World Induced Technical Change Hybrid (WITCH) is a regional integrated assessment model structure to provide normative and qualitative information on the optimal responses of world economies taking place due to climatic damages. It normally deals with the cost-benefit analysis or the optimal responses to climate alleviation policies such as the analysis of cost-effectiveness (Bosetti et al. 2007, 2009). WITCH has a very peculiar game-theoretical model which allows for the modelling of cooperative as well as non-cooperative interactions amongst all developing countries. According to RICE (Rice Integrated model of Climate and the Economy), the non-cooperative interaction is the result of an open-loop Nash game where the 13 regions of the world gets interacted on the environmental concerns in a non­cooperative manner, i. e. greenhouse gas (GHG) emissions, fossil fuels, energy research and development, and on learning-by-doing method in the available renew­able sources (Nordhas and Yang 1996). With this, the investment decision in one particular region significantly affects many other regions’ investment decisions at any point of time. Since the economy of a particular region is based on the lines of Ramsey-Cass-Koopmans optimal growth model and thus the model has been solved numerically by an assumption that the central planner is governing the economy (Barro and Sala-i-Martin 2003).

The process of implementation of composite materials is an important step that affects the final properties of the material. The process of implementation of mate­rial composites (thermoplastic matrix reinforced with natural fibers) is carried out

using the extrusion process, which allows the mixture of the two components at molten state. Melt blending processing is considered the method most used to com­pound material composites (Arrakhiz et al. 2013a), it’s more economical, flexible for formulation (Abu-Zahra et al. 2010), and compatible with industrial practice (Kannan et al. 2010). The conditions of implementation are selected so as to

homogenize the fiber/matrix mixture and ensure a good dispersion/distribution of fibers in the matrix, without degradation or fiber polymer matrix.

Extrusion is a process of forming material, but also for the continuous production of final or semifinal products (compound as granules, films, plates, tubes, insulation of cables….) within a system screw/barrel called extruder (Qaiss and Bousmina 2011). The term “extrusion” characterizes the processes constituting to force a material to

flow through an orifice (the dye). The matrix is then carried under the action of pressure obtained by screws. Polymers in the form of powders and pellets are drawn from a hopper of the gap between a rotating screw and heated barrel. They are car­ried forward, compacted, and the melt is convoyed through the dye before solidifi­cation by external cooling. Extrusion process offers also, the possibility to add support for the new polymer composites.

A various concentration of natural fibers (0, 5, 10, 15, 20, 25, 30 wt.%) were blended simultaneously with thermoplastic polymer using a single or twin screw extruder operating at 125 rpm screw for the polymer and 40 rpm for natural fibers. The extruder barrel (seven zones), was heated from hopper to dye in the case of natural fibers at optimized temperatures (respectively to 200, 200, 200, 180,180,180, and 180 °C) (Qaiss et al. 2012, 2013). The fibers are fed from the third heating zone to minimize the residence time of fibers and avoid fibers degradation. The compos­ites (cordon out of the extruder) were cooled in a water bath and then pelletized into granules of 2 mm length. The final shapes of the specimens for various characteriza­tion analyses were molded in an injection molding machine. The optimized tem­perature of injection press barrel was fixed at 200 and 180 °C for nozzle, the mold temperature was fixed at 45 °C (Arrakhiz et al. 2013a).

Bioelectricity has been produced by burning the sugarcane straw in high-efficiency broilers. The production of bioelectricity could reach 11,500 MW by 2015 which would cover 15 % of Brazilian electricity. Brazilian sugarcane mills are self-sufficient for energy to produce more bioelectricity to cover their own necessary demand. Sugarcane bioelectricity offers environmental and economic benefits and a guarantee of electrical energy. Sugarcane bioelectricity is outstanding due to costs competitive­ness and reduction of greenhouse grass emissions.

16.2 Conclusion

Brazil is the main sugarcane-producing country and tries to use sugarcane straw as an alternative energy production. The main challenge is the recovery of sugarcane straw from the field. Mechanical technology can help to recover the straw from the field. Scientists are trying to develop the suitable technology for maximum recovery of sugarcane straw and production of energy.

