Conceptual framework of bioethanol production from lignocellulose ...

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16 ENVIRONMENTAL BIOTECHNOLOGY 8 (1) 2012biomass cannot be renewed and used so fast (Gołaszewski2009a). The percentage share of biomass in the renewableenergy consumption is estimated to change globally from theexisting 77% into 52% in 2040 but at the same time the biofuelproduction efficiency will rise (EREC 2004). The biomassaccounting for approximately 10% in the mix of the primaryenergy sources now, will constitute approximately 30% in 2050(Macqueen and Korhaliller 2011).In the future the prospective biomass is indicated to besourced out from woody crops of short, 2-4-year rotation(mainly willow and poplar), that is vegetative forest stand(SRC – Short Rotation Coppice, SRWC – Short RotationWoody Crops), agricultural production and food industrylignocellulose waste as well as forestry (SRF – Short RotationForestry) that enjoy optimal fuel parameters upon the lapseof 8-15 years (e.g. Stolarski et al. 2009; Weih 2008). Thetendency of assigning agricultural land to tree crops isstrongly supported in Sweden, and also in Great Britain,Spain and the USA launched research programmes in thatrespect (Kumar 2009; Rowe et al. 2009). The subject of theresearch includes forest stand of relatively fast renewablepotential, namely alder-tree, ash-tree, beech, birch,eucalyptus, poplar, willow, maple-tree (Acer pseudoplatanusL.), mulberry-tree (Broussonetia papyrifera), great maple,Paulownia, acacia, and others. According to Berndes andfollowers (2003) and the International Energy Agency (2004)in 2025 lignocellulose-based energy is estimated to accountfor as much as 2/3 of biomass energy production, and theeffective conversion of lignocellulose into ethanol is going tobe the essential technology for biofuel production. Thus,from the agricultural point of view, from among manycurrently developed biofuel and ecopower technologies,technological arrangements for lignocellulose biomass-basedproduction of ethanol will be particularly important in a shorttime perspective as those specific technological arrangementsconstitute an intermediary stage in the process of developingintegrated processes of converting biomass to an universalenergy medium – hydrogen or electric current.Development of the biofuel market according to thescenario exhibited in Figure 1 will boost continual researchon mechanisms driving biological processes and knowledgetransfer for the purpose of developing technologies forbioenergy production, biofuel production and other bioproductsproduction (bioeconomics). Agricultural biorefinery oragrirefinery processing agricultural resources, producing awide spectrum of power products and non-power productsmay be the key element for the biofuel market. Thebiorefinery altogether with power generators will make upthe so called agripower compound – a local power cell withinthe system of dispersed sources of energy consumed locally(Gołaszewski 2009b). It is plausible to state that theagrirefinery will locally integrate three fundamental factorsof economic sustainable development in rural areas –bioeconomics, environment and society, and implementationof this system will directly contribute to sustainabledevelopment and energetic safety of the state.Figure 1. Biorefineries and biofuel generations developmentscenario.Biorefinery, 1 st Phase – 1 st generation biofuel made from sugarcrops, starch crops, and vegetable oil. In the past ten years:• Upgrade of existing 1st generation biofuel productiontechnologies.• Research on improvement of technological efficiency forproduction of 2 nd generation biofuel; biorefineryconceptual framework development; pilot installationsfor 2 nd generation biofuel production were built –commercialization is in process.Biorefinery, 2 nd Phase – 2 nd generation biofuel:• 2 nd generation biofuel production technology development.• Universal character of commercial biorefinery, the basicproduct of which will be biofuel; research is continued onimprovement of production efficiency for biofuel madefrom lignocellulose-based biofuel and integration ofbiorefining processes and power generation processes.• Power crops development (new biological diversity ofplants emerging from molecular biology engineering, newcrops technologies) within the context of agriculturalsustainable development.Integrated Biorefinery, 3 rd Phase – integrated biorefiningprocesses and power generation processes:• Power products (including universal biofuel – methanol) andnon-power products, dispersed agripower compounds.Universal Energy Medium Market – (bio)hydrogen, electriccurrent.Given the current state-of-the-art of development ofbiofuel production technology and existing systems of biofuelproduction and distribution, improvement of productionefficiency for bioethanol made from woody crops – thenatural resource that is available in large quantities and isproduced locally – is challenging today. Bioethanol, as a fuelfor motor vehicles has been produced, for tens of years, fromthe natural resource such as crop that is rich in sugar (sugarcane, sugar beet) or starch (grains, potato crops), is 1 stgeneration biofuel. Characteristic feature of 1 st generation
