154
livestock according to Gerber et al. (2013). Research suggests that the digestibility
of rice straw could be improved by up to 20% by pretreatment methods, such as
nutrients and inoculants (Sarnklong et al. 2010). In cattle, a 1% increase in straw
digestibility equates to a 4% increase in growth rate and proportional drop in yieldscaled emissions.
9.4.3 Bioenergy
9.4.3.1 Straw Combustion for Thermal Bioenergy
Rice straw can serve as a low-cost and renewable fuel source for combustion power
plants. According to LCA on the use of rice straw as thermal bioenergy in Thailand,
emissions can be reduced by 1.79 kg CO 2 eq kWh
−1
compared to coal power and
1.05 kg CO 2 eq kWh
−1
compared to natural gas-based power generation. Delivand
et al. (2011) found that substituting natural gas or coal fuels with rice straw fuels for
power generation would result in a considerable fossil fuel savings and lower
GHGEs. It was estimated that 0.378 tCO 2 eq t
−1
straw and 0.683 tCO 2 eq t
−1
straw
could be avoided if rice straw substitutes natural gas or coal in the power generation
sector, respectively.
9.4.3.2 Straw Anaerobic Digestion for CH 4 Bioenergy
Agricultural residues, such as rice straw, offer a valuable alternative feedstock for
biogas production since they contain a considerable amount of carbon that is beneficial for anaerobic codigestion with animal manure (Mussoline et al. 2012).
Anaerobic digestion (see more details in Chap. 5) is a biological process that can
degrade waste organic material by the concerted action of a wide range of microorganisms in the absence of oxygen. The process converts a large portion of rice straw
into biogas, which is typically a mixture of methane (60%) and carbon dioxide
(40%). If captured, biogas can be utilized as a clean fuel for heat and power generation. In principle, anaerobic digestion is an attractive option for mitigating the CH 4
associated with straw incorporation. However, in actual practice, particularly for
small-scale anaerobic digestion, the technology has not proven efficient enough to
be the most feasible mitigation strategy. Improving the technology to reduce leakage and match the digester capacity to biogas use in small-scale applications may be
required to be a viable mitigation option.
Regarding the use of rice straw for bio-ethanol production, a review by Cheng
and Timilsina (2011) reported that all advanced biofuel technologies have the
advantage of producing fuels with almost zero or very little net emissions to the
atmosphere.
J. Allen et al.
livestock according to Gerber et al. (2013). Research suggests that the digestibility
of rice straw could be improved by up to 20% by pretreatment methods, such as
nutrients and inoculants (Sarnklong et al. 2010). In cattle, a 1% increase in straw
digestibility equates to a 4% increase in growth rate and proportional drop in yieldscaled emissions.
9.4.3 Bioenergy
9.4.3.1 Straw Combustion for Thermal Bioenergy
Rice straw can serve as a low-cost and renewable fuel source for combustion power
plants. According to LCA on the use of rice straw as thermal bioenergy in Thailand,
emissions can be reduced by 1.79 kg CO 2 eq kWh
−1
compared to coal power and
1.05 kg CO 2 eq kWh
−1
compared to natural gas-based power generation. Delivand
et al. (2011) found that substituting natural gas or coal fuels with rice straw fuels for
power generation would result in a considerable fossil fuel savings and lower
GHGEs. It was estimated that 0.378 tCO 2 eq t
−1
straw and 0.683 tCO 2 eq t
−1
straw
could be avoided if rice straw substitutes natural gas or coal in the power generation
sector, respectively.
9.4.3.2 Straw Anaerobic Digestion for CH 4 Bioenergy
Agricultural residues, such as rice straw, offer a valuable alternative feedstock for
biogas production since they contain a considerable amount of carbon that is beneficial for anaerobic codigestion with animal manure (Mussoline et al. 2012).
Anaerobic digestion (see more details in Chap. 5) is a biological process that can
degrade waste organic material by the concerted action of a wide range of microorganisms in the absence of oxygen. The process converts a large portion of rice straw
into biogas, which is typically a mixture of methane (60%) and carbon dioxide
(40%). If captured, biogas can be utilized as a clean fuel for heat and power generation. In principle, anaerobic digestion is an attractive option for mitigating the CH 4
associated with straw incorporation. However, in actual practice, particularly for
small-scale anaerobic digestion, the technology has not proven efficient enough to
be the most feasible mitigation strategy. Improving the technology to reduce leakage and match the digester capacity to biogas use in small-scale applications may be
required to be a viable mitigation option.
Regarding the use of rice straw for bio-ethanol production, a review by Cheng
and Timilsina (2011) reported that all advanced biofuel technologies have the
advantage of producing fuels with almost zero or very little net emissions to the
atmosphere.
J. Allen et al.