1

HN Chanakya HK Khuntia

(Project Funded by CiSTUP, IISc, Bangalore)

Enhancing Productivity and Economics of Small-scale Biodiesel Units

Centre for Sustainable Technologies

Indian Institute of Science, Bangalore 560 012

April 2013

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Enhancing Productivity and Economics of Small-scale Biodiesel Units

HN Chanakya, Himanshu Kumar Khuntia,

Center for Sustainable technologies, Indian Institute of Science,

Bangalore, 560012

Abstract: Sustainable urban transport requires the use of biodiesel in a large way. Small-scale biodiesel units

that will service this need, produce over 25% of its inputs as biodiesel wastes containing waste

glycerol, unreacted primary oil, some methanol and a large quantity of residual organics – all of

which is found as a mixture and is difficult to manage. The transesterification reaction is generally

incomplete and a significant quantity of inputs are sent down as wastes. Until now there has been

no effort to integrate the biodiesel production along with the energy from it’s by product. The

analysis in this short communication shows that it can contribute 40% of additional revenue and

also make the biodiesel industry a self sustaining and zero waste industry. In the present project a

simple method capable of being used by small scale biodiesel units to recover a.un-reacted oil and

fatty acids, b.glycerol and c.methanol has been evolved. The glycerol fraction is mixed with

unwanted organics and we have shown it to produce good biogas. Further, the non-edible cake can

also be converted to biogas to provide heating energy for the overall process. A patent application

is being processed by SID for the novel waste separation process Further, a unique reactor design

specially suited for use only dry and semi-dry oil cake has been evolved and will also be sent for

patenting.

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Introduction Biodiesel Triacylglycerols (Oil) derived from living organism (plants and animals) that has been

transesterified using methanol and catalyst (NaOH / KOH) at a temperature of 60-65 deg C to form

long chain (C10-C24) methyl esters is called as biodiesel (Fig1) . More than 400 varieties of oil

crops have the potential to produce non edible oil that can be processed to biodiesel. The common

crops grown around the world to produce biodiesel are Madhuca indica (Mahua), Ricinus

communis (Castor), Pongamia Pinnata (Pongamia), Brassica napus (Rapeseed), Helianthus annuus

(Sunflower), Jatropha curcas (Jatropha). 1000 kg biodiesel formation requires an input of 990 kg

Crude Oil, 10-20 kg methanol, however 80-100 kg methanol is required to drive the esterification

reaction forward, 0.5-1.5 kg alkali catalyst (NaOH), total heat energy input 721 MJ (60°C), 200-

300 litres soft water for washing biodiesel. Biodiesel that can be directly used in the engines is

called as B100 however most of the countries around the globe have been using the biodiesel at

various blending ratio of 5% (B5) to 20% (B20) with petroleum diesel. The fuel properties of

biodiesel are similar to petroleum diesel therefore biodiesel can be used directly in the diesel engine

without any major modification. Biodiesel has a calorific value of 32600 MJ/m3, Flash point (°C)

100-170, Cetane number 48-65, Cloud point (°C) -3 to 12.

Fig 1. The chemical reaction of converting Triacylglycerols (lipid/oil) to biodiesel

Biodiesel production scenario in the world

Biodiesel production has been growing rapidly in the American and European continents. There has

been 295% growth in biodiesel production in 2009 when compared to 2005. Germany and France

are leading the race in biodiesel production achieving 2.5 and 1MTOe biodiesel production

respectively. About 90% of the biodiesel manufactured in Europe is consumed locally. Biodiesel

production in the United States has increased from 500,000 gallons in 1999 to 70 million gallons in

2005 (National biodiesel Board, 2006) (Fig 2).

