The combined effects of microporous HZSM-5 (Si/Al = 80) catalyst and mesoporous acidic AlSBA-15 on the degradation of HDPE are presented by data in Table 6. It was observed that a conversion of about 100 % yield toward liquid, gaseous, and residue products without any formation of solid waxy compound was achieved. According to literature, these two catalysts constitute principally Lewis and Bronsted acid sites with variable surface areas and pore sizes (Ooi and Bhatia 2007).

However, results shown here are in accordance with the shape selectivity effect in microporous and mesoporous materials. It was associated with the narrow pores to access active sites. It was noted that for acidic enhancement SBA-15 catalyst, the larger pore size and channels allowed the formation of higher hydrocarbon products such as light liquid products. The high yield of gaseous products shown by HZSM-5 catalyst was mainly due to the slow diffusion of cracked products within the internal pores. The findings made in this work were consistent with those reported by pre­vious researchers. It has been reported that the diffusion rate of hydrocarbon mol­ecules could be retarded using microporous catalysts (Urquieta et al. 2002).

Overall, the combined effects of HZSM-5 (80) and AlSBA-15 catalysts gave rise to positive improvements as compared to the performance of the individual cata­lyst. For all three combinations of catalyst ratio, light liquid degradation product yields were higher than 20 wt. %. The optimum liquid yield was demonstrated by the HZSM-5 (80) to AlSBA-15 catalyst ratio of 1:2 (which was 26.5 wt. %). Although the increment of both catalysts increased the liquid yield as compared to the catalyst ratio of 1:1, further addition of AlSBA-15 could provide higher liquid yield while simultaneously suppressing the yield of gaseous product more effec­tively. Another advantage of applying the 1:2 catalyst loading ratio was that it also inhibited the solid coke formation on the catalyst. This could be explained from the theory that larger composition of HZSM-5 catalyst will contribute to higher coke

Fig. 14 Composition of gas products at 673 K using composite HZSM-5(80) and AlSBA-15 catalysts at different ratios

Fig. 15 Liquid degradation products at 673 K using composite HZSM-5 (80) andAlSBA-15 catalysts at different catalyst ratios

formation and more rapid deactivation. In this respect, the mesoporous catalyst is generally more effective than the microporous catalyst in suppressing the formation of large molecules and thus causing less carbon deposits (Urquieta et al. 2002).

As can be seen in Fig. 14, the gas products distribution was quite uniform. For the catalyst ratio of 1:1, the smallest compositions were the carbon chain of C1 (12.4 %) and C5 (12.7 %) while the highest were the carbon chain of C3 (28.9 %) and C4 (28.6 %). However, all of them were marginally different. For unequal cat­alyst mixing ratios such as 2:1 and 1:2, the uniformity of product distribution was not able to be maintained. For HZSM-5(80) to AlSBA-15 catalyst ratio of 2:1, the smallest compositions were the carbon chain of C1 and C5 (about 13.0 %) while the highest proportion was the carbon chain of C4 (31.7 %). On the other hand, for catalyst ratio of 1:2, increasing amount of AlSBA-15 composition resulted in lower production of C5 carbon chain (8.9 %) while showing higher composition in the carbon chain of C3 (31.4 %).

Meanwhile, the effect of varying catalyst mixing ratio on the liquid phase degradation products is illustrated in Fig. 15. Mixture of HZSM-5(80) and AlSBA-15
catalysts with catalyst loading ratio of 1:1 produced nearly 89 % of carbon chain range C8-C12, C13-C16, and C17-C20 from the overall liquid composition. Increasing the ratio of either HZSM-5(80) or AlSBA-15 amount in the catalyst mixture appar­ently shifted the product distribution toward heavier carbon chain. The effect of adding HZSM-5(80) was more dominant as it increased the carbon chain range of C17-C20 to 35.7 % while adding AlSBA-15 only increased the carbon chain range of C13—C16 to 28.4 %.

4 Conclusions

The results reported and discussed in the present work demonstrate that micro — and mesoporous materials show promising properties to be used as catalysts in the degradation of HDPE into gaseous and liquid hydrocarbon fuels at 350-500 °C. HZSM-5 (14), HZSM-5 (80), SBA-15, and AlSBA-15 were used under various operating conditions to obtained liquid biofuels. Mixture of HZSM-5 (80) and AlSBA-15 with ratio of 1:2 exhibits higher degradation activity to yield higher liquid biofuels with valuable gas product at 400 °C. In addition, significant HDPE conversions into liquid fuel with lower coke contents were achieved in a batch reactor over the HZSM-5 catalyst as compared to mesoporous silica catalyst SBA-15. The pore shape of zeolites was very important for deter­mining their activities and product selectivity in the degradation of polymeric materials because it influenced the degradation and deactivation rates simulta­neously. SBA-15 containing aluminum catalyst was of a potential interest in the cracking of heavier feedstock such as palm oil waste into biofuels. The weaker acid properties exhibited by the mesostructured catalysts, i. e., SBA-15 and Al-SBA-15 were responsible for their reduced gaseous product production capaci­ties. However, their presence coupled with the combination of HZSM-5 catalysts in the conversion of polyethylene materials promoted a substantial conversion of the original long-chain hydrocarbons into lighter liquid hydrocarbon products (up to 26.5 wt. %). Furthermore, larger pore dimensions exhibited by these sol­ids did not allow for any product selectivity, resulting in the possible formation of a wide range of branched hydrocarbon and alkyl derivative aromatic products. These results suggest that catalytic degradation of HDPE leads into higher liq­uid hydrocarbons yield at lower temperature. It is stated that such type of chemi­cal recycling, i. e., conversion of waste HDPE into hydrocarbon feedstock used as resource for biofuel has been recognized as an ideal approach and could sig­nificantly reduce the net cost of disposal. It is concluded that under appropriate reaction conditions, suitable catalysts such as HZSM-5 (80) and AlSBA-15 have the ability to control both the product yield and product distribution from HDPE degradation, potentially leading to a cheaper process with more valuable products such as biofuel.

