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Energy 57 (2013) 284e294

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Energy

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Life cycle assessment of rice straw co-firing with coal powergeneration in Malaysia

S.M. Shafie a,*, T.M.I. Mahlia a,b, H.H. Masjuki a

aDepartment of Mechanical Engineering, University of Malaya, 50603 Kuala Lumpur, MalaysiabDepartment of Mechanical Engineering, Syiah Kuala University, Banda Aceh 23111, Indonesia

a r t i c l e i n f o

Article history:Received 11 June 2012Received in revised form25 May 2013Accepted 3 June 2013Available online 29 June 2013

Keywords:Co-firingRice strawPower generationLife cycle assessment

* Corresponding author. Tel.: þ60 17 499 4562.E-mail address: shafini@uum.edu.my (S.M. Shafie)

0360-5442/$ e see front matter � 2013 Elsevier Ltd.http://dx.doi.org/10.1016/j.energy.2013.06.002

a b s t r a c t

This paper investigates the economic feasibility of rice straw co-firing at coal power plants in Malaysiaand in doing so looks at the operating, capital, and logistic costs. Co-firing rice straw in an existing coalpower plant is a technique that could reduce CO2 emissions and make Malaysia less dependency on coalresources. In a country such as Malaysia with abundant biomass resources, utilizing biomass residue alsowould help reach government targets of developing renewable energy under the country’s Fuel Diver-sification Policy. The overall rice straw life cycle assessment presented here analyses environmental,energy and economic aspects for co-firing of rice straw at existing coal power plants in Malaysia. Analysisof GHG emissions and energy consumption throughout the entire co-firing rice straw life cycle was basedon selected coal power plant capacity output. This paper also analyses the implication of rice straw useunder different co-fired ratios, transportation systems and CO2 emission prices. The reduction of GHGemissions was found to be significant even at a lower co-firing ratio.

� 2013 Elsevier Ltd. All rights reserved.

1. Introduction

As worldwide population numbers increase, industrializingeconomics will need to diversify energy sources turning to thosethat are sustainable. Among potential sustainable sources, biomassresources are possible the world’s largest and most sustainable,comprising approximately 220 billion oven e dry tones of annualprimary production [1]. Annual world rice production in 2011 are721.4 MT, and 90.48% are from Asian country [2]. This productionwill create 973.89 MT of rice straw in the fields [3]. Only 20% ofworld rice straw production are purposely use and remaining is stillnot fully utilized [4].

1.1. Development of rice straw disposal management

About 80% of rice straw in the world is applying improperdisposal management that causes the source of pollution. Ricestraw is rarely used as sources of renewable energy [5] and openburning is common practice apply in majority of Asian countries

.

All rights reserved.

[6]. Table 1 lists the current rice straw disposal management acrossthe world.

China and California already utilize the rice straw as theresource for heat and power production. In China various projectsin Jiangsu Province have typical size 12e25 MW electrical capacityper power plant with 50%e60% of rice straw as a fuel [7].

The major challenges that are facing with rice straw areeconomical, technological and organization issues. In California, theresearcher focus on economic study on utilizing leached rice strawas fuel for existing biomass boilers [8].

1.2. Technology conversion for rice straw energy production

Based on commercial application, direct combustion andthermo chemical conversion are themost promising technology forrice straw heat and power generation [9]. Typically, direct com-bustion can be group into the fixed bed and fluidized bed com-bustion systems [10]. Study by Ref. [11], show that leached ricestraw can result in significant improvement of elemental compo-sition and ash fusibility on fluidized bed combustion characteris-tics. The problem occur in fluidized bed combustor fuel by ricestraw blend due to aggregation issue is reported the results of adetailed chemical and petrography study [12,13].

Nomenclature

A activity levelAS area served (km2)ADPP->CC average distance from paddy plantation to collection

centreADCC->MPaverage distance from collection centre to power plantASP average rice straw production (ton)ASY average straw yield (ton/ha)Cm.w molecular weight of carbonCC capital cost (RM)CCOAL national average cost of coal (RM/KG)CGHG emission price of equivalent carbon dioxide (RM)Ci carbon content fraction of diesel (mass C/mass diesel)CRS rice straw co-firing cost (RM/KG)CTP transport personnel cost (RM)CTV transport vehicle cost (RM)CO2,m.w molecular weight of CO2

CO2, T CO2 emission from tractorD volume of diesel combusted (l)DD density of diesel (kg/l)DT travel distance (KM)EP emission pollutant (CH4 or N2O)EGHG, CO GHG emission during co-firing (KG)EGHG, COALONE GHG emission during coal burn alone (KG)EF emission factorEFCO2

emission factor of carbon dioxideFA availability factorFC fuel combustion (L)FF farmland factorFOi fraction oxidized of diesel

HA harvested area (ha)HHVCOAL high heating value of coal (MJ/KG)HHVRS high heating value of rice straw (MJ/KG)sC collection efficiencyNPHRCOAL net plant heat rate of coal (MJ/kWh)NPHRRS, ALONE net plant heat rate of rice straw alone (MJ/kWh)PP paddy production (ton)PCRS purchased rice straw cost (RM/Year)QELEC electricity generated (kWh)QELEC, CALONE electricity generated by coal alone (kWh)QRS, ALONE electricity generated by burning rice straw alone

(kWh)RS-C rice straw collectionS source categorySY straw yield (ton/km2)SCTP specific cost for vehicle transport (RM/KM)SGR straw to grain ratioTCRS transportation rice straw cost (RM)TCTL total consumption hour trip of lorry (hour)TCTT total consumption hour trip of truck (hour)TCC->ECPP transportation from collection centre to existing coal

power plantTPP->CC transportation from paddy production to collection

centreWCOAL, ALONE weight of coal burn alone (KG)WCOAL, COweight of coal used in co-firing (KG)WRS, ALONE weight of rice straw burn alone (KG)WRS, CO weight of rice straw used in co-firing (KG)VCLORRY capacity of lorry (KG/lorry)VCTRUCK capacity of truck (KG/lorry)

S.M. Shafie et al. / Energy 57 (2013) 284e294 285

1.3. Co-firing of rice straw

Recent data showa rising pattern of coal consumption especiallythat consumed for electricity generation. Coal use increased by80.12% from 2000 to 2008 in Malaysia [14], and coal consumptionfor electricity generation contributed the most to GHG emissionswith 1.1993 kg/kWh [15]. Electricity generation and emission pat-terns in Malaysia from 1976 to 2008 has indicated that the highdependence of Malaysia on fossil fuel in electricity sector was themain cause of the country’s GHG emissions [16].

The co-firing of biomass alongwith coal in existing power plantsappears to bemost economical with large scale application [17] andoptimal option for increasing biomass energy utilization [18,19]while also benefitting the environment. Biomass co-firing hasbeen successfully demonstrated in over 228 installations

Table 1Lists the current rice straw disposal management across the world.

