This index measures the proportion represented by a fixed number of the largest companies of an industry when compared to the total of such an industry. Its cal­culation is as follows:

k

Cr (k) = Pi (1)

i=1

where к is the number of companies that are part of the calculation and Pi = participation of the ith company in the market. The index is easy to interpret, since it varies from 0 (zero) to 100. The closer it gets to 100, the higher the industry concentration is, i. e., if a small number of companies responsible for a big pro­portion of production, sales, or employment inside the industry, that means that the concentration will be higher. In this research, we will use the measure Cr(4), where the four largest companies will be considered in this analysis.

In this context, Bain and Qualls (1968) analyzes the market concentration clas­sifying markets into: Cr(4) equals or higher than 75 %: highly concentrated oli­gopoly; Cr(4) between 50 and 74 %: moderately concentrated oligopoly; Cr(4) between 25 and 49 %: weakly concentrated oligopoly; and Cr(4) lower than 25 %: atomistic.

As introduced above, a strong argument in favour of biofuels is that they emit less GHGs than fossil fuels when combusted (i. e. without taking into account emis­sions created during fuel extraction, growing, production and/or refining) and therefore mitigate a number of environmental issues associated with conventional fuels. Yet, it should be noted that all biofuels may not be equally environmentally friendly since the nature of the gases emitted depends on the specific composition of the biofuel in question, together with engine specifications. This section will provide a brief overview of bioethanol and biodiesel contents, the gases that they release and their respective health impacts.

Bioethanol contains oxygen, which helps create a more complete combustion of the fuel itself. An E10 blend of bioethanol (10 % bioethanol), for example, reduces the level of carbon monoxide produced by 30 % and particulate materials by 50 % in comparison with conventional gasoline (Whitten 2004). Benzene, which accounts for 70 % of toxic emissions from conventional gasoline, is also reduced by 25 % when E10 is combusted (EPA 2002). Furthermore, bioethanol contains no sulphur. As a result, there is no potential threat of sulphur emissions, which can contribute to the formation of acid rain. However, if the blended fuel contains a low percentage of bioethanol (e. g. less than 10 %), some low-level ozone could be emitted, though not to the extent of 100 % conventional gasoline (Natural Resources Defence Council 2006). In contrast to high-level ozone, which protects people from ultraviolet rays, low-level ozone can adversely affect the human respiratory system, together with plant life. By way of contrast, a higher percentage of conventional fuel in bioetha­nol blends produces carbon monoxide, unburned hydrocarbons, benzene and nitrous oxides (Demirbas 2009). When these combine with moisture and suspended air particulates, smog is formed. High-bioethanol-content fuels, such as E85, may also have negative effects on human health. They release aldehydes, such as acetalde­hyde, which causes nasal and eye irritation, and even breathing problems if the con­centration is high (McCarthy and Galvin 2006). Table 3 below presents a synopsis of the percentage variation of emissions from two blends of bioethanol in comparison with conventional gasoline.

Like bioethanol, the oxygen content in biodiesel is higher (usually 10-12 %) than for petroleum diesel. This reduces the emission of smog-forming particulate materi­als such as carbon monoxide by 11 % and unburned hydrocarbons by 21 % (EPA 2002). Though biodiesel may contain traces of sulphur, the risk of sulphur oxides and sulphate emissions is minimal. Some blends of biodiesel such as B20, however, could emit 2 % more nitrous oxide than conventional diesel (EPA 2002). This affects

the quality of air since nitrous oxide undergoes a chemical reaction in the presence of sunlight and causes smog formation. Table 4 above summarizes the findings of the US Environmental Protection Agency on the exhaust emissions from two vari­ants of biodiesel, viz. B100 and B20, compared to conventional diesel.

