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RD—Rural Development
Biosystems Engineering (2002) 81 (3), 347–354 doi:10.1006/bioe.2001.0021, available online at http://www.idealibrary.com on RD}Rural Development
The Energy Balance of Sunflower Production for Biodiesel in Greece L. Kallivroussis; A. Natsis; G. Papadakis Engineering Department, Agricultural University of Athens, 75, Iera Odos street, 118 55 Athens, Greece; e-mail of corresponding author: [email protected] (Received 24 November 2000; received in revised form 4 December 2001)
One requirement for an oilseed crop to be considered for biodiesel production is that it provides a positive energy return compared with the energy used to produce the fuel. This in part depends on the energy input for the oilseed production. This paper studies the energy balance between the input and the output per unit area for a sunflower crop grown in Greece, in order to evaluate it as a source for biodiesel production. Calculation of the energy input was based on the operations and various inputs as used by farmers in Evros in the north of Greece. To estimate the energy required to produce the sunflower seeds, to manufacture fertilizers and pesticides and to produce and use the farm machinery, appropriate energy equivalents from the literature were taken into account. The energy outputs were estimated by simply multiplying the yield of sunflower seeds and stems by their corresponding energy value. The total energy input was calculated to be 1049 GJ ha1, with fertilizers being the major inputs. Assuming a typical sunflower seed yield of 1800 kg ha1, as obtained under normal conditions on fertile drylands, and taking into account the energy value of the seed, the net energy value was estimated to be 3687 GJ ha1 and the ratio of energy outputs to energy inputs approximately 45:1. # 2002 Silsoe Research Institute. Published by Elsevier Science Ltd. All rights reserved
1. Introduction The interest in many vegetable oils as diesel fuel substitutes is increasing and various oil containing crops are grown for this purpose. Vegetable-oils, after having been processed, can be used directly, blended in mixtures with diesel fuel, or inter-esterified and used in existing compression ignition engines. The commercial success of such fuels depends on their physical and chemical characteristics, their economic competitiveness compared with petroleum-based fuels and on the achievement of a positive energy balance which in part depends on the energy input required to produce the oilseeds. Sunflower is one of the leading oilseed crops cultivated for the production of oil mainly used for human consumption. It has also been considered as an important crop for biodiesel production, particularly in southern European countries. In Greece, sunflower is mainly grown in Evros in the northern part of the country, where more than 70% of the sunflower cultivated area is located. It is usually cultivated on non-irrigated clay loam soils in a rotation with winter cereals. At present the total cultivated area is about 1537-5110/02/$35.00/0
26 000 ha, with a national statistical average yield of approximately 1500 kg ha1. The area grown has reduced since it is not economically competitive compared with other traditional crops, wheat and cotton. The increased interest for utilizing oil seeds for biodiesel production and the anticipated unfavourable economic conditions for winter cereals may encourage sunflower cultivation in the near future. This paper aims to study the energy input and output per hectare for the production of sunflower in Evros and to evaluate the crop as a source of biodiesel. It also identifies operations where energy savings could be realized by changing applied practices in order to increase the energy ratio.
2. Analytical approach The size of the farm holdings in the region is relatively small, with an average of about 70 ha, which is higher than the country average of 40 ha. The size of field considered in the analysis was 20 ha, which is representative for the region. The selection of the set of machinery for the production of the sunflower crop was 347
# 2002 Silsoe Research Institute. Published by Elsevier Science Ltd. All rights reserved
348
L. KALLIVROUSSIS ET AL.
Notation operation depth, m operation width, m total mass of tractor and implement, kg work productivity, m2 s1 energy per unit land area, J m2 field efficiency coefficient for the power losses through transmissions to PTO and draught bar g acceleration due to gravity, 981 m s2 G fuel consumption, g ha1 k specific draught for all operations but the ploughing, N m1
a b B C E Ef f
based on data obtained from an onsite survey. A tractor of 70 kW and all the appropriate implements were assumed. The distance from the farmyard to the field was 5 km, while from the field to the nearest storage facility was 10 km, representing typical average distances for the region. The number of operations involved in the sunflower production, and their energy requirements influence the final energy balance. The production information for the sunflower crop was gathered by means of interviews with farmers and a typical production method was determined from these data. Irrigation was not considered, since the annual rainfall can assure a satisfactory yield. In addition, since dryland cultivation reduces the growing season and increases natural drying capability, drying is not taken into consideration. The field operations and implements, considered in the analysis, are listed in Table 1. In Table 2 are shown the values for the several implement parameters and coefficients used in the calculations as explained in Appendix A.
