supply network synthesis on rubber seed oil utilisation as potential biofuel feedstock

7
Supply network synthesis on rubber seed oil utilisation as potential biofuel feedstock Wendy Pei Qin Ng a, * , Hon Loong Lam a , Suzana Yusup b a Department of Chemical and Environmental Engineering, Centre of Excellence for Green Technologies, The University of Nottingham, Malaysia Campus, Jalan Broga, 43500 Semenyih, Selangor, Malaysia b Chemical Engineering Department, Biomass Processing Laboratory, Centre of Biofuel and Biochemical, Universiti Teknologi PETRONAS, 31750, Bandar Seri Iskandar, Perak, Malaysia article info Article history: Received 14 November 2012 Received in revised form 6 February 2013 Accepted 7 February 2013 Available online 26 March 2013 Keywords: Supply network Rubber seed oil Biofuel Alternative fuel Power generation Waste-to-energy abstract This paper describes the synthesis of a rubber seed supply network to support the green energy demand in Malaysia. An optimised rubber seed supply network design, which maximises biomass utilisation, secures local biomass supply as well as reduces material loss and emissions resulted from inefcient logistic activities has been carried out. The utilisation of rubber seed oil (RSO) for biofuel production in Malaysia and its contribution to the national biomass renewable energy portion is forecasted. The supply network of the biomass is synthesised through mixed integer linear programming. Both centralised and de-centralised rubber seed processing facilities are studied. The network model shows that the selection of rubber seed processing plant is highly dependant on the volume of feedstock. A simplied real case study is presented to demonstrate the optimisation model. In addition, biodiesel price is largely dependent on the feedstock market. Thus, comparison of crude palm oil (CPO) and RSO production processes have been made in term of (i) energy and utility consumptions, (ii) feedstock price and (iii) environmental impact. Sensitivity analysis of rubber seed oil price for obtaining optimal blending ratio of rubber seed oil and crude palm oil has been performed in order to determine the market uncertainty of the biodiesel price. The potential of substituting rubber seed oil for crude palm oil as an alternative blending feedstock for biodiesel production has been validated. Ó 2013 Elsevier Ltd. All rights reserved. 1. Introduction The current world is moving towards sustainable green future and promoting waste-to-energy application. Research is carried out by various countries to increase the utilisation of biomass and substitute fossil fuel with renewable energy, which aims to improve energy security and to reduce the environmental impacts simul- taneously [1]. Over years, various agricultural crops have been explored for oil extraction to produce biofuel, e.g. biodiesel. Palm-based biodiesel has been increasingly produced as an alternative fuel since the past two decades [2]. However, the supply capacity of palm oil for biofuel production is constrained by the food-energy trade off. The world biodiesel market is estimated to develop at an average growth rate of over 30% annually by 2016, reaching 140 10 9 L [3]. Conventionally, the main raw materials used for biodiesel pro- duction are rapeseed oil (process design of biodiesel production using rapeseed oil [4]; ethanolysis of rapeseed oil for biodiesel production [5]), jatropha oil (catalysed by nanosized solid basic catalyst [6] and MgeZn mixed metal oxide catalyst [7]), waste cooking oil [8], sunower seed oil [9], crude palm oil [10] and so on. In Asian regions, CPO (comparison of crude palm oil) is the main oil source used for biodiesel production. The key players in Asia: Malaysia and Indonesia forecasted that the oil palm industry to grow by 2.5 Mt/y in order to meet the rising global appetite for palm oil [11]. However, the land availability for palm plantation is limited, which limits the expansion of oil palm industry. Furthermore, the uctuating raw material price (CPO) over years diminishes the economic viability of palm-based biodiesel production. Thus, an alternative feedstock for biodiesel production is crucial. RSO (rubber seed oil) is a potential feedstock for biodiesel pro- duction. RSO is extracted from rubber seed, in which its utilisation has been ignored. All this while, the main commercial product extracted from rubber tree was only rubber milk. Rubber wood is the main by-product during replanting. Diversication of this uti- lisation will contribute towards regional economic development. In this paper, utilisation of RSO as an alternative non-edible feedstock for biodiesel production is focused. * Corresponding author. Tel.: þ60 3 8924 8716; fax: þ60 3 8924 8017. E-mail addresses: [email protected] (W.P.Q. Ng), HonLoong.Lam@ nottingham.edu.my (H.L. Lam), [email protected] (S. Yusup). Contents lists available at SciVerse ScienceDirect Energy journal homepage: www.elsevier.com/locate/energy 0360-5442/$ e see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.energy.2013.02.036 Energy 55 (2013) 82e88

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  • dsun Te

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    Received 14 November 2012Received in revised form6 February 2013

    food-energy trade off. The world biodiesel market is estimated todevelop at an average growth rate of over 30% annually by 2016,reaching 140 109 L [3].