Country Practice Sources

Indonesia, Philippines Straw is heaped into piles at threshingsites and burned after harvest

[7]

Thailand, China,Northern India

All straw remains in the field andrapidly burned in situ

[7]

India, Bangladesh,Nepal

Straw removal and used for cooking,fodder and stable bedding

[7]

Valencia (Spain) A project for rice straw blankets todry farming

[8]

California Burning the rice straw due to lowcost disposal method

[3]

Thailand Annually, 8.5e14.3 MT about 90% ofrice straw is burned in the fields

[9,10]

Malaysia Open burning practice of rice straw [11,12]

worldwide most of these plants are located in Finland, USA, Ger-many, UK and Sweden [20]. However, the ongoing current projecton biomass co-firing are about 17 projects (commercialize projects)throughout the worlds [21]. Table 2 listed the current commer-cialize project (ongoing) on direct co-firing type with coal as pri-mary fuel [21]. Implementation of co-firing offers someadvantages; these advantages are increased boiler efficiency,reduction of cost and lowering of GHG emissions [22]. Co-firing alsoimproves the net energy balance because biomass residue com-bustion consumes less energy when mining and transportation ofcoal are factored into the economic analysis [23]. Utilization of ricestraw co-firing with coal is one solution to reduce such costs andalso to reduce dependency on fossil fuel resources.

LCA methodology is gaining attention for measuring the envi-ronment impact of the use of biomass as energy sources. Majority ofthe researchers agreed that this method is the best tool for esti-mation of GHG emissions [24] and helpful for environmentalimprovement [25]. Some papers that used LCA method are willowbased electricity generation [26], agriculture crop CHP [27], woodwaste in cogeneration plants [28] and others. Although, some paperalready applied the LCA of biomass system to electricity generation,the outcomes are varied regarding the approaches use such asfunctional unit and system boundaries. Table 3 indicates a literatureon LCA applied into biomass system electricity generation. Defi-nitely, prove that the results were varied between each studieddepending on aim of study and also the coverage of systemboundaries too. The main limitation of LCA is that the assumptionsand choice of allocation method made throughout the study canaffect the results too [28].

This paper studies the life cycle of rice straw co-firing at existingcoal power plants at Malaysia based on those plants that have the

Table 2Current commercialize project (ongoing) on direct co-firing type with coal as primary fuel.

Country Plant name Boiler Output (MW) Co-fired fuel

Denmark Ensted Grate 40 Straw, wood chipsDenmark Grenaa Co-Generation Plant CFB drum type 18.6 StrawDenmark Randers Cogeneration Plant Grate (spreader stoker) 52 Wood chipsFinland Kantvik Plant Grate 4 HFO, peatFinland Lohja Heating Plant BFB 22 Biomass, REF, HFOFinland Naantali CHP Plant PF 260 BiomassFinland Pori Mill CFB 12 Biomass, HFO, LFOFinland Salo Power Plant BFB 16 Biomass, peat, REF, HFO, LFO, BGASFinland Sakyla Power Plant Grate 9 HFO, BGAS, PeatFinland Linnankatu power plant PF 35 HFO, LFO, BiomassFinland Vaskiluoto power plant PF 258 BIOMASS, HFO, LFOSweden Stora Enso Fors Mill CFB 9.6 Wood, BarkUK Welsh Power Group PF 363 PLASTICs, various agri-productsUSA Bay Front Station Grate 44 Wood, shredded rubber, railroad tiesUSA City of Tacoma Steam Plant BFB 18 Wood, refused derived fuel (RDF)

S.M. Shafie et al. / Energy 57 (2013) 284e294286

nearest available rice straw supply. In the case of co-firing ricestraw with coal, the assessment was done from “cradle to grave”starting from paddy cultivation and harvesting, its transport toenergy conversion, and also from coal based electricity generationinvolving coal in mine, transportation and power generation (seeFig. 1). The aim of this study is: (i) to identify the most promisingexisting coal power plants that are suitable for rice straw co-firing,(ii) to examine GHG emissions and energy consumption for ricestraw life cycle, (iii) to evaluate the environment impact reductiondue to rice straw co-firing, and (iv) to analyse the potential eco-nomic impact of rice straw co-firing at power plants.

Table 3Literature on LCA applied into biomass system electricity generation.

Year Country Process

1999 Germany 10% co-firing straw and residual wood

1999 Italy IGCC with poplar

2004 Italy IGCC with biomass

2005 Italy IBGCC

2010 Spain Combustion of Poplar andEthiopian Mustard

2012 France CHP using wood waste

2013 Taiwan Bio-char co-firing with coal

2. Survey data

Information on the average paddy production in five regions(Table 3) from the five-year statistical data (2006e2010) of paddyproduction in Malaysia [29]. Thirteen states divided into five re-gions which were: North (Perlis, Kedah, Penang, Perak); Central(Selangor, NS, Malacca); South (Pahang, Johor); East (Kelantan,Terengganu); and Sabah/Sarawak. Among of these regions, Northand Central region are the best choices for rice straw co-firing atexisting coal power plant due to supply availability and small radiusof catchment area. Table 4 indicates the average paddy production

Comments Author

Using three different system to identify the environmentimpact of co-firingFunctional Unit: 1kwhResult: co-firing reduce the environment impact:35e37 g CO2/kWh

[25]

Comparison the environment impact between IGCCwith poplar and conventional fossil fuel aloneInclude the system boundaries for poplar exclude theconventional fossil fuelFU: 1 MWhResult: 110 kg/MWh

[26]

LCA was applied for biomass energy production onlyFU: 1 MJResult: 170 kg CO2/MWh

[27]

Comparison between LCA of biomass and LCA of IGCCAdapt the result for analyse the LCA of IBGCCBiomass FU: 1 MJResult: 130 kg CO2/MWh

[28]

Both energetic crop are compare to natural gasSystem boundaries: cultivation, harvest, transport,generation, disposalFU: 10 MW, 25 MW, 50 MWResult: Poplar is less impact than Ethiopian Mustardwhen use for energetic purpose

[28]

Comparison between 2 MW and 10 MW of electricitygenerated from CHP wood wasteSystem boundaries: wood storage-transport-powergenerationFU: 1 MJ electricity generatedResult: CO2 emission from 10 MW is less than CO2

emission from 2 MW

[29]

System boundaries: rice straw collection until systemco-firingFU: 1 kWh electricity generationResult: 1.04 kgCO2-eq/kWh for 10% co-firing and0.99 kgCO2-eq/kWh for 20% co-firing

[30]

Fig. 1. Flow diagram of life cycle co-firing rice straw.

S.M. Shafie et al. / Energy 57 (2013) 284e294 287

from 2006 to 2010 and lists the existing coal power plants inMalaysia.

The electricity generated from rice straw is calculated using Eq.(3) [30]. HHV employed in this analysis is 14.71 MJ/kg [31], andNPHR for rice straw fired alone is 17.4 MJ/kWh [30]. The averagepotential electricity generated from rice straw fired alone is936 GWh which consumed 1,107,618 tons of rice straw. Rice strawcannot be fired alone at the Manjung Power Station because of alimited rice straw supply.