As mentioned earlier, emissions also vary by engine type. Vehicles with conven­tional catalytic converters are capable of minimizing the emission of aldehydes from bioethanol blends of up to 23 % ethanol. These engines can be easily adapted for using high-bioethanol-content fuels such as E85 (Greene 2004). More advanced engines were found to reduce formaldehyde emission by 85 % and acet­aldehyde by approximately 58 % (MECA 1999). With regard to biodiesel, Kousoulidou et al. (2008) concluded, from studies conducted in the USA, that pre — 1998 diesel engines emit less nitrous oxide than 2004 diesel engines equipped with exhaust gas recirculation (EGR) and that the percentage of emissions increases with the share of biodiesel in the fuel blend. 2Of particular concern is the high per­centage of nitrogen dioxide (NO2), the most harmful of all nitrous oxides, released when such blends are used in modern (e. g. Euro 4) engines (Kousoulidou et al. 2008). The emission of particulate matter is usually low for all types of engines, except for those which emit a high soluble fraction and consume more lube oil.3

From the above discussion, it appears that the combustion of biofuels, in gen­eral, affects the environment to a lesser extent than fossil fuels. However, tail­pipe emissions are only the end result and therefore do not really explain the

2 These assertions are based on the findings of EPA (2002) and Sze et al. (2007).

3 Refer to Dwivedi and Sharma (2013) for further details on emissions from the various varieties of biofuels, together with engine specifications.

net emission or absorption of GHGs throughout the life cycle of biofuels, which includes cultivation of feedstock, the processing of the biomass and, finally, its combustion for end use.

Among the oleaginous microorganisms reported in the literature, filamentous fungi show the highest lipid accumulation after yeast, besides the capacity to produce a wide range of products, i. e., enzymes, antibiotic, and chemicals (Karimi and Zamani 2013). Some of the main differences between filamentous fungi and other oleaginous species (yeast, microalgae, and bacteria) on the production of oils are based on the capability of filamentous fungi to build pellets in submerged cultures, due to filamen­tous growth during fermentation. Moreover, the viscosity of the broth is reduced, thus improving the mixing and mass transfer performance. Finally, due to the formation of pellets, they are easy to harvest from broth by simple cell filtration, which reduces the cost compared with traditional methods like centrifugation (Xia et al. 2011).

To decrease the cost of the process, methanolysis from fungal biomass has been proposed as an alternative to the oil extraction process. Through the use of metha­nol and a catalyst, usually H2SO4 or HCl, some authors reported a yield of FAME conversion of 91 %, being the cetane number 56.4, thus making this technique an attractive alternative for the biodiesel industry (Liu and Zhao 2007).

The stored lipids in filamentous fungi contain a high percentage of saturated (Venkata Subhash and Venkata Mohan 2011) and polyunsaturated fatty acids (Mitra et al. 2012), accumulated during the stationary phase in special organelles, named lipid granules. Like bacteria, filamentous fungi may also consume a wide range of carbon sources, including lignocellulosic biomass (Table 6), thus provid­ing inexpensive raw material for biodiesel.

Although lignocellulose comprises hemicellulose, cellulose, and lignin, only hemicellulose and cellulose may be consumed as feedstock for biological conver­sion. For this purpose, to make carbohydrates accessible to microorganisms, lig — nocellulose needs a pretreatment before hydrolysis (Zeng et al. 2013). Zikou et al. (2013) used a mixture of xylose and glucose, which are abundant sugars from ligno — cellulosic biomass, to produce y-linolenic acids (GLA) by Zygomycetes T. elegans. Results showed that the best combination of xylose to glucose is 1:1, achieving 12.6 g/L lipids and 936 mg/L GLA. Instead, when glucose was used as the sole medium, the values were 15 g/L and 1,014 mg/L, respectively. M. isabellina was also tested, and a positive influence of the increment of these sugars separately in the medium over the accumulation of lipids was found (Ruan et al. 2012). The same filamentous fungus was used for the production of oil when rice hulls hydrolyz — ate, which is a lignocellulosic material, was used as a substrate. Authors proposed a mathematical model to simulate the consumption of sugar and nitrogen, the fat-free biomass formation, and the accumulation of lipids (Economou et al. 2011). Khot et al. (2012) isolated fungi of tropical mangrove wetlands, but only five out of 14 showed lipid accumulation above 20 % dry cell biomass. Fungi from this ecosystem were also used for the production of lignocellulosic enzymes. The oil of three out of the previous five was transesterified, the biodiesel properties predicted, and it was found that the most appropriate fungus was IBB M1, known as A. terreus strain. Another important issue to be fixed when lignocellulosic biomass is used consists in the inhibitory effects of the lignocellulose-derived compounds over oil accumulation