k0 specific draught for ploughing, N m2 Mr motion resistance, N NPTO equivalent PTO power, W P power to move the tractor and implement, W q specific fuel consumption, g MJ1 R draught force for all implements but the plough, N Rp draught force for ploughing, N Rr coefficient of rolling resistance u operation speed, m s1
2.1. Estimation of energy inputs The energy required for the production of sunflower is classified as either direct or indirect. Direct energy inputs include those quantities that are consumed during the production of the crop of sunflower seeds. The actual energy contained in diesel fuel, fertilizers and chemicals is characterized as direct energy inputs. Indirect energies are those required for manufacturing and maintenance of direct inputs and durable items, such as tractors and machinery. Indirect energy inputs are considered: the energy used in producing the steel from which machinery and implements are fabricated, the energy required to refine crude oil to diesel fuel, etc. The appropriate energy equivalents to estimate the indirect and direct energy inputs were provided by various sources. 2.1.1. Machinery The total energy associated with a particular farm machine consists of the energy for production, the
Table 1 Field operations}implements Field operation
Implement
Ploughing, at a depth of 26–30 cm Disc harrowing Fertilizer application (ammonium phosphate, N=60 kg ha1, P2O5=30 kg ha1) Applying pesticide (treflan, 25 kg ha1) Cultivating - pesticide incorporation Sowing seed at 35 kg ha1 Hoeing for weed control Hoeing manually for weed control Harvesting
Plough, 3 furrows of 35 cm width Disc harrow, 30 m width Fertilizer distributor, 500 kg capacity Sprayer, 500 l capacity Field cultivator, 30 m width Row planter, four rows Row crop cultivator, four rows Combine harvester, four row width
349
SUNFLOWER PRODUCTION FOR BIODIESEL PRODUCTION
Table 2 Implement parameters and coefficient values for several operations Operation Ploughing Disc harrowing Fertilization Spraying Cultivating-pesticide incorporation Sowing Hoeing Harvesting Transport Moving to and from field
Width, m 105 3 8 12 6 3 3 3
energy for repairs and maintenance and the energy for delivering to the farm. The energy for production includes the energy embodied in the materials of which a machine is made, and the energy used for the fabrication of a machine. The energy for repairs and maintenance includes the energy, both embodied and fabrication, contained in the repair parts and materials needed to maintain a machine throughout its useful life. The energy for transport includes the energy for distributing a machine from the factory to the consumer. The embodied energy for manufacturing was assumed to be 8638 MJ kg1 (Deluchi, 1991); for repairs and maintenance, 055 times the energy for manufacturing (Fluck, 1985); and 88 MJ kg1 (Lower et al., 1977) for delivery; giving a total energy cost of 1427 MJ kg1. This, together with the mass and life of each machine, was used to calculate the energy coefficients (Table 3). 2.1.2. Fertilizers The energy embedded in fertilizers is composed of the energy required to extract the raw material, to transport it, to manufacture the fertilizer and to transport and distribute the final product. For converting N and P2O5 rates to energy costs, the coefficients 742 MJ kg1
Speed, km h1
Field, efficiency
5 6 8 6 6 6 6 5 15 15
Work rate, ha h1
07 07 06 06 07 06 06 05
037 126 384 432 126 111 093 133 500 043
(Hoeft & Siemens, 1975; Sherft, 1975) and 143 MJ kg1 (Lorenz & Moris, 1995), were used, respectively. From the quantities of fertilizers applied (Table 1), the associated energy cost was calculated. 2.1.3. Seeds To determine the energy value of seed crops, several methods can be applied (Heichel, 1980). The most accurate would be to calculate the fossil energy budget for producing sunflower seeds; however, the required data are not available. Therefore, the estimation of energy costs embedded in seed was based on a seed energy value of 263 MJ kg1 (McIntosh et al., 1984), and the sowing rate (Table 1). Overall, the energy investment in seed was assumed to be twice the seed energy value (Pimental et al., 1974). 2.1.4. Pesticides The energy consumption related to the use of pesticides includes the energy inputs required for production, formulation, packaging and transportation. The energy consumed for the production of treflan was 1472 MJ kg1 active ingredient (Pimental, 1980). The energy for formulation, packaging and transportation
Table 3 Energy coefficients of farm machinery (Tsatsarelis, 1991) Item
Mass, kg
Life, h
Tractor 70 kW Plough Disc harrow Field cultivator Row crop planter Sprayer Fertilizer distributor Row crop cultivator Combine harvester Trailer
4450 600 400 300 470 250 300 300 12 500 1500
15 000 2500 2500 2500 2000 1500 2500 2500 3000 15 000
Energy coefficient, MJ h1 423 342 228 171 335 238 171 171 5946 143
350
L. KALLIVROUSSIS ET AL.
Table 4 Data for estimating energy outputs Yield, kg ha1
Item Seeds Oil Meal Stems
Energy value 1
1800 610 1190 4170 (20% m.c.)
263 MJ kg (McIntosh et al., 1984) 394 MJ kg1 (Pryde, 1981) 196 MJ kg1 (Rossell & Pritchard, 1991) 143 MJ kg1 dry matter (Apostolakis et al., 1987)
Note: m.c., water content, wet basis.
was 242 MJ kg1 active ingredient (Pimental, 1980) giving a total of 1714 MJ kg1 active ingredient. 2.1.5. Labour The energy costs of labour were estimated by taking into consideration the labour requirements of each operation and a coefficient which converts hours of labour into energy costs (Goering & Daugherty, 1981). It was assumed that a farm worker consumes 228 MJ h1. The inverse values of work rate (h ha1 from Table 2) were multiplied by 228 MJ h1 to obtain the energy cost of labour in ha h1. 2.1.6. Transport and moving to and from field The distance to transport fertilizers to the field was estimated to be 5 km and to transport the seeds from the field to the storage facility, 10 km. The tractor speed (15 km h1), the quantity of fertilizers and seed, and the mass of the machinery involved (tractor and trailer) were also taken into consideration. Transport between the farmyard and the field was based on a return distance of 10 km and on seven movements. The tractor speed (15 km h1) and the mass of the tractor and implements were also considered (see Appendix A). 2.1.7. Fuel The fuel requirements for sunflower production were estimated by taking into consideration the cultural
practices, the PTO power of the tractor needed to perform the operation and an average fuel energy density of 556 g MJ1. To estimate the energy costs for diesel fuel a coefficient of 556 MJ kg1 was used (Fluck, 1985). This fuel coefficient combines the energy content of the diesel fuel (about 81% of the total) and the energy consumed to produce and transport the fuel to the service station (about 19% of the total) (Cervinka, 1980). The method of calculating the diesel fuel requirements is given in Appendix A.