    Conventionally, the main raw materials used for biodiesel pro-duction are rapeseed oil (process design of biodiesel production

    atalyst [7]), wasteoil [10] and so on.oil) is the main oilplayers in Asia:palm industry tol appetite for palmantation is limited,. Furthermore, thers diminishes theduction. Thus, an

    alternative feedstock for biodiesel production is crucial.RSO (rubber seed oil) is a potential feedstock for biodiesel pro-

    duction. RSO is extracted from rubber seed, in which its utilisationhas been ignored. All this while, the main commercial productextracted from rubber tree was only rubber milk. Rubber wood isthe main by-product during replanting. Diversication of this uti-lisationwill contribute towards regional economic development. Inthis paper, utilisation of RSO as an alternative non-edible feedstockfor biodiesel production is focused.

    * Corresponding author. Tel.: 60 3 8924 8716; fax: 60 3 8924 8017.E-mail addresses: [email protected] (W.P.Q. Ng), HonLoong.Lam@

    Contents lists available at

    Ener

    els

    Energy 55 (2013) 82e88nottingham.edu.my (H.L. Lam), [email protected] (S. Yusup).The current world is moving towards sustainable green futureand promoting waste-to-energy application. Research is carried outby various countries to increase the utilisation of biomass andsubstitute fossil fuel with renewable energy, which aims to improveenergy security and to reduce the environmental impacts simul-taneously [1]. Over years, various agricultural crops have beenexplored for oil extraction to produce biofuel, e.g. biodiesel.

    Palm-based biodiesel has been increasingly produced as analternative fuel since the past two decades [2]. However, the supplycapacity of palm oil for biofuel production is constrained by the

    catalyst [6] and MgeZn mixed metal oxide ccooking oil [8], sunower seed oil [9], crude palmIn Asian regions, CPO (comparison of crude palmsource used for biodiesel production. The keyMalaysia and Indonesia forecasted that the oilgrowby 2.5Mt/y in order tomeet the rising globaoil [11]. However, the land availability for palm plwhich limits the expansion of oil palm industryuctuating raw material price (CPO) over yeaeconomic viability of palm-based biodiesel pro1. Introduction using rapeseed oil [4]; ethanolysis of rapeseed oil for biodieselproduction [5]), jatropha oil (catalysed by nanosized solid basicAccepted 7 February 2013Available online 26 March 2013

    Keywords:Supply networkRubber seed oilBiofuelAlternative fuelPower generationWaste-to-energy0360-5442/$ e see front matter 2013 Elsevier Ltd.http://dx.doi.org/10.1016/j.energy.2013.02.036in Malaysia. An optimised rubber seed supply network design, which maximises biomass utilisation,secures local biomass supply as well as reduces material loss and emissions resulted from inefcientlogistic activities has been carried out. The utilisation of rubber seed oil (RSO) for biofuel production inMalaysia and its contribution to the national biomass renewable energy portion is forecasted. The supplynetwork of the biomass is synthesised through mixed integer linear programming. Both centralised andde-centralised rubber seed processing facilities are studied. The network model shows that the selectionof rubber seed processing plant is highly dependant on the volume of feedstock. A simplied real casestudy is presented to demonstrate the optimisation model. In addition, biodiesel price is largelydependent on the feedstock market. Thus, comparison of crude palm oil (CPO) and RSO productionprocesses have been made in term of (i) energy and utility consumptions, (ii) feedstock price and (iii)environmental impact. Sensitivity analysis of rubber seed oil price for obtaining optimal blending ratio ofrubber seed oil and crude palm oil has been performed in order to determine the market uncertainty ofthe biodiesel price. The potential of substituting rubber seed oil for crude palm oil as an alternativeblending feedstock for biodiesel production has been validated.