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Fig2. The global biodiesel production trends. (Adapted from World energy out look 2006)

Fig 3. Global biodiesel production costs per liter. (Adapted from World energy out look 2006)

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In US and Europe the principal crop for making biodiesel has been castor, palm oil, sunflower oil,

rapeseed oil. However the Biodiesel policy in the western countries does not mandate the biodiesel

plantation to waste land. The biodiesel crops can be grown in any land alluvial land. Therefore

biodiesel plantation has been often looked as a threat to the food security. The cost of biodiesel

production is estimated to be $0.60 per litre equivalent in Europe (based on rapeseed) and

$0.50/litre in the United States (based on soybean) (Fig 3). About 80% of the net cost of biodiesel

production is shared by the unprocessed vegetable oil.

Biodiesel production in India In India there is preference to use non-edible oilseeds such as jatropha, pongamia, castor, etc. and

these have been tried extensively as these plants are already growing as well as they can be grown

on waste land without threatening food security by occupying land meant for food crops. The two

main oil crops that are being considered in India for large scale production of Biodiesel are

Pongamia pinnata and Jatropha Curcas. Pongamia pinnata is a nonedible oil yielding tree very

popular among biodiesel makers. A single tree is said to yield 9–90 kg seed per tree, indicating a

yield potential of 900–9000 kg seed/ha (assuming 100 trees/ha), 25% of which might be rendered

as oil. In general, Indian mills extract 24–27.5% oil, and the village crushers extract 18–22% oil.

Oil cake is a residue (byproduct) for this process. This being non-edible oilcake it is generally

consigned as a manure or fertilizer. Pongamia oil has a dark brown colour with repulsive odor and

contains primarily eight fatty acids palmitic, stearic, oleic, linoleic, lignoceric, eicosenoic, arachidic

and behenic. Pongamia oil contains oleic acid (44.5–71.3%), linoleic (10.8–18.3%), palmitic (3.7–

7.9%), stearic (2.4–8.9%), eicosenoic acid (9-eicosenoic acid) (9.5–12.4%). Jatropha Curcas

requires little water and fertilizer and can be grown on infertile soils. It is generally believed to be

pest-resistant and has an oil content of around 30–40%. It contains oleic acid (43.1%), linoleic

(34.4%), palmitic (14.2 %), stearic (6.9%), palmito-oleic (1.4%).

Materials and methods

Biological methane potential (BMP) assay was done to estimate the total amount of biogas that

could be generated from a given biodiesel waste substrate. The experiment was carried out in

125ml glass serum bottles fitted with a rubber stopper and crimped with tin caps so as to withstand

the gas pressure. Each bottle was filled with 50ml of the anaerobic bacterial sludge collected from

the plug flow bio-digester at CST (ASTRA), IISc. Thereafter the experiment was carried out at

increasing concentrations of substrates of 0.125 (2.5g/l), 0.5 (10g/l), 1 (20g/l), 2 (40g/l) at constant

bacterial inncoculum. The biogas volume generated in the bottle was measured by downward

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displacement of water. C, H, N % of the different biodiesel wastes (BW) was measure in Leco

TrueSpec (CHNS). The calorific value of different BW was estimated in Bomb calorimeter. This

was carried out in Bangalore test house. The oil/lipid, TS, VS, NVS etc present in different waste

was estimated by the methods in Standard method for examination of water and waste water

(APHA-AWA 1985).

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Results and discussions

Waste generated during the trans-esterification of oil to biodiesel.

The upstream and down stream processing of biodiesel manufacturing produces various organic

wastes with very subtle differences between different types of plant species. Several waste

generated during the upstream and downstream processing of biodiesel manufacturing from of

Pongamia and Jatropha is shown in fig 4 and 5. In general purified plant based oil devoid of water

is used in the process of making biodiesel. The methyl ester (biodiesel) is then formed by reacting

methanol with the raw oil or tri-acylglycerol component in the presence of sodium hydroxide and

heat as catalyst. This reaction is usually carried out with methanol and an alkali such as potassium

or sodium hydroxide. During this process glycerol is a by product that upon cooling to room

temperature settles at the bottom. This aids the separation of biodiesel from the glycerol; biodiesel

is collected at the top. It has been estimated that 10-20% of the weight of oil is converted to

glycerol. This indicates that for every ton of oil being processed for biodiesel, 100-200 kg of

glycerol is produced as a byproduct.

