Biomass estimates, characteristics, biochemical methane potential, kinetics and energy flow from Jatropha curcus on dry lands

biomass and bioenergy 33 (2009) 589–596

Available at www.sciencedirect.com

http://www.elsevier.com/locate/biombioe

Biomass estimates, characteristics, biochemical methane potential, kinetics and energy flow from Jatropha curcus on dry lands V. Nallathambi Gunaseelan* Department of Zoology, PSG College of Arts and Science, Coimbatore 641 014, India

article info

abstract

Article history:

In this study, we examined the production of Jatropha curcus plants on 1 ha of rain fed dry

Received 2 February 2008

lands. All of the plant components that would result from plantation tending, fruit

Received in revised form

harvesting and processing were sampled for their yield and chemical composition, and

15 August 2008

then subjected to the biochemical methane potential (BMP) assay. The component parts

Accepted 23 September 2008

exhibited significant variation in BMP which was reflected in their ultimate methane yield

Published online 18 November 2008

which ranged from 0.08 to 0.97 L g1 VS added, and their first order kinetics which ranged from 0.07 to 0.14 d1. We examined two integrated utilization schemes: the first which

Keywords:

converted plant prunings, fruit hulls and de-oiled seed cake to methane, and the oil to fatty

Methane yield

acid methyl-ester (FAME); the second was to convert the seeds, plant prunings and fruit

Kinetics

hulls entirely to methane. The basis for the plantation was, a density of 4444 plant ha1

Biochemical methane potential assay

(1.5 m  1.5 m spacing), with a seed yield of 0.911 kg TS plant1 (1 kg total weight) with an

Carbon flow

oil content of 35% providing an annual oil yield of 1.42 t y1. The corresponding yields of

Energy flow

pruned leaves, fruit hulls and de-oiled cake are 0.97, 1.0, and 2.35 t VS ha y1, respectively.

Biomass estimates

An integrated scheme of producing biogas by means of anaerobic digestion of the latter

Biogas digester

components and oil for biodiesel would produce 90 GJ ha1 y1 in total with the oil being

Anaerobic digestion

54 GJ. The alternative biogas only option which would convert the seed oil into methane

Dry lands

instead of biodiesel would produce 97 GJ ha1 y1. ª 2008 Elsevier Ltd. All rights reserved.

FAME

1.

Introduction

Rising and volatile crude oil prices have underlined the need for production of biodiesel and utilization up to 20% blend with petro-diesel. Jatropha curcus L. (Euphorbiaceae) has been identified in India as the most suitable oil seed bearing plant. The National Mission on biodiesel has been started as a demonstrative project in 2006–2007, by planting J. curcus in 4000 km2 out of 1.75 Mm2 of wastelands in India [1,2]. The wastelands include unoccupied dry lands near under-stocked forests, dry lands held by landlords, cultivable fallow lands,

public lands along railway tracks, roads and canals and marginal lands with unsuitable conditions for crop production due to soil and climatic constraints. J. curcus can be propagated through seeds or cuttings. It grows fast with little maintenance and can reach a height of 3–8 m. The ideal climatic conditions for J. curcus have been reported as an annual rainfall not exceeding 600 mm, atmospheric temperature not below 0  C and that the land is not waterlogged [3]. The size of the leaves ranges from 6 to 15 cm in length and width, with 2.5–7.5 cm long petiole. It has been reported that in rain fed wastelands, high-density plantations at 1.5 m (distance

* Corresponding author. Tel.: þ91 422 2626113; fax: þ91 422 2575622. E-mail addresses: [email protected], [email protected] 0961-9534/$ – see front matter ª 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.biombioe.2008.09.002

590

biomass and bioenergy 33 (2009) 589–596

Table 1 – Estimate of climatic data, plant development and pruned biomass potential of Jatropha curcus on dry lands in Coimbatore. Character Climatic datab Altitude (m above sea level) Summer temperature for 2007 ( C) Winter temperature for 2007 ( C) Annual rainfall for 2007 (mm) Vegetative development, 20 MAP Plant height (cm) Stem circumference (cm) Number of branches plant1 Pruned biomass plant1, 20 MAP Pruning of secondary and tertiary branches Wt. of leaves (kg, wet wt. basis) Wt. of wood (kg, wet wt. basis) Pruning at 30 cm from ground level Wt. of leaves (kg, wet wt. basis) Wt. of wood (kg, wet wt. basis) Generative development, 20 MAP Wt. of green fruit1 (g, wet wt. basis) Wt. of yellow fruit1 (g, wet wt. basis) Wt. of brown fruit1 (g, wet wt. basis) Wt. of fruit hull brown fruit1 (g, wet wt. basis) Wt. of seed1 (g, wet wt. basis) Wt. of testa seed1 (g, wet wt. basis) No. of green fruit plant1c No. of yellow fruit plant1c No. of brown fruit plant1c

a

Mean values 409 28.4 25.7 612

143.0 (9.9) 30.2 (3.4) 5.25 (1.7)