Yanni Sudiyani, Kiky Corneliasari Sembiring, and Indri Badria Adilina

Contents

20.1 Introduction…………………………………………………………………………………………………… 346

20.2 Lignocellulosic Biomass……………………………………………………………………………………. 346

20.3 Processing of Lignocellulose to Bioethanol…………………………………………………………….. 347

20.3.1 Pretreatment……………………………………………………………………………………… 347

20.3.2 Saccharification………………………………………………………………………………….. 353

20.3.3 Fermentation…………………………………………………………………………………….. 356

20.3.4 Separation and Purification…………………………………………………………………….. 360

20.4 Conclusions and Perspectives……………………………………………………………………………… 361

References ……………………………………………………………………………………………………………. 362

Abstract The demand for ethanol as a substitute of gasoline is rapidly increasing due to the recent increase of imbalance in oil market and interest in environmental issues. First-generation (G1) bioethanol which is currently derived mainly from food crops generate many problems such as net energy losses, greenhouse gas emis­sion, and increased food price. On the other hand, biofuel produced from lignocel — lulosic materials, so-called second-generation (G2) bioethanol, shows environmental advantages in comparison to G1. The development of bioethanol G2 from lignocel- lulosic materials possesses many advantages from energy and environmental aspects. Efficient conversion of lignocellulosic biomass to ethanol and value-added biochemicals is still today a challenging proposition. Basically, four steps are included in the production process of bioethanol G2, composed of pretreatment, saccharification, fermentation, and product separation/purification. In each step, there are several ideas to improve its productivity and benefitability. In this chapter,

Y. Sudiyani (*) • K. C. Sembiring • I. B. Adilina Research Center for Chemistry, Indonesian Institute of Sciences, Kawasan Puspiptek Serpong, 15314 Tangerang, Indonesia e-mail: sudiyani@gmail. com

K. R. Hakeem et al. (eds.), Biomass and Bioenergy: Processing and Properties,

DOI 10.1007/978-3-319-07641-6_20, © Springer International Publishing Switzerland 2014 we describe some details about the production process selection or ideas. New studies such as catalytic conversion of lignocellulosic biomass are also rapidly developing, although they are not yet mature to be utilized for industrial purposes.

Keywords Bioenergy • Lignocellulosic biomass • Pretreatment • Enzymatic saccharification • Catalytic conversion • Fermentation • Bioethanol

20.1 Introduction

Bioethanol, as a liquid fuel by the fermentation of renewable biomass, is important from viewpoint of global environmental protection. Biomass which includes animal and human waste, trees, shrubs, yard waste, wood, grasses, and agriculture residue is a renewable resource that stores energy from sunlight (McKendry 2002). Biofuel produced from lignocellulosic biomass, so-called second-generation (G2) bioetha­nol, shows environmental advantages in comparison to first-generation (G1) bio­ethanol from starch or sugar. However the conversion of lignocellulosic biomass to ethanol is more challenging due to the complex structure of the plant cell wall. The physical and chemical barriers caused by the close association of the main compo­nents of lignocellulosic biomass hinder the hydrolysis of cellulose and hemicellu — lose to fermentable sugars. Pretreatment is needed to alter the structural and chemical composition of lignocellulosic biomass to facilitate the rapid and efficient hydrolysis of carbohydrate to fermentable sugars (Chen et al 2005). The subject of this chapter emphasizes the lignocellulosic biomass in preparation for pretreatment, enzymatic saccharification, and fermentation for bioethanol G2 production and related studies on their catalytic conversion.

Different characteristics and properties of the natural fiber composites have to be investigated in order to maximize their potential usage and implementation in vari­ous applications. Adopting of any new material type in a certain application is lim­ited by several factors that affect its suitability in that particular application (Al-Oqla and Sapuan 2014; Dweiri and Al-Oqla 2006).

It is of paramount importance to know various physical, chemical, mechanical, and biological as well as economic and environmental properties of the composite in order to determine its compatibility with a particular application to ensure its contribution to the industrial sustainability (Al-Oqla and Sapuan 2014).