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Wastes associated with Jatropha Biodiesel process

Jatropha seeds

Kernels

Husk

Oil pressing to remove oil

Waste

Jatropha deoiled cakes

(Waste)Jatropha

Glycerol waste

Wastes associated with Pongamia Biodiesel process

Pongamia deoiled cakes

Waste

Oil pressing to remove oil

Pongamia seeds

Pongamia Glycerol Waste

Kernels

Husk

Fig4. The different waste generated during the upstream and downstream processing of Jatropha biodiesel.

.

Fig5. The different waste generated during the upstream and downstream processing of Pongamia biodiesel.

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The deoiled cakes especially from extraction of edible oil are being used as feed for cattle

(concentrate) whereas the de-oiled cakes from non-edible oil like Pongamia and Jatropha cannot be

used for cattle feed as it contains ricilonic acid that is poisonous to cattle’s upon consumption.

Therefore it is usually consigned as manure and sometimes as fuel. Therefore there was a need to

find an alternative use of the various waste produced during the upstream processes. One of the

major applications of these wastes can be as a source of energy. There would be multiple ways of

using the wastes for energy like direct combustion, biomethanation, gasification. However there has

been very little information available that would enable us to estimate the energy potential of these

wastes. Therefore calorific value of each of these wastes were analysed in bomb calorimeter as

shown in Table 1. It is very clear that all the substrates have a potential of generating energy with

the highest energy potential available for waste glycerol and deoiled cakes. Considering that

deoiled cakes are produced in a very high amount 30-40% of the initial biomass it would account

for the highest energy reserves among the wastes. Second to it would be the pods that account for

30-50% of the total biomass. The calorific value is a representative of total energy content however

it does not provide any information if it would be suitable for anaerobic digestion process.

Therefore in order to evaluate the anaerobic digestibility of these wastes and to evaluate its total

potential for biogas production a BMP assay was carried out. It was carried out in two main ways

e.g. the substrates containing oil and substrates devoid of oil by solvent extraction process (W/O).

This would aid in evaluating the inhibition effects of the lipid present in the substrates to anaerobic

digestion. Fig 6 and 7 show the BMP potential of Jatropha and pongamia wastes respectively along

with the oil contained in it. Fig 8 and 9 show the BMP potential of pongamia and Jatropha wastes

respectively without the oil contained in them. The N values in the table2 indicate that the

anaerobic digestion process can be carried out without supplementing any amount of N nutrients.

All the substrates were amenable to anaerobic digestion with varying inhibition rates at increasing

concentrations. The comparison of the BMP potential of different wastes indicate that pongamia

cake with oil has the highest potential of around 700ml biogas/g at a feed rate of 0.125g (5g/l)

however a similar feed rate without oil produces around 500ml/g. Therefore it can be attributed that

the oil present in the deoiled cakes can be degraded and that added 200ml of additional gas. The

substrate concentrations above 5g/l were found to be inhibitory to the anaerobic bacteria with

around 50-60% drop in the total biogas generation volume. The lowest biogas potential has been

for pongamia pods of around 100ml/g.

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Sample Calorific value cal/g

Jatropha Cake 4723

Jatropha Seed husk 4288

Jatropha fruit shell 3526

Pongamia pod 3686

Pongamia cake 4425Jatropha waste

glycerol 5022

Pongamia waste glycerol 4904

Sample %C %H %N Lipid % TS

VS % TS

NVS % TS

Jatropha Cake 44.186 6.0043 2.1396 8.98 92.75 7.25Jatropha Seed husk 47.538 5.9178 1.1895 4.95 96.05 3.95

Jatropha fruit shell 40.946 5.7276 1.0845 < 0.1 95.6 4.4Pongamia cake 44.614 6.721 2.6734 17.24 Nd Nd

Pongamia pod 43.284 5.7701 1.0794 < 0.1 Nd Nd

Table1. Calorific value of different wastes

Table2. Stoichiometric analysis of wastes.

