Low Carbon Economy, 2010, 1, 54-60
doi:10.4236/lce.2010.12007 Published Online December 2010 (http://www.SciRP.org/journal/lce)
Energy Analysis of Irrigated Jetropha Cultivation
for Producing Biodiesel
Akshay Gupta, Kv Bharadwaj, Suvha Lama, Jyotirmay Mathur
Malaviya National Institute of Technology, Jaipur, India.
Received June 23rd, 2010; revised October 10th, 2010; accepted November 4th, 2010.
ABSTRACT
Increase in yield of Jetropha plantation due to irrigation has been investigated considering the energy required to pump
out underground water for Jetropha plantation in India. Depth of the water table is the variable. Comparison has been
made with unirrigated Jetropha cultivation and increase in yield of bio-diesel has been compared with the primary en-
ergy required for operating the water pumps. Analysis has been carried out for areas having low, medium and high
rainfalls and with three depths of water tables 20 m, 40 m and 60 m. It has been found that in areas having low rainfall
and depth of water table 40 m, the energy balance is negative for first 4 years. Whereas in areas having low rainfall but
water table 20 m, energy balance becomes positive in the third year, whereas for 60m depth, it doesn’t become positive
in the fifth year even.
Keywords: Energy Analysis, Energy Balance, Pump Power, Primary Energy Equivalent, Energy Yield Stabilization
Matrix
1. Introduction
Biodiesel refers to a vegetable oil or animal fat based
diesel fuel consisting of a long chain alkyl esters. The
major components of vegetable oils and animal fats are
tri-acyl-glycerols (TAG). Chemically, TAG’s are esters
of fatty acids (FA) with glycerol. Biodiesel can be pro-
duced from a great variety of feedstocks. These feed-
stocks include most common vegetable oils (e.g., soy-
bean, cottonseed, palm, peanut, rapeseed/canola, sun-
flower, safflower, coconut) and animal fats (usually tal-
low) as well as waste oils (e.g., used frying oils). The
choice of feedstock depends largely on geography.
Biodiesel has several distinct advantages compared
with petro-diesel in addition to being fully competitive
with petro-diesel in most technical aspects:
 Derivation from a renewable domestic resource,
thus reducing dependence on and preserving petro-
leum
 Biodegradability
 Reduction of exhaust emissions (with the exception
of nitrogen oxides, NOX).
 Higher flash point, leading to safer handling and
storage.
 Excellent lubrication of the engine, a fact that is
steadily gaining importance with the advent of
low-sulfur petro diesel fuels, which have greatly
reduced lubricity. Adding biodiesel at low levels
(1-2%) restores the lubricity.
Biofuel development in India centers mainly around
the cultivation and processing of Jatropha plant seeds
which are very rich in oil (40%). Jatropha oil has been
used in India for several decades as biodiesel to cater to
the diesel fuel requirements of remote rural and forest
communities; Jatropha oil can be used directly after ex-
traction (i.e. without refining) in diesel generators and
engines. Jatropha provides immediate economic benefits
at the local level since it grows well in dry marginal
non-agricultural lands, thereby allowing villagers and
farmers to leverage non-farm land for income generation.
As well, increased Jatropha oil production delivers eco-
nomic benefits to India on the macroeconomic or na-
tional level as it reduces the nation’s fossil fuel import
bill for diesel production (the main transportation fuel
used in the country); minimizing the expenditure of In-
dia's foreign-currency reserves for fuel allowing India to
increase its growing foreign currency reserves (which
can be better spent on capital expenditures for industrial
inputs and production). And since Jatropha oil is car-
bon-neutral, large-scale production will improve the