    2013 Elsevier Ltd. All rights reserved.Article history: This paper describes the synthesis of a rubber seed supply network to support the green energy demanda r t i c l e i n f o a b s t r a c tSupply network synthesis on rubber seebiofuel feedstock

    Wendy Pei Qin Ng a,*, Hon Loong Lam a, Suzana YuaDepartment of Chemical and Environmental Engineering, Centre of Excellence for GreeJalan Broga, 43500 Semenyih, Selangor, MalaysiabChemical Engineering Department, Biomass Processing Laboratory, Centre of Biofuel anIskandar, Perak, Malaysia

    journal homepage: www.All rights reserved.oil utilisation as potential

    p b

    chnologies, The University of Nottingham, Malaysia Campus,

    ochemical, Universiti Teknologi PETRONAS, 31750, Bandar Seri

    SciVerse ScienceDirect

    gy

    evier .com/locate/energy

  • 1.1. Potential of rubber seed oil utilisation as biofuel

    The feasibility of biodiesel production using RSO has beeninvestigated since 20th century. Ramadhas et al. [12] developed atwo-step transesterication process (acid catalysed estericationfollowed by alkaline catalysed transesterication) to convert RSOinto its mono-esters. Ikwuagwu et al. [13] investigated the pro-duction of biodiesel using RSO through transestericationwith 6-Mexcess of methanol using NaOH as catalyst as well as the propertiesof the biodiesel produced. More recently, Morshed et al. [14]investigated the production of biodiesel from RSO in Bangladeshusing a three-stepmethod, which comprises of saponication of oil,acidication of the soap and esterication of free fatty acid. In

    The problem to be addressed in this paper is formally stated asthe followings: a setof rubber seed collectionpoints (suppliers) aAis to be allocated to a set of processing points cC and then to a set ofbiodiesel production plants (consumers) b B via roadway system(by truck). Processingpoint c canbe located at aor b, which indicatesthat all rubber seed collection points a and biodiesel productionplants b act as potential sites for processing point c. Biomass isdelivered from a to c with owrate WACa,c. Oil is extracted frombiomass with extraction rate of F3 and the crude oil with owrateOCBc,b is delivered from c to b. This crude oil is converted to biodieselwithowrateBIObunder the conversion rate of F4. Thisworkaims todevelop a rubber seed biomass supply network,which considers thelocal cost function developed based on actual logistics data sets. Theoptimum allocation of biomass for the generation of maximumeconomic potential is determined. The problem is described by thesuperstructure representation as shown in Fig. 2.

    3. Model formulation

    W.P.Q. Ng et al. / Energy 55 (2013) 82e88 83addition, RSO has vast utilisations for soap, vulcanized vegetable oiland surface coating formulation and productions [15].

    Experiment has been carried out by Ramadhas et al. [16] tostudy the characteristics of biodiesel produced from RSO. The resultshows that the biodiesel produced can be used directly in existingdiesel engines without further modication. Improved biodieselcold ow properties can be achieved by blending crude palm oilwith RSO and the quality of the biodiesel produced complies withinternational standards (ASTM Designation D6751-09a and EN14214) that it can be used as commercial substitute for diesel fuel[17]. Pilot scale RSO-based biodiesel plant has been established forfuel production [18].

    In Malaysia, rubber plantation appears to be the second largestagricultural sector after oil palm. Fig. 1 illustrates the proportion ofagricultural land use in Malaysia. Based on the current rubberplanting area of 1,022,700 ha [19] and the estimation of rubber seedproduction at about 300 kg/ha annually [20], it is estimated that306,810 t of rubber seed are available yearly in Malaysia.

    In Malaysia, the utilisation of rubber seed has not been exploreddespite its vast potential as value-added products. In addition,comprehensive studies related to Malaysian biomass supply chainare missing. Proper strategies and plans are currently beingdeveloped in EU for this initiative, e.g., Lam et al. [22] optimisesregional energy supply chain utilising renewables via P-graphapproach and Cucek et al. [23] synthesised regional network for thesupply of energy and bioproducts, which these can be extended toaccommodate rubber seed supply network.