0.5 (0.05) 0.45 (0.05) 0.65 (0.07) 4.65 (1.6)

5.03 13.56 2.58 0.56

(0.45) (1.06) (0.27) (0.06)

0.66 0.23 3.75 0.67 0.33

(0.04) (0.02) (2.21) (0.57) (0.57)

MAP indicates months after planting. a Figures in parentheses are standard deviations. b Data obtained from www.coimbatore.com [14]. c Plants have just reached the generative stage.

between two rows)  1.5 m (distance between two plants) spacing accommodating 4444 plant ha1 shall be desirable [1]. To give a bushy appearance, the plant should be pruned when it attains a height of 1.5 m and the secondary and tertiary branches are to be pruned to induce a minimum of 25 branches at the end of the second year. Once in ten years, the plant should be cut leaving 30 cm height from the ground level for rejuvenation [4]. The pruned leaves were often left in the field and if incorporated in the soil as mulch, would decompose, releasing nutrients back to the soil. Alternatively, utilization of the leaf biomass as feedstock in biogas digesters would result in production of methane fuel and digested slurry with the fertilizer elements. The slurry could be used as an organic manure to recycle nutrients [5,6]. J. curcus bears fruits from the second year of its plantation and the economic yield stabilizes from the fifth year onwards. Seeds become mature when the schizocarpic capsule changes from green to yellow and then dark brown. The brown fruits are dried in the shade and de-hulled to separate the hulls (Exocarp) from the seeds. J. curcus yield about 1 kg seed plant1 y1 in relatively poor soils from the fifth year onwards [3]. Generally 3 seeds were obtained from a single fruit and the seeds had oil content of 25–35% [4]. The seeds are de-shelled to separate the shell (Testa) and kernel or used as such for oil extraction.

Box 1 Calculation of residual biomass potential from Jatropha curcus plantation. Leaf biomass obtained from pruning branches and main stem 1.15 kg plant1 (Table 1) 247.25 g TS plant1 (Table 2) 219.3 g VS plant1 No. of plant ha1 4444 [1] Pruned leaf biomass ha1 1.1 t TS 0.97 t VS No. of seed plant1 y1 Wet wt. of seed plant1 (1000 g, [3])/Wet wt. of seed1 (0.66 g, Table 1) 1515 No. of brown fruit plant1 y1 No. of seed plant1 (1515)/No. of seed fruit1 (3, [4]) 505 Wt. of fruit hull plant1 y1 No. of brown fruit plant1 (505)  Wet wt. of hull fruit1 (0.56 g, Table 1) 282.8 g 248.3 g TS (Table 2) 227.4 g VS Fruit hull biomass ha1 y1 1.1 t TS 1.0 t VS Wt. of testa plant1 y1 No. of seed plant1 (1515)  Wet wt. of testa seed1 (0.23 g, Table 1) 348. 5 g 313.3 g TS (Table 2) 301.4 g VS Wt. of seed plant1 y1 1 kg 0.911 kg TS (Table 2) Wt. of seed ha1 y1 4. 05 t TS 3. 85 t VS De-oiled cake biomass plant1 y1 0.911  Percentage of de-oiled cake in seed (65%, [4]) 592.2 g TS (Table 2) 528.2 g VS De-oiled cake biomass ha1 y1 2. 63 t TS 2. 35 t VS Figures within square brackets indicate reference number.

Anaerobic digestion (AD) of organic wastes and energy crops to produce methane would benefit society by providing a clean fuel from renewable feedstocks. This could substitute fossil fuel-derived energy and reduce environmental impacts

591

biomass and bioenergy 33 (2009) 589–596

Table 2 – Chemical composition of Jatropha curcus plant parts. Sample

Jatropha curcus L. mature leaf lamina Mature leaf petiole Mature leaf entire Tender leaf entire Green fruit Yellow fruit Brown fruit Fruit hull Seed testa Seed kernel Seed entire De-oiled cake

Moisture Content (%)

VS (%TS)

73.6 (0.9)

90.2 (0.1)

6.91 (0.02)

9.7 (0.6)

87.3 (0.3) 78.5 (0.8) 74.4 (0.5) 89.1 (0.2) 86.7 (0.6) 8.8 (0.1) 12.2 (0.1) 10.1 (0.2) 5.2 (0.1) 8.9 (0.1) 5.9 (0.09)