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Jatropha Seed Husk - 0.5g/L

0

50

100

150

200

0 20 40 60 80 100

No. of Days

Gas

Vol

ume

(mL

) a b c

Jatropha Seed Husk - 0.25g/L

0

50

100

150

200

0 20 40 60 80 100

No. of Days

Gas

Vol

ume

(mL

)

a b c

Jatropha Fruit Shell - 2g/L

0

100

200

300

400

500

600

700

0 20 40 60 80 100

No. of Days

Gas

Vol

ume

(mL

) a b c

Jatropha Fruit Shell - 1g/L

0

50

100

150

200

250

300

0 20 40 60 80 100

No. of Days

Gas

Vol

ume

(mL

)

a b c

Jatropha Fruit Shell - 0.5g/L

0

50

100

150

200

250

300

0 20 40 60 80 100

No. of Days

Gas

Vol

ume

(mL

)

a b c

Jatropha Fruit Shell - 0.25g/l

0

50

100

150

200

250

300

0 20 40 60 80 100

No. of Days

Gas

Vol

ume

(ml)

a b c

Fig 6(a). The BMP of various jatropha wastes along with the lipid present in it.

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Jatropha Seed Husk - 1g/L

0

50

100

150

200

0 20 40 60 80 100

No. of Days

Gas

Vol

ume

(mL

)a b c

Jatropha Seed Husk - 2g/L

0

50

100

150

200

0 20 40 60 80 100

No. of Days

Gas

Vol

ume

(mL

)

a b c

Jatropha Cake - 0.25g/L

0

100

200

300

400

500

0 20 40 60 80 100

No. of Days

Gas

Vol

ume

(mL

) a b c

Jatropha Cake - 0.5g/L

0

100

200

300

400

500

0 20 40 60 80 100

No. of Days

Gas

Vol

ume

(mL)

a b c

Fig 6(b). The BMP of various jatropha wastes along with the lipid present in it.

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Jatropha Cake - 1g/L

0

100

200

300

400

500

0 20 40 60 80 100

No. of Days

Gas

Vol

ume

(mL

)

a b c

Jatropha Cake - 2g/L

0

100

200

300

400

500

0 20 40 60 80 100

No. of Days

Gas

Vol

ume

(mL

) a b c

Pongamia Cake - 0.25g/L

0

100

200

300

400

500

600

700

0 20 40 60 80 100

No. of Days

Gas

Vol

ume

(mL

)

a b c

Pongamia Cake - 0.5g/L

0

100

200

300

400

500

600

700

0 20 40 60 80 100

No. of Days

Gas

Vol

ume

(mL

) a b c

Pongamia Cake - 2g/L

0

100

200

300

400

500

600

700

0 20 40 60 80 100

No. of Days

Gas

Vol

ume

(mL

) a b cPongamia Cake - 1g/L

0

100

200

300

400

500

600

700

0 20 40 60 80 100

No. of Days

Gas

Vol

ume

(mL

) a b c

Fig 7a. The BMP of various Pongamia wastes along with the lipid present in it.

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Pongamia Pods - 0.25g/L

0

25

50

75

100

125

150

0 20 40 60 80 100

No. of days

Gas

Vol

ume

(mL

)

a b c

Pongamia Pods - 0.5g/L

0

25

50

75

100

125

150

0 20 40 60 80 100

No. of days

Gas

Vol

ume

(mL

)

a b c

Pongamia Pods - 1g/L

0

25

50

75

100

125

150

0 20 40 60 80 100

No. of days

Gas

Vol

ume

(mL

) a b c

Pongamia Pods - 2g/L

0

25

50

75

100

125

150

0 20 40 60 80 100

No. of Days

Gas

Vol

ume

(mL

)

a b c

Fig 7b. The BMP of various Pongamia wastes along with the lipid present in it.