    2. Methodology

    In this work, the feasibility of RSO utilisation as renewable fuel ismodelled. A simplied biomass supply network model is generatedto estimate the RSO percentage towards Malaysia national biomassrenewable energy portion. A sensitivity analysis of commercialrubber seed price is performed to study its market uncertainty. Theraw material price and crude oils production processes of RSO andCPO are compared.

    coconut1.8%

    cocoa0.3%

    rubber20.5%

    oil palm77.4%

    % of Commercially Cultivated Plantations Given Over to Main Tree CropsFig. 1. The land use based on the commercially cultivated main tree crops as of year2009 [21].Biomass is transferred from sources a to intermediates pro-cessing points c to sinks b, varying a 1...NA, c 1...NC and b 1...NB,c a W b. The biomass feedstock is subjected to its availabilityconstraint:XcC

    WACa;c CAPAa F1 F2 ca A (1)

    where WACa,c (kg/y) is the biomass owrate from a to c; CAPAa (ha)is the limit of biomass availability; F1 (kg/ha/y) is the amount ofbiomass available per ha of plantation or hectare yield; F2 is theproportion of biomass collected/utilised out of the total biomassavailable.

    The oil extraction rate from rubber seed is given as:XbB

    OCBc;b XaA

    WACa;c B1c F3 cc C (2)

    where OCBc,b (kg/y) is the oil owrate from c to b; B1 is the binaryvariable to denote the existence of processing facility c; F3 is the oilextraction rate from rubber seed.

    The crude oil extracted from rubber seed is converted to biofuel:

    BIOb XcC

    OCBc;b F4 cb B (3)

    b = 1

    b = 2

    b = NB

    a = 1

    a = 2

    a = NA

    c = 1

    c = 2

    c = NC

    b = 3a = 3 c = 3

    Source SinkIntermediate facilityFig. 2. Source and sink (superstructure) representation of the biomass allocation.

  • e s

    W.P.Q. Ng et al. / Energy 55 (2013) 82e8884where BIOb is the biodiesel production rate (kg/y); F4 is the con-version factor of crude RSO to produce biodiesel.

    Great-circle distance between two points is taken as the esti-mation of delivery distance between facilities. This distance isestimated using Spherical Law of Cosines [24]:

    DT acossinlat1 sinlat2 coslat1 coslat2 coslon2 lon1 r (4)

    where DT is distance (km); lat1, lat2, lon1, lon2 are the radian co-ordinates of respective supply and destination points; r is the earthradius (6371 km).

    The transportation cost for raw biomass, COTR (MYR/y) is esti-

    Fig. 3. Location of rubber seed suppliers and consumers with both thmated using the local cost function:

    COTR X

    aA;cC

    FC 0:10DTa;c 22:5WGTHC

    WACa;c (5)

    where FC is transportation xed cost (5 MYR/t equivalent to1.67 USD/t), DTa,c (km) is the distance between biomass source andintermediate processing hub, 0.10 is the variable cost for every unitof distance travelled (MYR/t/km), 22.5 is the standard weight costparameter (MYR/t), WGT is container weight cost parameter(9.6 MYR/t), HC is handling cost (15 MYR/t equivalent to 5 USD/t).

    The transportation cost of material delivery using tank truck(liquid phase) is estimated:

    Table 1Locations of biomass sources, processing plants and their capacities.

    Biomasssources

    Latitude(rad.)

    Longitude(rad.)

    Capacity(ha)

    Biodieselplant

    Latitude(rad.)

    Longitude(rad.)

    a1 0.1031 1.7607 255,832 b1 0.0668 1.8028a2 0.0867 1.7626 77,878 b2 0.0511 1.7727a3 0.0991 1.7836 156,418 b3 0.0258 1.8136a4 0.0520 1.7968 150,202 b4 0.0862 1.7589a5 0.0475 1.7883 191,808a6 0.0426 1.7928 119,810where CRW (MYR/kg) is the cost per unit weight of biomass.The biodiesel production cost is estimated [25]:COTR X

    cC;bB

    OCBc;b DTc;b

    CTR (6)

    where DTc,b (km) is the distance between intermediate processinghub and nal processing plant (sink), CTR is transportation cost(0.30 MYR/km/t equivalent to 0.10 USD/km/t).

    The raw material cost is calculated based on per unit weight ofraw material utilised using the equation:

    CORW X

    aA;cCWACa;c CRW (7)

    upply and demand points can act as intermediate processing points.COBb BIOb F5 cb B (8)

    where COBb is the annual biodiesel production cost excluding rawmaterial cost (MYR/y); F5 is the biodiesel production unit cost(MYR/kg).

    The RSO production cost is estimated:

    COOc XbB

    OCBc;b F6 ccC (9)

    Table 2Parameters for supply network optimisation and biomass conversion.