2.1. Environmental and energy assessment for rice strawpreparation

The assessment of GHG emissions includes the activitiesinvolved in the harvesting of rice straw, transportation of rice strawto the collection centre (PP->CC) and transportation to the existingcoal power plant (CC->ECPP). For the purposes of these calcula-tions, the assumption made that each district had one collectioncentre (CC). The CC located in the centre of each district for thepurpose of measuring the hauling distance from paddy field.Table 5 shows the average rice straw collection centre area andaverage hauling distance for the two regions studied. Theassumption was that a lorry with a 1.5 capacity tonne used formoving rice straw from paddy production to the collection centre;that is because the majority of vehicles used to transport paddywaste in Malaysia have a load capacity of between 1-to-3 tonnes[32]. Typically, a truck of 400800 used for transferring rice straw balesfrom the CC to the power plant. Rice straw transportation energy

Table 4Average paddy production from 2006 to 2010 and existing coal power plants in Malaysi

Regions Harvestedarea, ha

Paddy production, ton Averagyield,

North 371092.8 1476824 3.9797Central 40869.2 203653.8 4.9831

South 2535.4 8794.2 2.5375East 96169.6 341694.4 3.4686Sabah/Sarawak 161644.8 347439 2.1494

consumption calculated from the following: energy unit 43.1 MJ/L�1, and fuel consumption 5.5 kmL�1 for a lorry capacity of 1.5 t and4 kmL�1 [33] for a truck with a size of 400800.

The data used in determined the energy consumption and GHGemissions from rice straw preparation was taken from Ref. [34].

Application of rice straw as the sole feedstock for electricitygeneration has not yet been implemented in Malaysia, so theanalysis uses data from other analogous biomass resources such aswood-fired power generation and agriculture waste. Emissionfactors for rice straw combustion in the boiler assumed to be thesame as corncob and straw [35]. Emission factors for coal com-bustion in the boiler was adapted fromUSEPA External CombustionSources report [36]. Table 6 indicates the emission factor of ricestraw combustion in the boiler.

2.2. Economics component of rice straw preparation

The general operation for rice straw collection is baling. Table 7indicates the breakdown cost for rice straw bale at collection point[14]. Total rice straw cost is RM 28.20/bale at collection centre, butthe rice straw transportation cost from CC to the existing coal po-wer plant must be added.

VCLORRY and VCTRUCK are capacity of a vehicle (kg vehicle�1),where capacity of the lorry is 900 kg (2 bales per lorry) and thetruck is 9000 kg (20 bales per truck). (WRS/VC) is the number oftrips required by the lorry and truck for the rice straw trans-portation. SCTP (RM km�1) is the specific cost for vehicle transportswas RM 5 km�1 [37]. SCTP (RM person�1) is the specific transport

a.

e strawton/ha

Coal power plant Capacity

Manjung 3 � 700 MWJimah, Kapar 2 � 700 MW,

2 � 300 MW, 2 � 500 MWTanjung Bin 3 � 700 MW

Mukah, Sejingkat, PPLS 270 MW, 100 MW, 110 MW

Table 7Breakdown cost for rice straw bale.

Collection centre, RM/Bale

Driver Broker Rope Fuel Machine Transportation Total

5 1 1.7 1.6 8.9 10 28.2

Table 5Average rice straw collection centre area and average hauling distance for the twostudied region.

States State area,km2

Average CCarea, km2

Region Path Average haulingdistance, km

Perlis 821 821 North PP->CC 17.77Kedah 9500 791.67Penang 753 251 CC->MP 314.90Perak 21,035 2103.5Selangor 8104 900.44 Central PP->CC 15.99Malacca 1664 554.67NS 6686 955.14 CC->KP 104.30

S.M. Shafie et al. / Energy 57 (2013) 284e294288

fee; the assumption is RM 10 per trip for lorry and RM 100 per tripfor truck [38,39]. Modification costs assumed for the rice strawfeeding to the existing boiler were RM150,000 per MW of powergenerated [18,30,40].Average coal cost is RM0.3348 per kg [41].

3. Methodology

To analyse the environmental and economic implications of ricestraw use as fuel that fed along with coal to the boiler, a full lifecycle assessment used. The full chain energy analysis of rice straw,starting from paddy production to electricity generation at powerplant, precisely examined. Fig. 1 shows a flow diagram of rice strawco-firing life cycle.

3.1. Goal and scope definition

The goal of using life cycle assessment is to identify thecontribution of environment impact toward the co-firing rice strawat existing coal power plant available at Malaysia. The functionalunit is defined from the most potential of existing coal power plantcapacity output which are 6,132,000 MWh (Manjung Power Plant,MP) and 2,628,000 MWh (Kapar Power Plant, KP). Rice strawpreparation environment impact only considered the emissionsrelated to the climate change particularly CO2, CH4 and N2Oexpressed as CO2 equivalent tones (tCO2eq). Climate change givesthe highest contribution to the environment impact during thepaddy residue preparation compared to other environment con-ditions (such as ozone layer and eco-toxicity) [42]. Two existingcoal power plant at Malaysia are being use as case study for co-firing based on their availability of rice straw.

3.2. System boundary and data source

Fig. 1 show the system boundary of rice straw co-firing atexisting coal power plants. Major operating units located inside thissystem are paddy production, rice straw collecting, rice strawtransportation and power generation. Table 8 shows the mainprocess of life cycle of rice straw co-firing and their data sources.

3.3. Inventory analysis

This section explains how the collected datawere adapted to theLCA model and gives details on assumptions that were made. Theinventory data compiled using the Open LCA Framework. However,certain data cited from some international database such as United

Table 6Emission factor rice straw combustion in the boiler.

Emission, kg/MJ N2O CH4 SOX NOX CO CO2

Emission factor 5.59E-6 9.03E-6 2.02E-6 2.11E-4 2.58E-4 0.08384

State Inventory Database, Australia Database and SimaPro softwareprogramme. Rice straw power generation at Malaysia is still underresearch development. Currently Malaysia generate electricity us-ing the rice husk for own consumption but the consumption ricestraw as a fuel is in early planning. Therefore, the data for rice strawcombustion is using the wood combustion. Development of ricestraw co-firing with existing coal power plants is not commer-cialize yet even though other biomass resources, like wood chipalready in commercialize state. About 77 power plants across theworld apply the wood co-firing technique with output capacitybetween 20 MW and 2035 MW [21].

3.3.1. Paddy productionMalaysia paddy plantations are planting two times a year, which

are off season and main season. However, there were no significantdifferent among the tillage energy, fertilizing energy and harvest-ing energy between both season [43]. This paper uses the averagedata to indicate both seasons. Mechanical field operation derivedfrom fuel consumption from land preparation machinery, plantprotection machinery and harvesting machinery.

3.3.2. Rice straw collectionRice straw collection after harvest paddy residue could be

accomplished by use of baler machine and tractor. The data tookfrom five sites in Northern region of Malaysia that involved withrice straw collection. This area used field baling technique withpush-type baler. Each baler can produce bales weighing about450 kg each. After harvesting, rice straw must be dry for balingprocess, normally after two to three days after harvested. Rice strawtaken when the water content of the straw is less than 25% [44]. Inthis study an SGR ratio 0.75 [45] is used to estimate the strawresidue yields per area through Eq. (1).