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Pongamia cake W/O 0.25g

0

100

200

300

400

500

600

0 20 40 60 80 100 120

Days

Vol

ume

of g

as (m

l)

a b c

Pongamia cake W/O 0.5g

0

100

200

300

400

500

600

0 20 40 60 80 100 120

Days

Vol

of g

as (m

l)

a b c

Pongamia cake W/O 1g

0

100

200

300

400

500

600

0 20 40 60 80 100 120Days

Vol

of g

as (m

l)

a b c

Pongmia Cake W/O 2g

0

100

200

300

400

500

600

0 20 40 60 80 100 120Days

Vol

ume o

f gas

(ml) a b c

Pongamia Pod W/O 0.25g

0

100

200

300

400

0 20 40 60 80 100 120

Days

Vol

ume

of g

as (m

l)

a b cPongamia pod W/O 0.5g

0

100

200

300

400

0 20 40 60 80 100 120Days

Vol

ume

of g

as (m

l)

a b c

Pongamia Pod W/O 1g

0

100

200

300

400

0 20 40 60 80 100 120

Days

Vol

ume

of g

as (m

l)

a b cPongamia Pod W/O 2g

0

100

200

300

400

0 20 40 60 80 100 120

Days

Vol

ume

of g

as (m

l)

a b c

Fig8. The BMP of various Pongamia wastes devoid of lipid (W/O).

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Jatropha seed husk W/O 0.25g

0

25

50

75

100

125

150

0 20 40 60 80 100 120

Days

vol o

f gas

(ml) a b c

Jatropha seed husk W/O 0.5g

0

25

50

75

100

125

150

0 20 40 60 80 100 120

Days

Vol

ume

of g

as (m

l)

a b c

Jatropha Seed Husk W/O 1g

0

25

50

75

100

125

150

0 20 40 60 80 100 120

Days

Vol

ume

of g

as (m

l)

a b c

Jatropha Seed Husk W/O 2g

0

25

50

75

100

125

150

0 20 40 60 80 100 120

DaysV

olum

e of

gas

(ml)

a b c

Jatropha CakeW/O 0.25g

0

100

200

300

400

0 20 40 60 80 100 120

Days

Vol

ume

of g

as (m

l)

a b c

Jatropha Cake W/O 0.5g

0

100

200

300

400

0 20 40 60 80 100 120

Days

Vol

ume

of g

as (m

l)

a b c

Fig 9a. The BMP of various Jatropha wastes devoid of lipid (W/O).

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Jatropha Cake W/O 1g

0

100

200

300

400

0 20 40 60 80 100 120

Days

Vol

ume

of g

as (m

l)

a b c

Jatropha Cake W/O 2g

0

100

200

300

400

0 20 40 60 80 100 120

Days

Vol

ume

of g

as (m

l)

a b c

Jatropha Fruit Shell (w/o oil) - 0.25g/L

0

50

100

150

200

250

0 20 40 60 80 100

No.of Days

Gas

Vol

ume

(mL

)

a b c

Jatropha Fruit Shell (w/o oil) - 0.5g/L

0

50

100

150

200

250

0 20 40 60 80 100

No. of Days

Gas

Vol

ume

(mL

)a b c

Jatropha Fruit Shell (w/o oil) - 1g/L

0

50

100

150

200

250

0 20 40 60 80 100

No. of Days

Gas

Vol

ume

(mL

)

a b c

Jatropha Fruit Shell (w/o oil) - 2g/L

0

50

100

150

200

250

0 20 40 60 80 100

No. of Days

Gas

Vol

ume

(mL

) a b c

Fig 9b. The BMP of various Jatropha wastes devoid of lipid (W/O).