89.4 88.7 90.0 93.0 92.0 92.8 91.6 96.2 95.6 95.0 89.2

5.91 (0.05) 5.77 (0.07) 6.43 (0.03) 5.27 (0.08) 5.81 (0.07) 6.51 (0.05) 6.26 (0.02) 7.34 (0.01) 6.23 (0.03) 6.63 (0.07) 5.32 (0.08)

24.1 (0.7) 9.4 (1.1) 7.1 (0.4) 14.3 (0.9) 10.1 (0.5) 12.5 (1.1) 30.4 (0.6) 32.1 (0.5) 17.1 (0.3) 13. 9 (0.7) 17.7 (0.9)

(0.1) (1.0) (0.2) (1.1) (0.7) (0.2) (0.3) (0.1) (0.1) (0.3) (0.5)

pH

C/N ratio

Acid-detergent fiber Lignin (g g 1 VS)

Cellulose (g g 1 VS)

Ash (g g1 VS)

0.200 (0.002)

0.310 (0.005)

0.01 (0.002)

0.134 0.180 0.144 0.090 0.098 0.097 0.142 0.083 0.052 0.042 0.056

0.324 (0.006) 0.338 (0.008) 0.344 (0.015) 0.301 (0.015) 0.326 (0.013) 0.302 (0.006) 0.393 (0.008) 0.624 (0.009) 0.073 (0.007) 0.274 (0.009) 0.369 (0.005)

0.01 (0.001) 0.006 (0.001) 0.00 0.02 (0.001) 0.005 (0.001) 0.02 (0.001) 0.01 (0.001) 0.01 (0.005) 0.00 0.01 (0.002) 0.02 (0.002)

(0.001) (0.001) (0.005) (0.004) (0.001) (0.001) (0.003) (0.007) (0.003) (0.008) (0.005)

Figures in parentheses are standard deviations.

including global warming and acid rain [7]. It has been reported that feedstocks with carbon to nitrogen (C/N) ratio of less than 15 are generally required for stable biological conversion [8] and that maximum performance of biogas digesters occurred when the C/N of the feed was between 25 and 30 [9]. A previous study on AD of J. curcus fruit shells (Hulls) pretreated to separate fibers from pulp, gave about 2.5 L biogas L1 d1 with 70% CH4 at 4 g VS L1 d1 loading rate and 3 day HRT in 23.8 L up flow anaerobic filter [10]. It has been reported that de-oiled cake produced a biogas yield of 355 L kg1 COD degraded with 70% CH4 in anaerobic filter reactor of 110 L volume [11] and 220–250 L kg1 with 65–70% CH4 content, at mesophilic temperature in 5 L glass digesters [12]. However, the ultimate CH4 yields and rates from different parts of J. curcus, de-oiled cake and the overall biomass potential expected from J. curcus plantation were not well

elucidated. BMP assay, a method developed to estimate the ultimate conversion and associated methane yield of organic substrates, has been widely applied to determine the B0 from a variety of feedstocks. The BMP assay has proved to be a relatively simple and reliable method for comparison of extent and rate of conversion to methane [13]. The purpose of this study was to examine the production of J. curcus plants on 1 ha of dry lands, to determine their chemical characteristics, BMP and conversion kinetics and to account for their energy and carbon flows.

2.

Materials and methods

2.1.

Location of study area

The production of J. curcus plants were estimated in the rain fed dry lands near Bolampatty forest range, Chinnar check post,

0.4

CUMULATIVE METHANE YIELD (L g-1 VS added)

0.35

Table 3 – BMP of fresh Jatropha curcus plant parts and cellulose.

0.3

Sample 0.25 0.2 0.15 0.1 0.05 0 0

2

6

9

14

21

31

70

105

TIME (Days) Mature Leaf - Lamina

Mature Leaf - Petiole

Mature Leaf - Entire

Tender Leaf - Entire

Fig. 1 – BMP cumulative methane production of Jatropha curcus leaf parts.

Jatropha curcus L., mature leaf lamina Mature leaf petiole Mature leaf entire Tender leaf entire Green fruit Yellow fruit Brown fruit Fruit hull Seed testa Seed kernel Seed entire De-oiled cake Cellulose

Ultimate methane yield (L g1 VS added) 0.227 (0.016)a 0.335 0.237 0.224 0.326 0.518 0.469 0.306 0.080 0.968 0.610 0.230 0.404

(0.009)b (0.004)a (0.006)a (0.011)c (0.008)d (0.011)e (0.008)c (0.021)f (0.032)g (0.002)h (0.002)a (0.002)i

CH4 production rate constant (d1) 0.089 (0.008)a 0.114 0.122 0.138 0.129 0.126 0.127 0.115 0.113 0.069 0.081 0.133 0.083

(0.005)a,b (0.005)b,c (0.007)b,c (0.006)b (0.001)b (0.002)b,c (0.005)b (0.042)c (0.003)d (0.001)c (0.001)c (0.001)e

Figures in parentheses are standard deviations. a–i Means in columns with different superscripts differ (P < 0.05).