(continued)

D. E. Leiva-Candia and M. P. Dorado

(lignin aldehydes, furan aldehydes, and weak acid). When M. isabellina was used to determine the inhibitory effect of these compounds, the lignin derivative was found to be the main inhibitor considering lipid accumulation, while acetic and formic acid doubled the lipid accumulation with respect to the control test (Zeng et al. 2013). It was concluded that the most suitable combination of fungus and lignocellulosic material substrate for fungal oil production was provided by the strain M. isabellina when it consumed non-detoxified lignocellulosic hydrolyzate, due to both the high oil content and the simplified process of fermentation (Zheng et al. 2012b).

In terms of environmental preservation, the bioremediation of soils contami­nated by hydrocarbons is an important issue. For this purpose, the use of A. terreus has been investigated to transform petroleum hydrocarbons in oils to be used in the biodiesel industry. Results showed that the use of hydrocarbons as carbon source provides sevenfold higher lipid accumulation compared to the use of glucose as sub­strate (Kumar et al. 2010). Crude glycerol is a by-product of the biodiesel industry, which has recently been released in high quantities due to the increasing biodiesel demand. It usually comprises residues of alcohol (methanol or ethanol) and a basic catalyst. This by-product has been tested as a carbon source for Mucor sp., C. echi — nulata, M. ramanniana, T. elegans, Z. moelleri (Chatzifragkou et al. 2011; Bellou et al. 2012), and M. isabellina (Chatzifragkou et al. 2011). Chatzifragkou et al. (2011) used the fungi mentioned above and compared lipid accumulation with that of yeasts. Results showed that all fungi were able to accumulate higher amount of oil than yeasts under nitrogen-limited conditions. Bellou et al. (2012) focused their research on the production of PUFA produced by filamentous fungi. In the majority of the tested fungi, authors observed that PUFA was mainly accumulated in myce­lial membranes during mycelial growth. However, one of the studied filamentous fungi (Mortierella ramannniana) depicted the opposite trend. In this sense, PUFA continued decreasing after the end of the growth phase, thus suggesting PUFA is involved in primary metabolism of this microorganism (Bellou et al. 2012).

Filamentous fungi have been genetically engineered focusing on lipid produc­tion, giving relevance to metabolic routes governing fatty acid synthesis and lipid storage. Unique metabolic features have been identified in Mortierella alpina and Mortierella circinelloides, particularly with respect to NADPH metabolism and sterol biosynthesis, which might be related to differences in fungal lipid phenotype (Vongsangnak et al. 2013). The gene coding for acetyl-CoA carboxylase (ACC) was isolated from Mucor rouxii. This gene is able to increase by 40 % the total fatty acid content of non-oleaginous microorganism (Ruenwai et al. 2009). Wynn et al. (1999) studied the significant role of malic enzyme on lipid accumulation. Authors used a fungus with low lipid accumulation (M. circinelloides) and found out that the enzyme disappeared 15 h after the depletion of the nitrogen source, which was coincident with the end of lipid accumulation. Instead, when a high-lipid accumula­tion fungus like Mortierella alpine was used, the enzyme was held 60 h after the completion of the nitrogen source, which lasted longer than the lipid accumulation.

The accumulation of lipids from filamentous fungi is increasingly attractive because of the high oil yields, versatility of the microorganisms to use different car­bon sources (including wastes like lignocellulosic material), and the possibility to

be grown in submerged cultures, which give the opportunity to easily collect the biomass. In this context, genetic engineering may be a magnificent tool to help in the inclusion of these microorganisms to provide an alternative oil to the biodiesel industry. Although most research in this area is focused on the production of high — value-added products such as enzymes and polyunsaturated fatty acids, among many others, the production of microbial oil could provide an extra value to the process.