Abaca grows well in the regions having an altitude below 500 m with an average rainfall and temperature of 2,000-3,200 mm/annum and 27 °C respectively and 75-80 % relative humidity. The latitudinal extent of its successful cultivation is approximately 5°S and 15°N (Moreno 2001). However, the areas with average tem­perature ranging from 20 to 27 °C and having altitudinal extent upto 1,000 m are also suitable for cultivation (Halos 2008; Sievert 2009). The plants require fairly rich, well-drained loamy soil for cultivation. The plants have been reported to thrive well in shade and show improvement in plant height, leaf area, length and girth of pseudostem and more importantly the fiber yield which has been found to be signifi­cantly increased (upto 165 %) under shady conditions (Bande et al. 2012). Recent results have also shown that 50 % reduction in light quality leads to significant improvement in plant height, pseudostem length, and cumulative leaf area.

The increased productivity of abaca under shady conditions has been suggested to be due to decrease in photoinhibition and photooxidative damage (Bande et al. 2013). The plants are propagated by seeds and by vegetative propagules like suck­ers, corm or tissue culture; but the vegetative propagation is the widely adopted practice (Sievert 2009). Suckers are traditionally used for replantation of old planta­tions and corms are preferred for new plantations. The mature rootstock pieces or vegetative propagules are usually planted at the start of the rainy season with the average distance of 2.0 m x 2.0 m and 2.5 m x 3.0 m for smaller and larger varieties respectively. It has been reported that intercropping abaca plants with leguminous plants leads to increased yields as they provide shade effect besides enriching the soil with nitrogenous fertilizers by the symbiotic nitrogen fixers associated with their root nodules (Halos 2008; Bande et al. 2013). The plants are initially allowed to grow for about 12-26 months after which the fibers (petioles) are harvested every 3-8 months. The plants are allowed to grow for a maximum lifespan of 8-10 years and are replaced thereafter. The volcano slopes have been reported to be a preferred environment for its luxurious growth (Borneman and John 1997). Normally the use of fertilizers is not practiced in abaca cultivation but the recent studies have revealed that fertilizer application (NPK) to abaca plantations enhances their growth perfor­mance by positively affecting dry matter production and growth kinetics (Bande et al. 2012, 2013).

Although the abaca cultivars have been introduced to other regions like Malaysia, Central America, Indonesia, etc., they are commercially cultivated in Philippines (except the northernmost part) and Ecuador. The important productive areas of

abaca cultivation are located in Bicol, Caraga, Southern and Western Mindanao, and Eastern Visayas (FIDA 2009). Today it is cultivated in 56 provinces of which the top five producers include Catanduanes, Northern Samar, Leyte, Davao oriental, and Surigao del Sur that account for 32.0, 10.2, 9.8, 5.8, and 5.0 % share in total produc­tion respectively. United Kingdom, Japan, China, Indonesia, and USA are the top­most importing countries of raw abaca fibers and that Germany, USA, Japan Germany, Italy, china, and Hong Kong being the major importer of processed abaca products like pulp, cordage, fibercrafts, and fabrics (FIDA 2012).

Being a renewable resource, the demand for the abaca production is increasing day by day and the reports (FIDA 2012) have confirmed that abaca is being culti­vated on about 172,524 ha and the average production has increased from 66,903 to 73, 274 m. As far as the abaca industry is concerned, the major players include involving about 111,103 farmers, many strippers, classifiers, about 506/17 abaca traders/trader-exporters (licensed), 13 licensed fiber exporters involved in grading and baling process, and many manufacturing or processing units involved in the production of commercial abaca commodities as given in Table 3.1.

As a kind of natural fiber, kapok fiber shows the highest hollowness and the lowest specific mass that any microchemical fiber is incomparable. Kapok fibers consist of natural microtubules with fine tube structure (ca. 8-10 pm in diameter and ca.

0. 8-1.0 pm in wall thickness) (Chung et al. 2008), and the hollow ratio can reach 97 %. One end of the fiber that tapers to one point is closed, and the other end is bulbous shape and may be closed tightly (Xiao et al. 2005). As a single-cell fiber, cotton fiber looks like ribbons, rolled in a helicoidal manner around the axis, while kapok fiber is not convoluted. Figure 6.1 shows the SEM micrographs of longitudi­nal and cross-sectional view of kapok fiber. A longitudinal view of kapok fiber shows smooth cylindrical surface, while a cross section reveals a wide open lumen (Mwaikambo and Bisanda 1999). Kapok fiber shows a unique hollow structure, and this feature is expected to enlarge its specific surface area, endowing the fiber with outstanding moisture transfer property and making it an ideal environment-friendly natural thermal fiber (Feng et al. 2006).

