Initiatives for the use of biomass in Ligno Cellulosic Feedstock Biorefineries: the sugar platform in the world and in Brazil
Oil, natural gas and their products represent 55% of global energy consumption, yet they will not last more than a few decades. Thus, it is necessary to find substitutes for these fuels and an alternative that presents itself is the use of organic matter (biomass). This article presents the initiatives taken in the world, and especially in Brazil regarding the use of raw materials in the context of lignocellulosic biorefinery. The focus will be on the sugar platform for the production of second-generation ethanol, aimed at getting a prominent position in this agribusiness market segment. The survey of information availability was obtained through a literature search. The results suggest that the technology is still undergoing research and development and it is of great interest in consolidating the global market for ethanol.
Keywords: Biorefinery; Biomass; Lignocelulosic feedstock; Ethanol; Brazil.
Climate change and increase in oil prices combined with the strategic needs of energy production have stimulated an unprecedented race to the production of alternative fuels, preferably renewable sources of energy (BUCKERIDEG et al, 2010).
The use of biomass for energy is growing in importance as a possible way to mitigate the problems above mentioned. There are different routes to convert biomass energy in the final desired energy flow, either in the form of heat, fuel or electricity (BNDES & CGEE, 2008).
Thus, there are opportunities for the development of an industry based on renewable raw materials. In addition to the biofuel known, a stream of innovations in development may be laying the foundations for an integrated industry operating biomass (COUTINHO & BOMTEMPO, 2010).
In this scenario, Brazil stands in a privileged position to assume leadership in integral use of biomass because this has great potential for cultivation of renewable raw materials , making use of comparative and competitive advantages such as : (i) wide area for agricultural crops (highlight to the sugar cane industry), (ii) the greatest biodiversity, (iii) intense solar radiation, (iv) water in abundance, (v) diversity of climate, and (vi) a pioneer in the production of biofuel ethanol (CGEE, 2010). The country has also conditions to be the main recipient of investment funds, derived from the carbon market segment in the production and use of bioenergy.
Brazil currently enjoys a comfortable position with respect to ethanol production technology. In this sector, Brazil is the world leader in the production of sugar cane, ethanol and sugar with 572.7 million tons, 27.7 billion gallons and 31.3 million tons, respectively, in the 2008/2009 harvest (CORTEZ, 2010).
On average, 50% of the sugarcane harvested is destined to ethanol production and the remaining 50% is allocated to sugar production. About 2 / 3 of the sugar produced are destined for foreign markets while the rest supplies the domestic market. About 85% of ethanol production is directed to the domestic market, of this, 90% is intended for use as fuel, and the rest serves the foreign market (BASTOS, 2007).
However, to maintain this position in a competitive scenario, where other players are interested in this subject with heavy investments in research, development and innovation (R, D & I), Brazil needs to maintain investment to support the development of new technologies and skills training (BUCKERIDEG et al, 2010).
Currently, the conversion of lignocellulosic material by the sugar platform – this material is present in the straw and bagasse from sugar cane - into fermentable sugars for ethanol production, called second-generation ethanol, is being considered in Brazil as a promising alternative to meet world demand.
In this way, the article´s objective is to expose the main initiatives taken in the world, and especially in Brazil on the use of raw materials in the context of lignocellulosic feedstock biorefinery. The focus will be on the sugar platform for the production of second-generation ethanol, aimed at a prominent position in this market segment in the agribusiness.
Ferdinand et al (2006) affirm that the concept of producing goods from agricultural commodities, such as biomass, is not new, however, to use biomass as a feedstock in the production of various products in a manner similar to an oil refinery where fossil fuels are used as input is relatively new. Its main objective is to transform organic materials into usable products processing industries using a combination of technologies and biotechnological processes.
The basic principles of the traditional oil refinery and the biorefinery are schematically represented in Figure 1. An oil refinery mainly supplies transport fuels and energy, and only a relatively small fraction is used for chemistry. At a biorefinery a relatively larger amount is used for chemistry and material utilization. According to Kamm et al. (2006), bio based industrial products can only compete with petro-chemical based products when biomass resources are processed optimally through biorefinery systems, where new value chains are developed and implemented.
Figure 1: Oil refinery versus biorefinery (KAMM et al., 2006)
In their studies Annevelink et al (2007) showed the existence of seven types of biorefineries, which are still in research and development: (i) Conventional Biorefineries (CBR); (ii) Green Biorefineries (GBR); (iii) Whole Crop Biorefineries (WCBR); (iv) Ligno Cellulosic Feedstock Biorefineries (LCFBR); (v) Two Platform Concept (TPCBR) Biorefineries; (vi) Thermo Chemical Biorefineries (TCBR); and (vii) Marine Biorefineries (MBR).