592

biomass and bioenergy 33 (2009) 589–596

1.2

0.5

CUMULATIVE METHANE YIELD (L g -1 VS added)

CUMULATIVE METHANE YIELD (L g-1 VS added)

0.6

0.4 0.3 0.2 Immature Green Fruit Yellow Fruit Mature Brown Fruit Fruit Hull

0.1 0 0

2

6

9

14

21

31

70

105

Testa Kernel Cellulose

1

Seed - Entire Deoiled Cake

0.8

0.6

0.4

0.2

0 0

TIME (Days)

2

6

9

14

21

31

70

105

TIME (Days) Fig. 2 – BMP cumulative methane production of Jatropha curcus fruits.

Sadivayal, about 35 km west of Coimbatore, Tamilnadu, India (10 560 N, 76 410 E). Situated at an altitude of 409 m above sea level, the sites experienced rainy season of about 5 months during June to August, October and November and dry season during the remaining months in a year. Coimbatore experienced a mean temperature of 28.4  C during summer and 25.7  C during winter and an average rainfall of 61.2 cm in 2007 [14].

2.2. Estimation of residual biomass potential of J. curcus Pruning study was done in 5 random sites after the end of North-East Monsoon in November 2007.The propagation method, months after planting (MAP) and the performance of any earlier pruning were enquired from the owner of the sites. The plants were propagated by the generative method of precultivating seeds in pots and were at 20 MAP. The plants were not pruned earlier. The stem circumference and height of the plants were determined using a measuring tape. The generative development characteristics such as the weight of fruit1, weight of fruit hull brown fruit1, weight of seed1and the weight of testa seed1 were determined immediately after harvest using an electronic balance. 15 plants, at the rate of three in a site, were pruned by cutting the stem at 30 cm above the ground level. Another set of 15 plants, at the rate of three

Fig. 3 – BMP cumulative methane production of Jatropha curcus seed parts and cellulose.

in a site, were pruned by cutting the secondary and tertiary branches and the wet weight of the leaves and wood was separately determined immediately using a balance. From the wet weight, the TS and VS contents of the biomass were calculated. Based on the literature data [3,4], the biomass of fruit hull, testa and de-oiled cake obtained from a plant were calculated. In a previous study on seed oil content variation in J. curcus in different altitudinal ranges [15], a similar method was used for approximately calculating the number of fruit tree1, and the number of seed tree1. Since the information on the age and propagation method of the plants was missing, the reported data could not be compared with this study.

2.3.

Feedstock

Fresh samples of J. curcus plant parts were obtained from the study area during March 2007 and their moisture contents were determined immediately. J. curcus de-oiled cake was obtained from the Bioenergy Department, Tamilnadu Agricultural University, Coimbatore. Microcrystalline Cellulose powder marketed by Burbidges and Co., Bombay-13, India and inoculum were used as controls. All the samples except cellulose were dried at 60  C, ground in a blender to pass through 2 mm mesh and stored at 4  C until used.

Table 4 – Gross energy content of Jatropha curcus components calculated from their chemical composition. Sample

Mature leaf Fruit hulls Seed entire De-oiled cake Oil

Total protein (%TS)

Total carbohydrates (%TS)

Lipid (%TS) Literature dataa [26]

Calculated Energyb MJ kg1

Energy MJ kg1 Literature dataa [26]

14.0 5.3 18.2 9.4 N.D

57.7 72.4 36.8 64.2 N.D

N.R N.R 35.0 1.5 N.R

12.0 13.0 22.4 12.9 N.D

N.R 11.1 20.8–25.5 N.R 37.8–45.8

N.R Not reported. N.D Not determined. a Number within square bracket is the reference. b Calculation based on 16.7 MJ kg1 for carbohydrate and protein and 37.7 MJ kg1 for fat.