    Particular Parameter

    1 Rubber seed yield (F1) [20] 300 kg/ha/y2 RS utilisation/collection (F2) 20 wt%3 RSO extraction from rubber seed (F3) 30 wt%4 RPO/CPO conversion (F4) 98 wt%5 Rubber seed cost (CRW) 1.00 MYR/kg6 Palm fresh fruit bunch cost [26] 0.71 MYR/kg7 Transportation cost 0.30 MYR/km/t8 Biodiesel price (COBIO) [25] 4.26 MYR/t9 Biodiesel production cost (F5) 0.45 MYR/t10 Estimated RSO production cost (F6) 0.20 MYR/kg11 Capital adaption scale factor (F7) 0.7512 CPO production capital investment (CAC) 1,500,000 MYR13 Payback period 3 y

  • Table1showstheestimatedcoordinatesof the supplyanddemand

    Table 3Allocation of rubber seed and RSO to processing facilities (t/y).

    Intermediate processing facilities c

    c1 (a1) c2 (a2) c3 (a3) c4 (a4) c5 (a5) c6 (a6) c7 (b1) c8 (b2) c9 (b3) c10 (b4)

    Biomass sources a a1 e e e e e e e e e 15,350a2 e e e e e e e e e 4673a3 e e e e e e e e e 9385a4 e e e e 9012 e e e e ea5 e e e e 11,508 e e e e ea6 e e e e 7189 e e e e e

    e e e e e e

    8313 e e e e ee e e e e e

    e e e e e 8822

    W.P.Q. Ng et al. / Energy 55 (2013) 82e88 85where COOc is the annual RSO production cost excluding raw ma-terial cost and capital cost (MYR/y); F6 is the estimated RSO pro-duction unit cost (MYR/kg).

    The capital cost of RSO production is dened as:

    CARc F7 CAC B1cPBwhere CARc is the capital cost for RSO production (MYR/y); F7 is thescale down factor to accommodate CPO capital investment as RSOcapital investment cost; CAC is estimated CPO capital investmentcost (MYR); PB is payback period (y).

    The economic potential of the intermediate processing facility isconstrained to achieve the rate of return on investment:XbB

    BIObCOBIOCORWCOBbCOOcB1c CARc (10)

    The objective is to maximise the economic function (annualprot before tax) and it is dened as:

    OBJ MaxX0@ X

    bB;cCBIObCOBIOCOTRCORWCOBb

    COOcCARc1A

    (11)

    where COBIO is the selling price of RSO-based biodiesel produced(MYR/kg), which is benchmarked from published biodiesel price[26].

    4. Illustrative case study

    A demonstration of Malaysian local case study is presented to

    Biodiesel plants b b1 e e e eb2 e e e eb3 e e e eb4 e e e eillustrate the application of the proposed model. The data of thecase study is based on the modication of actual crop distribution,biodiesel plants currently under operation and transportation costby truck. Fig. 3 shows the geographical locations of the facilities.

    Table 4The possible substitution or increase production of biodiesel at various proportion ofrubber seed utilisation under OER 30%.

    Rubber seedutilization (%)

    Replacement/increasedbiomass power productionrelative to 68 MW ofbiomass power (%)

    Revenue fromRSO-based biodieselproduction (MYR/y)

    20 29 145,56130 44 593,30440 59 1,041,04750 73 1,488,79060 88 1,758,725facilities and their respective production capacities. The supply pointsact as the rubber seed collection points located near/in rubber plan-tations. The rubber seeds collected are sent to potential processingfacility c, which all a and b act as potential locations for processingfacility c. RSO is extracted from rubber seeds in c and sent to existingbiodiesel production plants b for biodiesel production. Roadwaytransportation system by truck is employed for material delivery.

    Table 2 shows the parameters used for the optimisation model.The supply network model is solved with the objective functionEquation (11) subjected to other constraints listed above.

    The mixed integer non-linear supply network model is solvedusing the optimisation software General Algebraic Modelling Sys-tem (GAMS) 23.4.3 with the solver BARON. The optimum allocationscheme proposed is tabulated in Table 3.

    The model is let free to go for centralised processing system ordecentralisedprocessing system.The result shows that themodeloptsfor centralised processing facility system (Table 3). Two processingfacilities or hubs are chosen for oil extraction out of 10 potentials.