Ligno Cellulosic Feedstock Biorefinery
The ligno cellulosic feedstock biorefinery uses a mix of sources of biomass for a range of products through a combination of technologies. This biorefinery is the separation and use of three basic chemical fractions: (a) hemicellulose, polymers of sugar with five carbons, (b) cellulose, polymers of glucose with six carbon atoms, and (c) lignin, polymers of phenol (FERNANDO et al, 2006). Figure 2 shows the products that can be obtained from these chemical fractions.
Figure 2: Potential products from a Lignocellulosic Feedstock Biorefinery (KAMM et al., 2006)
According to Pereira Jr. et al (2008), the use of lignocellulosic biomass within the context of the biorefinery is based on two different platforms, as the concept of Two Platform Concept (TPCBR) biorefineries illustrated in Figure 3, which are intended to provide "building blocks" for a variety of products.
The syngas platform, also known as thermochemical platform, is based on thermochemical conversion processes for the reaction of raw materials at high temperatures with a controlled amount of oxygen (gasification) to produce syngas (CO + H2) or the absence of oxygen (pyrolysis) to produce bio-oil, which after a hydrodeoxigenation process produces a liquid mixture of hydrocarbons similar to those present in oil.
Figure 3: Two Platform Concept Biorefinery (KAMM et al., 2006)
The sugar platform, subject matter of the article, is based on processes of chemical and biochemical conversion of sugars extracted from biomass by a separation of its main components. For this, the pre-treatment is essential in order to disorganization of the lignocellulosic complex and consequently increase the accessibility of enzymes to cellulose molecules (PEREIRA JR et al., 2008).
The pretreatment, which involves subjecting the lignocellulosic material to a series of operations aimed at promoting the breaking of ties that bind the macro. Such operations are responsible for the suitability of raw materials such as bagasse from sugar cane, the conditions of processing by microorganisms. These can be classified as physical, physicochemical, chemical and biological agent that acts as the structural change. Figure 4 shows a simplified scheme for the separation of the main components of lignocellulosic materials.
Figure 4: Separation of lignocellulosic components
Pereira Jr. (2006) notes that the decision to use the hydrolysis process depends on the type of lignocellulosic material employed. In hydrolysis of hemicellulose (which occurs in milder conditions than in the case of cellulose), the strategy has been the use of dilute sulfuric acid. In the case of cellulose, since chemical hydrolysis requires conditions of high severity (high temperature, large exposure times and high concentrations of acid), a higher resistance to hydrolytic attack, the use of enzymatic hydrolysis is more appropriate (by the absence of severe conditions), this strategy differs from technological conception of old cases where there was a joint chemical hydrolysis of cellulose and hemicellulose, as are polysaccharides with different susceptibilities to hydrolytic attack.
The total hydrolysis of cellulose yields only glucose, which can be converted to a series of chemical and biochemical as illustrated in Figure 2, with particular reference to its biological conversion to ethanol, said 2nd generation to be derived from lignocellulosic materials.
This new technology platform could revolutionize industries as in the case of Brazil, which generates a large amount of residues such as bagasse from sugar cane, however, the effective utilization of lignocellulosic materials in microbiological processes collides with two major obstacles: the crystalline structure of cellulose, highly resistant to hydrolysis and the lignin-cellulose association, which forms a physical barrier that prevents access to microbiological or enzymatic substrate (CGEE, 2010). Additionally, the acid hydrolysis of cellulose has the disadvantage of requiring the use of high temperature and pressure, leading to destruction of part of the carbohydrates and the obtainment of products of degradation toxic to microorganisms. The enzymatic saccharification, in turn, requires the use of physical treatments (grinding, heating, irradiation) or chemical treatments (sulfuric acid, phosphoric acid, alkali) to achieve viable yields.
Brazilian potential for generating lignocellulosic feedstock
In view of the vast biodiversity found in its territory, Brazil has a wide variety of agricultural residues and agro-industrial bioprocessing which arouses a great interest in economic and social development. Among these samples containing residues derived from activities such as pulp and paper industries (sawdust, shavings and eucalyptus and pine declassified chips), sawmills (sawdust), alcohol and sugar mills (bagasse from sugar cane) and , in general, agricultural production units generating crop residues such as cereal straw, corn, wheat, corn cob, rice hulls and oats, among others (RAMOS, 2000).