Domestic price of Brazilian ethanol is regulated by the government since the cre­ation of PROALCOOL. For this reason, domestic price is stable along the time (Fig. 4).

In Brazil, the prices of ethanol show relative stability despite the instability of prices in petroleum international market. This fact is due to economic policy in Brazil, especially the price policy, that is regulated by the government.

Aldara da Silva Cesar, Mario Otavio Batalha and Luiz Fernando de O. Paulillo

Abstract The national program for production and use of biodiesel (PNPB) intends to include family farming in this sector. Oil Palm cultivation was deemed as ideal for social inclusion in Brazil’s Northern region, and the social projects linked to this production are pilot projects, with about 185 families. This study, which can be classified as multi-case, uses exploratory bibliographic and documen­tal research techniques as well as interviews with the agents inserted in the chain. The study analyzes the governance structure of the biodiesel production chain in Brazil regarding the social link of palm oil. In light of the transaction cost econom­ics (TCE) theory, this chapter analyzes three key transaction attributes between family farmers and industry, namely frequency, uncertainty, and asset specificity, all classified in this study as high ranking. The institutional environment is decisive for the inclusion of palm oil farmers included by means of formal contracts. However, the biodiesel plants located in Brazil’s Northern region—as well as those planning to begin this business—show trends to verticalize their agricultural activities. Thus, the social fuel seal (SCF) assumes its influence in the operating dynamics of that chain’s social pillar.

Keywords Palm oil • Family farming • Social fuel seal • PNPB • Biodiesel

A. da Silva Cesar (H)

GASA—Grupo de Analise de Sistemas Agroindustriais Departamento de Engenharia de Agronegocios, Universidade Federal Fluminense, Niteroi, Brazil e-mail: aldaracesar@id. uff. br

M. O. Batalha • L. F. de O. Paulillo

GEPAI—Grupo de Estudos e Pesquisas Agroindustriais Departamento de Engenharia de Produfao, Universidade Federal de Sao Carlos, Sao Carlos, Brazil e-mail: dmob@ufscar. br

L. F. de O. Paulillo e-mail: dlfp@ufscar. br

A. Domingos Padula et al. (eds.), Liquid Biofuels: Emergence, Development and Prospects, Lecture Notes in Energy 27, DOI: 10.1007/978-1-4471-6482-1_6, © Springer-Verlag London 2014

1 Introduction

The national program for production and use of biodiesel (PNPB) created a strong domestic demand for biodiesel (Pousa et al. 2007). PNPB’s most important under­taking was the enactment of Law No. 11.097/2005, in which the compulsory addi­tion of biodiesel to petroleum diesel was decreed in 2008 in Brazil (Brazil 2005). Biodiesel was incorporated into the Brazilian energy matrix in 2007 on an optional basis and mandatory in 2008 with the addition of 2 % of biodiesel to petroleum diesel (B2)—this addition is currently set at 5 %. Since then, the sector has rapidly increased in the country.

Brazil produced 2.7 million liters in 2011 and has a twofold capacity for the mandatory requirement. The federal program also established a set of policies to encourage diversification of the energy matrix, promoting the inclusion of family farmers in this sector.

The social fuel seal (SFS) was created to focus on the regional development (Garcez and Vianna 2009), and according to this mechanism, companies must provide conditions (quantity, minimum price, and technical service) via contracts to foster the relationship with small farmers. In contrast, the seal has tributary advantages (tax exemption), allowing access to the ANP Auctions, favoring better financing terms with public banks, plus serving as a positive marketing tool for the companies that have the seal.

The diversification feasibility in the production of raw materials used to manu­facture biodiesel favors Brazilian competitiveness. However, the most widely used raw material for biodiesel production in the country has been soybean. In 2012, soybean oil accounted for 75.24 % of the raw materials used by the plants, while beef tallow and cotton oilseed accounted for 17.19 and 4.53 %, respectively (ANP 2012). However, in Brazil, palm oil for biodiesel production is still very small, accounting for 0.18 % in 2012.