From the fine structure of the walls of kapok fiber, five layers, i. e., cuticle (S), primary wall (W1), secondary wall (W2), tertiary wall (W3), and inner skin (IS), have been clearly observed in lateral and longitudinal cross sections. The W1 is characterized by an interlaced fibril-like network (Xiao et al. 2006), while the fibrils of W2 and W3 are arranged angled or parallel to the fiber axis. The thickness of W1 is about 200 nm, and this thickness seems the same for W2 and W3 (ca. 500 nm). The cuticle S is the protective layer of kapok fiber and shows the highest packing density. In addition, the fibrils of W1 and W3 are closely packed and accordingly, the structure of them is more compact than that of W2. However, the structure of IS is relatively loose, and the fibrils are easily escaped from IS and then dispersed in the lumen. Between the adjacent layers, a transition layer with the low packing density is present. In transitional layers, the interactions between the fibrils are weaker than those in the individual layers. As for different walls, the variety in the fibril size from protofibrils to fibrils is observed for the smallest structural units. The smallest fibril size is found to be 3.2-5.0 nm in different walls (Shi et al. 2010).

The main components of kapok fiber are cellulose, lignin, and xylan (Fengel and Przyklenk 1986; Gao et al. 2012). The outer cell wall layer contains less lignin and more of the minor polysaccharides mannan and galactan and more proteins than the main part. There is a high mineral content in the outer layer which obviously influ­ences the surface properties of the kapok fiber. Kapok fiber includes a high ratio of syringyl/guaiacyl units (4-6) and a high level of acetyl groups (13.0 %) as com­pared with normal plant cell walls (about 2-4 %) (Chung et al. 2008). The bulk density of the kapok fiber is 0.30 g/cm3, the crystallization degree is 35.90 %, and the specific birefringence is 0.017 (Xiao et al. 2005). The kapok fiber shows the well-resolved spectrum of cellulose I, and the crystallinity is lower than cotton fiber (Cao et al. 2010).

To enhance the intrinsic properties or alter the surface characteristics, natural kapok fiber is usually pretreated including (1) chemical treatment, such as alkali/ acid treatment, solvent treatment, oxidation treatment and acetyl treatment, and
(2) physical treatment, such as ultrasonic treatment and radiation treatment, by which the surface impurities can be removed and the interfacial properties will be improved.

Solvent treatment is a popular method to change the surface property of kapok fiber. Previous studies have shown that the kapok fiber has lost their silky luster after solvent treatment. By comparing the spectra of untreated and solvent-treated kapok fiber, the increase in absorption bands at 3,410 and 2,914 cm-1 can be observed, and this information is an indication of the removal of plant wax from the surface of kapok fiber. Except for the above absorption bands, there is no significant variation in other bands for water-treated and chloroform-treated kapok fiber. But for NaOH — treated fiber, the absorption bands at 1,740 and 1,245 cm-1 show a remarkable reduction in their intensities. This is ascribed to the fact that the alkali treatment can remove all the esters linked with aromatic ring of lignin, resulting in a significant de-esterification of kapok fiber. For NaClO2-treated kapok fiber, the absorption bands around 1,602 and 1,504 cm-1 nearly disappear, owing to the cleavage of the aromatic ring in lignin (Wang et al. 2012a).

Furthermore, for untreated, water-treated, HCl-treated, NaOH-treated, NaClO2- treated, and chloroform-treated fiber, the crystallinity index is determined to be 35.34 %, 33.93 %, 22.17 %, 32.00 %, 26.97 %, and 27.17 %, respectively. This result implies that the crystalline region of lignocellulose in kapok fiber shows no remarkable change for water-treated kapok fiber, while HCl, NaClO2, and chloro­form treatment will change the aggregate structure and expand the proportion of amorphous region of kapok fiber. But for NaOH-treated kapok fiber, there appears no remarkable reduction in the crystallinity when compared to NaClO2 treatment, even though a significant de-esterification occurs for kapok fiber during this process (Wang et al. 2012a).