    In the case study, the estimated price of rubber seed is taken tobe 1000 MYR/t with an oil extraction ratio (OER) of 30 wt%; whilst,palm fresh fruit bunch is sold at 716 MYR/t with an average OER of20 wt% as of May 2012 [27]. These result in the raw material grosscosts of 3000 MYR/t for RSO and 3580 MYR/t for CPO excluding theprocessing costs. This brings a gross prot of 580 MYR/t of crude oilwith respect to RSO, only in term of raw material cost. The protsgained from substituting RSO with CPO can be further improvedfrom its OER. The oil yield of rubber seed can be increased bygrowing higher oil yield rubber clone. For example, Ebewele et al.[15] states that, in Nigeria, rubber clone NIG800 gives higher RSOyield than other clones: NIG800 at 45%, GTI at 40% and RRIM707 at38%. In order to increase the RSO yield, research on various rubberclones that gives high RSO yield is needed.

    40,00005001,0001,5002,0002,5003,0003,5004,0004,500

    05,000

    10,00015,00020,00025,00030,00035,000

    0 20 40 60 80

    Powe

    r ge

    nera

    tion

    (MW

    )

    Biod

    iese

    l pro

    duct

    ion

    (t/y)

    Rubber seed utilisation (%)Fig. 4. The proportional increment of biodiesel production/energy recovered withincreasing rubber seed utilisation (with OER 30%).

  • Hyw

    d m

    s

    h

    ext

    ergyDrying (optional)(moisture reduction)

    Milling(size reduction)

    Conditioning(to stop enzymatic

    activities)

    Pressing(to extract oil)

    Filtration(to remove foots)

    Crude oil

    Rubber seed

    Natural drying

    MechanicalHammer

    Gas heatedrotary dryer60C-70C

    Screw press /Motor driven scre

    a perforate

    Filter press

    Comparison of oil

    W.P.Q. Ng et al. / En86For illustration purposes, if the biodiesel produced is consideredfor electricitygeneration,with a net heatingvalue of 37.47MJ/kg, thecurrent renewable fuelmodel is able to replace approximately29%ofthe current 68 MW of biomass power generated by the Malaysianlocal biomass [28]. This value may be further increased with higherutilisation of available rubber seeds and the promotion of plantinghigher seedling rubber trees. Table 4 shows thepossible substitutionor increase production of biodiesel under various rubber seed uti-lisation percentage, up to 60% with the rest reserved for other uti-lisation purposes, such as animal feedstock and replantationpurposes. It is noted that higher amount of energy is recoveredwithhigher rubber seed utilisation. In addition, the amount of revenueachieved frombiodiesel diesel production increaseswith increasingutilisation of rubber seed for biodiesel production. Fig. 4 shows theamount of biodiesel produced at different seed utilisation levels andtheir corresponding amount of power that can be generated.

    4.1. Merits of RSO extraction technology

    The RSO extraction process consumes less energy than thatrequired for CPO production. Fig. 5 shows a qualitative comparisonof the typical oil extraction processes between rubber seed [29] andpalm fresh fruit bunch. RSO extraction process does not involvehigh heating energy (steam) to cook the biomass fruit. Further-more, RSO extraction process involves less processing steps ascompared to that in CPO production. This implies lower utilitiesconsumption and investment costs.

    4.2. RSO and biodiesel price sensitivity analysis

    Commercially, the raw materials used for biodiesel productioninclude methanol and CPO through transesterication process.

    Fig. 5. A qualitative comparison of RSOSterilization(to cook FFB and stopenzymatic activities)

    Stripping(to extract fruits from

    bunches)

    Purification / Clarification(to remove foots)

    Crude oil

    Palm FFB

    draulic presswhich rotates inetal cage

    Pressure vessel110C steam

    45 min-100 min3bar

    Tresher hopper +Tresher (rotary)

    drum

    Clarifier (highpeed centrifuger +vacuum drying)

    90C

    Pressing(to extract oil)

    Digestion(convert stripped fruits to

    a homogeneos mash)

    Digester (steameated vessel with

    stirring arms)100C

    raction processes

    55 (2013) 82e88Despite the relatively high amount of biodiesel manufacturing li-cences issued by the Malaysian government, there are only 10 bio-diesel productionplants under operation. This situation is caused bythe increasing raw material e CPO price over the years, which di-minishes the economic viability of biodiesel production. From atechno-economic and sensitivity analysis of Malaysian palm-oilbased biodiesel production, it is noted that the biodiesel price isonly compatible with fossil diesel with tax exemption and subsidypolicy implemented [25]. Feedstock cost contributes to the largestproportion (79%) of the total biodiesel production cost. Therefore,the substitution of CPO with RSO for biodiesel production willreduce the dependency of utilising only one type of feedstock. Thisensures the economic feasibility and prot prominence of biodieselproduction. However, the oating markets of rubber seed as well aspalm fresh fruit bunch result in an unstable feedstock price, whichdirectly affects the crude oil prices and biodiesel production price.