Gołaszewski et al. Bioethanol from lignocellulose 17biofuel includes natural competitiveness as compared tofodder or food production, relatively high production cost ascompared to petrochemical fuel (low competitiveness) andlow environment-friendly impact (Gołaszewski 2009c;Gołaszewski et al. 2008a). The aforementioned drawbacksare non-existent in the case of 2nd generation biofuelobtained from woody crops or agricultural waste or residuesof high cellulose content called cellulose or lignin-cellulose ormore often lignocellulose crops to highlight the substantialcontent of lignin – polymer that is hard to convert into simplechemical compounds, and which may serve, beside nonpoweropportunities, as the hard fuel for gasificationprocesses and pyrolysis and further conversion into biofuel,and bioethanol too.This paper aims at elaborating upon the conceptualframework of the biorefinery in the aspect of competitivenessof agricultural market and conferring upon conversion oflignocellulose biomass into bioethanol within the context ofbiorefining processes.BIOREFINERY AND AGRICULTURAL MARKETGiven the forecast biofuel incorporation index of 10% in thefuel market in the European Union by 2020, agriculture isassumed to take part in this policy and at the same time it willbe one of the beneficiaries enjoying the implementation ofthe biofuel market development policy. Figure 2 presents thecurrent and forecast interrelation between the fundamentalbiofuels, namely biodiesel and bioethanol (EuropeanCommission 2007). In the future the relation between thesebiofuels will probably not change as the use of biodiesel willprevail, including 2 nd generation biodiesel made fromsynthesis gas (Fischer-Tropsch Synthesis) obtainable frombiomass and fossil fuel (coal). However, the growth rate ofbioethanol is estimated to be higher in the next coming threeyears. The market share of bioethanol will rise 2.5-fold fromthe existing 3 up to 8 million tonnes of oil equivalent (mtoe)in 2020.Figure 2. Agricultural market of biodiesel and bioethanol andincorporation of biofuels in the fuel market in the EuropeanUnion by 2020. Source: European Commission (2007).Currently cellulose forestry-based biomass serves thepurpose of producing 2 nd generation bioethanol but theconversion processes for lignocellulose resource obtained fromagricultural land (arable land and marginal land) are beingdeveloped. From the general point of view the assumptions forthe technological process of producing ethanol from celluloseare recognized, nevertheless the production efficiency isunsatisfactory, which most of all results from high cost ofbiomass and cost-consuming degradation of cellulose intomonosaccharides. According to Himmel and followers (2007),the biofuel industry and bioethanol production will be boostedby the progress in research performed to the extent of: (i)relatively slow kinetics of cellulose chemical hydrolysis intosaccharides, (ii) low capacity of saccharides obtained fromother polysaccharides (hemicellulose), and (iii) delignification.Biofuels represent just one out of prospective marketableproducts obtained from lignocellulose crops-based biomassbut the industrial reclaim of organic chemical compoundsand material from a variety of resources and furtherprocessing of the same is the essence of the researchconducted today in the context of the future biorefineryprocesses, including Clark and Deswarte (2008):• Structural metabolites: cellulose, hemicellulose and ligninbeing building material for stems, leaves, cell walls.• Vestiges metabolites: oil, carbohydrates, proteins found inbulbs, roots, nuts, fruit, seeds.• Secondary metabolites: phenols, organic nitrogencompounds (e.g. alkaloids), terpenes produced in stems,leaves, roots, seeds and fruit.• Stem fibre and leave fibre.• Flower pigments and aromatic oil, fruit, stem, leave androot pigments and aromatic oil.• Wax, resin and rubber found in leaves, seed sprouts andfruit.• Bio-oil obtained from whole plants, crops utensils-relatedresidues.In the past decade essential biotechnological progress wasaccomplished in result mostly of the genetic engineering appliedto the food and fodder production and human health care.A new charter in white biotechnology development (facilitatedby microorganisms and enzymes) and conventional chemicalengineering focusing on applied research and developmentworks over new semi-products and final products for industrialpurposes, is drawn up by biorefinery (Laufenberg et al. 2003;Patel et al. 2006; Willke and Vorlop 2004). Biorefineryrepresents the installation for biomass conversion processesentailing simultaneous production of a variety of bioproducts,including biofuel, bioenergy, food ingredients, fodder,biomaterials and biochemicals. Biorefinery-based processes offractioning biomass involve methods of physical, chemical,biochemical, biological (microbiological and enzymaticprocesses) and thermochemical conversion. Biorefinery-basedprocesses are equivalent to crude oil refining processes, howeverthere are essential and principal differences; natural resourceprocessed in the biorefinery may be obtained locally and the
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