Although several challenges remain in the trail toward algae biofuels commercialization and its adoption as a biofuel, as seen so far, an increasing number of companies and policy makers seem to believe the rewards outweigh the risks. Thus, the expectation pathway for algae-based biofuels remains uncertain.

Theoretically, microalgae have been shown to be a potential source to produce biodiesel because of their many advantages as a sustainable feedstock for biodiesel production compared to other feedstocks (Ahmad et al. 2011). Nevertheless, not only more innovations are still needed for the development of technologies that reduce costs while increasing the yields of production (Singh and Gu 2010), but it is also required a comprehensive set of policies to assist the development of micro­algae technology.

In the management area, it is extremely important in the early phases of this prom­ising industry, to deliberate new business models that look at the bioenergy poten­tial of algae through the transportation fuels market, as well as production of other higher-value products so as to make the economics practicable (Singh and Gu 2010).

2 Conclusion

The continued use of fossil fuels for energetic purposes is gradually becoming clearer to the society that is unsustainable. Innovative technologies and sources of energy must be developed to replace fossil fuels. In this context, biofuels play a vital role in meeting the energy needs of human beings. There is reason to believe they will continue to do so in the future albeit in a different manner. The basic economic motivation for biofuels is that they are a convenient, low-priced, domes­tically producible and a substitute for oil. However, alternative sources of biofuel derived from terrestrial crops such as sugarcane, soybeans, maize, and rapeseed inflict a lot of pressure on the global food markets, contribute to water scarcity, and precipitate the destruction of forests. Besides that, many countries cannot grow most of the terrestrial crops due to climate factors or lack of fertile cultiva­tion areas for energetic purposes. In this context, algal biofuels can really make a contribution for the future world sustainability.

In the presented chapter, it is clear that algae are now being intensively researched as a potential biofuel feedstock. In addition to their potentially high yields per unit land area, algae can grow in unsuitable land for agriculture, includ­ing industrial areas. Thus, their exploitation offers the possibility of a feedstock for producing biofuel that avoids damage to ecosystems and competition with agricul­ture associated with other biomass resources. Although many testing and start-up companies are in operation in several countries, cost information is scarce. Along the aforementioned literature review, a consensus was found that biofuels from algae are, in any case, still at the research and development stage and face numer­ous obstacles related to energy and water needs, and productivity.

Consequently, we revisited the recent developments in biofuel algae-based mar­kets and their technical issues, political standpoints, and environmental impacts. From a research and technology perspective, we stressed the importance of the US bioenergy policies and the European SET plan, as well as by the scenarios from IAE in 2010. These policies inform that several countries have introduced mandates and targets for biofuel expansion and, moreover, that production, international trade, and investment have increased sharply in the last few years.

The introduction of these new policies is essential for lowering the costs of algae biofuels, encourage investment, and develop greater diffusion of this emer­gent technology. Otherwise, in the lack of public policy, currently production costs will eventually remain too high to replace fossil fuels. In the same manner, it is expected that these policies will stimulate innovation to tackle some of the prob­lems in this emerging market.

The problems concerning large-scale production of biodiesel from algal farms on non­arable land include inconsistent and insufficient algal productivities, uncertain capital and operating costs, volatile market prices, and unknown levels of government support. Our survey permits to conclude that although intensive work is being done on many technolog­ical issues, economic studies and respective data are scattered, incomplete, and divergent.

With the onset of new policies, incentives, and massive investment in the pri­vate and public spheres, more researchers are forging new understanding in the science required to make algal biofuels economically feasible. In the present situ­ation, however, the technology to efficiently produce biodiesel from microalgae is not yet competitive. However, with policy support and incentives, we believe that the algal biofuel industry will continue to develop and assuming that this technology follows renewable energy cost trends, costs will decrease to even­tual economic viability. In parallel, processes must be developed to reduce costs and increase production. In this respect, the currently fast rate of development of algae biofuel technology and the actual rising of petroleum-based fuels prices are encouraging algae-based biofuels feasibility in the next few years.

Nevertheless, as shown in this chapter, we are witnessing a rise of companies’ strategies of entering new markets. Reports and news of new activities of algae — based companies are frequently on the news nowadays. These are signs that the uncertainties around the commercialization of this still not mature technology are not sufficient to hinder investment decisions.

Acknowledgments Lauro Andre Ribeiro and Patricia Pereira da Silva would like to acknowledge that this work has been partially supported by FCT under project grant PEst-C/EEI/ UI0308/2011 and from the Brazilian National Council for the Improvement of Higher Education (CAPES). This paper has been framed under the Energy for Sustainability Initiative of the University of Coimbra and supported by the R&D Project EMSURE Energy and Mobility for Sustainable Regions (CENTRO 07 0224 FEDER 002004).