Liu and Wang (2011) investigated the effect of mercerization on microstructure of kapok/cotton yarns, with the findings that the chemical compositions of fiber showed no appreciable changes after mercerization treatment, but this treatment could decrease the crystallinity of kapok/cotton yarns, transforming partial cel­lulose I to cellulose II. Chen and Xu (2012) found that the ultrasonic treatment with water had little influences on the morphological structure and chemical com­ponent of the kapok/cotton-blended yarns, except for some loss of kapok flocks. Via the combination process of chlorite-periodate oxidation, kapok fiber was found to harbor a certain amount of polysaccharides, together with lowered lignin content. Although a distorted hollow shape and rough surface were observed, the characteristic fine hollow shape was still maintained in all of the chemically oxidized kapok fiber (Chung et al. 2008). To provide the functions or facilitate further modification, some polymerizable monomers had been grafted onto the kapok fiber by Co60 y-ray radiation-induced graft copolymerization, such as styrene, glycidylmethacrylate (GMA), and acrylic acid (AA) (Cho et al. 2007; Kang et al. 2007).

The effectiveness of vegetative mulches against evaporation may be limited unless they are thick to a sufficient diameter because their high porosity permits rapid diffu­sion and air currents. The initial rate of evaporation under mulch is reduced so water is saved if rainfall is frequent. But, in case of extended periods of dry spells, mulch may keep the surface of soil moist and hence prolong the first stage of evaporation, thus producing no net saving of water (Hillel 2007) . With the cane harvest via mechanical ways without burning, the addition of straw on the surface of soil is responsible for the reduction in the soil evaporation, increase in the content of water for plant transpiration, and hence improvement of the efficiency of water usage (Ball-Coelho et al. 1993; Chapman et al. 2001).

Since the surface of soil is completely covered with sugarcane for 60-90 days after emergence of shoot, mulching mostly affects evaporation/transpiration during the first 90 days. Peculiar to this, requirement of water for sugarcane is more sig­nificant during the first period of the cycle, i. e., tillering, sprouting, and establish­ment, whereas during the vegetative growth period, there is a decrease in water demand becoming negligible during maturation period (Leal et al. 2013). Chapman et al. (2001) confirmed this pattern with field trials when the loss of water was similar for both green (unburned) and burned canes in late growth, while the loss of water from soil in early growth under green cane was only 32 % of that from burned cane.

Many studies were conducted with the aim to quantify and correlate the benefits of mulch on crop yield. Ball-Coelho et al. (1993) measured higher water content of soil in the mulched plots in the Goiana experiment in Brazil, which was apparently related to higher soil micropore space, due to activity of higher plants and fungi in the presence of layer of litter. The yield of harvestable cane of first ratoon crop was 17 mg ha-1, with the 70 % content of moisture, greater in mulch than in the treat­ment of burned cane. This response of yield is attributed to increased water retention of soil and reduced growth of weed under the mulch.

Tominaga et al. (2002) also measured higher content of soil water in sugarcane without burning of straw, compared to plots burned before harvest and bare soil control plots. The simulation of production of stalk of sugarcane in South Africa using APSIM model indicated that the higher production observed in unburned management was related to the higher content of soil water (Thorburn et al. 2007).

According to a study, the use of sugarcane straw around 0.1 m thick cover spread on interrow spaces is the most practical way to increase the effectiveness of irrigation by reduction in the loss via evaporation from the surface of soil by capillary rise. The straw maintained the moisture at a higher level for a relatively longer time com­pared to uncovered soil surface (Shrivastava and Solomon 2011). The conclusion drawn from this study is that maintenance is responsible for increase in yield by 10 % for systems under irrigation. In another study, water loss in terms of percent­age was quantified in the upper layer of soil (0-0.2 m). It was determined that with­out the treatment of straw, the loss of water was 0.45 mm/day, while with the treatment of straw, it was 0.21 mm/day (Peres et al. 2010).

Another interesting aspect is the use of vertical mulch — a modification of sub­soiling, in which organic materials, such as straw and filter cake, or inorganic mate­rials, such as gypsum and sand, are inserted in the slot created by the subsoiler (Garcia 2005). Howell and Pheen (1983) tested the benefits of vertical mulch in irrigation studies concluding that it was responsible for intake of water resulting in 25 % increase in cotton yield in California. In the fields of sugarcane, the use of vertical mulching is responsible for increase in the effective rooting depth, hence improved intake of water, greater hydraulic flow, and increased capacity of available moisture (Meyer et al. 1992).

