68
H. A. Tajarudin et al.
straw (203.61 Mt year
−1 ), and cane bagasse (180.73 Mt year
−1 ) (Sarkar et al. 2012).
Asia is the main producer of rice straw and wheat straw, while America is the top
contributor for corn straw and cane bagasse generation. The total of four sources
can potentially produce 418.9 GL per year bioethanol, in which rice straw alone
can potentially produce 205 GL per year (Kim and Dale 2004; Georgieva et al.
2008). For the campus scope, the agricultural residue still among the contributor
for the waste in the campus as clearly in the majority of the campus throughout
the nation having their some area of clear land which allows the students or staff
to farm anything. Unfortunately, during the harvesting process, commonly a huge
agricultural residues are throw away/burn. By implementing the technique that was
written in this review, all the campus should be implemented this technique.
Forest residues include by-products of wood processing mills (sawdust and woodchips) and forest harvest residues from logging operation and forest thinning. These
residues typically contain a substantial amount of bark that has different biochemical
composition and structure than wood. Bark has less carbohydrate with more extractives and ash, thus leads to lower ethanol yield than woody biomass (Taherzadeh
et al. 1997). However, debarking of logging residues is not necessary due to technical challenges and cost related issue. It was reported that bark inclusion (up to 30%
dry weight) in the feedstock has a negligible effect on hydrolysates fermentation.
The recorded ethanol yield was able to reach more than 0.43 g g
−1 (Robinson et al.
2002). Though not all the campus have forest area (some campus having large area of
reserve forest), but they are still in the campus which has their own backyard which
is being kept for the landscape purpose. So, the residue also can be applied in the
bioprocess for harvesting the bioethanol.
Municipal solid waste (MSW) is waste generated from household and commercial establishments. Generally, most MSW contains high fractions of organics and
papers with lower amounts of inorganic material such as plastics, glass, and metals. Estimation on annual MSW generation around the world has exceeded 2 billion
tonnes per year, which suggest a potential threat to environmental sustainability in
near future (Karak et al. 2012). With regard to that matter, bioethanol derived from
MSW is definitely one of the promising solutions. A study reported that net life cycle
energy used in producing MSW ethanol is less than the energy used for producing
corn ethanol or cellulosic biomass ethanol (Kalogo et al. 2007). The production of
MSW-ethanol also requires less energy from the petroleum source, thus saving more
fossil energy (Taherzadeh and Karimi 2008).
Patently, cost-effective, and well-established technologies are required for
economically feasible bioethanol production. Apart from the difficulty in saccharification process, feedstock characteristics also determine the total cost of bioethanol.
Although plant biomass is cheap and abundant, few challenges remain as critical
impediments. These include low biomass yield, naturally recalcitrance and costly
feedstock’s management. The recent breakthrough involves genetic engineering
technology for expression of desired feedstock characteristics in dedicated energy
crops. The introduction of ester linkage into the lignin backbone by Ralph et al.
(2014) gives nearly double saccharification yield of glucose as compared to normal
biomass. Other researches have increased biomass by up to 63% whereas ethanol
H. A. Tajarudin et al.
straw (203.61 Mt year
−1 ), and cane bagasse (180.73 Mt year
−1 ) (Sarkar et al. 2012).
Asia is the main producer of rice straw and wheat straw, while America is the top
contributor for corn straw and cane bagasse generation. The total of four sources
can potentially produce 418.9 GL per year bioethanol, in which rice straw alone
can potentially produce 205 GL per year (Kim and Dale 2004; Georgieva et al.
2008). For the campus scope, the agricultural residue still among the contributor
for the waste in the campus as clearly in the majority of the campus throughout
the nation having their some area of clear land which allows the students or staff
to farm anything. Unfortunately, during the harvesting process, commonly a huge
agricultural residues are throw away/burn. By implementing the technique that was
written in this review, all the campus should be implemented this technique.
Forest residues include by-products of wood processing mills (sawdust and woodchips) and forest harvest residues from logging operation and forest thinning. These
residues typically contain a substantial amount of bark that has different biochemical
composition and structure than wood. Bark has less carbohydrate with more extractives and ash, thus leads to lower ethanol yield than woody biomass (Taherzadeh
et al. 1997). However, debarking of logging residues is not necessary due to technical challenges and cost related issue. It was reported that bark inclusion (up to 30%
dry weight) in the feedstock has a negligible effect on hydrolysates fermentation.
The recorded ethanol yield was able to reach more than 0.43 g g
−1 (Robinson et al.
2002). Though not all the campus have forest area (some campus having large area of
reserve forest), but they are still in the campus which has their own backyard which
is being kept for the landscape purpose. So, the residue also can be applied in the
bioprocess for harvesting the bioethanol.
Municipal solid waste (MSW) is waste generated from household and commercial establishments. Generally, most MSW contains high fractions of organics and
papers with lower amounts of inorganic material such as plastics, glass, and metals. Estimation on annual MSW generation around the world has exceeded 2 billion
tonnes per year, which suggest a potential threat to environmental sustainability in
near future (Karak et al. 2012). With regard to that matter, bioethanol derived from
MSW is definitely one of the promising solutions. A study reported that net life cycle
energy used in producing MSW ethanol is less than the energy used for producing
corn ethanol or cellulosic biomass ethanol (Kalogo et al. 2007). The production of
MSW-ethanol also requires less energy from the petroleum source, thus saving more
fossil energy (Taherzadeh and Karimi 2008).
Patently, cost-effective, and well-established technologies are required for
economically feasible bioethanol production. Apart from the difficulty in saccharification process, feedstock characteristics also determine the total cost of bioethanol.
Although plant biomass is cheap and abundant, few challenges remain as critical
impediments. These include low biomass yield, naturally recalcitrance and costly
feedstock’s management. The recent breakthrough involves genetic engineering
technology for expression of desired feedstock characteristics in dedicated energy
crops. The introduction of ester linkage into the lignin backbone by Ralph et al.
(2014) gives nearly double saccharification yield of glucose as compared to normal
biomass. Other researches have increased biomass by up to 63% whereas ethanol