2.2. Estimation of energy outputs The energy outputs, the sunflower seed crop and stems were estimated by simply multiplying the quantities by their corresponding energy value. The seed yield was assumed to be 1800 kg ha1, which can be obtained under normal climatic conditions on fertile drylands in Northern Greece. The quantity of sunflower stems, which remains in the field as residue, is about 4170 kg ha1 (Gemtos, 1991). The energy output of the sunflower seed crop is further apportioned between the oil and the meal, based on the relative amounts of each obtained by expeller extraction. Sunflower seeds contain typically 40–42% oil (Hofman et al., 1980). Assuming a typical extraction
Table 5 Labour requirements Operation Ploughing Disc harrowing Fertilization Spraying Cultivating-pesticide incorporation Sowing Hoeing Harvesting Transport Moving to and from field Total
Work rate, ha h1
Labour, h ha1
Human energy inputs, MJ ha1
037 126 384 432 126 111 093 133 500 043
27 08 05 07 08 15 59 13 08 24
62 18 11 16 18 34 135 30 18 55
174
397
351
SUNFLOWER PRODUCTION FOR BIODIESEL PRODUCTION
Table 6 The equivalent PTO power, the power required for motion, the energy and fuel requirement per operation Operation
Equivalent PTO power, (NPTO), kW
Ploughing Disc harrowing Fertilization Spraying Cultivating-pesticide incorporation Sowing Hoeing Harvesting Transport Moving to and from field Total
Power to move tractor (NPTO þ P)/f, kW and implement (P), kW
Energy per Fuel unit land area, consumption, (E), MJ ha1 (G), kg ha1
265 134 05 06 69 64 98 662
35 40 52 38 39 40 39 85 349 121
389 241 79 65 187 175 204 747 349 121
3754 689 74 55 533 619 679 3584 535 1015
209 38 04 03 30 34 38 199 29 56
1303
838
2557
11537
640
Note: f, coefficient for power losses.
rate of 80%, a 1000 kg of seeds, yield approximately 340 kg of oil and 660 kg of meal (FAO & EBRD, 1999). Depending on the use of sunflower meal, various energy values can be used. Sunflower press extracted meal is usually used as an animal feed, in particular for ruminants with similar results to soya bean meal, when substituted on an equal protein basis. The energy value of the sunflower meal is less than that of soya bean meal because of the added fibre content of hulls. The metabolizable energy for ruminants is reported to be 95 MJ kg1 compared to 123 MJ kg1 for soya bean meal (Rossell & Pritchard, 1991). The data for the energy output calculations is presented in Table 4.
3. Results and discussion Work rates and labour requirements were estimated for the different field operations, (Table 5). In Table 6
are shown the equivalent PTO power, the power for forward motion, the energy and fuel consumption per operation (calculated by Eqns (A.4), (A.5), (A.7) and (A.8), respectively in the Appendix A). Fuel energy density of 556 g MJ1 was assumed. Hofman et al. (1979) calculated the energy consumption for sunflower production in North Dakota, United States to be 682 GJ ha1, McIntosh et al. (1984) calculated the energy inputs for dryland sunflower production in North and South Idaho, United States at 122 and 105 GJ ha1, respectively. The large differences are due to different cultural practices. The energy requirements for sunflower production by operation are listed in Table 7. The energy costs appearing in Table 7 were calculated after multiplying the energy coefficients of Table 3 by the hours that each item of equipment or tractor was used for sunflower production (Table 5). The total direct and indirect energy consumed was calculated to be 1049 GJ ha1. Fertilization is the input with the largest energy input
Table 7 Distribution of energy consumption by operation Energy consumption, MJ ha1
Operation Machinery
Tractor
Labour
Fuel
Primary tillage Secondary tillage Fertilization Weed control Sowing Hoeing Harvesting Transport
92 6 4 19 37 16 793 12
113 34 11 43 47 39 0 134
6 2 1 3 3 14 3 7
1162 420 22 17 189 211 1106 473
Total
979
421
39
3558
Total energy Material
4881 429 184
5494
MJ ha1
%
1373 420 4919 511 460 280 1902 626
131 40 469 49 44 27 181 60
10 491
100
352
L. KALLIVROUSSIS ET AL.
Table 8 Distribution of energy consumption by production input Quantities used, kg ha1
Production input Seed Fuel Nitrogen Phosphorus Herbicides Indirect machinery Labour
Energy content, MJ kg1
35 640 600 300 25
263 556 742 143 1714 228
Total
Table 9 Energy outputs from sunflower crop Energy, MJ ha1 Item
Meal as fuel
Meal as animal feed
Seeds Oil Meal Stems
47 358 24 034 23 324 47 705
24 034 11 305 47 705
Total
95 063
83 044
Energy, MJ ha1
%
184 3558 4452 429 429 1400 39
18 339 424 41 41 133 04
10 491
1000
estimated to be 830 GJ ha1 and the energy ratio for the seed yield is approximately 34:1 (Table 9). This analysis shows that efforts to improve the overall energetic efficiency should be focused on fertilizer usage and fuel consumption. However, significant reduction of fertilizers is not considered feasible as it would decrease production yields. A saving in diesel fuel by improving tractor operating performance may be possible.
4. Conclusions
(47% of total) because of the large quantities of nitrogen fertilizers. Harvesting was about 18%, and primary tillage 13%. Transport of harvested crop seeds and labour to the field required about 6% of the total energy inputs. The other operations require only a small portion of the total energy inputs with hoeing the least. Table 8 shows the energy requirements by production input. Nitrogen fertilizer accounts for about 42% of the energy used. In addition, more than 90% of the energy sequestered in applying fertilizers is from nitrogen due to the large energy requirements for producing it. Fuel for the tractor and combine is the second largest energy inputs, followed by the energy embodied in the machinery which is used to perform the field operations. Labour is an insignificant input. The total energy outputs were 951 GJ ha1 of which the seed was over half (Table 9). The energy balance assumes that the pressure extracted meal is used as a solid fuel. The ratio of energy-out to energy-in, for a seed yield of 1800 kg ha1, is about 45:1. This result is in good agreement with that of Bona et al. (1999) who showed that under Italian conditions, an energy balance of 5:1 was obtained with low energy input cropping techniques. Assuming that the sunflower meal is used as a feed for ruminants the total energy outputs were
Sunflower seed is a good store of biomass, and a crop considered for biodiesel production in Greece. The energy inputs and outputs were estimated to be 1049 and 474 GJ ha1 (stems not included), respectively, which translates into an energy ratio of 45:1. The possibilities to reduce the energy inputs are very limited.
