BG Research Online
Chandra, V.V. and Hemstock, S.L. (2015) The Potential of Sugarcane Bioenergy
in Fiji. Sugar Tech, 18 (3). pp. 229-235. ISSN 0972-1525
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1
The Potential of Sugarcane Bioenergy in Fiji
1
Abstract: Biomass production, utilisation and losses from 1993-2012 were analysed for Fiji. 2
Total theoretical annual average biomass potential was 83PJ. Sugarcane alone has the 3
potential energy of 52PJ annually and 137.64 million litres of ethanol could be produced from 4
sugarcane, cassava and sweet potatoes in a year. Sugarcane (excluding the local sugar 5
consumption) has the potential to produce 129.25 million litres of ethanol which is 29% more 6
than the total motor spirit imported in 2010. Bagasse has the potential to generate 8.2PJ of 7
energy. 8
Key Words: (biomass, bioethanol; energy, residues, production, Fiji). 9
1. Introduction 10
Fiji is a least developed country (LDC) with a land mass of 18,272 km2 spread over an Exclusive
11
Economic Zone (EEZ) of 1.3 million km2. Viti Levu is the largest island, which covers 10,390
12
km2 followed by Vanua Levu with 5538 km2. These two islands account for 87 percent of the
13
land area and 90 percent of the population (Woods et al. 2006). 14
The total land area in Fiji is approximately 1,827,000 ha of which 9.17% is arable, 4.65% is 15
used for perennial crops (Anonymous 2014b). Lands in Fiji are managed through three unique 16
systems – Native land, Crown land and Freehold land. Out of the total land in Fiji, 83% is Native 17
land, 10% is Freehold land and 7% is Crown land (Anonymous 2012). The majority of Native 18
lands are leased to sugar cane farmers on 30 year agricultural leases administered by the 19
iTaukei Lands Trust Board (iLTB). This study found that sugarcane was the major source of 20
biomass energy in terms of food (sugar) and energy as fuels (bagasse). 21
Bagasse has been used as a primary energy source for many years, however methodologies 22
for assessing the potential of other sources of biomass energy are still emerging in Fiji. Sugar 23
production in Fiji began in 1872 (Anonymous 2009) and since then it has played an important 24
role in the country’s economy and has been providing biomass (bagasse) energy for all four 25
sugar mills with surplus electricity production. However, a significant decrease of 44% in 26
sugarcane production occurred between the year 2000-2011 (Figure 1) which has effectively 27
lowered the biomass energy contribution to Fiji’s energy supply. Obviously further similar 28
decreases in sugarcane production will threaten the sugarcane bioenergy potential. 29
2 30
Figure 1: Sugarcane production details for the period of 22 years (Fiji Bureau of Statistics 31
2012). 32
The decrease in sugarcane production was mainly due to declines in the number of growers. 33
This is because farmers were evicted from their farms upon expiry of leases and as a result 34
their farms remained either idle or not fully utilised by the incoming farmers. Another factor 35
which contributes to the decline is the increase in farming costs due to increase in labour, 36
transportation and fertilizer prices, resulting in less profit to farmers (Khan 2011). However, 37
even with current production, the sugarcane industry has the potential to lead the renewable 38
energy contribution to Fiji’s overall energy balance. 39
Field survey indicated that the farmers are of the opinion that the current sugarcane payment 40
should be increased to FJ$100/tonne in order to initiate their interest again. However this is 41
not viable in the current sugar production scenario with the European Union sugar quota 42
ending in 2017. A payment of ??US$/tonne could only be possible if the sugar industry 43
strengthens its bioenergy programme and produces ethanol and electricity. Farmers are
44
interested in selling their sugarcane residue (cane tops) to mills for electricity generation. 45
Currently, hydro energy dominates the renewable energy sector in Fiji. In 2012, 822,804 46
MWh of electricity was generated (Dean 2012) as shown in Figure 2. Generation constituted 47
63.6% Hydro, 33% diesel and heavy fuel oil, 1% wind and 2.4% from Independent Power 48
Producers (IPPs) supported from bagasse produced by Fiji Sugar Corporation and wood chips 49
produced by Tropik Wood Industries Limited. In Fiji, energy is consumed by 5 important 50
sectors - transport, commercial, agriculture, industrial and residential. Figure 3 below depicts 51
the proportion of energy consumed by different sectors in Fiji out of total energy (41.7 PJ)