Both gases and liquid oil products from the reactor were analyzed using a Hewlett- Packard GC equipped with a Supelco Plot Q column and a GC/MS, respectively. Similarly, the liquid oils could also be analyzed using a gas chromatograph with a flame ionization detector while the gaseous products were analyzed using gas chromatograph with a thermal conductivity detector. In addition, some of the car­bonaceous compounds that adhered on the cooling glass tube were eliminated using и-hexane and were measured as waxes. The mass of coke deposited on the catalysts after the degradation was determined by weight difference of the catalyst before and reheating the catalysts at 600 °C for 5 h. In addition, the amount of coke deposit on the catalyst could also be calculated by measuring the desorbed amount of carbon dioxide during temperature programmed oxidation of the used catalysts.

Commercial algae production facilities employ both open and closed cultivation systems. Each of these has advantages and disadvantages, but both require high capital input (Pienkos and Damns 2009). Open ponds are much more cheaper than closed systems because it demands relatively high capital and O&M costs associated with installation and operation of PBRs (Benemann 2012; Buford et al. 2012).

Lower costs and the possibility to scale up to several hectares make open ponds the main choice for algae commercial production (Benemann 2012). However, open pond cultures suffer from many limitations that can disrupt algal productiv­ity during unexpected environmental events. Another challenge for this system includes having access to an adequate supply of water for growth due to continu­ing loss of water through evaporation. Therefore, open ponds must be in a geo­graphic setting that has a fairly near source of water and a relatively flat terrain to avoid costly earthworks (Buford et al. 2012). Moreover, the open systems are susceptible to wind-born biological agents that can affect the cultivation, such as grazers, infectious fungi, lytic bacteria, viruses, other algae, and also lower tem­peratures in colder climates (Benemann 2012).

These open pond limitations stimulate PBRs development; however, only a few commercial plants use closed PBRs systems, mainly due to high costs as men­tioned before. Nowadays, according to Benemann (2012), microalgae cannot be grown in PBRs for commodities and are not even successful for high-value prod­ucts. However, PBRs can be used for seed culture production, though only for ~0.1 % of the biomass. Closed PBRs are significantly more expensive to construct, but have not been engineered to the extent of other reactors in commercial prac­tice, and so there may be opportunities for significant cost reductions.

Neither open ponds nor closed PBRs are mature technologies. Therefore, until large-scale systems are built and operated over a number of years, many uncer­tainties will remain. Cultivation issues for both open and closed systems, such as reactor construction materials, mixing, optimal cultivation scale, heating/cool — ing, evaporation, O2 build-up, and CO2 administration, have been considered and explored to some degree, but more definitive answers await detailed and expansive scale-up evaluations (Pienkos and Darzins 2009).

Concerning the various algal species and strains, they vary from study to study, depending on location and culture techniques. For that reason, it is not yet possible to predict what species or strain will be the best suited for commercial biofuel pro­duction, but it is most likely that it will differ from case to case, depending on the location, cultivation techniques chosen, processing technologies available, nutri­ents source, local climacteric conditions, and among other potential factors.

As highlighted in the previous chapters, the different technological, economic, and social conditions around the world have led to diverse paths being taken in the pro­duction of fuels from renewable sources. In its essence, the production of energy from biomass of agricultural origin presents the challenge of integrating three impor­tant facets. One facet represents the energy needs of society, a system that is sensitive to changes in relative prices and to variations in the intensity of economic activities. The second facet represents the farmers, who normally take their decisions regarding land use based on their own mental maps that include the variations in the costs and possible returns implied in the major agricultural commodities they are accustomed to negotiate. Finally, the third facet, industrial production, requires a stable supply of raw materials provided at competitive levels (minimum efficiency scale) in order to ensure the feasibility of their production. The main challenges involving renewable energy are located within these three groups of actors. To deliver a competitive final product in the energy sector, there must be a robust and sustainable chain, without which bioenergy cannot compete with other forms of energy.

Although different paths have been taken in the production of ethanol and bio­diesel around the world, objectives and incentive mechanisms have been much the same, that is, governments have taken the initiative. In Brazil, for example, the Proalcool program was introduced to provide energy security, while the Biodiesel program, besides energy issues, is aimed at ensuring social inclusion and diversifi­cation of agricultural production.

The main policies used for this purpose, in both the above cases, have been the mandatory blending ethanol and biodiesel with conventional fuels (gasoline and die­sel, respectively), subsidies to farmers and industrial producers, and tax incentives throughout the supply chain. However, it is not yet clear, anywhere in the world, for how long the biofuel industry will be dependent on government incentives.

Some chains that are currently exploited for the production of biodiesel are likely to disappear in the future. Theoretically, the agricultural productivity level may be high, as in the case of castor beans, but the productive structure is frag­ile in many countries. The bioenergy industry, like other industries, is dependent on government incentives, but the productive structure is still very fragile. Even

A. Domingos Padula et al. (eds.), Liquid Biofuels: Emergence, Development 265

and Prospects, Lecture Notes in Energy 27, DOI: 10.1007/978-1-4471-6482-1,

© Springer-Verlag London 2014

after several years in operation, the risks for the industrial producers remain high. The main problems associated with the production of biodiesel from castor beans in Brazil, for example, are technological difficulties in the manufacturing process, low productivity and low volume in the agricultural area, the presence of informal intermediaries in the chain, unstable prices for castor oil, lack of technical assis­tance to farmers, and lack of associative experience, which has led to poor coop­eration on the part of farmers with the biodiesel companies.

As for the production of biodiesel from alternative oilseeds such as canola, sunflower, palm, jatropha, and castor, their respective supply chains have not yet established a structure capable of meeting the objectives of government programs, are still far from being competitive, and do not demonstrate economic, environmental, and social viability. In this context, only the soybean chain achieves competitive lev­els in the economic sphere, although its productive structure does not benefit small farmers, and the high technology applied in the field does not provide the increased employment that government incentive programmes generally seek to ensure.