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Waste glycerol is currently being piled-up in the store house as there is no demand and value for it

is very low. The waste glycerols produced from such processes are quite dirty and laden with a lot

of unwanted gums, resins, particulates, etc. and does not find attractive and economic end-used.

They are likely to become pollutants of soil and water if left unattended. The existing methods for

purification of the waste glycerol is very expensive and energy intensive that again increases the

cost of the product. Overall 150 million gallons of biodiesel is being produced per year with the

waste glycerol amount being 50 million kg due to which has resulted in a tenfold decrease in

glycerol prices (Yazdani et al 2007). Glycerol has potential application in food, drug, cosmetic and

tobacco industries where as the crude biodiesel glycerol contains lot of impurities that has low

commercial value. Further purification of glycerol by chemical and physical methods increases the

overall cost of glycerol therefore there is a need to look for alternative products that would create a

demand for glycerol. As the number of the biodiesel plants are increasing so does the stocks of

waste glycerol. Alternative uses for glycerol need to be found. Therefore one essential application

of waste glycerol can be to convert it to biogas via anaerobic digestion process. Fig 14 shows the

comparison of the BMP between pure glycerol and biodiesel waste glycerol. The BMP analysis

indicate a very high biogas potential of around 800l/kg of glycerol, however it has an extremely

slower rate of reaction requiring more than 400 days to produce it. Therefore it was hypotized that

there might be many other components present in the waste glycerol that might be causing

inhibition to the anaerobic bacteria. It can be attributed to unreacted oil, unseparated biodiesel,

natural gums etc. Therefore attempts were made to remove biodiesel and unreacted oil from the

waste glycerol. This can aid in recovering the biodiesel and unreacted oil back from the waste

glycerol junk and there in render the waste glycerol much more amenable to use by the anaerobic

bacteria. Fig 10, 11, 12 show the various experimental analysis carried out in order to separate the

biodiesel and oil from the waste glycerol mass. The process was carried out using a preferential

solubility mechanism of glycerol and other polar components towards water and insolubility of

biodiesel and unreacted oil. Acids like sulphuric acid and hydrochloric acid playa a vital role in

converting the sodium fatty acid soap back to free fatty acid and oil. This can be clearly observed in

the fig 13 where the top layer is the oil that has been separated by the novel process that has been

developed.

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Jatropha Glycerol Waste (Reaction Time)

0

20

40

60

80

100

120

0 5 10 15 20 25 30 35 40 45 50 55 60 65

time(min)

O &

M

oil% ML%

Fig 10. Jatropha waste glycerol reaction time at constant temperature.

Jatropha Glycerol Waste (Acid requirement Hcl)

0

20

40

60

80

100

120

0 0.2 0.4 0.6 0.8 1

Acid(ml)

O&

M

ML% oil%

Fig 11. Acid requirement of Jatropha waste glycerol.

Pongamia Biodiesel waste (Acid requirement Hcl)

0

20

40

60

80

100

120

0 0.2 0.4 0.6 0.8 1

Acid(ml)

O&

M

oil% ML%

Fig12 Acid requirement of Pongamia waste glycerol.

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Fig 13. The oil separation from waste glycerol by the developed chemical process. The top

dark black layer being oil, biodiesel and the bottom layer being water soluble component like

glycerol.