Acknowledgements The authors wish to thank Mr V. Melidis from N.AG.RE.F., S.G.E. Orestiados, for his help in collecting local data.
References Apostolakis M; Kyritsis S; Souter X (1987). The biomass energy potential of agricultural and forest wood wastes. Publication of the Greek Productivity Centre, Athens (in Greek) Bona S; Mosca G; Vamerali T (1999). Oil crops for biodiesel production in Italy. Renewable Energy, 16, 1053–1056 Cervinka V (1980). Fuel and energy efficiency. In: Handbook of Energy Utilization in Agriculture (Pimental D, ed.), pp. 15–21. CRC Press, Boca Raton, FL Deluchi M A (1991). Emissions of greenhouse gases from the use of transportation fuels and electricity. ANL/ESD/TM-22,
353
SUNFLOWER PRODUCTION FOR BIODIESEL PRODUCTION
Center for Transportation Research, Agronne National Laboratory, Agronne, IL, US Department of Energy, November FAO & EBRD (1999). Sunflower}Crude and Refined oils. Agribusiness Handbooks, Vol. 2. Food and Agriculture Organisation of the United Nations & European Bank for Reconstruction and Development Fluck R C (1985). Energy sequestered in repairs and maintenance of agricultural machinery. Transactions of the ASAE, 28, 738–744 Gemtos Th (1991). The production of residues in Greece and the possibility to use them. Yearbook. Technological Educational Institution of Piraeus, Greece (in Greek) Goering C E; Daugherty M J (1981). Energy inputs and outputs of eleven vegetable oil fuels. ASAE Paper No 813586, American Society of Agricultural Engineers, St. Joseph, MI Heichel G H (1980). Assessing the fossil energy costs of propagating agricultural crops. In: Handbook of Energy Utilization in Agriculture (Pimental D, ed.), pp. 27–33. CRC Press, Boca Raton, FL Hoeft R C; Siemens J C (1975). Energy consumptions and return from adding nitrogen to corn. Illinois Research, 17(1), 10–11 Hofman V; Dinusson W F; Zimmerman D; Helgeson D L; Fannins C (1979). Sunflower oil as a fuel alternative. North Dakota Extension Service Bulletin 13, EENG-5 Hofman V; Dinusson W F; Zimmerman D; Helgeson D L; Fannins C (1980). Sunflower oil as a fuel alternative. North Dakota State University, Cooperative Extension Service, Circular AE-694 Lorenz D; Moris D (1995). How much energy does it take to make a gallon of ethanol? Publication of the Institute for Local-Self Reliance (ILSR), Washington DC, 8pp Lower Jr O J; Benock G; Gay N; Smith E M; Burgess S; Wells L G; Bridges T G; Springate L; Bling J A; Brattord G; Debertin D (1977). Production of beef with minimum grain and fossil energy inputs. BEEF, Vols. 1, II, III. Report National Science Foundation McIntosh C S; Smith S M; Withers R V (1984). Energy balance of on-farm production and extraction of vegetable oil for fuel in the United States Inland Northwest. Energy in Agriculture, 3, 155–166 Pimental D (1980). Energy inputs for the production, formulation, packaging and transport of various pesticides. In: Handbook of Energy Utilization in Agriculture (Pimental D, ed.), pp 35–42 CRC Press, Boca Raton, FL Pimental D; Lynn W R; MacReynolds W K; Hewes M T; Rush S (1974). Proceedings Workshop on Research Methodologies for Studies Energy, Food, Man and Environment, Phase I. Cornell University, Ithaca, NY. Pryde E H (1981). Vegetable oils vs. diesel fuel, chemistry and availability of vegetable oils. Regional Proceedings of Workshop on Alcohol and Vegetable Oil as Alternative Fuels, USDA, Washington DC Rossell J B; Pritchard J L R (1991). Analysis of Oilseeds Seeds, Fats and Fatty Foods. Elsevier Applied Science, London and New York Sherft J L (1975). Energy use and economics in the manufacture of fertilizers. In: Energy, Agriculture and Waste Management (Jewell J, ed.). Proceedings of the
1975 Cornell Agricultural Waste Management Conference, Ann Arbor Tsatsarelis C A (1991). Energy requirements for cotton production in central Greece. Journal of Agricultural Engineering Research, 50, 239–246 Tsatsarelis C A (2000). Principles of Soil Mechanical Cultivation and Sowing, 510pp Giahoudi-Giapouli Publishers, Thessaloniki, Greece (in Greek)
Appendix A: Calculation equations A.1. Work rate The work rate C, for each operation was calculated by C ¼ buEf
ðA1Þ
where b is the total operation width, u is the operation speed and Ef is the field efficiency of the implement considered. A.2. Draught force The draught force Rp for ploughing was calculated by Rp ¼ k0 ab
ðA2Þ
where k0 is the specific draught of the soil and a is the operation depth. A value of 699 kN m2 was used for k0 (Tsatsarelis, 2000). The draught force R for all implements except the plough, was calculated by R ¼ kb
ðA3Þ
where k is the specific draught, per unit of implement width. Typical values for k depending on the implement used were taken from Tsatsarelis (2000). A.3. Equivalent power at the power take-off The required equivalent PTO power NPTO per operation was calculated by NPTO ¼ Ru
ðA4Þ
A.4. Motive power The required power P to move the tractor and implement was estimated by P ¼ Mr u
ðA5Þ
where Mr is the motion resistance calculated by Mr ¼ gBRr
ðA6Þ 2
where g is the acceleration due to gravity (981 m s ), B the total mass of tractor and implement or trailer, and Rr the rolling resistance coefficient of 005 (Tsatsarelis, 2000).
354
L. KALLIVROUSSIS ET AL.
A.5. Energy The energy per unit land area E required per operation was calculated by NPTO þ P E¼ ðA7Þ fC where f is a coefficient to account for the power losses from the engine transmission to PTO and drawbar. Typical values for f
were used, depending on the operation considered, ranging from 06 to 08 (Tsatsarelis, 2000). A.6. Fuel The fuel consumption G per operation was calculated by G ¼ Eq where q is the specific fuel consumption.