ASP ¼ ðPP=HAÞ � SGR (1)

Availability of rice straw based on nearness of rice straw supplyto a power plant; using this criterion, the most suitable co-firingcoal power stations are Kapar Power Station and Manjung PowerStation. Optimization of rice straw area served and radius distanceestimated using the Eq. (2) [46].

AS ¼ ASP=ðSY � hC � FA � FFÞ (2)

3.3.3. Rice straw transportationBale rice straw applied for analysing transportation sector. Two

transportation paths considered paddy production (PP) to the CCand the CC to coal power plants. Transportation emissions calcu-lated using the GHG Emissions from transportation or mobilesources, Version 2.3 software [47]. Paddy production to collectioncenter route considered of 1 tone lorry capacity that occupies 2bales rice straw per lorry. A small size lorry is use due to convenientway to transmit through small road with short distance. Trans-portation of rice straw from the collection centre to existing coalpower plant (MP/KP) used a truck of 400800 size. That is becausetruck transportation is the most feasible option in the residuecollection systems because trucks have a high degree of mobility[3]. Transportation of rice straw from paddy production to the coal

Table 8Main process of life cycle of rice straw co-firing and their data sources.

Process Subsystems Sources of data

1. Paddy production Fertilizers Measure data from Northern paddy farm areaLiterature data [36]

Irrigation Measure data from interview session(Senior Engineer, Irrigation and drainage service, MADA)

Mechanical field operations Data from questionnaire to selected farmer in Northern regionLiterature [37]

Pesticides Data from Ref. [38]Literature data [39]

2. Rice straw collection Mechanical equipment Data from four case project of rice straw in MADA area3. Rice straw transportation Transportation system Data from four case project of rice straw in MADA area4. Power generation Rice straw bale combustion Data from wood waste combustion

Electricity generation

S.M. Shafie et al. / Energy 57 (2013) 284e294 289

power plant, in Malaysia, modelled according to the routes, thetype of transport and distances shown in Table 9.

3.3.4. Power generationThe environment impact relevant to the rice straw co-firing

taken from the US LCI database based on wood waste combustionand inventory data from Ecoinvent. The analysis of co-firing ricestraw used Equation (3) to obtain the amount of rice straw neededfor electricity generation. Both coal power plants are situated nearthe sea, so the availability factor of paddy farm is assumed to be 25%(that includes a deduction of 50% for being located by sea and adeduction of 25% for infrastructure condition). The farmland factorestimated at 50% due to weather conditions that may cause inac-cessibility to collect rice straw. The collection efficiency estimated40% [48]. Availability of rice straw to co-fire with coal was a 30%ratio for the north region and 20% for the central region.

QELECT ¼ QRS;AL=NPHRRS;AL ¼ HHVRS �WRS;AL=NPHRRS;AL

(3)

Fig. 2 show the flow diagram of coal alone life cycle basedelectricity generation. It’s used to analyse the life cycle assessmentof coal alone based electricity generation, in order to make thecomparison between the co-firing rice straw and coal alone basedelectricity generation. The data taken from US LCI database andinventory data from Ecoinvent referred on bituminous coal elec-tricity generation at power plants. The relationship for electricitygeneration and coal needed for coal alone electricity generationexamined using Equation (4). The apply parameter based onManjung Power (MP) Plant technical characteristics [49].

QELECT;CALONE ¼ HHVCOAL �WCOAL; ALONE=NPHRCOAL (4)

3.4. GHG emission evaluation criteria analysis

The greenhouse gases CO2, CH4 and N2O emitted during thecombustion of diesel in the tractor which uses to carry the balermachine. The estimation of CO2 from tractor diesel combustion

Table 9Transportation of rice straw from paddy production to the coal power plant.

Transport route Type of transport Distance (km)

North Central

Paddy productionto collection centre

Small lorry (1.5 tone lorry) 17.77 15.99

Collection centreto coal power plant

Long truck (less than 32 tone) 314.90 104.30

calculated using the Eq. (5) [50]. And Eq. (6) used to estimate theCH4 and N2O emissions. Power generation produces air-bornemissions including CO2, SOX, NOX and CH4. CO2 emissions fromcombustion coal fired alone estimated using Eq. (7) [19].

CO2;T ¼X

i¼1

D� DD � Ci � DOi ��CO2; m:w=Cm:w

�(5)

EP ¼ AS � EFP;S (6)

CO2 ¼ FC � HHVC � EFCO2(7)

3.5. Life cycle impact assessment

The impact assessment method used in this study was CML2001 based on problem oriented approach [51]. The used impactassessment categories in this study cover climate change fromcarbon dioxide emission, eutrophication as a result of nitrous ox-ides, acidification from sulphur dioxide and human toxicity arisingfrom hydrogen fluorine and other inorganic chemical such asberyllium.

3.6. Economic evaluation criteria

The commercialization of biomass (rice straw) co-firing facesdifficulty because the economics are not favourable; biomass costsare higher than coal costs [18]. Economic evaluation of each co-firing option based on savings in fuel cost arising from price dif-ferences of coal and biomass, and income generated through thesale of emission credits [52]. The analysis involves calculating totaloperating costs and total capital investment in order to determinethe additional cost due to CO2 mitigation.

3.6.1. Operating costOperating cost determined based on two components: pur-

chased rice straw cost (PCRS ¼ CRS � MRS) [53] and total rice strawtransport cost (TCRS ¼ CTV þ CTP). Total transportation cost of ricestraw related to the annual travel distance (DT, in km year�1) costper vehicle and the fee paid for transport personnel. Rice strawtransportation has two segments: from paddy production to thecollection centre and from collection centre to existing coal powerplant. Annual travel distance used the average distance drawn fromthe optimization of rice straw served in Eq (8). Therefore, the totalannual travelled distance (DT) estimated as:

DT ¼ ðADPP/CC �WRS=VCLÞ þ ðADCC/MP �WRS=VCT Þ (8)

Hence, transport vehicle cost is (CTV ¼ DT � SCTP). Transportpersonnel cost is assumed to be:

Fig. 2. Flow diagram of coal alone based electricity generation life cycle.

S.M. Shafie et al. / Energy 57 (2013) 284e294290

CTP ¼ððTCTL=WHÞ � SCTPL �WRS=VCLÞ (9)

þ ððTCTT=WHÞ � SCTPT �WRS=VCT ÞIn calculating the transport personnel cost, the following as-

sumptions were made. Working hours per year estimated to be3120 h year�1. The respective time consumption for lorry and truckfor moving rice straw to the power plant were 0.5 h trip�1 and48 h trip�1. Time consumed for lorry and truck deliveries to the KP(Kapar Plant) respectively would be an h trip�1 and 8 h trip�1.

3.6.2. Capital costCapital cost strongly depends on the amount of rice straw to co-

fired at power plants and whether the rice straw can fed to theexisting coal boiler via the existing feeding system or requiresseparate feeding system [40]. The capital cost (CC) for rice straw co-firing using existing feeding systems calculated as

CC ¼ 150;000� �WRS � HHVRS=

�WC;AL � DWC

�� HHVC�� PO

(10)

Total rice straw co-firing costs are (CRS ¼ PCRS þ TCRS þ CC). TheCO2 emission price [30] calculated using Eq. (11).