In terms of the production of ethanol, countries have developed different tech­nologies based on the available raw materials. In Brazil, ethanol from sugarcane is competitive, and in the USA, corn is used to meet the production needs, while in Europe, due to its climate and public policies, beet is the most widely used feed­stock for ethanol production.

The production and consumption of renewable energy has evolved rapidly around the world. Since the first commercially viable projects in Brazil, the USA and Europe new technologies have been developed and applied. One of the technological frontiers involves the harnessing algae for fuel production, as seen in Global Market Issues in the Liquid Biofuels Industry and Algae: Advanced Biofuels and Other Opportunities. Research undertaken in various parts of the world suggests enzymatic hydrolysis rep­resents a commercially exploitable frontier, with the use of lignocellulosic materials, which is the focus of American energy policy (Sorda et al. 2010).[19]

By optimizing the biomass-derived energy production chain, the use of lig — nocellulosic materials, together with the establishment of local/regional energy systems, could increase the share of renewables in the global energy mix. Such initiatives might benefit those locations where development has not fully occurred.

The speed with which new inputs are researched and introduced also poses new challenges for the industrial sector. The investments are high, and the adoption of new inputs assumes the need for changes or adaptations that are often uneconomi­cal for companies. This may explain the delay in adopting the hydrolysis and fuel synthesis technologies in developing countries.

For the industrial producer, the presence of sunk costs increases uncertainty, as do instability in the biomass supply and insecurity in relation to contracts with suppliers and buyers, which are mostly state-owned companies that also act as players in the energy market. Such uncertainties may endanger the continuity of private investment, so perpetuating dependence on public investments.

Throughout the chapters of the book, one can see that some authors believe that the developing countries, which have cheaper sources of biomass than the industri­alized countries, can achieve greater competitiveness in the production of biofuels and that they may even compete with fossil fuels in the future. On the other hand, in the developed countries, there is a transition toward new renewable fuel produc­tion technologies, employing production systems with multiple inputs and multi­ple conversion technologies for the production of different forms of end use—fuel, electricity, and heat.

From the point of view of society, the relevance of continuing to devote con­siderable subsidies to big industries in support of biofuel production needs to be debated in countries with serious regional distortions and high levels of pov­erty with unmet education, sanitation, and health needs. Globally, this may be an opportune moment to discuss program agendas, reset the project designs, reorga­nize the productive structure, and relocate resources to those areas where they are really efficient, effective, and efficacious.

In summary, there are doubts about the future of biofuels, mainly regarding the energy and economic policies related to the production and consumption of such fuels. The current level of subsidies will probably change substantially over the coming years. It may be interesting to think that in the future, the high levels of government resources currently provided may no longer be affordable. Energy companies throughout the world are making efforts to master the technologies necessary to improve efficiency. As pointed out in the introduction to this book, there are economic challenges that must be overcome, to establish levels of pro­ductivity and price competitiveness compared to oil. Maybe, allowing market rules to select which technologies survive may be a means of ensuring that biofuels become consolidated in the global energy mix.

Countries need to adopt energy policies that establish incentives for farmers to use land for both food and energy production. These policies could encourage the pro­duction of non-food crops in less noble areas in terms of soil quality. These policies should also seek to establish incentives and stable contracts for the industrial produc­ers, because uncertainty dramatically reduces the interest of companies in the market.

The various types of initiatives presented and discussed in this book show there is a need to consolidate the biofuel productive chains, with the adoption of improved production practices in all the links of the chain. There is an evident need for more effective relationships between the links in the biofuel supply chains. The structure and organization of bioenergy production chains must consider the need to reduce water consumption, reduce emissions by changing land use, rationalize the use of pesticides and other chemicals, lower emissions from the tractors and the trucks used to transport biomass to the biorefinery as well as in the transportation of fuel to the points of consumption. Finally, by establishing more effective manage­ment, biofuels could fulfill their role as promoters of sustainability in all its aspects.

Meeting current demands involves making technological, economic, and social choices. Meeting future demands involves anticipating and identifying trends and future needs, in an exercise of creative imagination. Overcoming current chal­lenges involves making decisions today that can only be evaluated in the future.

The algal biomass production process requires one or more solid-liquid separation steps. Generally, first stage involves a separation of biomass from the bulk sus­pension (including flocculation, flotation, or gravity sedimentation). The second stage (thickening) raises the concentration of the slurry through techniques such as centrifugation, filtration, and ultrasonic aggregation; hence, it is generally a more energy intensive step than bulk harvesting (Brennan and Owende 2010).

The flocculation is the first (preparatory) stage that is intended to aggregate the microalgae cells in order to increase the effective “particle” size. Unlike floccula­tion, flotation methods are based on the trapping of algae cells, using dispersed microair bubbles. Gravity and centrifugation sedimentation methods are based on characteristics of suspended solids and are determined by density and radius of algae cells and sedimentation velocity. It is the most common harvesting technique for algae biomass in wastewater treatment because of the large volumes treated and the low value of the biomass generated. The filtration process is better suited for harvesting relatively large (>70 mm) microalgae such as Coelastrum and Spirulina. The membrane microfiltration and ultrafiltration (hydrostatic pressure) are viable alternatives to recovery of biomass from smaller algae cells (<30 mm), such as Dunaliella and Chlorella (Brennan and Owende 2010). Some species are much easier to harvest, considering algae densities and size. The strain character­istics, cost, and energy efficiency are the main factors to select harvesting technol­ogy (Brennan and Owende 2010).