ðA8Þ
The Energy Balance of Sunflower Production for Biodiesel in Greece L. Kallivroussis; A. Natsis; G. Papadakis Engineering Department, Agricultural University of Athens, 75, Iera Odos street, 118 55 Athens, Greece; e-mail of corresponding author: [email protected] (Received 24 November 2000; received in revised form 4 December 2001)
One requirement for an oilseed crop to be considered for biodiesel production is that it provides a positive energy return compared with the energy used to produce the fuel. This in part depends on the energy input for the oilseed production. This paper studies the energy balance between the input and the output per unit area for a sunflower crop grown in Greece, in order to evaluate it as a source for biodiesel production. Calculation of the energy input was based on the operations and various inputs as used by farmers in Evros in the north of Greece. To estimate the energy required to produce the sunflower seeds, to manufacture fertilizers and pesticides and to produce and use the farm machinery, appropriate energy equivalents from the literature were taken into account. The energy outputs were estimated by simply multiplying the yield of sunflower seeds and stems by their corresponding energy value. The total energy input was calculated to be 1049 GJ ha1, with fertilizers being the major inputs. Assuming a typical sunflower seed yield of 1800 kg ha1, as obtained under normal conditions on fertile drylands, and taking into account the energy value of the seed, the net energy value was estimated to be 3687 GJ ha1 and the ratio of energy outputs to energy inputs approximately 45:1. # 2002 Silsoe Research Institute. Published by Elsevier Science Ltd. All rights reserved
1. Introduction The interest in many vegetable oils as diesel fuel substitutes is increasing and various oil containing crops are grown for this purpose. Vegetable-oils, after having been processed, can be used directly, blended in mixtures with diesel fuel, or inter-esterified and used in existing compression ignition engines. The commercial success of such fuels depends on their physical and chemical characteristics, their economic competitiveness compared with petroleum-based fuels and on the achievement of a positive energy balance which in part depends on the energy input required to produce the oilseeds. Sunflower is one of the leading oilseed crops cultivated for the production of oil mainly used for human consumption. It has also been considered as an important crop for biodiesel production, particularly in southern European countries. In Greece, sunflower is mainly grown in Evros in the northern part of the country, where more than 70% of the sunflower cultivated area is located. It is usually cultivated on non-irrigated clay loam soils in a rotation with winter cereals. At present the total cultivated area is about 1537-5110/02/$35.00/0
26 000 ha, with a national statistical average yield of approximately 1500 kg ha1. The area grown has reduced since it is not economically competitive compared with other traditional crops, wheat and cotton. The increased interest for utilizing oil seeds for biodiesel production and the anticipated unfavourable economic conditions for winter cereals may encourage sunflower cultivation in the near future. This paper aims to study the energy input and output per hectare for the production of sunflower in Evros and to evaluate the crop as a source of biodiesel. It also identifies operations where energy savings could be realized by changing applied practices in order to increase the energy ratio.
2. Analytical approach The size of the farm holdings in the region is relatively small, with an average of about 70 ha, which is higher than the country average of 40 ha. The size of field considered in the analysis was 20 ha, which is representative for the region. The selection of the set of machinery for the production of the sunflower crop was 347
# 2002 Silsoe Research Institute. Published by Elsevier Science Ltd. All rights reserved
348
L. KALLIVROUSSIS ET AL.
Notation operation depth, m operation width, m total mass of tractor and implement, kg work productivity, m2 s1 energy per unit land area, J m2 field efficiency coefficient for the power losses through transmissions to PTO and draught bar g acceleration due to gravity, 981 m s2 G fuel consumption, g ha1 k specific draught for all operations but the ploughing, N m1
a b B C E Ef f
based on data obtained from an onsite survey. A tractor of 70 kW and all the appropriate implements were assumed. The distance from the farmyard to the field was 5 km, while from the field to the nearest storage facility was 10 km, representing typical average distances for the region. The number of operations involved in the sunflower production, and their energy requirements influence the final energy balance. The production information for the sunflower crop was gathered by means of interviews with farmers and a typical production method was determined from these data. Irrigation was not considered, since the annual rainfall can assure a satisfactory yield. In addition, since dryland cultivation reduces the growing season and increases natural drying capability, drying is not taken into consideration. The field operations and implements, considered in the analysis, are listed in Table 1. In Table 2 are shown the values for the several implement parameters and coefficients used in the calculations as explained in Appendix A.