Among all the aspects raised, the increased infiltration and lower evaporation in the presence of straw mulch, compared to bare soil, is an advantage regarding pro­duction of stalk, mainly in areas where irrigation is not being practiced thus there is high deficit of water in the period of vegetation growth.

The estimation of available woody biomass resources in general are associated with several forms of errors such as the inherent errors as per the field assessment data and the errors due to misalignment of various factors, for example, lack of coherence between satellite geometry and training plot positions. To overcome the errors
which originate during ground biomass estimation, the standard errors were derived by making use of the principles of error propagation for products or quotients (Barry 1987). The following Eq. 12.16 can be used to determine the uncertainty while esti­mating the ground biomass density in the biomass density class covering an area, Aclass, with a standard error of aA, i. e.

2

where a and aAGB correspond to standard error and mean square error (respec­tively) of the estimating ground biomass density in a particular biomass density class, AGBp represents the mean value of the predicting ground biomass density in the biomass density class.

Similarly, the overall uncertainty in the estimation of total ground biomass is determined by using Eq. 12.17, i. e. the sum-up of all the ground biomass estimates in the verified biomass density classes in the specified area of interest finally gives the total ground biomass.

(12.17)

where N is the number of biomass density classes in a specific area of interest.

12.2 Conclusion

In conclusion, we reviewed the methods available for the estimation, analysis, production and consumption of biomass and related products for the fulfilment of various forms of energy needs in the current world. The work presented here broadens the understanding of economic analysis of the operational and transportation costs in addition to technological innovations required for the production and consumption of biomass. Further work in this field is to explore and enhance the individual web-based options for serving the information to various practitioners working in various fields like woodland dynamics, socio-economic and energy security domains. A thorough understanding of these factors not only entrench poverty, unemployment but also have terrible implications for a nation’s economy from rural backgrounds. Also, the contin­ued dependence of rural lifestyle on biomass resources to meet the sustenance and livelihood in poor economic conditions are exerting unsustainable pressure on the limited resources that are available. For example, the diminishing of fuel-wood sup­plies is making the rural people to spend more time to collect wood from the forests and in this way, they spend less time on food preparation and other activities such as farming, childcare, housekeeping, sanitation, socializing and education. The other issue of concern includes the high cost of wood purchasing from vendors and the personal security in and around the places where wood is collected.

The carbon-based materials are converted to AC by thermal decomposition in a furnace using a controlled atmosphere and heat by physical activation or chemical activation (Hsieh and Teng 2000; Mohan et al. 2005) involving the following steps: (1) removal of all water (dehydration), (2) conversion of the organic matter to elemental carbon, driving off the non-carbon portion (carbonization), and (3) burning off tars and pore enlargement (activation) (Ahmadpour and Do 1997). The two common methods for the preparation of activated catalyst are physical and chemical activation, the differ­ence between the two methods and their advantages (Table 15.5).

Different chemical activating agents and related recent studies are presented in Table 15.6. Different physical forms of AC that usually can be found, including: (1) granular activated carbon (GAC); (2) powdered activated carbon (PAC); (3) acti­vated carbon fibers (ACF); and (4) activated carbon cloths (ACC). GAC and PAC

Table 15.5 Comparison between physical activation and chemical activation method Physical activation Chemical activation

Diasa et al. (2007), with permission

are the most widely used activated catalyst. Hard materials are used to prepare GAC, such as coconut shells, including particles retained in an 80-mesh sieve (0.177 mm); PAC obtained when small particles are the raw materials, like wood sawdust, (includes particles <0.177 mm); ACF prepared from homogeneous poly­meric raw materials and, in contrast to GAC and PAC, they show a mono dispersed pore size distribution (Kasaoka et al. 1989).

Phenolic or viscose rayon initially used to develop ACC in the early 1970s (Bailey et al. 1971). Thus the utilization of discarded materials possesses several advantages, mainly involve the eco-friendly nature and their economically feasibility.