In Brazil, despite its limited participation in the matrix, palm oil was chosen as the ideal oilseed for the north of the country since the beginning of PNPB. Palm oil plantations enable social inclusion due to its high employment rate (one direct job is generated for every 10 ha under oil palm cultivation), with gains such as income generation for farmers, workers’ improved quality of life, inserting man­power in the field, and the expansion of local businesses (Cesar et al. 2013). However, of the 100,371 family farming establishments participating in PNPB in 2011, only 246 are located in the north of the country (0.2 %). Of these, 185 farmers are assisted with palm oil and are heavily subsidized by public actions and partnership with the company that fosters such arrangements (Brazil 2011).

Thus, in 2004, the PNPB institution definitely promoted building a productive structure and an institutional framework for the production of biodiesel in Brazil. It is important to investigate the type of governance structure undertaken by the palm biodiesel supply chain some years after the implementation of PNPB, which is a key issue in order to study the oleaginous supply from family farming, given the importance assumed by the SFS seal in the operating dynamics of this sector. Within this scope, this chapter examines the governance structure of the biodiesel

production chain in Brazil. This work is divided into five sections, including the introduction. The second section presents the methodological procedures. The third section includes some considerations about the theoretical referential. Next, the fourth section provides the research results, which are divided in the description of the fomented arrangements related to oil palm.

Sugary biomass contains sucrose as a sugar source, a disaccharide consisting of glucose and fructose, which are both hexose monosaccharides (C6) (Fig. 2). Sucrose undergoes hydrolysis to release glucose to be converted into 1G ethanol via fermentation using a S. cerevisiae yeast (Oh et al. 2012).

Examples of sucrosic biomass include sugarcane and sweet sorghum, the lat­ter of which has a considerable concentration of free monosaccharide D-glucose when compared with sugarcane (Table 3). Sugarcane has a high content of sucrose which releases glucose after a hydrolysis step, and it is the most relevant feedstock for 1G ethanol production. However, sweet sorghum could be used as a comple­mentary crop during the sugarcane off season.

Analytical data are important for these feedstocks because we can obtain sugars content for bioethanol production. Then, we can monitor the process of conver­sion, their yields, and the product quality. It could be seen in the item 3.1.

Despite its vocation as a potential source of biofuels, many challenges have hindered the development of biofuels technology from microalgae to become commercially viable.

Among them, and based on recent literature, we elect as the most important:

1. The selection of species must balance the requirements for biofuel production and extraction of valuable by-products (Ono and Cuello 2006);

2. Achieving greater photosynthetic efficiency through the continuous develop­ment of production systems (Pulz and Scheibenbogen 1998);

3. Developing techniques for growing a single species, reducing evaporation losses, and diffusion of CO2 (Ugwu et al. 2008);

4. Few commercial cultivating “farms,” so there is a lack of data on large-scale cultivation (Pulz 2001);

5. Impossibility of introducing flue gas at high concentrations, due to the pres­ence of toxic compounds such as NOx and SOx (Brown 1996);

6. Choosing algae strains that require freshwater to grow can be unsustainable for operations on a large-scale and exacerbate freshwater scarcity (Mcgraw 2009);

7. Current harvest and dewatering are still too energy intensive (Chen et al. 2009);

8. Some recent life cycle analyses (LCAs) project algae biofuels as having poor energy or greenhouse gas benefits (Benemann 2012; Clarens et al. 2010);

9. Depending on the processes, PBR systems can consume more energy than they produce (Slade and Bauen 2013);

10. Another disappointment that will likely arise is the scarcity of sites with favorable climate, land, water, and CO2 resources, all required in one place (Benemann 2012; Clarens et al. 2010; Slade and Bauen 2013);

11. CO2 supply is relatively expensive, due to high capital and operational costs for piping CO2 to, and transferring it into, the ponds (Benemann 2012).