21

Acclimatized innoculum , Biodiesel glycerol (0.5%) ,

Nutrients (N &P)

0

100

200

300

400

500

600

700

800

0 50 100 150 200 250 300

Days

Gas

(ml)

A

B

Biodiesel Glycerol (0.5 %)

0

100

200300

400

500

600

700

800

900

1000

0 50 100 150 200 250 300

Days

Gas

(ml)

A

B

Biodiesel glycerol (0.5%), Nutrient (N&P)

0

100

200

300

400

500

600

700

800

900

0 50 100 150 200 250 300 350 400

Days

Gas

(ml) A

B

Pure Glycerol 0.5%

0

100

200

300

400

500

600

0 25 50 75 100 125 150 175 200

Days

Gas

(ml)

A B

Pure Glycerol 1%

0

25

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75

100

125

150

175

0 20 40 60 80 100

Days

Gas

(ml)

A B

Pure Glycerol 1%,Nutrients (N & P)

0

25

50

75

100

125

150

175

0 20 40 60 80 100

Days

Gas

(ml)

A B

Fig 14. Comparisons of BMP of waste glycerol along with pure glycerol.

22

Improper policy, planning and targets:

National Policy on Biofuels 2009 aims to achieve 5 per cent blending of petroleum diesel with

biodiesel by 2012, 10 per cent by 2017 and 20 per cent after 2017. In order to achieve the goals, 32

million ha of wastelands and 8 million ha of non crop land would be required from the existing 55

million ha of wasteland in India. Minor irrigation and better yielding variety can meet the 20%

diesel blending target (ADB 2011). The current petroleum diesel consumption in India is 60 MT

(2010) (Fig 4). Road transportation accounts for 60.4% (36.24 MT) of the diesel consumption.

Therefore at 5% blending target 1.812 MT biodiesel would be required in 2012; however the

current production of 70,000 tons pa meets only 3.86% of the 5% blending target. By 2020 the goal

to achieve 20% blending of diesel would require 24.61 MT of biodiesel or 350times increase in

biodiesel production within the next 8years (Fig 4). It looks highly unlikely to achieve those targets.

Biodiesel price of Rs 26.5/l is fixed by Government of India in Biofuel Policy 2009. However the

market price of unprocessed Oil/raw oil/SVO is Rs 28/kg. Additional chemicals (methanol, catalyst

(NaOH)) and processing costs such as water, energy costs accounts for Rs 5-7/l. therefore the total

production cost of Biodiesel Rs 33-35/l. Pay back by selling 99% pure glycerine would account to

Rs 3-4/l biodiesel at a market cost of Glycerin Rs 27/l (2011). However the cost of purifying

glycerol is estimated to be Rs 30-40/kg. Therefore the policy has failed to clearly estimate the

production and selling price of the biodiesel. Therefore it has also failed to attract the investors in

this field. However the small scale manufacturers have succumbed to the price fixed by the

government and they have been selling biodiesel at Rs 60-110/l. The petroleum diesel cost in India

(Bengaluru) is Rs 51.41/l therefore under those circumstances biodiesel seems to be more

expensive than diesel and so their market demand would be questionable. Again by 2020 there

would also be 18 per cent rise in the cost of oilseeds that would directly increase the biodiesel price.

Biodiesel production and its cost is directly related to the supply and cost of methanol. The total

methanol demand in 2014 is estimated to be 1.25Mt/year (Fig15). The net import of methanol

would be 4 times higher than the production in India and estimated to be 0.93Mt/year. Currently

methanol is produced from petroleum products and as the cost of petroleum increases in the

international market so would be the cost of methanol, which would have a direct impact on the

biodiesel cost.

23

• The net import of methanol is 4 times higher than the production in India.• Import of methanol has increased by 22% from 0.4 Mn-tons in 2004 to 0.85 Mn-tons in 2009.• Domestic methanol demand would grow at CAGR of 6.8% from FY10 to FY14.• The growth drivers being the biodiesel industries.

No methanol.!!. No biodiesel..!!

India Chem 2012

Fig 15. The requirement and demand for methanol in India. Adapted from India chem2012

and Tata strategic analyses.

