, many countries are implementing biofuel policies to
reduce the dependence on fossil fuels, to improve energy and food secu-
rity or to create job opportunities and to develop the rural regions.
Around 4.4 EJ were produced as liquid biofuels in 2014 [9]; ethanol and
biodiesel currently supply about 3% of world’s energy demand in road
transport, with forecasts to contribute up to 30% in 2050, when it is
expected that 1.7 2.1 billion cars will be running in our planet, about
2.6 times the global fleet in 2010 [8,10]. The renewable alternatives to
the increasing consumption of liquid fuels are essentially liquid biofuels
(Fig. 4.1).
Global biodiesel production, around 30 billion liters, is based largely
on vegetable oils, mostly from rapeseed and sunflower (Europe), soybeans
(United States, Brazil, and Argentina), palm (Indonesia), and other sources
such as jatropha and coconut, cooking oils (the main feedstock in China),
and animal fats [11]. The top producers were the United States, which
accounted for 16% of the total production, followed by Brazil and
Germany (both with 11%), Indonesia (10%), and Argentina (9.7%).
Europe accounted for 39% of global biodiesel production in 2014 [8].
Different raw materials used as feedstock for biodiesel, including agri-
cultural residues and lignocellulosic biomasses, have recalcitrant properties
that represent a critical factor for their use and require highly efficient,
environmental friendly, and cost-effective pretreatments for subsequent
hydrolysis and fermentation processes [12,13].
Nevertheless, lignocellulosic biomass, which is the most abundant and
biorenewable biomass on earth is the feedstock offering the most promis-
6
ing perspectives [14,15]. It has been estimated that 3700 3 10 tof