593

biomass and bioenergy 33 (2009) 589–596

Biomass 4.05 t TS ha–1y–1 Energy a

91 GJ

DE-OILED CAKE *

Production of

EXTRACTION

PRUNED LEAVES *

ANAEROBIC DIGESTION (BMP ASSAY) TEMPERATURE 35°C, DURATION 105 DAYS

SEEDS

Oil yield b 1.42 t ha –1 y –1 Energy a 54 GJ

Biomass 2.63 t TS ha–1y–1 Energy a 34 GJ

Biomass 1.1 t TS ha –1 Energy a 13 GJ

Jatropha curcus plantation on

FRUIT HULLS *

Biomass 1.1 t TS ha–1y–1 Energy a 14 GJ

rain fed dry lands at a density of 4444 plant ha

–1

INTEGRATION OF ALL RESIDUAL BIOMASS *

Biomass 4.83 t TS ha–1y–1 Energy a 61 GJ

TRANS – ESTERIFICATION d KOH 14 kg Methanol 170 kg

BIODIESEL d 1.35 t ha–1 y–1 Energy d 53 GJ Glycerin d 156 kg ha–1 y–1

CH4 yield Energy

541 m3 18 GJ

CH4 yield Energy

230 m3 8 GJ

Energy recovery c 62 %

CH4 yield Energy

309 m3 10 GJ

Energy recovery c 71 %

CH4 yield 1080 m3 Energy 36 GJ

Energy recovery c 59 %

Energy recovery c 53 %

Fig. 4 – Schematics of energy flow during biodiesel and methane production from Jatropha curcus. a Energy content in biomass calculated from data in Table 4; b Based on 35% oil in seed; 1 m3 CH4 [ 33.81 MJ; c Energy recovery is defined as the energy value of CH4 divided by the energy value of biomass added to digester; d Heating value of biodiesel [ 38.93MJ kgL1; d Methanol @ 120 g kgL1, KOH @ 10g kgL1,Glycerin @ 110g kgL1 and biodiesel @ 950g kgL1 oil [3].

2.4.

Seed inoculum

Inoculum was obtained from a 5 L mesophilic (35  C), CSTR, daily fed at a loading rate of 2 g volatile solids (VS) L1 d1 with a hydraulic retention time of 20 days. Mixture of vegetable wastes and cattle manure served as feed for the CSTR. Performance of the fermenter was stable with an average methane yield of 0.32 L g1 VS added. The average total volatile fatty acids (VFA) and pH of the effluents were 180 mg L1 as acetic acid and 7.8, respectively.

2.5.

BMP assay

BMP assay is carried out in an environment where there is excess inoculum, excess nutrients and substrate concentration below inhibitory levels. Methane production rate constants (k) and ultimate methane yields (B0) were determined using the method of Owen et al. [16] with a few modifications [17]. A 0.5 g total solid (TS) of each sample was added to a 135 mL serum bottle along with 75 mL of the nutrient solution and seed inoculum. An inoculum concentration of 20% (v/v) was used for each assay. All media preparations and transfers were done in an atmosphere of nitrogen and carbon dioxide (70:30, (v/v)). Sealed bottles were inverted and incubated at 35  1  C after the air in the headspace was sucked out by using a vacuum pump. Samples were run in triplicates and controls included inoculum

and cellulose. The inoculum control bottle contained only 75 mL of the nutrient solution and seed inoculum. Cellulose control bottle contained 0.5 g TS of cellulose along with 75 mL of the nutrient solution and seed inoculum [16]. Assay bottles were periodically analyzed for gas production and composition for 105 days. Gas production was determined with a glass syringe by the volume displacement technique [18]. The methane content of the biogas was determined using a Chemito model 8510 gas chromatograph with dual thermal–conductivity detectors. The stainless steel column was packed with Porapak Q. Injector, oven and detector temperatures were 100, 50 and 150  C, respectively. The nitrogen carrier gas flow was 30 mL min1. The methane volumes were corrected by subtracting the mean methane volume of the inoculum control and were converted to standard temperature and pressure (STP, 0  C and 760 mm Hg). Methane yields were calculated by dividing the corrected methane volume by the weight of sample VS added to each bottle.

2.6.

B0 and k

The degradation of each sample was assumed to follow a first order rate of decay. Thus, the production of methane was assumed to follow the equation
B ¼ Bo 1  ekt

594

biomass and bioenergy 33 (2009) 589–596

Biomass 1.1 t TS ha–1y–1

Production of Jatropha

TOC @ 21%TS 231 kg

FRUIT HULLS *

TOC @ 25.5% TS 281 kg

curcus plantation on rain fed dry lands at a density of 4444 plant ha

DE-OILED CAKE *

Biomass 2.63 t TS ha–1y–1 TOC @ 26.1% TS 686 kg

–1

INTEGRATION OF ALL RESIDUAL BIOMASS *

Biomass 4.83 t TS ha–1y–1 TOC

1198 kg

ANAEROBIC DIGESTION (BMP ASSAY) TEMPERATURE 35°C, DURATION 105 DAYS

Biomass 1.1 t TS ha –1

PRUNED LEAVES *

CH4 yield 230 m3 Mass 164 kg Carbon 123 kg

Carbon recovery a 53 %

309 m3 221 kg 166 kg

Carbon recovery a 59 %

CH4 yield Mass Carbon

CH4 yield Mass Carbon

CH4 yield Mass Carbon

541 m3 386 kg 290 kg

1080 m3 771 kg 578 kg

Carbon recovery a 42 %

Carbon recovery a 48 %

Fig. 5 – Schematics of carbon flow during methane production from the residual biomass of Jatropha curcus. a Carbon recovery is defined as the mass of carbon in the CH4 divided by the mass of total organic carbon (TOC) in the biomass added to digester.