Ahmad Zuhairi Abdullah, Shazia Sultana, Steven Lim and Mushtaq Ahmad

Abstract The potential application of acidic HZSM-5 and AlSBA-15 materials for catalytic degradation of high-density polyethylene (HDPE) into liquid hydrocarbon fuels was investigated using a tubular batch reactor. The reaction was carried out at various catalyst loadings between 5 and 15 % with 1:1, 2:1, and 3:1 HZSM-5 to AlSBA-15 ratios. The catalysts exhibited remarkable catalytic activity with conver­sions into liquid light hydrocarbons of up to 25 %. The gaseous product distribution showed a wide spectrum of hydrocarbons (Ci-C5) while the most predominant prod­ucts were C3 and C4 (47 and 40 %, respectively). Meanwhile, the liquid products were mostly in the range of C8-C25 depending on the reaction parameters and the amount produced decreased with increasing carbon number. Thus, catalytic degrada­tion of HDPE was a promising route for obtaining valuable fuels and petrochemicals from waste polymers. It required relatively low degradation temperatures to obtain liquid hydrocarbons with boiling points within that of gasoline range. At the same time, it could reduce the environmental problems caused by waste polymers.

Keywords High-density polyethylene • HZSM-5 • ALSBA-15 • Catalytic degradation • Hydrocarbon fuel

1 Introduction

In recent decades, plastic materials consumption has undergone a significant growth. According to an estimate, the global production and consumption of plas­tics have increased by about 10 % annually. At the same time, synthetic plastics

A. Z. Abdullah • S. Sultana (*) • S. Lim

School of Chemical Engineering, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang, Malaysia e-mail: shaziaflora@hotmail. com

M. Ahmad

Biofuel Laboratory, Quaid-i-Azam University, Islamabad 45320, Pakistan

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_13, © Springer-Verlag London 2014

recycling has gained considerable attention all over the world due to the serious environmental problems caused by waste plastics and resources needed for man­ufacturing of such huge quantity of plastic materials. There are several methods practiced currently for degradation and disposal of high-density polyethylene (HDPE) such as landfill, thermal degradation, and incineration. However, all of these methods have not gained social acceptance for disposal of the waste mate­rial (Lee et al. 2002). The disposal is also currently becoming legally restricted because of a decrease in landfill availability, cost increase, and strong pollution concerns such as emissions of various combustion products.

Recycling of plastics should be projected to minimize the pollution. It has lower energy demand to support the process to offer high energy conservation while at the same time enhancing the efficiency of the process. Plastics recycling technolo­gies have been historically divided into four general types. Primary and secondary recycling processes involve the processing of waste/scrap materials into a product with characteristics similar to and different from those of original product, respec­tively. Tertiary recycling involves the production of basic chemicals and fuels from plastics waste/scrap as part of the municipal waste stream or as a segregated waste. Meanwhile, quaternary recycling process retrieves the energy content of waste/ scrap plastics by burning or incineration. Although the primary and secondary recy­cling processes are the most common being applied in the society, tertiary recycling and quaternary recycling have been regarded as more sustainable (Garforth et al. 1997). In contrast to landfill, thermal, and incineration methods used for degrada­tion of HDPE, chemical recycling using catalysts has emerged as a potentially inter­esting alternative. It can achieve degradation of plastic wastes for conversion into a variety of useful products, mainly as liquid fuels and raw chemical feedstock (Lee et al. 2002). In this regards, catalytic degradation using materials such as zeolites is considered to be suitable due to their unique pore diameter. These materials seem to be especially useable as catalyst supports for waste polymer degradation.

Generally, zeolites are aluminosilicate members of the family of microporous solids known as ‘molecular sieves’ and an ‘open’ structure that can accommodate a wide variety of cations. Meanwhile, mesoporous silicates such as MCM-41 and SBA-15 are porous silicates with huge surface areas (normally >1,000 m2/g), large pore sizes (2 nm < size < 20 nm), and ordered arrays of cylindrical mesopores with very regular pore morphology (Garforth et al. 1997).

In recent years, several researchers have reported the synthesis of a new class of porous materials which are supposed to combine the properties of both zeolites and ordered mesoporous aluminosilicates (Trong et al. 2001). Some examples of mesoporous materials that have been investigated in the past include MCM-41, KFS-16, and SAPO-37 (Jalil 2002; Marcilla et al. 2002; Miskolczi et al. 2005; Sakata et al. 2002). In continuing the efforts to degrade the HDPE waste into useful products such as liquid fuel, this study has been initiated. The objective of the research is the use of a laboratory tubular batch reactor to study: (i) the potential application of HZSM-5 and AlSBA-15 as acidic microporous and mesoporous catalysts for degradation of HDPE, (ii) the activ­ity of these catalysts and their effects under various operating conditions on product dis­tribution and selectivity, and (iii) to enhance the potential benefit of catalytic polymer recycling for industrial application in the future.