    Applying the cost analysis model for biodiesel production pro-posed by Ong et al. [25], the crude oil price used for biodieselproduction has to be capped at 2940 MYR/t to make biodieselcompetitive with fossil diesel price at 1.80 MYR/L. This cost at2940 MYR/t is rarely to be attainable by CPO, as CPOs price aver-ages at 3150 MYR/t in 2011 and 3090 MYR/t from January tillSeptember 2012. RSO may substitute part of the CPO by blendingRSO with CPO for biodiesel production [30]. Fig. 6 shows themaximum price of RSO at various RSO/CPO blending ratio with CPOprice xed at 3150 MYR/t. At this price, the biodiesel productionprice falls below 2940MYT/t, at which this price allows biodiesel tobe competitive with fossil diesel in price.

    Economically, local sourcing may increase the cost of raw ma-terial, rubber seed in this case. However, this can be offset byreducing the distance travelled through efcient supply chaindesign. Local sourcing of raw material further reduces the supply

    [29] and CPO production process.

  • chain risks e volatile fuel prices, possible lead times, currency ex-change risks, etc. Proper planned supply network reduces the un-necessary emission resources required resulted from logisticactivity and it improves fuel efciency. These reduce both emis-sions and total supply network cost [31]. Furthermore, biofuel is asource of renewable energy. The utilisation of biomass or initiallydumped waste for biofuel production reduces the exploitation offossil fuels. Biofuel strategy is relatively green as it recovers wasteenergy. Biofuel contributes less global warming as its incinerationemits to the atmosphere only the carbon dioxide that their sourceplants absorbed out of the atmosphere.

    In most developing countries, the roadway transportation sys-tem is well developed. However, the biomass supply network hasnot been established. There is absence of systematic tool anddatabase to carry out proper logistic planning. This optimisationmodelling system is one of the approaches for logistic planning, in

    W.P.Q. Ng et al. / Energywhich the most efcient route and biomass allocation can bedetermined. Furthermore, this system provides information forinvestors to approach biomass suppliers to secure their suppliesand demands of RSO. This tool gives the insight of supply networkbased on the interaction between the supply and demand such asblending ratios, biomass availability and price. Besides, this supplynetwork synthesis provides an insight on green energy generationfrom local resources. It reduces the transportation costs andemissions and enhances the local socio-economy. RSO productionconsumes relatively less utilities; this further reduces the energyrequirement and environmental impact.

    5. Error analysis of model

    The assumptions made in this paper have neglected the preci-sion of facility capital cost estimation and the seasonal availabilityof feedstock:

    1. Seasonal feedstock. The model assumes for constant supply ofRS throughout the year. However, RS production is seasonalthat for certain months rubber trees will have no seedproduction.

    2. Adapted capital cost. The capital cost for RSO processing facilityis adapted from CPO processing facility by scaling down theinvestment cost with reasonable scaling factor by estimation.

    3. Simplied cost function. The cost function considered in themodel does not include calculations for depreciation, tax andpresent values.

    There are other factors that affect the results accuracy. However,the main objective of the paper is to introduce the possibility of

    0%10%20%30%40%50%60%70%80%90%100%0%

    10%20%30%40%50%60%70%80%90%

    100%

    0 1,000 2,000 3,000 4,000

    CPO

    (%)

    RSO

    (%)

    Maximum RSO price (MYR/t)maximum feasible priceFig. 6. The maximum price of RSO to cap the biodiesel production price at 2940 MYR/twith CPO price at 3150 MYR/t.rubber seed oil as potential biofuel feedstock and one method forthe selection of intermediate processing facilitys location.

    6. Conclusions and future works

    Rubber seed supply network has been synthesised based on asimplied case study in Peninsular Malaysia. Based on the devel-oped model, the results demonstrated that the current renewablefuel model is equivalent to approximately 29% of the current68 MW of biomass power generated by the Malaysian localbiomass. The relationship between the feedstock volume andprocessing site has been identied, which is crucial in performingeconomic decision as well as logistic planning. The potential ofsubstituting RSO for CPO as an alternative blending feedstock forbiodiesel production has been validated. The feasibility of potentialutilisation of RSO has been determined based on the blending ratioof RSO with CPO.