where B is the cumulative methane yield at time t. B0 was assumed to equal the final B after 100 days of fermentation. k was estimated by taking the reciprocal of the time from the start of the BMP assay until when B equaled 0.632 B0 [19].

2.7.

Analytical methods

The total solids (TS), volatile solids (VS), total volatile fatty acids (VFA, steam distillation method) and pH were analyzed by standard methods [20]. The TS were analyzed for total organic carbon (TOC), total kjeldahl nitrogen, total soluble carbohydrate, acid-detergent fiber (ADF), lignin, cellulose and ash by the procedures adopted earlier [21]. The total protein content was calculated by multiplying the kjeldahl nitrogen content by 6.25. The energy content of the J. curcus components was calculated from their chemical composition by the AOAC procedure [22]

2.8.

Statistical methods

Data were analyzed by using the computer software MS Excel, Windows 2000 Professional.

3.

Results and discussion

3.1.

J. curcus residual biomass yield

planting, pruning of J. curcus grown on dry lands, would give leaf biomass of 0.219 kg VS plant1 (Table 1).The calculated residual biomass from fruit hulls and de-oiled cake would be 0.227 and 0.528 kg VS plant1 y1, respectively from the fifth year onwards (Box 1). In an earlier study on phenological traits and yield of J. curcus (25.3 MAP) [23], wide variations in generative parameters and a low yield of 1.52 g for weight of brown fruit1 and 0.491 kg for weight of 1000 seeds (dry or wet weight basis not mentioned) were reported. This study showed values of 2.58 g and 0.66 kg (wet weight basis) as weight of brown fruit1 and weight of 1000 seeds, respectively for J. curcus (20 MAP) (Table 1). Assuming 4444 plant ha1 at 1.5 m  1.5 m spacing [1], the resource potential estimates for pruned leaves, fruit hulls and de-oiled cake have been 0.97, 1.0 and 2.4 t VS ha1 y1, respectively (Box 1). An assumed seed yield of 1 kg (0.911 kg TS) plant1 y1 [3] and seed oil content of 35% [4] would provide an annual oil yield of 1.42 t ha1.

3.2.

Most of the J. curcus plant parts showed high VS and cellulose contents and low lignin content. The C/N ratios were in the range required for stable biological conversion (Table 2).

3.3.

The climatic data of the study area indicated that it was suitable for the growth of J. curcus. Within two years after

Chemical characteristics of J. curcus plant parts

BMP data for J. curcus plant parts

A plot of the corrected cumulative methane yields of J. curcus leaves (Fig. 1) showed significant difference (P < 0.05) in the methane yields of mature leaf lamina and petiole. There was

595

biomass and bioenergy 33 (2009) 589–596

Scheme 1. Seeds used for biodiesel production and de – oiled cake for CH4 production

SEEDS

Biomass 4.05 t TS ha–1y–1

Oil yield b 1.42 t ha–1 y–1 Energy a 54 GJ

EXTRACTION

TRANS – ESTERIFICATION c KOH 14 kg Methanol 170 kg

BIODIESEL c 1.35 t ha–1y–1 Energyc 53 GJ Glycerin c 156 kg ha–1y–1

Production of

Biomass 2.63 t TS ha–1y–1 Energy a 34 GJ

DE-OILED CAKE *

Jatropha curcus plantation on rain fed dry lands at a

Scheme 2. Seeds used only for CH4 production

density of 4444 plant ha – 1 Biomass 4.05 t TS ha–1y–1 SEEDS

Energy

a

91 GJ

ANAEROBIC DIGESTION (BMP ASSAY) TEMPERATURE 35°C, DURATION 105 DAYS

Energy a 91 GJ

CH4 yield Energy

541 m3 18 GJ

CH4 yield 2349 m3 Energy 79 GJ

Fig. 6 – Schematics of energy flow during biodiesel and methane option and methane only option from Jatropha curcus seeds. a Energy content in biomass calculated from data in Table 4; b Based on 35% oil in seed; 1 m3 CH4 [ 33.81 MJ; c Heating value of biodiesel [ 38.93MJ kgL1; cMethanol @ 120 g kgL1, KOH @ 10g kgL1, Glycerin @ 110g kgL1 and biodiesel @ 950g kgL1 oil [3].