This study confined to catalyst-based degradation of plastics into liquid fuels by converting HDPE into a resource which can be used as feedstock for liquid bio­fuel synthesis. It emphasizes the methods using catalysts under optimum operat­ing conditions for converting HDPE into liquid and gaseous fuels for specific applications. However, the conversion methods of HDPE into fuel depend on the types of plastics to be targeted and the properties of other wastes that might be used in the process. Additionally, the effective conversion requires appropriate technologies to be selected according to local economic, environmental, social, and technical characteristics. In our study, we use HDPE as raw material, and prior to their conversion into fuel resources, HDPE was subject to various meth­ods of pretreatment to facilitate the smooth and efficient treatment during the subsequent conversion process. Because during liquid fuel production, HDPE containing liquid hydrocarbon can be used as feedstock for biofuel synthesis. It is well noted in literature that the type of plastic being used determines the pro­cessing rate as well as the product yield of hydrocarbon to be used as resource for biofuel production (Miskolczi et al. 2005). In our study, we discussed the potential application of acidic HZSM-5 and AlSBA-15 materials for catalytic degradation of HDPE into liquid hydrocarbon as feedstock for liquid biofuel using tubular batch reactor. The reaction was carried out at various catalyst load­ings between 5 and 15 % with 1:1, 2:1, and 3:1 HZSM-5 to AlSBA-15 ratios in order to optimize the reaction conditions to achieve higher hydrocarbon yield as feedstock for liquid biofuel. Catalyst characterization and variables affect­ing conversion of HDPE into liquid hydrocarbon yield have been discussed as below.

The common techniques for oil extraction are mechanical pressing, the usage solvents, and supercritical fluid extraction. Each of these different methods pre­sents its own advantages and disadvantages. The first oil extraction method can be divided into expression and ultrasonic-assisted extraction and the efficiency nor­mally ranges from 70 to 75 % (Rengel 2008). The main drawback of this method is that it generally requires drying the algae beforehand, which is an energy intensive step.

Using solvents such as n-hexane, benzene, ethanol, chloroform, and diethyl ether can efficiently extract the fatty acids from algae cells. However, the use of chemi­cals in the process could present environmental, safety, and health issues. In many cases, manufacturers of algae oil use a combination of mechanical pressing and chemical solvents in extracting oil to improve efficiency (around 95 %).

Supercritical extraction requires high-pressure equipment that is both expensive and energy intensive. In this process, carbon dioxide is heated and compressed until it reaches a liquid-gas state. Then, it is applied to the harvested algae and acts like a solvent (Mendes et al. 1995; Ferreira et al. 2013).

Apart from these, there are some other more expensive and less known and uti­lized methods which are enzymatic extraction that uses enzymes to degrade the cell walls with water acting as the solvent; and osmotic shock is a sudden reduc­tion in osmotic pressure that can cause cells in a solution to rupture.

Once the oil is extracted through these methods, it is referred to as “green crude.” However, it is not ready to be used as biofuel until it undergoes a process called transesterification. This step is a chemical reaction in which triglycerides of the oil react with methanol or ethanol to produce (m)ethyl esters and glycerol (Rengel 2008). This reaction creates a mix of biodiesel and glycerol that is further processed to be separated and leaves ready to use biodiesel.

Direct conversions from a non-dry state are being studied and some pos­sibilities that may play an important role in offsetting the costs and improve oil extraction efficiency are arising. Among these, it is important to highlight in situ transesterification and hydrothermal liquefaction (Chen et al. 2009; Patil et al. 2008) Nevertheless, due to limited-level information in these processes for algae, more research in these areas is still needed.

Meanwhile, a lot of work is being made to reduce energy input and costs of extraction processes. Many industries claim they have come up with cost-effective methods in this area; however, until large-scale facilities are deployed, it is hard to tell which one will work in a large-scale basis.

The whole algae, bio oil, or the residues from oil extraction are excellent feed­stock for making other fuels and products via different processes. Some of these products will be presented in the next chapter.

Aldara is currently Associate Professor at Agribusiness Engineering Department at Fluminense Federal University and Coordinator of the Agribusiness Research Group (called Grupo de Analise de Sistemas Agroindustriais) in Volta Redonda’s Campus, Rio de Janeiro. Since 2007, she has been studying the competitive driv­ers of the biodiesel production chain and issues related to environmental and social sustainability in Brazil, especially on account of the policy related to the National Program for Production and Use of Biodiesel (PNPB).

Biswarup Sen is an Assistant Professor in Department of Environmental Engineering and Science, and member of Green Energy Development Centre, Feng Chia University, Taiwan. He got his Ph. D. from Indian Institute of Technology, Madras, India. He has over 60 publications with research expertise in anaerobic biotechnology for biofuels and biochemicals and has received several research grants and honors. He serves as the Review Editor of “Frontiers Microbial Physiology and Metabolism” and Reviewer of several international journals.

Bruce A. McCarl—Regents Professor and distinguished Professor of Agricultural Economics, Department of Agricultural Economics, Texas A&M University, College Station, TX 77843-2124, US, email: mccarl@tamu. edu

Carlos Alberto Oliveira de Oliveira is a professor at Faculty of Technology of the Cooperative, and a researcher of agribusiness and rural development at Agricultural and Livestock Research Foundation (Fepagro), the official service of the State of Rio Grande do Sul, Brazil.

Dr. Christian Rammer is senior researcher at ZEW’s Department of Industrial Economics and International Management. His research activities include empiri­cal research on innovation in firms, technology transfer, and research policy. He worked as a senior researcher at the Austrian Research Center Seibersdorf, Systems Research Technology-Economy-Environment and as an assistant pro­fessor and lecturer at the Department for Economic Geography at the Vienna

A. Domingos Padula et al. (eds.), Liquid Biofuels: Emergence, Development 269

and Prospects, Lecture Notes in Energy 27, DOI: 10.1007/978-1-4471-6482-1,

© Springer-Verlag London 2014

University of Economics and the University of Linz. Christian Rammer holds an M. Sc. in Regional Analysis and a Ph. D. from the University of Vienna.

