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

Published Date
1 August 2013, Vol.57:284–294, doi:10.1016/j.energy.2013.06.002

Title 
Life cycle assessment of rice straw co-firing with coal power generation in Malaysia

• Author 

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

• aDepartment of Mechanical Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia
• bDepartment of Mechanical Engineering, Syiah Kuala University, Banda Aceh 23111, Indonesia

Received 11 June 2012. Revised 25 May 2013. Accepted 3 June 2013. Available online 29 June 2013.

Highlights

• •
  The overall rice straw preparations are between 0.152 and 0.163 kg CO₂-eq per kg rice straw.
• •
  Depending on co-firing ratio the CO₂ reduce up to 77% less and SO_X to 55% less.
• •
  Calculated cost of co-firing is 93.29% higher compared to conventional baseline coal cost.

Abstract

This paper investigates the economic feasibility of rice straw co-firing at coal power plants in Malaysia and in doing so looks at the operating, capital, and logistic costs. Co-firing rice straw in an existing coal power plant is a technique that could reduce CO₂ emissions and make Malaysia less dependency on coal resources. In a country such as Malaysia with abundant biomass resources, utilizing biomass residue also would help reach government targets of developing renewable energy under the country's Fuel Diversification 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. Analysis of GHG emissions and energy consumption throughout the entire co-firing rice straw life cycle was based on selected coal power plant capacity output. This paper also analyses the implication of rice straw use under different co-fired ratios, transportation systems and CO₂emission prices. The reduction of GHG emissions was found to be significant even at a lower co-firing ratio.

Keywords

• Co-firing
• Rice straw
• Power generation
• Life cycle assessment

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Nomenclature

A

activity level

A_S

area served (km²)

AD_PP->CC

average distance from paddy plantation to collection centre

AD_CC->MP

average distance from collection centre to power plant

AS_P

average rice straw production (ton)

AS_Y

average straw yield (ton/ha)

Cm.w

molecular weight of carbon

C_C

capital cost (RM)

C_COAL

national average cost of coal (RM/KG)

C_GHG

emission price of equivalent carbon dioxide (RM)

C_i

carbon content fraction of diesel (mass C/mass diesel)

C_RS

rice straw co-firing cost (RM/KG)

C_TP

transport personnel cost (RM)

C_TV

transport vehicle cost (RM)

CO_2,m.w

molecular weight of CO₂

CO_2, T

CO₂ emission from tractor

D

volume of diesel combusted (l)

D_D

density of diesel (kg/l)

D_T

travel distance (KM)

E_P

emission pollutant (CH₄ or N₂O)

E_{GHG, CO}

GHG emission during co-firing (KG)

E_{GHG, COALONE}

GHG emission during coal burn alone (KG)

EF

emission factor

emission factor of carbon dioxide

F_A

availability factor

FC

fuel combustion (L)

F_F

farmland factor

FO_i

fraction oxidized of diesel

H_A

harvested area (ha)

HHV_COAL

high heating value of coal (MJ/KG)

HHV_RS

high heating value of rice straw (MJ/KG)

ŋ_C

collection efficiency

NPHR_COAL

net plant heat rate of coal (MJ/kWh)

NPHR_{RS, ALONE}

net plant heat rate of rice straw alone (MJ/kWh)

P_P

paddy production (ton)

PC_RS

purchased rice straw cost (RM/Year)

Q_ELEC

electricity generated (kWh)

Q_{ELEC, CALONE}

electricity generated by coal alone (kWh)

Q_{RS, ALONE}

electricity generated by burning rice straw alone (kWh)

RS-C

rice straw collection

S

source category

S_Y

straw yield (ton/km²)

SCTP

specific cost for vehicle transport (RM/KM)

SGR

straw to grain ratio

TC_RS

transportation rice straw cost (RM)

TCT_L

total consumption hour trip of lorry (hour)

TCT_T

total consumption hour trip of truck (hour)

TCC->EC_PP

transportation from collection centre to existing coal power plant

TPP->CC

transportation from paddy production to collection centre

W_{COAL, ALONE}

weight of coal burn alone (KG)

W_{COAL, CO}

weight of coal used in co-firing (KG)

W_{RS, ALONE}

weight of rice straw burn alone (KG)

W_{RS, CO}

weight of rice straw used in co-firing (KG)

VC_LORRY

capacity of lorry (KG/lorry)

VC_TRUCK

capacity of truck (KG/lorry)

 Table 1

Table 1.

 Table 2

Table 2.

 Table 3

Table 3.

Fig. 1.

 Table 4

Table 4.

 Table 5

Table 5.

 Table 6

Table 6.

 Table 7

Table 7.

 Table 8

Table 8.

 Table 9

Table 9.

Fig. 2.

 Table 10

Table 10.

 Table 11

Table 11.

 Table 12

Table 12.

Fig. 3.

Fig. 4.

Fig. 5.

Fig. 6.

 Table 13

Table 13.

Fig. 7.

Fig. 8.

Fig. 9.

• ∗ 
  Corresponding author. Tel.: +60 17 499 4562.

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http://www.sciencedirect.com/science/article/pii/S0360544213004969