k0 specific draught for ploughing, N m2 Mr motion resistance, N NPTO equivalent PTO power, W P power to move the tractor and implement, W q specific fuel consumption, g MJ1 R draught force for all implements but the plough, N Rp draught force for ploughing, N Rr coefficient of rolling resistance u operation speed, m s1
2.1. Estimation of energy inputs The energy required for the production of sunflower is classified as either direct or indirect. Direct energy inputs include those quantities that are consumed during the production of the crop of sunflower seeds. The actual energy contained in diesel fuel, fertilizers and chemicals is characterized as direct energy inputs. Indirect energies are those required for manufacturing and maintenance of direct inputs and durable items, such as tractors and machinery. Indirect energy inputs are considered: the energy used in producing the steel from which machinery and implements are fabricated, the energy required to refine crude oil to diesel fuel, etc. The appropriate energy equivalents to estimate the indirect and direct energy inputs were provided by various sources. 2.1.1. Machinery The total energy associated with a particular farm machine consists of the energy for production, the
Table 1 Field operations}implements Field operation
Implement
Ploughing, at a depth of 26–30 cm Disc harrowing Fertilizer application (ammonium phosphate, N=60 kg ha1, P2O5=30 kg ha1) Applying pesticide (treflan, 25 kg ha1) Cultivating - pesticide incorporation Sowing seed at 35 kg ha1 Hoeing for weed control Hoeing manually for weed control Harvesting
Plough, 3 furrows of 35 cm width Disc harrow, 30 m width Fertilizer distributor, 500 kg capacity Sprayer, 500 l capacity Field cultivator, 30 m width Row planter, four rows Row crop cultivator, four rows Combine harvester, four row width
349
SUNFLOWER PRODUCTION FOR BIODIESEL PRODUCTION
Table 2 Implement parameters and coefficient values for several operations Operation Ploughing Disc harrowing Fertilization Spraying Cultivating-pesticide incorporation Sowing Hoeing Harvesting Transport Moving to and from field
Width, m 105 3 8 12 6 3 3 3
energy for repairs and maintenance and the energy for delivering to the farm. The energy for production includes the energy embodied in the materials of which a machine is made, and the energy used for the fabrication of a machine. The energy for repairs and maintenance includes the energy, both embodied and fabrication, contained in the repair parts and materials needed to maintain a machine throughout its useful life. The energy for transport includes the energy for distributing a machine from the factory to the consumer. The embodied energy for manufacturing was assumed to be 8638 MJ kg1 (Deluchi, 1991); for repairs and maintenance, 055 times the energy for manufacturing (Fluck, 1985); and 88 MJ kg1 (Lower et al., 1977) for delivery; giving a total energy cost of 1427 MJ kg1. This, together with the mass and life of each machine, was used to calculate the energy coefficients (Table 3). 2.1.2. Fertilizers The energy embedded in fertilizers is composed of the energy required to extract the raw material, to transport it, to manufacture the fertilizer and to transport and distribute the final product. For converting N and P2O5 rates to energy costs, the coefficients 742 MJ kg1
Speed, km h1
Field, efficiency
5 6 8 6 6 6 6 5 15 15
Work rate, ha h1
07 07 06 06 07 06 06 05
037 126 384 432 126 111 093 133 500 043
(Hoeft & Siemens, 1975; Sherft, 1975) and 143 MJ kg1 (Lorenz & Moris, 1995), were used, respectively. From the quantities of fertilizers applied (Table 1), the associated energy cost was calculated. 2.1.3. Seeds To determine the energy value of seed crops, several methods can be applied (Heichel, 1980). The most accurate would be to calculate the fossil energy budget for producing sunflower seeds; however, the required data are not available. Therefore, the estimation of energy costs embedded in seed was based on a seed energy value of 263 MJ kg1 (McIntosh et al., 1984), and the sowing rate (Table 1). Overall, the energy investment in seed was assumed to be twice the seed energy value (Pimental et al., 1974). 2.1.4. Pesticides The energy consumption related to the use of pesticides includes the energy inputs required for production, formulation, packaging and transportation. The energy consumed for the production of treflan was 1472 MJ kg1 active ingredient (Pimental, 1980). The energy for formulation, packaging and transportation
Table 3 Energy coefficients of farm machinery (Tsatsarelis, 1991) Item
Mass, kg
Life, h
Tractor 70 kW Plough Disc harrow Field cultivator Row crop planter Sprayer Fertilizer distributor Row crop cultivator Combine harvester Trailer
4450 600 400 300 470 250 300 300 12 500 1500
15 000 2500 2500 2500 2000 1500 2500 2500 3000 15 000
Energy coefficient, MJ h1 423 342 228 171 335 238 171 171 5946 143
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L. KALLIVROUSSIS ET AL.
Table 4 Data for estimating energy outputs Yield, kg ha1
Item Seeds Oil Meal Stems
Energy value 1
1800 610 1190 4170 (20% m.c.)
263 MJ kg (McIntosh et al., 1984) 394 MJ kg1 (Pryde, 1981) 196 MJ kg1 (Rossell & Pritchard, 1991) 143 MJ kg1 dry matter (Apostolakis et al., 1987)
Note: m.c., water content, wet basis.
was 242 MJ kg1 active ingredient (Pimental, 1980) giving a total of 1714 MJ kg1 active ingredient. 2.1.5. Labour The energy costs of labour were estimated by taking into consideration the labour requirements of each operation and a coefficient which converts hours of labour into energy costs (Goering & Daugherty, 1981). It was assumed that a farm worker consumes 228 MJ h1. The inverse values of work rate (h ha1 from Table 2) were multiplied by 228 MJ h1 to obtain the energy cost of labour in ha h1. 2.1.6. Transport and moving to and from field The distance to transport fertilizers to the field was estimated to be 5 km and to transport the seeds from the field to the storage facility, 10 km. The tractor speed (15 km h1), the quantity of fertilizers and seed, and the mass of the machinery involved (tractor and trailer) were also taken into consideration. Transport between the farmyard and the field was based on a return distance of 10 km and on seven movements. The tractor speed (15 km h1) and the mass of the tractor and implements were also considered (see Appendix A). 2.1.7. Fuel The fuel requirements for sunflower production were estimated by taking into consideration the cultural
practices, the PTO power of the tractor needed to perform the operation and an average fuel energy density of 556 g MJ1. To estimate the energy costs for diesel fuel a coefficient of 556 MJ kg1 was used (Fluck, 1985). This fuel coefficient combines the energy content of the diesel fuel (about 81% of the total) and the energy consumed to produce and transport the fuel to the service station (about 19% of the total) (Cervinka, 1980). The method of calculating the diesel fuel requirements is given in Appendix A.