�CC �WC;AL

�þ �CG � EG;C;AL

� ¼ �CC �WC;CO

�þ �CRS �WRS;CO

�

þ �CG � EG;CO

�þ CC(11)

Table 10Rice straw availability in the two studied region.

North Central

Rice straw yield (t/km2) 297.92 368.19Availability factor 0.25 0.25Farmland factor 0.5 0.5Area served (km2) 311535.4 34176.2Radius distance (km)/one trip 314.9 104.3Suitable coal power station Manjung Kapar

4. Study and location

Malaysia has several operating coal power plants with boileroutput capacities ranging from 100 MW to 700 MW. Currently, coalfor electricity generation in Malaysia fully imported from othercountries which include Australia (60%), Indonesia (30%), China(5%) and South Africa (5%) these will facing to the major issue ofsupply risk in the future [54]. However, proximate supply avail-ability of rice straw for co-firing indicated that the most suitable co-firing coal power stations were the Kapar Power Station and theManjung Power Station (KP and MP). The Manjung coal-fired po-wer plant is located on a man-made island off the coast of Perak inMalaysia. It generated 2100 MW from its three 700 MW units ofboiler. According to [55], this one unit of boiler already experiencethe co-firing of pelletized EFB with 1%e3% co-firing ratio for oneweek only due to storage problem and increase the slugging. KaparPower Plant is a major station in the Klang Valley in the region ofMalaysia. This power station, which fired natural gas, oil and coal,located 56 km west of Kuala Lumpur facing the Strait of Malacca.Table 10 indicates the availability of rice straw for the two regionsstudied. These coal power stations generated 300MWand 700MWfor each boiler capacity.

5. Results and discussion

5.1. Energy consumption and GHG emission for rice strawpreparation

Life cycle of rice straw preparation involves the processes ofpaddy production (PP), rice straw collection (RS-C), transportationof rice straw to the collection centre (CC) for each district andtransportation of rice straw from CC to the existing coal powerplant. Table 11 shows energy consumption and GHG emissions ofthe overall life cycle of rice straw preparation. All the process stagesinvolve the 5% ratio of rice straw co-firing at existing coal powerplant with capacity 700 MW (MP) and 300 MW (KP). Overall en-ergy consumption for MP and KP are 0.1113 TJ/MWh and 0.1019 TJ/MWh respectively. Overall GHG emissions for rice straw prepara-tion (starting from paddy production until rice straw available atcoal power plant, Fig. 1) range between 0.4067 and 0.5994 kg CO2-eq per kg rice straw ready at coal power plant. Current CO2 emis-sion at MPwith unit capacity 700MWwas 365.8 kg CO2/MWh [56].Considering each process, the largest contribution to the GHGemissions is from paddy production due to large volume ofmethane emissions. CH4 emission for North region is 50.53 kg CH4per ha and Central region is 19.13 kg CH4 per ha. The dominantcause of this different are due to soil condition and land use pattern[57]. Therefore, a decrease in CH4 emission would be the best op-tion for reducing the GHG emissions from paddy plantation [58].

Transportation of rice straw from paddy plantation to powerplant contributes about 11%e15% of total CO2-eq emission with 5%co-firing ratio. Adding the co-firing ratio up to 20% dramatically risethe percentage of transportation to 83.47% of total CO2-eq emission.

5.2. GHG emission for power generation

Rice straw co-firing with coal occurs in an existing coal powerplant with capacity 700 MW for MP and 300 MW for KP. Thebaseline emission coal power plant inWest Malaysia is taken 0.6 kgCO2-eq/kWh [59]. Direct co-firing is used when rice straw is mixedwith coal at the existing coal feeder, and the fuel mixture can go toexisting coal mills that pulverize coal and rice straw together and

Table 11Energy consumption and GHG emissions for overall rice straw preparation.

Region Process Energyconsumption,TJ

GHG emissions, ton

CO2 Nitrousoxide

Methane CO2-eq

North PP 455.47 �4.86 847.42 4268.47 5111.03RS-C 19.88 63.89 0.48 0.08 64.44TPP->CC 27.96 92.40 175.74 0.06 268.19TCC->MP 68.14 228.61 372.91 0.18 601.70Total 571.45 380.04 1396.55 4268.79 6045.37

Central PP 112.12 �1.47 256.21 1290.54 1545.29RS-C 4.89 21.87 0.16 0.03 22.06TPP->CC 6.2 36.18 68.81 0.02 105.02TCC->KP 5.56 32.45 52.93 0.02 85.41Total 128.77 89.03 378.11 1290.61 1757.78

y = 0.0279x + 0.9433

y = 0.0485x + 0.9404

94%

95%

96%

97%

98%

99%

100%

0 0.2 0.4 0.6 0.8 1 1.2

CO

2 R

ed

uctio

n (%

)

Cofiring

MP

KP

Fig. 3. CO2 reduction pattern for both power plant (MP and KP).

y = -2910.4x2 + 209.29x + 6947

0

0.005

0.01

0.015

0.02

0.025

010002000300040005000600070008000

0 0.2 0.4 0.6 0.8 1 GH

G E

mis

sio

n p

er u

nit electricity

ge

ne

ra

te

d, k

to

n/M

Wh

CO

2E

mis

sio

n, k

to

n

Cofiring Ratio

CO2 Emission,kton

CO2 Saving,kton

GHG Emission, kton/MWh

Fig. 4. CO2 emission in kTon, CO2 saving in kTon and GHG emission per unit electricitygenerated as a function of co-firing ratio.

S.M. Shafie et al. / Energy 57 (2013) 284e294 291

distribute to the burner based on co-firing ratio rate [52]. If the co-firing percentage is very small (less than 8%), the pre-blended coaland rice straw can be fired in existing facilities with minimummodification [60]. The direct co-firing is the simplest and lowest-cost option. Based on Ref. [22], with a co-firing ratio of less than8%, direct co-firing can be used and biomass can be combined withcoal prior to the pulverisers. Ref. [61] indicated the composition ofdifferent coal and biomasses in physical properties, elementalcomposition, inorganic properties and proximate analysis. Co-firingbiomass can create deposit and corrosion problems depending onthe form of biomass fuel. Review paper [62] indicated that nocorrosion observed below a 10% straw co-firing, and no chlorineinitiated corrosion observed at either co-firing level. But the op-portunity for successfully co-firing rice straw remains high due totechnical feasibility proven based on generation of 7000 MW bywood products [18].

Table 12 lists the GHG emissions at a power plant for coal firedalone and co-firing rice straw at 5% with coal. Majority of airemission that causes global warming and acid rain reducedsignificantly through the practice of co-firing. Fig. 3 show the CO2reduction pattern for both power plant (MP and KP). KP CO2emission drop sharply with slope reduction, m ¼ 0.048, which isdouble from MP CO2 emission reduction. However, some literature[63] indicates that SO2 and CO2 reduction can be up to 75% and 93%respectively depending on the co-firing ratio. In 1991, CO2 emissionwas 5.35 million ton from coal power plant, increased to 28.17million ton in 2000, however it will be 107.71 million ton CO2emission ton in 2020 [64]. The synthesis results prove that co-firingcan help the mitigation of CO2 emission in the power industrysector.