Daniel Fernando Rolling is an Agronomist. Master in Agribusiness and currently a Ph. D. student of the Vegetal Production Program of the University of Santa Catarina state—UDESC, Brazil.

Dr. David Leiva-Candia is a Civil Engineer (expertise in bioprocesses), University of La Frontera, Chile, and holds an M. Sc. in Industrial Process Control (University of Cordoba, Spain) and a Ph. D. in second-generation biofu­els (University of Cordoba, Spain). He is postdoc at the Department of Physical Chemistry and Applied Thermodynamics, University of Cordoba. His research is focused on the production and quality analysis of microbial oil from different oleaginous yeast grown in waste feedstocks. He has been collaborating in several research projects concerning biofuels, biorefinery, and engine testing.

Eckhard Boles is a professor of molecular biosciences at Goethe University Frankfurt, Germany, since 2002. His research is focused on metabolic engineering of yeast strains for industrial purposes and transport of nutrients across the yeast plasma membrane. He has published more than 80 articles in international peer- reviewed journals and contributed to 13 important patents in the field of yeast bio­technology. Landmark patents were the construction of the first recombinant yeast strain able to ferment the pentose sugar L-arabinose, the cloning of the first bacte­rial xylose isomerase enabling yeast cells to ferment xylose and engineering yeast for the production of isobutanol. He is co-founder of the Swiss biotech company, Butalco, and has acted as a scientific advisor for several companies.

Gunter Festel is founder and CEO of the investment firm FESTEL CAPITAL. He has co-founded, as a Founding Angel, various technology start-ups in Germany and Switzerland like Autodisplay Biotech, Butalco, and Greasoline and is part­time faculty member at the Swiss Federal Institute of Technology, Zurich, and the Technical University, Berlin. He is the chairman of the board of the Association of German Biotechnology Companies, a member of various advisory boards and con­sultant to the OECD as well as different governmental departments in Germany, Austria, and Switzerland. Gunter Festel holds different master degrees and two Ph. Ds in natural sciences and economics.

Dr. Hong To joined Southern Cross Business School, Gold Coast, Australia, as a Postdoctoral Fellow in Applied Economics in 2010, after completing her Ph. D. in Economics at Department of Economics of University of Ottawa in Canada. Hong has undertaken research in the area of environmental economics, economic model­ing, and policy formulation.

Mario Otavio Batalha is Chemical Engineer, M. Sc. and Ph. D. in Industrial Engineering; professor at the Department of Industrial Engineering and Graduate Program in Sao Carlos Federal University—UFSCAR, Brazil.

Marta Wlodarz—Postdoctoral Researcher at Center for Energy Policy and Economics, Department of Management, Technology and Economics, ETH Zurich, 8032 Zurich, Switzerland, email: wlodarzm@ethz. ch

Martin Bellof is Business Development Manager at Autodisplay Biotech GmbH. Prior to joining Autodisplay, he worked for Macquarie Capital (formerly Investment Banking Group) in Frankfurt and Sydney and studied Biology and Business at Technical University of Darmstadt. In his final thesis, Martin analyzed success factors of corporate venture capital in the pharmaceutical and biotechnology industries.

Martin Wurmseher studied Business Administration at the University of Munich and is currently a Ph. D. student at the Chair of Technology and Innovation Management at the Department of Management, Technology, and Economics at ETH Zurich. Prior to his Ph. D. studies, he gained several years of profes­sional experience in Finance, Accounting, and Auditing in the banking industry. Furthermore, he holds the Swiss-Certified Public Accountant and the Financial Risk Manager (FRM) designations, gained professional experience in the Biotechnology industry, and is a member of the start-up research group at ETH Zurich.

Dr. Michael Charles Associate Professor, is a member of the Southern Cross Business School at Southern Cross University, Gold Coast, Australia. He has a Ph. D. from the University of Queensland and a Master of International Business Studies from the Queensland University of Technology. His current research mainly focuses on transport and environmental policy, public values and infra­structures, and systems in transition.

Dr. Pilar Dorado graduated from the University of Cordoba, Spain, in Agriculture Engineering. She followed this with an international master in Irrigation and Drainage (Ministry of Agriculture and Fishering, Spain) and a Ph. D. in Agriculture Engineering, in 2001. She was appointed lecturer in the Department of Mechanical and Mining Engineering at the University of Jaen. In 2005, she moved to the University of Cordoba (Department of Physical Chemistry and Applied Thermodynamics), and in 2012, she was appointed professor. She is head of the research group BIOSAHE since 2002. She has lead/participated in a number of Spanish Ministry-funded projects and two European-funded projects. Her research has been directed toward new renewable alternative fuels for internal combustion engines, including engine testing and the biorefinery concept.

Dr. Shazia Sultana is young scientist with research and teaching experience in the field of Renewable energy, Biofuel technology and Plant Systematics and Biodiversity. One hundred research publications (to date) in top international journals, more than 1000 citations, with high IF, H & I indices, 06 international books published and circulated internationally. Dr. Sultana is awardees of various national and international awards. Currently, she is working as fellow researcher in School of Chemical Engineering, Universiti Sains, Malaysia, and senior research associates in Biofuel Laboratory, Quaid-I-Azam University, Islamabad, Pakistan.

Dr. Silvio Vaz Jr. is a research scientist at Brazilian Agricultural Research Corporation (EMBRAPA). Holds a B. Sc. degree in Chemistry, a M. Sc. degree in Physical Chemistry, and a D. Sc. degree in Analytical Chemistry from University of Sao Paulo. His research lines are Analytical Chemistry and Renewable Chemistry.