52 produced (Anonymous 2004). 53 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 0 5000 10000 15000 20000 25000 19 90 19 91 19 92 19 93 19 94 19 95 19 96 19 97 19 98 19 99 20 00 20 01 20 02 20 03 20 04 20 05 20 06 20 07 20 08 20 09 20 10 20 11 Su gar can e Pr o d u ction (000 t o n s) N o . o f Gr o we rs Year Number of Growers Sugarcane Production
3 54
55
Figure 2: Electricity generated in year 2012 (Dean 2012) 56
57
Figure 3: Energy consumption by sector (Nakavulevu 2013) 58
The total amount of fossil fuels imported in 2010 was 773 million litres from which 101.8
59
million litres was motor spirit afor transportation and small machine operations. Gas Diesel
60
oil had the highest import among other fuels (391 million litres) as this is also used for power
61
generation apart from agricultural and transportation usage. 62
Biofuels could play a vital role in Fiji’s transport sector via the use of biodiesel (and its blends 63
with diesel for diesel engine vehicles) and via ethanol (and its blends for petrol (gasoline) 64
engine vehicles). Coconut oil (CNO) is the only biofuel currently produced in Fiji. CNO can be 65
used directly in modified diesel engines or blends with petroleum diesel. Ethanol on the other 66
hand can be produced from sugarcane juice, molasses, cassava and sweet potatoes which are 67
Diesel and HFO 33.0% Biomass 2.4% Hydro 63.6% Wind 1.0% Renewable 67.0%
Total Electricity Generated 822,804 MWh
Industrial 14% Commercial 22% Residential 14% Transport 42% Agriculture 8%
4 readily available in Fiji. However, there are some reservations to the use of cassava and sweet 68
potatoes because of perceived food security issues. The use of molasses does not pose any 69
such threats. 70
The current fuel standards specify that diesel can contain 5% volume by volume maximum 71
biodiesel (Anonymous 2011) and petrol (gasoline) can contain 10% volume by volume ethanol 72
maximum (Anonymous 2007). Fiji currently does not have any policies for ethanol blending 73
in place. However, it is anticipated that policies will be in place in the near future. Table 1: 74
Annual crop production in Fiji, product energy content and residue energy content 75 Feedstock Annual average 10 Yr production yield (Ton/Ha) Product Energy Content (GJ/Ha) Residue energy content (GJ/Ha) Total Energy Content (GJ/Ha) Cassava 12.79 71.62 67.02 138.64 Sugarcane 45.68 242.11 492.43 734.54 Sweet Potatoes 3.75 20.63 8.25 28.88
Notes: Annual average yield was calculated using data from FAOSTAT for years 2003-2012. Product energy
76
content for crops and residues were obtained from (Hemstock and Hall 1995; Amoo-Gottfried and Hall 1999;
77
Rosillo-Calle et al. 2006a). Total energy content is a sum of Product energy content and Residue energy content.
78
Table 1 shows that sugarcane has the best prospects for ethanol production in Fiji. The 79
molasses produced, which is currently exported, could contribute to the production of 34 80
million litres of ethanol from which 25% could be used locally and the rest could be exported 81
for high returns (Nakavulevu 2013). 82
In order to assess the biomass energy potential in Fiji - including sugarcane bioenergy 83
(ethanol) potential - terrestrial above ground biomass production and usage was analysed for 84
the twenty years from years 1993-2012 using FAOSTAT database and local data. The specific 85
energy values were derived from earlier work (Hemstock and Hall 1995, 1997; Amoo-86
Gottfried and Hall 1999; Rosillo-Calle et al. 2006b). 87
Total biomass production, present utilization levels, available theoretical energy and potential 88
available biomass residues from agriculture and forestry were calculated. All biomass energy 89
flows were followed from their production at source, losses at harvest and all processes 90
through to end use. Finally, production categories were clustered into an end use group such 91
as food, fuel and residues. 92
2. Methodology 93
Data Source
94
Data on agricultural production (food), forestry removals and livestock production were 95
obtained from FAOSTAT, 2014 and were used to estimate the total theoretical biomass 96
available. Data on sugarcane, bagasse and molasses were obtained from Bureau of Statistics 97
and Fiji Sugar Corporation and compared with FAOSTAT. 98
Production data
5 Potentially recoverable residues from forestry and agricultural land use were estimated using 100
the technique suggested by (Rosillo-Calle et al. 2006b). The 20 year annual average
(1993-101
2012) crop productiondata were obtained from (FAOSTAT 2014) and were verified with other
102