2.2. Estimation of energy outputs The energy outputs, the sunflower seed crop and stems were estimated by simply multiplying the quantities by their corresponding energy value. The seed yield was assumed to be 1800 kg ha1, which can be obtained under normal climatic conditions on fertile drylands in Northern Greece. The quantity of sunflower stems, which remains in the field as residue, is about 4170 kg ha1 (Gemtos, 1991). The energy output of the sunflower seed crop is further apportioned between the oil and the meal, based on the relative amounts of each obtained by expeller extraction. Sunflower seeds contain typically 40–42% oil (Hofman et al., 1980). Assuming a typical extraction
Table 5 Labour requirements Operation Ploughing Disc harrowing Fertilization Spraying Cultivating-pesticide incorporation Sowing Hoeing Harvesting Transport Moving to and from field Total
Work rate, ha h1
Labour, h ha1
Human energy inputs, MJ ha1
037 126 384 432 126 111 093 133 500 043
27 08 05 07 08 15 59 13 08 24
62 18 11 16 18 34 135 30 18 55
174
397
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SUNFLOWER PRODUCTION FOR BIODIESEL PRODUCTION
Table 6 The equivalent PTO power, the power required for motion, the energy and fuel requirement per operation Operation
Equivalent PTO power, (NPTO), kW
Ploughing Disc harrowing Fertilization Spraying Cultivating-pesticide incorporation Sowing Hoeing Harvesting Transport Moving to and from field Total
Power to move tractor (NPTO þ P)/f, kW and implement (P), kW
Energy per Fuel unit land area, consumption, (E), MJ ha1 (G), kg ha1
265 134 05 06 69 64 98 662
35 40 52 38 39 40 39 85 349 121
389 241 79 65 187 175 204 747 349 121
3754 689 74 55 533 619 679 3584 535 1015
209 38 04 03 30 34 38 199 29 56
1303
838
2557
11537
640
Note: f, coefficient for power losses.
rate of 80%, a 1000 kg of seeds, yield approximately 340 kg of oil and 660 kg of meal (FAO & EBRD, 1999). Depending on the use of sunflower meal, various energy values can be used. Sunflower press extracted meal is usually used as an animal feed, in particular for ruminants with similar results to soya bean meal, when substituted on an equal protein basis. The energy value of the sunflower meal is less than that of soya bean meal because of the added fibre content of hulls. The metabolizable energy for ruminants is reported to be 95 MJ kg1 compared to 123 MJ kg1 for soya bean meal (Rossell & Pritchard, 1991). The data for the energy output calculations is presented in Table 4.
3. Results and discussion Work rates and labour requirements were estimated for the different field operations, (Table 5). In Table 6
are shown the equivalent PTO power, the power for forward motion, the energy and fuel consumption per operation (calculated by Eqns (A.4), (A.5), (A.7) and (A.8), respectively in the Appendix A). Fuel energy density of 556 g MJ1 was assumed. Hofman et al. (1979) calculated the energy consumption for sunflower production in North Dakota, United States to be 682 GJ ha1, McIntosh et al. (1984) calculated the energy inputs for dryland sunflower production in North and South Idaho, United States at 122 and 105 GJ ha1, respectively. The large differences are due to different cultural practices. The energy requirements for sunflower production by operation are listed in Table 7. The energy costs appearing in Table 7 were calculated after multiplying the energy coefficients of Table 3 by the hours that each item of equipment or tractor was used for sunflower production (Table 5). The total direct and indirect energy consumed was calculated to be 1049 GJ ha1. Fertilization is the input with the largest energy input
Table 7 Distribution of energy consumption by operation Energy consumption, MJ ha1
Operation Machinery
Tractor
Labour
Fuel
Primary tillage Secondary tillage Fertilization Weed control Sowing Hoeing Harvesting Transport
92 6 4 19 37 16 793 12
113 34 11 43 47 39 0 134
6 2 1 3 3 14 3 7
1162 420 22 17 189 211 1106 473
Total
979
421
39
3558
Total energy Material
4881 429 184
5494
MJ ha1
%
1373 420 4919 511 460 280 1902 626
131 40 469 49 44 27 181 60
10 491
100
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L. KALLIVROUSSIS ET AL.
Table 8 Distribution of energy consumption by production input Quantities used, kg ha1
Production input Seed Fuel Nitrogen Phosphorus Herbicides Indirect machinery Labour
Energy content, MJ kg1
35 640 600 300 25
263 556 742 143 1714 228
Total
Table 9 Energy outputs from sunflower crop Energy, MJ ha1 Item
Meal as fuel
Meal as animal feed
Seeds Oil Meal Stems
47 358 24 034 23 324 47 705
24 034 11 305 47 705
Total
95 063
83 044
Energy, MJ ha1
%
184 3558 4452 429 429 1400 39
18 339 424 41 41 133 04
10 491
1000
estimated to be 830 GJ ha1 and the energy ratio for the seed yield is approximately 34:1 (Table 9). This analysis shows that efforts to improve the overall energetic efficiency should be focused on fertilizer usage and fuel consumption. However, significant reduction of fertilizers is not considered feasible as it would decrease production yields. A saving in diesel fuel by improving tractor operating performance may be possible.
4. Conclusions
(47% of total) because of the large quantities of nitrogen fertilizers. Harvesting was about 18%, and primary tillage 13%. Transport of harvested crop seeds and labour to the field required about 6% of the total energy inputs. The other operations require only a small portion of the total energy inputs with hoeing the least. Table 8 shows the energy requirements by production input. Nitrogen fertilizer accounts for about 42% of the energy used. In addition, more than 90% of the energy sequestered in applying fertilizers is from nitrogen due to the large energy requirements for producing it. Fuel for the tractor and combine is the second largest energy inputs, followed by the energy embodied in the machinery which is used to perform the field operations. Labour is an insignificant input. The total energy outputs were 951 GJ ha1 of which the seed was over half (Table 9). The energy balance assumes that the pressure extracted meal is used as a solid fuel. The ratio of energy-out to energy-in, for a seed yield of 1800 kg ha1, is about 45:1. This result is in good agreement with that of Bona et al. (1999) who showed that under Italian conditions, an energy balance of 5:1 was obtained with low energy input cropping techniques. Assuming that the sunflower meal is used as a feed for ruminants the total energy outputs were
Sunflower seed is a good store of biomass, and a crop considered for biodiesel production in Greece. The energy inputs and outputs were estimated to be 1049 and 474 GJ ha1 (stems not included), respectively, which translates into an energy ratio of 45:1. The possibilities to reduce the energy inputs are very limited.