12. Large-scale cultivation of algal biomass will require a lot of nitrogen and phosphorus; at a small-scale, recycling nutrients from wastewater could potentially provide some of the nutrients required (Slade and Bauen 2013).

Finally, to reach positive energy balance, it will be needed technological advances and highly optimized production systems. The amount of GHG decreases when the microalgae yield increases, primarily because CO2 is the main raw material utilized in photosynthesis during the growth of microalgae. Therefore, it is impor­tant to achieve high yields of biomass and oil in the cultivation plant. The miti­gation of environmental impacts, and in particular water management, presents both challenges and opportunities, many of which can only be resolved at the local level. Existing cost estimates need to be improved, and this will require empiri­cal data on the performance of systems designed specifically to produce biofuels (Slade and Bauen 2013).

1.1 Bacteria

The synthesis of intracellular lipids in oleaginous bacteria occurs during the log­arithmic phase and the beginning of the stationary growth phase (Gouda et al. 2008). However, only few species of bacteria can accumulate lipids suitable for biodiesel, as they mainly accumulate polyhydroxy alkanoates (PHA) and poly­hydroxy butyrate (PHB) (Kosa and Ragauskas 2011; Shi et al. 2011). The spe­cies that produce a large amount of lipids are those belonging to Streptomyces, Nocardia, Rhodococcus, and Mycobacterium (Alvarez and Steinbuchel 2002). The amount of triglycerides (TAG) and fatty acid composition differs depending on the species used for fermentation (Table 5). Gouda et al. (2008) tested Rhodococcus opacus and Gordonia sp. using different agroindustrial wastes (molasses, potato infusion, wheat bran, hydrolyzed barley, orange waste, tomato peel waste, arti­choke waste, and Na-gluconate) as carbon sources. Molasses provided the high­est percentage of lipid in cell, 93 and 96 % for R. opacus and Gordonia sp.,

respectively, while carob waste offered the best source for TAG accumulation, being 88.9 and 57.8 mg per liter of medium for R. opacus and Gordonia sp., respectively, and C17:1 the main fatty acid produced (20.7 %) by R. opaccus. When Gordonia sp. consumed molasses, they followed the same trend in terms of the accumulation of lipid in cell mass (96 %). However, the highest accumulation of TAG (57.8 mg/L) was achieved when orange waste was consumed, being C22:0 the predominant fatty acid, in a percentage close to 35 %. Two different strains of bacterium R. opacus, DSM 1069 and PD630, were inoculated in lignocellulosic compounds (4-hydroxybenzoic and vanillic acids) (Kosa and Ragauskas 2012). The experiments showed that both strains can consume these carbon sources and accumulate lipids close to 20 % of their own weight.

With regard to bacterial biodiesel properties and subsequent engine testing, only one analysis has been reported (Wahlen et al. 2012). In this study, the bacte­rium R. opacus was grown in sucrose and biodiesel properties were compared with those from microalgae and yeast oil-based biodiesel. Biodiesel bacterial molecu­lar properties differ considerably with the other biofuels in terms of carbon chain length. The physical properties were similar to other microbial biodiesel, with the exception of the heating value that was lower. When bacterial biodiesel was ran on a diesel engine, it provided the lowest power output, while NOx and HC emissions were higher and lower than other microbial biodiesel, respectively.

Bacteria that accumulate the highest proportion of triglycerides are providing neither sufficient oil yield under industrial conditions nor an economically sound process. For these reasons, genetic engineering is supporting this biotechnology to be considered a viable alternative for the biodiesel industry. Rucker et al. (2013) demonstrated the feasibility of the lipid metabolism of E. coli for TAG accumu­lation, but the yield achieved was below the threshold to be considered a viable source for biodiesel production. Authors propose two metabolic engineering steps, to increase either the supply of phosphatidic acid during late exponential and sta­tionary phase growth or the supply of acyl-CoA.