In Brazil, the amount of lignocellulosic residues generated annually is approximately 350 million tons (PEREIRA JR, 2008). Considering that the major source of lignocellulosic materials is the sugar cane industry and adopting the cellulose, hemicellulose and lignin content in the bagasse as a benchmark, one gets respectively the potential quantity of 164.5, 96.25 and 71.05 million tons that can be obtained from lignocellulosic residues in Brazil.
This work aims to present the main initiatives taken in the world, and especially in Brazil regarding the use of raw materials in the context of lignocellulosic biorefinery. The focus will be on the sugar platform for the production of second-generation ethanol, aimed at a prominent position in this market segment in agribusiness. The methodology adopted in this exploratory study was based on literature and documents from a information survey. To achieve the goal, information is presented to provide an overview of the global and the Brazilian research efforts to develop new technologies for obtaining the second-generation ethanol.
Although currently there is no commercial plant to produce ethanol from lignocellulosic materials, many pilot and demonstration plants have been developed, and several commercial projects are under development. Table 1 shows the global companies that have been used technologies for producing second-generation ethanol and additional information.
Table 1 - Companies that employ technologies to produce second-generation ethanol and process characteristics (CGEE, 2010)
Table 1 shows that most companies explore the concept of biorefineries in accordance with the sugar platform. Most plants are located in the U.S., but countries like Canada, Sweden, Finland, Russia and Japan are also headquarters of some initiatives. Table 2 shows the projects approved by the U.S. Department of Energy (DOE) for construction of small biorefineries in the country at the end of 2008.
Table 2 - Projects approved by the U.S. DOE for the construction of small biorefineries in the U.S. (CGEE, 2010)
Table 2 shows a trend toward the implementation of the biochemistry platform and there are initiatives thermochemical technologies such as BTL. (biomass-to-liquid).
It is worth emphasizing that it was implemented the Biomass Program of the Department of Energy in the United States to create a new industry - the biomass industry - consolidated with the establishment of biorefineries that can transform many types of biomass, at competitive prices relative to current fossil sources, fuels, chemicals, electricity and heat. The use of biorefineries and cellulosic biomass emerge as key to achieving the goals of production/consumption of ethanol, due to limitations of the sources currently employed (BASTOS, 2007).
In this context, the country plans to invest $ 385 million in six cellulosic ethanol biorefineries capable of producing 480 million liters of cellulosic ethanol per year as part of the plan of U.S. government and make cellulosic ethanol competitive by 2012 in order to reduce consumption gasoline in the U.S. over the next 20 years. Table 3 presents the six projects selected by the U.S. DOE.
Table 3 - DOE's investments in projects to produce cellulosic ethanol in the U.S. 2007-2010 (BASTOS, 2007)
One of the Brazilian companies that invest more in Research, Development & Innovation (R, D & I) on biorefineries, in particular from of residues of sugar cane, is Petrobras SA, a company with shared ownership with the Brazilian State, that operates in 27 countries, in the energy segment, primarily in exploration, production, refining, marketing and transportation of petroleum and its products in Brazil and abroad (PETROBRAS, 2011).
According to Baratelli Jr. (2007) the company's competitive strategy is to expand the market share of biofuels leading producer of biodiesel and expanding participation in the ethanol business. Table 4 shows the routes for production of biofuels and the stage of technological effort undertaken by Petrobras and its research centre (CENPES) for the development of technologies.
Table 4 - Effort technological routes to biofuels production for Petrobras (BARATELLI JR., 2007)
Table 4 shows that biofuels that require a high technological effort by PETROBRAS are second generation ones, such as cellulosic ethanol and pyrolysis and synthesis gas-BTL fuel which, in turn, use biomass source material as a source of cellulosic - the feedstock for lignocellulosic biorefineries. With the development of the bioethanol project (ethanol from lignocellulose) - a biofuel produced from organic residues - Petrobras enters the production of the so-called second generation biofuels (PETROBRAS, 2011).
After the laboratory tests stage, the bioethanol production project is to be tested on a pilot scale, using an experimental unit installed in CENPES. A pilot plant for ethanol from lignocellulose, located in CENPES and developed in partnership with the Brazilian company Albrecht , is unique in Brazil using enzyme technology. For ethanol production from organic residues, the plant uses a breaking down process with the action of enzymes. The project was developed by Petrobras, in partnership with the Federal University of Rio de Janeiro (UFRJ) and other universities.
Any plant residues can be used as a source of biomass in experimental plant, but the system is set to bagasse from sugar cane, being the most significant agro-industrial waste in the country. Another raw material being used in the tests is the castor bean, starchy residue from the production process of biodiesel from castor beans.