no significant difference (P < 0.05) in B0 and k for entire mature leaf and tender leaf (first four terminal leaves in a branch). The k for the leaves and petiole ranged from 0.09 to 0.14 d1 (Table 3). The BMP profile of J. curcus fruits showed variability in CH4 yields (Fig. 2) but similar (P < 0.05) kinetics (Table 3). The cumulative methane yields from J. curcus seed parts (Fig. 3) showed variability in methane yields and kinetics. The kernel showed the highest yield of 0.97 L g1 VS but the lowest kinetics among all the parts of J. curcus (Table 3). The highest BMP of 0.94 L g1 VS was reported for vegetable oil in a previous study [13]. All the components of J. curcus gave monophasic curves of methane production and more than 90% of the methane yield was achieved between 14 and 30 days of fermentation. A fast biodegradation rate of 14–30 days would reduce the required size for a reactor and would make the process economically more attractive. The yields and kinetics of J. curcus leaves and de-oiled cake were significantly similar (P < 0.05). The B0 of J. curcus de-oiled cake and fruit hulls from this study compared well with the literature data [10–12].

3.4.

cellulose [24] and 0.39 L g1 VS and 0.18 d1 from Avicel cellulose [25] were presented previously.

3.5.

Energy and carbon flows

The energy content calculated from the chemical composition of the samples used in this study (Table 4) was within the range reported in the literature [26]. An integrated scheme based on utilization of residual biomass obtained from J. curcus for CH4 production along with biodiesel production is illustrated in Fig. 4. J. curcus seed biomass of about 4 t TS ha1 y1 would produce 54 GJ oil. AD of de-oiled cake, pruned leaves and fruit hulls would produce 36 GJ with a total of 90 GJ ha1 y1. The energy recovery in methane (ratio of energy content in CH4 to the energy conserved in the biomass from solar source) varied between 53 and 71%. The TOC content of the residual biomass would be about 1.2 t ha1. AD of the biomass would yield 1080 m3 CH4 with the amount of carbon being 0.58 t. The carbon recovery in methane (ratio of mass of carbon in CH4 to the mass of total organic carbon conserved in the biomass from solar source) accounted for 42–59% (Fig. 5).

B0 and k for cellulose 3.6.

Microcrystalline cellulose exhibited slightly higher yield than expected, 0.404 versus a theoretical yield of 0.371 L g1 VS added (Table 3). Measurements of 0.40 L g1 VS from alpha-

Jatropha seeds for biodiesel or biogas

The statement whether J. curcus seeds for biodiesel or biogas could be examined from the energy flow chart (Fig. 6). The

596

biomass and bioenergy 33 (2009) 589–596

schematics of two options namely, utilization of J. curcus seeds for biodiesel and de-oiled cake for methane (Scheme 1) and their utilization only for methane production (Scheme 2) showed that Scheme 1 would produce 72 GJ ha1 y1 and Scheme 2 would produce 79 GJ CH4 ha1 y1. However, the conversion step from oil to biodiesel consumes energy in oil extraction, oil purification and requires methanol and KOH in Transesterification [3]. Considering the energy obtained from Scheme 2 was no less than that of Scheme 1, it is suggested that J. curcus seeds could be used as feedstock for biogas digesters, based on the technological requirement.

4.

Conclusions

This study demonstrated that all of the components of the J. curcus plant are capable of conversion by anaerobic digestion, with significant yields. One option that emerges from our work is a total plant concept for conversion to methane rather than the co-production of methane and Jatropha oil. The energy yield is almost 10% greater when evaluated at the point of Jatropha oil production. Since the added conversion step from oil to biodiesel consumes energy and has losses as well as adding in fossil carbon from the methanol, this option in the right technical circumstances would be worth evaluating. Our work only tested for BMP under conditions that are far from the technical performance levels of industrial AD. Work is under way to study the possible effect of inhibitory compounds on the performance of AD and the extent of possible utilization of the digested slurry.