Fig. 4 shows the CO2 emission reduction in kTon and GHGemissions per unit electricity generated as a function of co-firingratio. The simulated result gives quadratic polynomial relation forco-firing ratio between 5% until 95% which is ECO2;CO ¼�2910R2RS;CO þ 209:2RRS;CO þ 6947. The higher reduction is dueanalysis involve the life cycle of co-firing rice straw and life cycle ofcoal alone based electricity generation (Fig. 1).

Table 12Life cycle of GHG emission at Manjung Power Plant (MP) and Kapar Power Plant (KP) fo

Power plant Emission, kton CO2 C

MP Coal alone 138837.40 15% rice straw 6950.22 1Percentage (%) reduction 94.99 1

KP Coal alone 59501.755% rice straw 2980.42Percentage (%) reduction 94.99 1

GHG emissions per kWh electricity generated show a powerregression type relationship between 5% until 20% co-firing ratio.The relationship to the various co-firing ratio function is, GHGemission reduction per MWh ¼ 0.001 (RRS,CO)�1.

Rice straw co-firing indicated higher GHG reduction comparedto switch grass co-firing with only 13.46% at 0.2 co-firingratio. This comparison is from a simulated result [30] where;EGHG,CO ¼ �606RSW,CO þ 996.13. With a greater co-firing ratio, theCO2 reduction is more drastic compared to reduction at GHGemissions per unit electricity generated. It must be highlighted thatrice straw co-firing can mitigate CO2 emission exponentiallyregarding the co-firing ratio with; CO2 SAVING ¼ 236.5e2.653RRS,CO.Co-firing rice straw 5% can saving the CO2 emission about297.8 k ton CO2 emission.

Fig. 5 shows the result of environment impact for three differenttype of combustion: coal alone, MP power generation and KP powergeneration. The characterized data for 6,132,000MWh of coal aloneelectricity has been compared with the characterized data for6,132,000 MWh co-firing rice straw based electricity generated.

r coal fired alone and 5% co-firing rice straw with coal.

H4 N2O SOX CO NOX

5.39 0.29 46.13 167.61 1664.332.37 0.17 17.15 0.79 19.099.60 42.16 62.83 99.53 98.856.59 0.13 19.77 71.83 713.285.29 0.07 7.38 0.35 8.279.71 42.24 62.66 99.52 98.84

Fig. 5. Comparison for different type of system toward the environment impact.

Fig. 6. Comparison for different type of rice straw preparation system toward the environment impact.

S.M. Shafie et al. / Energy 57 (2013) 284e294292

Four impact categories are considered: climate change, eutrophi-cation, acidification and human toxicity. Coal power alone gives thehighest impact for all categories. Co-firing can reduce all the impactcategories by 73.22% (human toxicity), 92.54% (acidification), and94.97% (climate change) and 98.83% (eutrophication). The climatechange reduction is corresponded to the decline of CO2 emission.For all impact categories the utilization of rice straw co-firing atexisting coal power plants give a better environmental perfor-mance than coal alone based electricity generation [65].

Fig. 6 presents the comparison for different component of ricestraw preparation system toward the environment impact. Refer toFig. 6, rice straw combustion gives the highest impact for all cate-gories. Transportation of rice straw is contributing the highestimpact under the rice straw preparation. The summary of envi-ronmental impact associated with the co-firing rice straw listed inTable 13. The result based on MP power generation which is700 MW. In order to identify each component involved the paddyproduction output is set to 4,322,259 kg of rice straw at field. Therice straw collection output is 9605 bale of rice straw. The rice strawproduction amount is 0.0742 kg CO2 per kg rice straw ready at fieldsequivalent to 296.38 kg CO2 per ha. The paddy productions also give

Table 13Environment impacts of rice straw preparation for MP (700 MW).

Environment system Categories, unit

Acidification,kg SO2-Eq

Climatkg CO

Paddy production 8.22E3 3.21E5Rice straw collection 3.74E2 2.78E4Transportation 1, TPP->CC 1.82E2 4.05E4Transportation 2, TCC->KP 3.81E2 9.84E4Rice straw combustion 1.37E5 1.05E7

a significant impact to the eutrophication due to emission of NOX

and SOX through the use of fertilizer and chemical agriculture.Nevertheless paddy production contributes to climate change andeutrophication it also creates a great advantage due to absorption ofcarbon dioxide through photosynthesis process [66].

5.3. Economic analysis

Co-firing rice straw with coal is intended to reduce the CO2emissions that coal power plants emit. But this technique requiresinvestment/costs due to biomass purchase, transport and modifi-cation of existing coal power plants. Fig. 7 shows the effect of theco-firing ratio on cost of rice straw co-firing. The synthesized cost ofco-firing is the adding of rice straw (operation cost and capital cost)minus the credit of SOX emission. The overall cost of co-firing iscontributed to by rice straw cost. Without the CO2 emission credit,the co-firing cost shows a 93.29% rise from baseline coal cost. Fig. 8indicates the co-firing ratio effect of reduction in CO2 and additionalcosts. With increasing the co-firing ratio, the reduction of CO2emission is increased as coal is replaced by rice straw and emissionsthe CO2 neutral rice straw. The additional cost rate also grows due

e change,2-Eq

Eutrophication,kg NOX-Eq

Human toxicity,kg 1,4-DCB-Eq

1.63E4 7.65E36.42E2 1.72E43.13E2 3.2E26.53E2 6.66E22.44E5 2.06E5

050

100150200250300350400450500550

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

RM

Billio

ns

Cofiring Ratio

C_RS

C_COAL

C_SOX

Baseline Coal Cost

SYNTHE_COST

Fig. 7. Effect of co-firing ratio on cost of rice straw co-firing.

0.0E+00

2.0E+08

4.0E+08

6.0E+08

8.0E+08

1.0E+09

1.2E+09

1.4E+09

1.6E+09

1.8E+09

2.0E+09

0.0E+00

5.0E+08

1.0E+09

1.5E+09

2.0E+09

2.5E+09

3.0E+09

3.5E+09

4.0E+09

4.5E+09

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

Ad

dito

na

l C

os

t (R

M/y

ear)

Re

du

ctio

n in

C

O2( M

to

ns / year)

Cofiring Ratio

Reduction inCO2

AC

Fig. 8. Co-firing ratio effect of reduction in CO2 and additional cost.

S.M. Shafie et al. / Energy 57 (2013) 284e294 293

to higher amount of feeding rice straw to the boiler (capacity costand transportation cost). However, the effect of increasing theadditional cost dominates the reduction in CO2 emissions and thiscauses the increasing of CO2 emission price show in Fig. 8.

CO2 emission price corresponds to the reduction of CO2 emis-sion with linearly increased with co-firing ratio. Fig. 9 shows theeffect of co-firing ratio on the CO2 emission price and GHG reduc-tion relative to coal fired alone.