    This study can be extended by incorporating more compre-hensive case data that includes exact point sources of rubber seedand rened transportation distances between facilities. Integrationof other type of renewable biomass sources into the supplynetwork, synthesis of a supply network considering the most usageof interested biomasses and consideration of transportationscheduling and truck-loading limits can be incorporated. In addi-tion, the supply network can be extended to larger region, such asSouth East Asia and biomass energy supply chain footprints can beinvestigated, for its footprint-based multi-criteria optimisation [32]and the correlations among footprints within a biomass energysupply chain [33].

    Acknowledgement

    The nancial support from Malaysia Ministry of Higher Educa-tion (MOHE) PRGS-Grant (158-200-158), University of NottinghamEarly Career Research and Knowledge Transfer Award (A2RHL6)and Global Green Synergy Sdn Bhd Industrial Grant are gratefullyacknowledged.

    Nomenclature

    a subset index of c (for biomass source)b subset index of c (for biofuel production facility)B1c binary variable to denote the existence of processing

    facility cBIOb biodiesel production rate (kg/y)c set index for possible processing facilityCAC estimated CPO capital investment costCAPAa limit of biomass availability (ha)CARc capital cost for RSO productionCOBb annual biodiesel production cost excluding raw material

    cost (MYR/y)COBIO selling price of RSO-based biodiesel produced (MYR/kg)COOc annual RSO production cost excluding raw material cost

    and capital cost (MYR/y)CORW transportation cost for raw biomass (MYR/y)COTR transportation cost of raw biomass material/liquid phase

    material using tank truck (MYR/y)CPO crude palm oilCRW cost of biomass (MYR/kg)CTR liquid item transportation cost 0.30 MYR/km/t

    equivalent to 0.10 USD/km/tDTa,c distance between biomass source and intermediate

    processing hub (km)DT distance between intermediate processing hub and nal

    55 (2013) 82e88 87c,b

    processing plant (km)

  • F1 amount of biomass available per ha of plantation orhectare yield (kg/ha/y)

    F2 proportion of biomass collected/utilised out of the totalbiomass available.

    F3 oil extraction rate from rubber seedF4 conversion factor of crude RSO to produce biodieselF5 biodiesel production unit cost (MYR/kg)F6 estimated RSO production unit cost (MYR/kg)F7 scale down factor to accommodate CPO capital

    investment as RSO capital investment costFC transportation xed cost 5 MYR/t equivalent to

    1.67 USD/tGAMS General Algebraic Modelling System

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    [13] Ikwuagwu OE, Ononogbu IC, Njoku OU. Production of biodiesel using rubber[Hevea brasiliensis (Kunth. Muell.)] seed oil. Ind Crops Prod 2010;12:57e62.

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    W.P.Q. Ng et al. / Energy 55 (2013) 82e8888and CaO. Energy 2012;48:392e7.[6] Deng X, Fang Z, Liu YH, Yu CL. Production of biodiesel from Jatropha oil

    catalyzed by nanosized solid basic catalyst. Energy 2011;36:777e84. http://dx.doi.org/10.1016/j.energy.2010.12.043.

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    [10] Crabbe E, Nolasco-Hipolito C, Kobayashi G, Sonomoto K, Ishizaki A. Biodieselproduction from crude palm oil and evaluation of butanol extraction and fuelproperties. Process Biochem 2001;37(1):65e71.HC handling cost 15 MYR/t equivalent to 5 USD/tlat latitude coordinate (rad.)lon longitude coordinate (rad.)MYR Malaysian ringgit, 3 MYR 1 USDNaOH sodium hydroxideOCBc,b oil owrate from c to b (kg/y)OER oil extraction ratePB payback period (y)r earth radius 6371 kmRSO rubber seed oilWACa,c biomass owrate from a to c (kg/y)WGT container weight cost parameter 9.6 MYR/t

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    Supply network synthesis on rubber seed oil utilisation as potential biofuel feedstock1. Introduction1.1. Potential of rubber seed oil utilisation as biofuel

    2. Methodology3. Model formulation4. Illustrative case study4.1. Merits of RSO extraction technology4.2. RSO and biodiesel price sensitivity analysis

    5. Error analysis of model6. Conclusions and future worksAcknowledgementNomenclatureReferences