One of the most interesting uses of bacteria in the production of biodiesel was described by Kalscheuer et al. (2006). In this study, the genetically modified bac­teria E. coli was recombined with two different enzymes from Zymomonas mobilis and Acinetobacter baylyi. The target was to produce fatty acid ethyl esters (FAEE) in vivo, called “microdiesel.” Under fed-batch fermentation using renewable car­bon sources, they achieved a FAEE concentration of 1.28 g L-1, corresponding to a FAEE content of the cells of 26 % of the cellular dry mass. Gordonia sp. KTR9 may be considered among the suitable bacteria for in vivo synthesis of fatty acid ethyl esters from short-chain alcohols. This species has a large num­ber of genes dedicated to both the formation of fatty acids and lipid biosynthesis. Furthermore, it tolerates the addition of more than 4 % methanol, 4 % ethanol, and 2 % propanol in the medium (Eberly et al. 2013).

It may be concluded from above works that biodiesel produced from bacterial oil can be considered as an alternative to first — and second-generation biodiesel. However, more research is needed to both improve bacterial oil yield and provide economically viable substrates.

D. E. Leiva-Candia and M. P. Dorado

After the process of extracting the oil from algae, the resulting product can be converted to biodiesel. The biodiesel produced from algal oil has physical and chemical properties similar to diesel from petroleum, to biodiesel produced from crops of first generation and compares favorably with the International Biodiesel Standard for Vehicles (EN14214) (Brennan and Owende 2010).

Contrasting to other sources of feedstock to produce biofuels, algae-based bio­fuels present several advantages. These advantages comprise:

1. Capability of producing oil during all year long; therefore, the oil productivity of microalgae is greater compared to the most efficient crops;

2. Producing in blackish water and on not arable land (Searchinger et al. 2008); not affecting food supply or the use of soil for other purposes (Chisti 2007);

3. Possessing a fast-growing potential and several species has 20-50 % of oil con­tent by weight of dry biomass (Chisti 2007);

4. Regarding air quality, production of microalgae biomass can fix carbon dioxide (1 kg of algal biomass fixes roughly 183 kg of CO2) (Chisti 2007);

5. Nutrients for its cultivation (mainly nitrogen and phosphorous) can be obtained from sewage; therefore, there is a possibility to assist the municipal wastewater treatment (Cantrell et al. 2008);

6. Growing algae do not require the use of herbicides or pesticides (Rodolfi et al. 2008);

7. Algae can also produce valuable coproducts, such as proteins and biomass; after oil extraction, the coproducts can be used as animal feed, medicines, or fertilizers (Spolaore et al. 2006; Brennan and Owende 2010), or fermented to produce ethanol or methane (Hirano et al. 1997);

8. Biochemical composition of algal biomass can be modulated by different growth conditions, so the oil yield can be significantly improved (Qin 2005); and

9. Capability of performing the photobiological production of “biohydrogen” (Ghirardi et al. 2000; Ferreira et al. 2013).

The above combination of the potential for biofuel production, CO2 fixation, wastewater treatment, and the possibility of production of biohydrogen highlights the potential applications of the microalgae cultivation.

Compared to other biofuel technologies, the most favorable factors for the culti­vation of microalgae for the production of biofuels are they can be grown in brack­ish (salt) water, on non-fertile land, and the oil yield production is far superior.

Catalysts were degassed under vacuum at 160 °C for 5 h, and then, the sur­face area of catalysts was measured using a surface analyzer. The pore size distributions and pore volume were determined. Scanning electron microscope (SEM) was used for determination of surface morphology and shape of catalyst particles.

Collector

Furnace

I hermocouplc

Fig. 1 Schematic diagram of experimental apparatus

1.3 Preparation of ZSM-5 and SBA-15 Catalysts

The catalysts were activated by calcination at 420 °C in nitrogen for 1 h, cooled to 350 °C, and then calcined further in air at 540 °C for 12 h. After this, the catalysts were crushed into powder. Both polyethylene and catalyst powder were sieved to ensure that particle sizes remained around 60-150 mesh and then blended by grind­ing the desired amount of catalyst and polyethylene according to a certain ratio.