The amount of co-firing of rice straw may be decided on thebasis of available incentives for CO2 reduction [40].

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0

20

40

60

80

100

120

140

160

0 20 40 60 80

GH

G R

ed

uctio

n o

f co

firin

g r

elative to

co

al f

irin

g a

lo

ne

(m

etric

to

n C

O2/M

Wh

)

CO

2E

mis

sio

n P

ric

e(R

M/m

etric

to

n C

O2)

Cofiring Ratio

CO2 Emission price

Relative

Fig. 9. Effect of co-firing ratio on the CO2 emission price and GHG reduction relative tocoal fired alone.

6. Conclusion

This feasibility study examined economic, energy and GHGemissions implications with respect to Malaysian power plants of-fering the most potential for co-firing rice straw. The most suitablecoal power stations for the co-firing technique were the ManjungPower Station (MP) and the Kapar Power Station (KP); suitabilitywas based on high availability of average straw yield near the plants.Emissions from rice straw preparation ranged from 0.152 to0.163 kg CO2-eq per kg for rice straw already at power plant. Thebiggest constraining factor for co-firingwasGHGemissions fromtherice straw hauling process from the collection centre to the powerplant. Depending on co-firing ratio, the CO2 emission could be 77%less and SOXemissions could be 55% less. These reductions lower theimpact on global warming and reduce acid rain potential. Costs ofco-firing rice straw is 93.29% higher compared to conventionalbaseline coal cost. This is because the computed cost of co-firing ishighly dependent on rice straw cost, which is expensive because oftransportation and capital costs. The rice straw co-firing techniquecan be competitive with coal if the CO2 incentive is applied.

The successful implementation of biomass co-firing requires fullsupport from government and various stakeholders. Subsides fromgovernment can help develop this co-firing technique, andawareness of global warming issues also could become a key factorin encouraging the consumption of renewable energy.

References

[1] Bakos GC, Tsioliaridou E, Potolias C. Technoeconomic assessment and strategicanalysis of heat and power co-generation (CHP) from biomass in Greece.Biomass and Bioenergy 2008;32:558e67.

[2] Rice market monitor [cited 2012 31 October]; Available from: http://www.foa.org/economic/est/publications/rice-publications/rice-market-monitor-rmm/en/; 2012.

[3] Kadam KL, Forrest LH, Jacobson WA. Rice straw as lignocellulosic resource:collection, processing, transportation, and environmental aspects. Biomassand Bioenergy 2000;18:369e89.

[4] Hanafi Emtenan M, Khadrawy HHE, Ahmed WM, Zaabal MM. Some obser-vations on rice straw with emphasis on updates of its management. WorldApplied Sciences Journal 2012;16(3):354e61.

[5] Binod P, Sindhu R, Singhania RR, Vikram S, Devi L, Nagalakshmi S, et al. Bio-ethanol production from rice straw: an overview. Bioresource Technology2010;101(13):4767e74.

[6] UNEP. Converting waste agricultural biomass into energy source. Osaka,Japan: Division of Technology, Industry and Economics; 2009.

[7] Bakker R. Rice straw for electricity & heat production, in Biobased ProductDivision, W.U.-A. Senior Scientist, Editor: Cairo; 2009.

[8] Jenkins BM, Bakker RR, Williams RB, Bakker-Dhaliwal R, Summers MD.Commercial feasibility of utilizing rice straw in power generation. ProceedingsBioenergy 2000.

[9] Suramaythangkoor T, Gheewala SH. Potential alternatives of heat and powertechnology application using rice straw in Thailand. Applied Energy 2010;87:128e33.

[10] Jeng Shiun Lim, Zainuddin Abdul Manan, Sharifah Rafidah Wan Alwi,Haslenda Hashim. A review on utilization of biomass from rice industry as asource of renewable energy. Renewable and Sustainable Energy Reviews2012;16:3084e94.

[11] Bakker RR, Jenkins BM, Williams RB. Fluidized bed combustion of leached ricestraw. Energy and Fuels 2002;16:356e65.

[12] Thy P, Jenkins BM, Williams RB, Lesher CE, Bakker RR. Bed agglomeration influidized combustor fueled by wood and rice straw blends. Fuel ProcessingTechnology 2010;91(11):1464e85.

[13] Huanpeng Liu, Yujie Feng, Shaohua Wu, Dunyu Liu. The role of ash particles inthe bed agglomeration during the fluidized bed combustion of rice straw.Bioresource Technology 2009;100(24):6505e13.

[14] Sabri A. Rice straw project report 2011, S.M. Shafie, Editor, MADA: PPK B2,MADA Sanglang, 06000, Jitra Kedah; 2012.

[15] Mahlia TMI. Emissions from electricity generation in Malaysia. RenewableEnergy 2002;27:293e300.

[16] Shekarchian M, Moghavvemi M, Mahlia TMI, Mazandarani A. A review of thepattern of electricity generation and emission in Malaysia from 1976 to 2008.Renewable and Sustainable Energy Reviews 2011;15:2629e42.

[17] IEA. Technology roadmap: bioenergy for heat and power. France: Interna-tional Energy Agency; 2012.

[18] Hughes E. Biomass cofiring: economics, policy and opportunities. Biomass andBioenergy 2000;19:457e65.

S.M. Shafie et al. / Energy 57 (2013) 284e294294

[19] Suramaythangkoor T, Gheewala SH. Potential of practical implementation ofrice straw-basedpower generation inThailand. Energy Policy 2008;36:3193e7.

[20] Al-Mansour Fouad, Zuwala J. An evaluation of biomass co-firing in Europe.Biomass and Bioenergy 2010;34(5):620e9.

[21] IEA. Database of biomass cofiring initiatives 2009.[22] Demirbas A. Sustainable cofiring of biomass with coal. Energy Conversion and

Management 2003;44:1465e79.[23] Mann MK, Spath PL. A life cycle assessment of biomass cofiring in a coal-fired

power plant. Clean Products and Processes 2001;3:81e91.[24] Sebastián F, Royo J, Gómez M. Cofiring versus biomass-fired power plants:

GHG (Greenhouse Gases) emissions savings comparison by means of LCA (LifeCycle Assessment) methodology. Energy 2011;36(4):2029e37.

[25] Singh A, Pant D, Korres NE, Nizami AS, Prasad S, Murphy JD. Key issues in lifecycle assessment of ethanol production from lignocellulosic biomass: chal-lenges and perspectives. Bioresource Technology 2010;101(13):5003e12.

[26] Heller MC, Keoleian GA, Mann MK, Volk TA. Life cycle energy and environ-mental benefits of generating electricity from willow biomass. RenewableEnergy 2004;29(7):1023e42.

[27] Kimming M, Sundberg C, Nordberg Å, Baky A, Bernesson S, Norén O,Hansson P-A. Biomass from agriculture in small-scale combined heat andpower plants e a comparative life cycle assessment. Biomass and Bioenergy2011;35(4):1572e81.