Reuse of biodiesel wastes

The analysis (Fig 16, 17) show that for 1000 kg of oil seeds (total biomass) processed about 110 –

125 kg of biodiesel produced. There is approx 800-850 kg of solid wastes, 10-25 kg dirty glycerol

and 25-30 litres of high strength waste water (COD>50gm/l) also produced. Biodiesel occupies

20% of the total energy available in the oil seed which is equivalent to 3667.5 MJ. The remaining

energy is caught in the pod, deoiled cakes and glycerol which is equivalent to .14500 MJ of energy.

Currently there is no integrated management of these wastes and all the efforts are concentrated

towards production of biodiesel without realizing that a major junk of the energy is left unused. If

the additional waste is tapped and converted to energy via biogas then it can generate 240m3 of

biogas which is equivalent to 4800MJ of energy. If biogas is converted to electricity, then at 30%

engine efficiency 400kwhr of electricity can be produced. Biodiesel production process requires

750MJ of energy. The remaining 4050MJ energy can be traded that can fetch Rs 1350 @Rs 4/unit

electricity achieving 40% additional income.

24

Jatropha and Pongamiadeoiled cakes

Biogas that can be used directly for combustion

Direct Fuel for combustion or Producer gas (gasification)

Fuel pellets

Undigested matter can be used directly as compost, growing

mushrooms, vermicomposting etc

Waste glycerol

Chemical Extraction

Oil ( Biodiesel & unreacted oil )

Crude glycerol

Shells / Pods

Biodiesel occupies ~20% of the total energy available in an oil seed.80% of the remaining energy is wasted and needs to be tapped.

Fig 16. Biodiesel wastes and their potential energy application

25

Mechanical press

Manual de-seedingor mechanical

50 m3 biogas(100l/kg biogas yield)

Pongamia pinnata Yield (22 – 225) kg pods/tree/year

Pods 1000kg

Oil Seeds / Kernels 50% (500kg)

Oil 25% (125 kg)

Crude Biodiesel 112.5 kg

3667.5 MJ

De-seeded Pod 50% (500kg)

7500 MJ

Deoiled cakes 75% (375 kg)

6750 MJ

Waste glycerol 10% (12.5 kg)

250 MJ

Wash water (31.2 litres)

Hot Water and Acid extraction

Anaerobic digestion

Total Biogas ~ 240m3

Energy – 4800 MJ Electricity – 400 kWhr (30%

engine efficiency)@Rs 4/unit- Rs 1600

Com

post 175 kg

N &

P rich liquid fertilizer

Transesterification

187.5 m3 biogas(500l/kg biogas yield)

Crude glycerol etc 50% (5kg)

Un reacted /waste oil 50% (5kg)

2m3 biogas400l/kg biogas yield

0.62m3

biogasCOD -50gm/l

Methanol recovery 20% (2.5 Kg) Biodiesel ~

142.85 litresAt Rs 26.5/lit

Rs 3785 Oil recovery 25%

Mass and Energy Balance for Pongamia Biodiesel process

Fig 17. Mass and energy balance for Pongamia biodiesel process

26

27

Figure 18 (a-c) show various sections of the fabricated 100L capacity biodigester for biodiesel

waste (non-edible oil-cake). This plant is designed to avoid settling of added cake and release

of only the liquid – a common problem when cattle dung plants are adapted for oil-cakes.

28

Conclusion:

The current biodiesel production trends show that it would be difficult for India to achieve the 20%

blend targets by 2020.Both Pongamia and Jatropha even though being waste land crops would

require significant care and nutrients during the gestation period to achieve a better yield of oil

seeds. The biodiesel pricing policy should be revived in order to attract investors as the current

pricing is influenced by petroleum diesel prices. The current process is energy wise uneconomical

as it looses 80% of the energy in the form of wastes. Large scale biodiesel plants are unsuitable and

uneconomical due to unavailability of seeds through out the year therefore the government should

promote large number of small scale decentralized industries (1-2tons/day). Decentralized

industries should have access to the package of small scale biodiesel manufacturing technology

along with integrated renewable energy recovery technologies.

29

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