Climate Change Mitigation - Climate Resilient Agriculture for Ensuring Food Security - page 321

energy used in growing and processing the bioen-
ergy feedstock (Spatari et al. 2005 ).
A signifi cant barrier to production of biofuels
from grain is the competitive need of the grain
for food and feed. Systems to utilize cellulosic
biomass are not yet commercially viable,
although much research and subsidies are being
implemented to stimulate its use. Even if research
at the laboratory scale is promising, challenges
exist in scaling up the infrastructure to provide a
feasible supply chain for cellulosic bioenergy
(Richard 2010 ).

on results in an unacceptably small net reduc-
tion in fossil fuel use (Scharlemann and
Laurance 2008 ).
• Production systems with suitable enzymes for
utilizing cellulosic feedstocks have not yet
become commercially viable.
• The resources for biogas generation are not
properly managed to generate its maximum
biogas potential.
• The lack of availability and the structural
operation of biogas digesters are not able to
generate and develop family size biogas
plants.
The use of husks as a fuel appears to be a
promising mitigation option. Husk could be used
for direct burning, in biomass gasifi er, as bri-
quettes or as solid char. Its relative cost is around
US$4 per t CO 2 e saved, and the reduction poten-
tial ranges from 0.9 to 1.2 t CO 2 e ha −1 (depending
on the level of biomass production). Rice husk
can easily be collected at milling facilities, so
that this source of renewable energy seems even
more promising than utilization of straw
(Wassmann and Pathak 2007 ).
The potential for mitigation is huge, particu-
larly if cellulosic biomass sources can be com-
mercialized. However, the economics are such
that biofuels require help from legislation and
subsidies to penetrate the market, at least in parts
of the USA where currently a proportion of gaso-
line must be ethanol at certain times of the year
more to mitigate air pollution from ozone than to
mitigate GHG emissions (Regalbuto 2009 ), and
there is a legislative mandate for 16 billion gal-
lons of cellulosic ethanol by 2022 (Robertson
et al. 2008 ). Similarly, Europe has a mandate that
10 % of all transport fuels be from renewable
sources by 2020 (Robertson et al. 2008 ).

13.3.2 Advantages

• Some of the biofuel production such as Jatropha
and oil palms can be grown in dryland and fal-
low area, through commercial experiences.
• About 70-88 million biogas plants can be run
with fresh/dry biomass residues.
• The substrates such as cattle waste and
biomass used for this technology are easily
available. Their availability to biogas plants
can meet the requirement of 12-30 million
families.

13.3.3 Disadvantages

• A larger area of land will be required to satisfy
global biofuel demand. Projected growth of
biofuel crops until 2030 may require over
30 million hectares of land (IEA 2009 ).
However, Field et al. ( 2008 ) suggested a need
for 1,500 million hectares of land under culti-
vation of biofuel crops. Melillo et al. ( 2009 )'s
calculations show biofuel crops would require
1,600-2,000 million hectares by the year 2100
assuming most fuel demand would be met by
biofuels by this time. It is practically impos-
sible to spare such a large area of cropland to
grow biofuel plants.
• The land requirement for biofuel crops would
compete with that for food and feed crops,
causing food prices to increase.
• In many cases for current ethanol production
from grain, the fossil fuel associated with use

13.4 Mitigation Potential

13.4.1 Technical Mitigation Potential

Figure 13.16 outlines the technical mitigation
potential differentiated between management tech-
niques and all affected GHGs. It can clearly be seen
that the more sustainable management of croplands
has a substantial potential for mitigation.