sources (Khan 2009; Fiji Bureau of Statistics 2012) to provide a broader assessment. Crop 103
residues and by-products for which the data was not available were derived using technical 104
coefficients and conversion factors obtained from various sources (Hemstock and Hall 1995, 105
1997; Amoo-Gottfried and Hall 1999; Rosillo-Calle et al. 2006b; Jingura and Matengaifa 2008; 106
Okello et al. 2013; Shonhiwa 2013). 107
The annual dung production was formulated from the livestock population and calculated 108
using coefficients verified from various sources which take into consideration the production 109
of fresh dung per animal, the dry material content and seasonal factors (Amoo-Gottfried and 110
Hall 1999; Rosillo-Calle et al. 2006b; Mohammed et al. 2013). Livestock population data was 111
derived from FAOSTAT. 112
The agricultural crop and above ground biomass production only were considered by this 113
research - water surfaces were not included in this study. All roundwood volumes were 114
assumed to be solid with the conversion equivalence of 1m3 of solid roundwood = 1.3 ton
115
(Hemstock and Hall 1995; Rosillo-Calle et al. 2006b) 116
Molasses to ethanol conversion was as follows: 1 tonne of molasses (cane) feedstock can 117
produce 250 litres of ethanol, 1 tonne of cassava (fresh root) can produce 180 litres of 118
ethanol, 1 tonne of sugarcane can produce 70 litres of ethanol and 1 tonne of sweet potatoes 119
can produce 150 litres of ethanol (Kishore and Srinivas 2003; Silalertruksa and Gheewala 120
2010). 121
The following energy values (GJ/t air dry, 20% moisture content) assume direct combustion: 122
1 tonne fuelwood = 15 GJ; 1 tonne of stem wood = 15 GJ; 1 tonne forest and tree harvesting 123
residues = 15 GJ; 1 tonne charcoal = 31 GJ and conversion efficiency of fuelwood to charcoal 124
= 15 % by weight (Hemstock and Hall 1995; Rosillo-Calle et al. 2006b). The term “end use” 125
refers to the gross biomass energy devoted to specific use such as food, fuel etc. 126
3. Results 127
Annual Average Primary production established on forestry, agriculture and livestock 128
Agricultural production (annual crop and residues)
129
Excluding residues, the average annual crop production in Fiji from 1993-2012 was about 130
3,268,097 tons with a potential energy of 20.14 PJ. Previously, sugarcane, the economic 131
backbone of Fiji, was by far the most dominant crop in Fiji providing approximately 90% 132
(2.95Mt) of the total crop harvest in terms of mass and approximately 77% (15.6 PJ) in terms 133
of energy potential. 134
The annual average crop residue (1993-2012) theoretically available as a biomass energy 135
resource was 4,924,517 tons (potential energy of 38.65 PJ). Sugarcane was by far the most 136
6 dominant residue, despite declining production, providing 96% (4.7 Mt) of the total residue 137
harvested by mass and 94% (36.4 PJ) of the total energy potential. 138
However, comparing annual averages (from1999-2003 and 2008-2012) as presented in Table 139
2, the production of fruits, vegetables, maize, groundnuts, coconuts, roots and tubers and 140
coffee increased but that of sorghum, sugarcane, cocoa beans, ginger and rice decreased. 141
Sugarcane and rice production which has significant impact on energy contribution, 142
decreased by 39 % and 36 % respectively. 143
Agricultural feedstock production suitable for Ethanol
144
The 20 year annual average production for molasses was 131,004 tonnes; cassava 43,300 145
tonnes; and sweet potatoes 5,721 tonnes. The potential ethanol (annual average) that can be 146
theoretically produced from molasses is 32.75 million litres; 7.79 million litres can be 147
produced from cassava; and 0.85 million litres from sweet potatoes. Figure 4 depicts that 148
molasses is the best feedstock for ethanol production in Fiji. Cassava production recently 149
surpassed the production of molasses because there was continuous decline in production of 150
sugarcane as shown in Figure 1 however cassava is primarily a source of food in Fiji; whereas 151
molasses is a by-product of which 90% is exported. 152
153
Figure 4: Production of feedstock and potential ethanol production 154 5,000,000 10,000,000 15,000,000 20,000,000 25,000,000 30,000,000 35,000,000 40,000,000 45,000,000 50,000,000 20,000 40,000 60,000 80,000 100,000 120,000 140,000 160,000 180,000 200,000 Litr es o f E th an o l To n n es o f Fee d sto ck Year Molasses Cassava
sweet Potatoes Ethanol from Molasses Ethanol from Cassava Ethanol from Sweet Potatoes
7 Table 2: Five year annual average crop production, estimated crop residues and energy potential (1993-2012)
155