The experimental plant is capable of producing about 220 gallons of ethanol per ton of crushed cane sugar. At this stage of the research project, researchers working on the optimization of production process and aims to reach the milestone of 280 liters per ton of pulp the same equipment. As a result of this research, Petrobras has taken out two patens on the subject (BR 0605017-4 and BR 0505299-8) to the Brazilian Patent Office.
The pilot plant of bioethanol from lignocellulose puts Petrobras in the forefront regarding second generation biofuels, those produced from organic residues and does not compete with agricultural foodstuff production. The use of residues such as bagasse from sugar cane can substantially increase ethanol production without increasing the planted area, increasing the productivity of the existing process for waste recovery.
Thus, the production of biofuels in the near future may also be complementary to food production. Petrobras predicts that in 2012 in a semi-industrial plant for bioethanol will be built. Figure 6 shows a illustration of the technological route adopted by Petrobras for lignocellulosic bioethanol production.
Figure 6: Route Technology adopted by PETROBRAS for lignocellulosic bioethanol production (BARATELLI JR, 2007)
The process of making ethanol from plant residues is divided into four stages. In the first stage, there is the pretreatment of sugarcane’s bagasse in which it is adopted the mild acid hydrolysis process, where the residue has the crystalline structure fiber broken and the sugar recovery is easier to hydrolyze.
Then comes the delignification of cellulose-rich solid. Lignin is removed, the complex that gives the fiber strength and protects cellulose from microbial action but presents a great inhibition to the process.
In the third phase, the liquid from the pretreatment acid, rich in sugar, is fermented by the Pichia stipitis yeast adapted to be used in this fermentation.
The solid from the stage of delignification, rich in cellulose, is also treated: it goes through a process of saccharification (conversion of sugars) by means of enzymes and is fermented by the Saccharomyces cerevisiae yeast, the same fungus used in making bread. Petrobras is still studying the enzymes more effective for this manufacturing process, testing enzymes available in the market and researching new enzyme preparations.
In the final step, both liquids from the different fermentations are distilled. The product of this distillation is ethanol, which has the same characteristics of that made from sugar cane in the industrial process.
It is worth mentioning that the Brazilian government action is not restricted to its participation in Petrobras, considering the importance that the issue arouses in the renewable energy agenda for national policy. Brazil's government also invests resources in R,D & I, as can be seen in Table 5, and human resource training.
Table 5 - R,D & I investment by the Brazilian government in the use of biomass since 2005 (PEREIRA JR, 2008)
The theme of renewable energy is present on the national agenda of all nations around the globe as a viable alternative source of fossil fuels like oil and coal. Experts believe that the processing of biomass for energy, fuels and chemicals may constitute a key industry in this century, thus creating a new industrial paradigm. New technologies, based on the use of all the plant and the integration of traditional and new processes, will be needed.
Brazil is among the target countries for the development of such technologies due to its large existing biodiversity and knowledge gained over the past decades, particularly due to production of ethanol from sugar cane.
In this context of innovation, a new opportunity for biomass utilization arises in the country: the use of ligno cellulosic biomass from agricultural residues, particularly the sugar industry to produce second-generation ethanol within the context of biorefineries explored in this article.
It was noted that government initiatives are being taken in order to establish a suitable environment for the development of new products and processes. However, technological and commercial challenges must be overcome to permit Brazil to maintain its position in the global agribusiness and produce products with higher added value, contributing to the development of bio-economy and taking advantage of this window of opportunity to increase its economic growth in a sustainable manner.
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 Sugarcane bagasse is composed of 47% cellulose, 27,5% hemi-cellulose and 20.3 - 26.3% liginine (Aguiar, 2010)
Escola de Química da Universidade Federal do Rio de Janeiro (UFRJ). Cidade Universitária – Centro de Tecnologia, Bloco E – 2º nadir – DPO – Área de Gestão e Inovação Tecnológica – Rio de Janeiro/RJ – CEP: 21949-900. email: email@example.com
2 - Escola de Química da Universidade Federal do Rio de Janeiro (UFRJ). Cidade Universitária – Centro de Tecnologia, Bloco E – 2º nadir – DPO – Área de Gestão e Inovação Tecnológica – Rio de Janeiro/RJ – CEP: 21949-900. email: firstname.lastname@example.org
3 - Escola de Química da Universidade Federal do Rio de Janeiro (UFRJ). Cidade Universitária – Centro de Tecnologia, Bloco E – 2º nadir – DEB – Área de Processos Bioquímicos – Rio de Janeiro/RJ – CEP: 21949-900. email: email@example.com
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Monday, 28 November 2011.