Acknowledgements The authors wish to thank Mr V. Melidis from N.AG.RE.F., S.G.E. Orestiados, for his help in collecting local data.
References Apostolakis M; Kyritsis S; Souter X (1987). The biomass energy potential of agricultural and forest wood wastes. Publication of the Greek Productivity Centre, Athens (in Greek) Bona S; Mosca G; Vamerali T (1999). Oil crops for biodiesel production in Italy. Renewable Energy, 16, 1053–1056 Cervinka V (1980). Fuel and energy efficiency. In: Handbook of Energy Utilization in Agriculture (Pimental D, ed.), pp. 15–21. CRC Press, Boca Raton, FL Deluchi M A (1991). Emissions of greenhouse gases from the use of transportation fuels and electricity. ANL/ESD/TM-22,
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Center for Transportation Research, Agronne National Laboratory, Agronne, IL, US Department of Energy, November FAO & EBRD (1999). Sunflower}Crude and Refined oils. Agribusiness Handbooks, Vol. 2. Food and Agriculture Organisation of the United Nations & European Bank for Reconstruction and Development Fluck R C (1985). Energy sequestered in repairs and maintenance of agricultural machinery. Transactions of the ASAE, 28, 738–744 Gemtos Th (1991). The production of residues in Greece and the possibility to use them. Yearbook. Technological Educational Institution of Piraeus, Greece (in Greek) Goering C E; Daugherty M J (1981). Energy inputs and outputs of eleven vegetable oil fuels. ASAE Paper No 813586, American Society of Agricultural Engineers, St. Joseph, MI Heichel G H (1980). Assessing the fossil energy costs of propagating agricultural crops. In: Handbook of Energy Utilization in Agriculture (Pimental D, ed.), pp. 27–33. CRC Press, Boca Raton, FL Hoeft R C; Siemens J C (1975). Energy consumptions and return from adding nitrogen to corn. Illinois Research, 17(1), 10–11 Hofman V; Dinusson W F; Zimmerman D; Helgeson D L; Fannins C (1979). Sunflower oil as a fuel alternative. North Dakota Extension Service Bulletin 13, EENG-5 Hofman V; Dinusson W F; Zimmerman D; Helgeson D L; Fannins C (1980). Sunflower oil as a fuel alternative. North Dakota State University, Cooperative Extension Service, Circular AE-694 Lorenz D; Moris D (1995). How much energy does it take to make a gallon of ethanol? Publication of the Institute for Local-Self Reliance (ILSR), Washington DC, 8pp Lower Jr O J; Benock G; Gay N; Smith E M; Burgess S; Wells L G; Bridges T G; Springate L; Bling J A; Brattord G; Debertin D (1977). Production of beef with minimum grain and fossil energy inputs. BEEF, Vols. 1, II, III. Report National Science Foundation McIntosh C S; Smith S M; Withers R V (1984). Energy balance of on-farm production and extraction of vegetable oil for fuel in the United States Inland Northwest. Energy in Agriculture, 3, 155–166 Pimental D (1980). Energy inputs for the production, formulation, packaging and transport of various pesticides. In: Handbook of Energy Utilization in Agriculture (Pimental D, ed.), pp 35–42 CRC Press, Boca Raton, FL Pimental D; Lynn W R; MacReynolds W K; Hewes M T; Rush S (1974). Proceedings Workshop on Research Methodologies for Studies Energy, Food, Man and Environment, Phase I. Cornell University, Ithaca, NY. Pryde E H (1981). Vegetable oils vs. diesel fuel, chemistry and availability of vegetable oils. Regional Proceedings of Workshop on Alcohol and Vegetable Oil as Alternative Fuels, USDA, Washington DC Rossell J B; Pritchard J L R (1991). Analysis of Oilseeds Seeds, Fats and Fatty Foods. Elsevier Applied Science, London and New York Sherft J L (1975). Energy use and economics in the manufacture of fertilizers. In: Energy, Agriculture and Waste Management (Jewell J, ed.). Proceedings of the
1975 Cornell Agricultural Waste Management Conference, Ann Arbor Tsatsarelis C A (1991). Energy requirements for cotton production in central Greece. Journal of Agricultural Engineering Research, 50, 239–246 Tsatsarelis C A (2000). Principles of Soil Mechanical Cultivation and Sowing, 510pp Giahoudi-Giapouli Publishers, Thessaloniki, Greece (in Greek)
Appendix A: Calculation equations A.1. Work rate The work rate C, for each operation was calculated by C ¼ buEf
ðA1Þ
where b is the total operation width, u is the operation speed and Ef is the field efficiency of the implement considered. A.2. Draught force The draught force Rp for ploughing was calculated by Rp ¼ k0 ab
ðA2Þ
where k0 is the specific draught of the soil and a is the operation depth. A value of 699 kN m2 was used for k0 (Tsatsarelis, 2000). The draught force R for all implements except the plough, was calculated by R ¼ kb
ðA3Þ
where k is the specific draught, per unit of implement width. Typical values for k depending on the implement used were taken from Tsatsarelis (2000). A.3. Equivalent power at the power take-off The required equivalent PTO power NPTO per operation was calculated by NPTO ¼ Ru
ðA4Þ
A.4. Motive power The required power P to move the tractor and implement was estimated by P ¼ Mr u
ðA5Þ
where Mr is the motion resistance calculated by Mr ¼ gBRr
ðA6Þ 2
where g is the acceleration due to gravity (981 m s ), B the total mass of tractor and implement or trailer, and Rr the rolling resistance coefficient of 005 (Tsatsarelis, 2000).
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A.5. Energy The energy per unit land area E required per operation was calculated by NPTO þ P E¼ ðA7Þ fC where f is a coefficient to account for the power losses from the engine transmission to PTO and drawbar. Typical values for f
were used, depending on the operation considered, ranging from 06 to 08 (Tsatsarelis, 2000). A.6. Fuel The fuel consumption G per operation was calculated by G ¼ Eq where q is the specific fuel consumption.
ðA8Þ