Crop Category
Annual Average Crop
Production (tonnes) Crop Energy (GJ)
Annual Average
Residue (tonnes) Residue Energy (GJ)
Total Energy Content (Crop + Residue) (GJ) 1999-2003 2008-2012 1999-2003 2008-2012 1999-2003 2008-2012 1999-2003 2008-2012 1999-2003 2008-2012 Fruits 35,761 37,992 114,436 121,576 71,522 75,985 936,943 995,401 1,051,379 1,116,977 Vegetables 16,889 18,399 54,044 58,877 16,889 18,399 101,333 110,395 155,377 169,273 Maize 720 815 10,581 11,978 1,008 1,141 13,100 14,829 23,681 26,807 Groundnuts 212 284 5,305 7,100 446 596 7,130 9,542 12,435 16,642 Coconuts 162,240 207,750 3,244,800 4,155,000 53,539 68,558 696,010 891,248 3,940,810 5,046,248 Roots and Tubers 43,919 67,970 241,555 373,833 17,568 27,188 96,622 149,533 338,176 523,366 Sorghum 30 25 438 370 42 35 542 459 980 829 Sugar cane (000) 3,291 1,979 17,442 10,490 5,265 3,167 40,545 24,386 57,987 34,877 Cocoa, beans 16 7 253 109 16 7 243 105 496 214 Coffee, green 14 16 108 125 14 16 202 233 310 358 Ginger 2,934 2,560 9,388 8,193 1,173 1,024 7,041 6,145 16,428 14,338 Rice 14,688 9,366 215,911 137,680 60,220 38,401 806,948 503,048 1,022,858 640,728
Production figures were obtained from FAOSTAT (FAOSTAT 2014) and waste factor and energy content values were obtained from Refs. (Hemstock and Hall 1995, 1997;
156
Amoo-Gottfried and Hall 1999; Rosillo-Calle et al. 2006b). Roots and Tubers consist of potatoes, sweet potatoes, cassava and yams.
8 0 10 20 30 40 50 60 70 80 90 100 Production Total = 83,134,357 GJ (100%) Harvest
Total Wood Cut 16,623,924 GJ (20%) Removals 9,963,899 GJ (12%) Dung 7,700,849 GJ (9%) All Industrial 9,174,870 GJ (11%) Losses 6,660,024 GJ (8%) Fuel Wood & Charcoal
789,029 GJ (1%) Dung < 831,344 GJ (<1%) Losses 6,869,506 GJ (8%) End Use (%) Sugarcane Food 15,663,768 GJ (19%)
Other Agri (Food) 4,486,062 GJ (5%) Other Agri (Residue) 2,248,882 GJ (3%)
Sugarcane Residue 36,410,872 GJ (44%) Bagasse 8,263,376 GJ (10%) Losses 30,396,377 GJ (37%)
Based on annual average (1993-2012) FAOSTAT (www.fao.org)
The scale is based on the total biomass harvested in agriculture and forestry. Figures in parenthesis indicate % total production
PJ = 1015 J = 106 GJ
Total may not add up due to rounding
All Industrial 9,174,870 GJ (11%)
Sugarcane Food 15,663,768 GJ
(19%)
Other Agri (Food) 4,486,062 GJ (5%) Bagasse 8,263,376 GJ (10%)
Fuel Wood & Charcoal 789,029 GJ (1%) Dung < 831,344 GJ (<1%)
158
Figure 5: Biomass energy flows in Fiji Annual average (1993-2012) 159
9 Available biomass end-use analysis
160
Agricultural crop resources
161
Total crop energy available is 58.6 PJ which is around 71 % of the total biomass production as 162
represented in figure 5. The total food production was 20.0 PJ and total available crop residue 163
was 38.6 PJ. It was noted that agriculture provides the highest source for biomass energy from 164
which 30.39 PJ is lost or unutilized. 165
Ethanol Potential
166
Total theoretical ethanol production potential (annual average) from molasses is around 167
32.75 million litres (figure 4) which is approximately 32% of the total petrol (gasoline) 168
imported in Fiji in year 2010. The average demand for ethanol in Fiji is around 8 million litres 169
(Nakavulevu 2013). Thus the surplus 24.75 million litres of ethanol can be exported. As per 170
the August 2014 Ethanol price of US$ 2.27 per gallon (Anonymous 2014a), Fiji has a potential 171
to generate approximately US14 million dollars by exporting surplus ethanol produced from 172
molasses. If sugar export becomes unattractive due to EU’s decision to cut subsidies and sugar 173
production is limited to local consumption only, it would leave 1,378,998 tonnes (Khan 2011) 174
of sugarcane which could potentially produce 96.5 million litres of ethanol which is 96.5% of 175
the motor spirit imported in 2010. The decline in sugarcane production from 2010 is 176
significant (44%) but it still does not pose any threat to the ethanol production. The E10 177
blending presently demands approximately 10 million litres of ethanol which the present by-178
product molasses production will be able to meet. However for future ethanol production for 179
the use in possible flex fuel vehicles or for the export market, an increase in cane production 180
should be encouraged to establish long term stability. 181
4. Discussion 182
Energy production 183
The potential energy theoretically available from agriculture, livestock and forestry is 83.13 184
PJ as shown in Figure 5. However, only around 47% of the theoretical available biomass 185
energy is used in the material form such as fuel, food timber etc. The other 53% is unused due 186