Acknowledgements The author thank Professor Dr. Ralph P Overend and the referee for the valuable suggestions to improve this manuscript. The financial assistance from the University Grants Commission, New Delhi (Sanction No. MRP-2454/06(UGCSERO)) and the encouragement by Dr. B. Sampathkumar, (Secretary), Dr. Sheela Ramachandran, (Principal), PSG College of Arts & Science are acknowledged.

references

[1] JATROPHA – The wonder oil bearing tree. Available from: www.banajata.org [accessed 04.08]. [2] Singh SK. Global agriculture information network (GAIN). Report IN7047. India Biofuels Annual; 2007. p. 5–12. [3] Biswas S, Kaushik N, Srikanth G. Biodiesel: Technology and Business opportunities – An insight. Paper presented at Biodiesel towards energy independence – Focus on Jatropha curcus; 2006. Available from: www.tifac.org. [accessed 04.08]. [4] Ahmed M. Cultivation of Jatropha curcus L. North Eastern Development Finance Corporation Ltd. (NEDFi), Assam, India. Available from: WWW.biodiesel.nedfi.com [accessed 04.08]. [5] Gunaseelan VN. Anaerobic digestion of Gliricidia leaves for biogas and organic manure. Biomass 1988;17:1–11. [6] Gnanamani A, Kasturi Bai R. Influence of biodigested slurry on rice–gram cultivation. Bioresource Technology 1992;41:217–21.

[7] Chynoweth DP, Owens JM, Legrand R. Renewable methane from anaerobic digestion of biomass. Renewable Energy 2001;22(3):1–8. [8] Chynoweth DP, Srivastava VJ. Biothermal conversion of biomass and wastes to methane. In: Fifth symposium on biotechnology for fuels and chemicals. Oak Ridge, Tennessee: US Department of Energy; 1983. [9] Hills DJ, Roberts DW. Anaerobic digestion of dairy manure and field crop residues. Agricultural Wastes 1981;3:179–89. [10] Lopez O, Foidl G, Foidl N. Production of biogas from Jatropha curcus fruit shells. In: Symposium on Jatropha 97. Austria: Austrian Ministry of Foreign Affairs; 1997. [11] Staubmann R, Foidl G, Foidl N, Gubitz GM, Lafferty RM, Valencia VM, et al. Production of biogas from Jatropha curcus seeds press cake. In: Symposium on Jatropha 97. Austria: Austrian Ministry of Foreign Affairs; 1997. [12] Chandra R, Vijay VK, Subbarao PMV. A study on biogas generation from non-edible oil seed cakes: potential and prospects in India. In: Second joint International conference on sustainable energy and environment (SEE 2006). Bangkok, Thailand; 2006. [13] Chynoweth DP, Turick CE, Owens JM, Jerger DE, Peck MW. Biochemical methane potential of biomass and waste feedstocks. Biomass and Bioenergy 1993;5(1):95–111. [14] Emerging planet India private limited, Coimbatore. Weather in Coimbatore, India, 2008. Available from: http://www. coimbatore.com/travel/weather [accessed 04.08]. [15] Pant KS, Khosla V, Kumar D, Gairola S. Seed oil content variation in Jatropha curcus L. in different altitudinal ranges and site conditions in Himachal Pradesh, India. Lyonia 2006; 11(2):31–4. [16] Owen WF, Stuckey DC, Healy JB, Young LY, Mc Carty PL. Bioassay for monitoring biochemical methane potential and anaerobic toxicity. Water Research 1979;13:485–92. [17] Gunaseelan VN. Biochemical methane potential of fruits and vegetable solid waste feedstocks. Biomass and Bioenergy 2004;26:389–99. [18] Miller TL, Wolin MJ. A serum bottle modification of the Hungate technique for cultivating obligate anaerobes. Applied Microbiology 1974;27(5):985–7. [19] Hashimoto AG. Pretreatment of wheat straw for fermentation to methane. Biotechnology and Bioengineering 1986;28:1857–66. [20] APHA. Standard methods for the examination of water and waste water. 15th ed. New York: American Public Health Association Inc.; 1980. [21] Gunaseelan VN. Regression models of ultimate methane yields of fruits and vegetable solid wastes, sorghum and Napier grass on chemical composition. Bioresource Technology 2007;98:1270–7. [22] AOAC. Official methods of analysis. 12th ed. Washington, DC, USA: Association of Official Analytical Chemists; 1975. [23] Heller J. Physic nut. Jatropha curcus L. Promoting the conservation and use of underutilized and neglected crops. Rome: International Plant Genetic Resources Institute; 1996. p. 1–66. [24] Richards BK, Cummings RJ, Jewell WJ, Herndon FG. High solids anaerobic methane fermentation of sorghum and cellulose. Biomass and Bioenergy 1991;1(1):47–53. [25] Turick CE, Peck MW, Chynoweth DP, Jerger DE, White EH, Zsuffa L, et al. Methane fermentation of woody biomass. Bioresource Technology 1991;37:141–7. [26] Jongschaap REE, Corre WJ, Bindraban PS, Brandenburg WA. Claims and facts on Jatropha curcus L. Wageningen: Plant Research International B.V; 2007. p. 1–42.