[28] Perilhon C, Alkadee D, Descombes G, Lacour S. Life cycle assessment applied toelectricity generation from renewable biomass. Energy Procedia 2012;18:165e76.

[29] Crop statistical data. Kuala Lumpur: Official Portal of Agriculture Department;2012.

[30] Qin X, Mohan T, El-Halwagi M, Cornforth G, McCarl BA. Switchgrass as analternate feedstock for power generation: as integrated environment, energyand economic life-cycle assessment. Clean Technologies and EnvironmentalPolicy 2006;8:233e49.

[31] Calvo LV, Otero M, Jenkins BM, Moran A, Garcia AI. Heating process charac-teristics and kinetics of rice straw in different atmospheres. Fuel ProcessingTechnology 2004;85(4):279e91.

[32] Abdullah MA. A cost analysis of paddy transportation and distribution systemsin Muda Agricultural Development Authority Granary area. University PutraMalaysia: Kuala Lumpur: Department of Agriculture; 2006.

[33] Martensson L. Emissions from volvo’s trucks (standard diesel fuel). V.T. Cor-poration, Editor; 2003.

[34] Shafie SM, Mahlia TMI, Masjuki HH. Life cycle assessment of rice straw-basedpower generation in Malaysia. Kuala Lumpur: University Malaya; 2012.

[35] EEA. EMEP/CORINAIR emission inventory guidebook-2006, in Group 1: com-bustion in energy and transformation industries 2006.

[36] USEPA. Chapter 1: external combustion sources. United States EnvironmentalProtection Agency; 2003.

[37] A.R.Adlansyah, Potential for co-firing biomass with coal in Malaysia, in Centrefor Renewable Energy: University Tenaga National.

[38] Sabri A. Rice straw project report for 1/2011. MADA B11: Kedah 2011.[39] Employment outlook and salary guide 2011/2012: Malaysia, Kelly, Editor,

Kelly Services; 2011.[40] De S, Assadi M. Impact of cofiring biomass with coal in power plants e a

techno-economic assessment. Biomass and Bioenergy 2009;33:283e93.[41] Abdullah Z. Higher coal prices eat into TNB 9 month net profit. Berita Harian:

Kuala Lumpur: Business Times; 2009.[42] Shafie SM, Mahlia TMI, Masjuki HH, Rismanchi B. Life cycle assessment (LCA)

of electricity generation from rice husk in Malaysia. In: 2011 2nd internationalconference on advances in energy engineering (ICAEE). Bangkok: EnergyProcedia; 2012. p. 499e504.

[43] Bockari-Gevoa SM, Wan Ismail WI, Azmi Y, Chan CW. Analysis of energyconsumption in lowland rice-based cropping system of Malaysia. Songkla-nakarin Journal of Science and Technology 2005;27(4):819e26.

[44] Kadama Kiran L, Forrestb Loyd H, Jacobsonb WA. Rice straw as a lignocellu-losic resource: collection, processing, transportation, and environmental as-pects. Biomass and Bioenergy 2000;18:369e89.

[45] Gadde B, Menke C, Wassmann R. Rice straw as a renewable energy source inIndia, Thailand, and the Philippines: overall potential and limitations for en-ergy contribution and greenhouse gas mitigation. Biomass and Bioenergy2009;33:1532e46.

[46] Delivand MK, Barz M, Gheewala SH. Logistics cost analysis of rice straw forbiomass power generation in Thailand. Energy 2011;36:1435e41.

[47] Greenhouse gas protocol. All Tools [cited 2012 12 February]; Available from:http://www.ghgprotocol.org/calculation-tools/all-tools; 2011.

[48] Petrolia DR. The economics of harvesting and transporting corn stover forconversion to fuel ethanol: a case study for Minnesota. Biomass and Bioenergy2008;32:603e12.

[49] Salim MF. Manjung power station-the new experience. Jurutera 2004:24e7.[50] EPA. Direct emissions from mobile combustion sources. In: Leaders C, editor.

Greenhouse gas inventory protocol core module guidance. United States:United States Environmental Protection Agency; 2008. p. 38.

[51] Frischknecht R, Jungbluth N, Althaus H-J, Bauer C, Doka G, Dones R, et al.Implementation of life cycle impact assessment methods. Dübendorf: SwissCentre for Life Cycle Inventories; 2007.

[52] Basu P, Butler J, Leon MA. Biomass co-firing options on the emission reductionand electricity generation costs in coal-fired power plants. Renewable Energy2011;36:282e8.

[53] Caputo AC, Palumbo M, Pelagagge PM, Scacchia F. Economics of biomass en-ergy utilization in combustion and gasification plants: effects of logisticsvariables. Biomass and Bioenergy 2005;28(1):35e51.

[54] TNB. Energy security [cited 2012 12 December]; Available from: http://www.tnb.com.my/nuclear/energy-security.html; 2012.

[55] Adlansyah AR. Upgrading of Malaysian biomass for cofiring with coal, UNITEN,Editor: Malaysia; 2010.

[56] CARMA. Carbon monitoring for action. CARMA; 2007.[57] Shao JA, Huang X, Gao M, Wei CF, Xie DT, Cai ZC. Response of CH4 emission of

paddy fields to land management practices at a microcosmic cultivation scalein China. Journal of Environmental Sciences (China) 2005;17(4):691e8.

[58] Minamikawa K, Sakai N, Yagi K. Methane emission from paddy fields and itsmitigation options on a field scale. Microbes and Environments 2006;21(3):135e47.

[59] Chee IMS. GHG emission baselines for the power generation sector inMalaysia, P.T. Malaysia, Editor, PTM; 2004.

[60] Sami M, Annamalai K, Wooldridge M. Co-firing of coal and biomass fuelblends. Progress in Energy and Combustion Science 2001;27(2):171e214.

[61] Demirbas A. Combustion characteristics of different biomass fuels. Progress inEnergy and Combustion Science 2004;30(2):219e30.

[62] Sondreal EA, Benson SS, Hurley JP, Mann MD, Pavlish JH, Sanson ML, et al.Review of advances in combustion technology and biomass cofiring. FuelProcessing Technology 2001;71:7e38.

[63] Saidur R, Abdelaziz EA, Demirbas A, Hossain MS, Mekhilef S. A review onbiomass as a fuel for boiler. Renewable and Sustainable Energy Reviews2011;15(5):2262e89.

[64] Abul Quasem Al-Amin, Chamhuri Siwar, Abdul Hamid Jafar, Nurul Huda.Pollution implications of electricity generation in Malaysian economy: aninput-output approach. In: Singapore economic review conference (SERC).Singapore: Meritus Mandarin Hotel; 2007.

[65] Hongtao Liu, Polenske Karen R, Youmin Xi, Ju’e Guo. Comprehensive evalua-tion of effects of straw-based electricity generation: a Chinese case. EnergyPolicy 2010;38(10):6153e60.

[66] Maria Luiza Grillo Renó, Electo Eduardo Silva Lora, José Carlos Escobar Palacio,Osvaldo José Venturini, Jens Buchgeister, Oscar Almazan. A LCA (life cycleassessment) of the methanol production from sugarcane bagasse. Energy2011;36(6):3716e26.