to losses during harvesting and processing, charcoal conversion and residue losses from 187
agriculture and forestry. A total of 8.98 PJ of biomass was directly used for energy as 188
presented in Figure 5. 189
Total sugarcane residue comprises of 44% of the total biomass energy theoretically available 190
from harvesting as shown in Figure 5, while wood comprises of 20%, dung 9% and other 191
agricultural crop residue comprises 3%. Sugarcane residues are by far the most encouraging 192
source of energy theoretically available with an energy content of 36 PJ which is 86% of the 193
total energy consumed in year 2004. 194
Total annual average ethanol production potential is 41.39 million litres of which 79% is from 195
molasses, 18.8% from cassava and 2.2% from sweet potatoes. The theoretical energy content 196
10 of the potential ethanol that can be produced in Fiji is 879.65 PJ (with a conversion factor 197
21.25 MJ/L (Harvey 2010; Dunlap 2014; Wikipedia 2014)). If current sugarcane production is
198
only used for local sugar production and ethanol production, a total of 129.25 million litres of 199
ethanol can be produced - this is roughly equivalent to Fiji’scurrent motor spirit use. 200
Biomass energy utilization and losses
201
In Fiji, sugarcane bagasse meets the energy requirement of 4 sugar mills and surplus for grid 202
electricity. An average of 886,628 tons of bagasse is used annually to generate 8.26 PJ of 203
energy. 8 biogas digesters operate using livestock dung for producing biogas for cooking and 204
lighting with the resulting digestate being used as a soil improver or food for milkfish 205
production. However, despite many successful projects, the technology is still not widely used 206
and only less than 1% (0.72 PJ) of available potential is utilized. 207
Total losses account for 53% of the total biomass theoretically available. The energy content 208
in the losses amounts to 40.5 PJ as shown in figure 5. Losses can be categorized as conversion 209
losses and unutilized residues. Conversion losses totalled 6.6 PJ which was lost during 210
roundwood harvesting and processing. Dung and agricultural residues are unutilized biomass 211
resulting inlossed of 6.86 PJ and 30.89 PJ respectively. This energy is equivalent to 90% of the 212
energy consumed in 2004. Currently the sugarcane residue (excluding bagasse) is either left 213
in situ or burnt in the field which only creates pollution and wastes material which could 214
otherwise be used with bagasse. 215
Opportunity for improved utilization 216
Total annual production of agricultural residues and dung per capita was 44 GJ and 8.8 GJ 217
respectively. Only 10.79% (0.83 PJ) dung and 21% (8.2 PJ) agricultural residue was utilized 218
which is very low. More could be utilised if communities and household understood the 219
benefits of using biogas digesters. 220
The recoverable forestry residue theoretically available is 6.66 PJ which is equivalent to 444 221
metric tons of wood. The recoverable forestry residue and agricultural residue together forms 222
a major potential energy source but it is common practice to burn these residues on site to 223
clear the area. 224
Sugarcane residues (leaves and cane tops) hold a significant amount of energy which could 225
also be used with bagasse in the sugar mills (cogeneration) to generate electricity and export 226
to national grid. This will reduce the use of fossil fuels and its emissions. 227
Sugarcane molasses also holds a significant amount of energy if transformed into ethanol. 228
Currently 90% of the by-product which is exported which could be used to produce ethanol 229
and blended with imported gasoline (E10), thus reducing gasoline importss by around 10%, 230
leading to substantial savings. 231
5. Conclusion 232
11 This shows that the largest portion of biomass energy is from agricultural crops and the largest 233
use of biomass in Fiji is as food source (sugar), followed by industrial wood and bagasse. It has 234
also been emphasized that ethanol has a bright future in Fiji and sugarcane molasses can 235
easily meet the local (E10) demands. 236
Appropriate planning and support at national and local levels (including solving land tenure 237
issues) could lead to biomass energy being the most important renewable for Fiji’s energy 238
sector. The utilization of sugarcane residues by sugar mills will enhance electricity generation 239
which can be exported to grid. This will contribute to a reduction in petroleum usage and 240
carbon emissions. 241
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