Dr. Suman Sen is an academic at Southern Cross University, Gold Coast, Australia. His research interests are in the area of transport energy, public trans­port, road user charging, transport planning and policy, transport sustainability, business management, and corporate social responsibility and ethics. Suman also has an MBA and an MA in economics.

Vitor Francisco Dalla Corte is an Economist. Master in Business Administration, and currently, a Ph. D. student of the Agribusiness Graduate Program of the Federal University of Rio Grande do Sul — UFRGS, Brazil.

[1] These matters are dealt with in detail in chapter “Environmental Issues in the Liquid Biofuels Industry”.

[2] Bioethanol energy content is two-thirds that of gasoline, and therefore is referred to as litre of gasoline equivalent (lge).

[3] India, Pakistan, Swaziland and Zimbabwe have production costs that are broadly similar to those experienced in Brazil (Demirbas 2009; Dufey 2006).

[4] Biodiesel energy content is 10-12 % less than that of diesel, and therefore is referred to as litre of diesel equivalent (lde).

[5] de Gorter and Just (2010) have shown that crop prices, i. e. corn prices in the case of the United States, are directly linked to that of bioethanol. A theoretical framework with regard to the rela­tionship between sugar cane prices and bioethanol prices in Brazil or between palm oil/soybean prices and biodiesel prices in the European Union can be formulated easily in a similar way.

[6] This seal is awarded to biofuel producers who buy a minimum percentage of feedstock from family farmers, provide technical assistance, and enter into contracts with these farmers.

P. F. A. Shikida (*) • B. F. Cardoso • V. A. Galante • D. Rahmeier Universidade Estadual do Oeste do Parana, Toledo, Brazil e-mail: peryshikida@hotmail. com

B. F. Cardoso

e-mail: barbarafcardoso@gmail. com

[8] A. Galante

e-mail: vgalante@hotmail. com D. Rahmeier

e-mail: daliane. rahmeier@gmail. com

A. Finco • D. Bentivoglio • M. Rasetti Universita Politecnica delle Marche, Ancona, Italy e-mail: a. finco@univpm. it

D. Bentivoglio

e-mail: d. bentivogho@univpm. it M. Rasetti

e-mail: m. rasetti@univpm. it

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_2, © Springer-Verlag London 2014

[9] The list below gives the main tools which are/have been used to promote biofuels in the EU: Proposal directive European Communication COM (2012) 595 final: ILUC proposal; European Communication COM (2010) 160/01; COM (2010) 160/02: sustainability criteria; European Decision 2010/335: Guidelines for the Calculation of Land Carbon Stocks; Renewable Energy Directive (RES-D) Directive 2009/28/EC: RED; Directive 2009/30/EC: Fuel Quality Directive (FQD); EU Climate and Energy Package 17th December 2008; Directive Biofuels Directive 2003/30/EC: Biofuels Directive; Directive 2003/17/EC: Fuel Quality Directive; Directive 98/70/EC: Fuel Quality Directive; Directive 2003/96/EC: Energy Taxation; Common Agricultural Policy (CAP).

D. F. Kolling (*)

Crop Science Graduate Program, Santa Catarina State University,

2090 Luiz de Camoes, Lages, SC, Brazil e-mail: dfkolling@gmail. com

[11] F. Dalla Corte

Agribusiness Graduate Program, Federal University of Rio Grande do Sul, 7712 Bento Gonfalves, Porto Alegre, RS, Brazil

C. A. O. Oliveira

Agricultural and Livestock Research Foundation (Fepagro),

570 Gonfalves Dias, Porto Alegre, RS, Brazil

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_3, © Springer-Verlag London 2014

[12] Classic market (spot)—non-specific transaction in which there is no effort to sustain the relationship, which is the case closest to the pure competition market.

2. Hybrid forms—trust relationships can be built with higher asset specificity and higher recurrence of transactions. In this case, there are no transaction incen­tives between agents and the firm. Thus, the agents are highly motivated to ful­fill the contract.

3. Vertical integration or hierarchy—regards vertical integration necessary for sporadic transactions and in the presence of highly specific assets. In this case, the transactions between agents are incorporated into the hierarchy of the firm.

[13] Global-warming potential—An index, based upon radiative properties of well-mixed greenhouse gases, measuring the radiative forcing of a unit mass of a given well-mixed greenhouse gas in the present-day atmosphere integrated over a chosen time horizon, relative to that of carbon dioxide. The GWP represents the combined effect of the differing times these gases remain in the atmos­phere and their relative effectiveness in absorbing outgoing thermal infrared radiation. The Kyoto Protocol is based on GWPs from pulse emissions over a 100-year time frame [definition adapted from IPCC 4th Assessment Report, Working Group I, The Physical Science Basis (IPCC 2007)].

[14] The top three GHG-emitting sectors are energy (26 %), industry (19 %) and agriculture (14 %).

[15] Carbon debt is the time required to counterbalance the CO2 emissions resulting from the con­version of a native ecosystem to biomass production.

[16] These include low-till or no-till cultivation, crop rotations and other cultivation practices that need minimal inputs such as fertilizers, pesticides and herbicides.

[17] Negative values indicate a net reduction in GHGs.

[18] Bioethanol cannot, however, be shipped by existing crude oil or petroleum pipelines as it absorbs water and other impurities, all of which affects fuel purity and degrades the infrastruc­ture (Eggert et al. 2011).

[19] Sorda G, Banse M, Kemfert C (2010) An overview of biofuel policies across the world, Energy Policy, 38(11)