Energy Analysis of Irrigated Jetropha Cultivation for Producing Biodiesel 55
country’s carbon emissions profile. Finally, since no food
producing farmland is required for producing this biofuel
(unlike corn or sugar cane ethanol, or palm oil diesel), it
is considered the most politically and morally acceptable
choice among India’s current biofuel options; it has no
known negative impact on the production of the massive
amounts grains and other vital agriculture goods India
produces to meet the food requirements of its massive
population. Other biofuels which displace food crops
from viable agricultural land such as corn ethanol or
palm biodiesel have caused serious price increases for
basic food grains and edible oils in other countries. Jat-
ropha plant cultivation and subsequent production of
bio-fuel is a crucial part of India’s plan to attain energy
sustainability.
The paper on ‘Jatropha biodiesel production and use’
by Achten [1] discusses the best available methods, their
shortcomings and the potential risks and remedies for
each production step. Work done by Mr. Mukherjee,
Department of Horticulture, Agricultural Research Cen-
ter, Jaipur provides insights into cultivation practices and
economic feasibility of Jatropha plantation, its use as an
alternative fuel and as a tool for protection of environ-
ment. The information regarding pump energy and re-
lated data was obtained from ‘Pump Life Cycle Costs: A
Guide to LCC Analysis for Pumping Systems’, an execu-
tive summary developed in collaboration between Hy-
draulic Institute, Europump and the US Department of
Energy’s Office of Industrial Technologies. Data gener-
ated in these and various other research papers was ap-
plied in our research work in estimation of the feasibility
of Jatropha plantation with regard to the amount of rain-
fall and the depth of the water table of a particular area.
Scope of this work covered finding the energy balance of
irrigated Jetropha cultivation of obtaining biodiesel by
calculating the primary energy consumption for water
pumping from underground water sources and comparing
the same with the calorific value of the bio-diesel.
2. Primary Energy Req ui r em e nt fo r
Irrigation
In many parts of rural India, the major source of irriga-
tion is wells. So we used the energy required for the
pumps to pull water from the wells as our input energy.
The water table depth is very low in few states, such as
Rajasthan. The depth of the ground water table varies
from few meters to almost 100 m in some areas, meaning
we need to dig almost 300 ft to reach the water table. In
some parts, the depth of the water table is decreasing
rapidly at approximately 2-3 m each year [2].
The first step in calculating the energy required for
water pump, the following correlation for pump power
was used [3]




366
p
m
PQH

 (1)
where,
Q – Volumetric flow rate, H – Depth of the water, ηp ηm –
Efficiencies of pump and motor respectively
The required water quantity ‘Q’ was calculated using
the fact that the irrigational requirement of Jetropha
Karkus plant species is 1500 mm water per hectare per
year [4]. Assuming one hectare of plantation, the irriga-
tional requirement was converted as:
3
1.5 10000Qmyr (2)
10 hrs per day is considered as the duration of watering
of the plant [4]. Hence the volumetric flow rate is:
3
41.1Qmyr (3)
The average efficiency of the pump and motor com-
bined (ηp * ηm) is considered to be approx. 63.5% [5]
0.635
pm


 (4)
After substitution of these values, the only remaining
variable in (1) is the depth of the water table. Assuming
the water table depth from ground level to be ‘H’ meters,
we calculate the energy required to pump the water

 

,1500366 0.635
64.54
input electricalel
el
EHKWh
HKWh
 
 (5)
Considering the primary energy to electrical energy
average conversion factor to be 30% [6], primary energy
equivalent of electrical energy used for water pumping
can be calculated as given below:


64.54 36000.33
697.101
inputprimary
primary
EH
H
MJenergy ha yr

 (6)
3. Calculation of Energy Output as Biodiesel
Information about increase in yield of Jetropha kurkas
with irrigation was collected from the Agricultural Re-
search Institute of India (ARII), Jaipur [7]. There is a
marked difference between the net yield from a rain fed
plants and irrigated plants as shown in Tables 1, 2 and 3.
This difference increased considerably with increase in
number of years, varying from 250 kg seeds/hectare of
yield in the first year to almost 8000 kg seeds/hectare of
yield by the 6th year onwards. This data was concentrated
to the arid regions of Rajasthan and taking the average
rainfall of about 600 mm per year into consideration [2].
Since after the end of fifth year, the yield in both the
categories does not change, the energy balance calcula-
tions have been carried out only for first five years. If the
energy balance is negative at the end of fifth year, the
deficit of energy would never reduce thereafter.

Energy Analysis of Irrigated Jetropha Cultivation for Producing Biodiesel 56
Let us assume that increase in yield is X kg seeds/
hectare of plantation. Considering 38% oil in the seed
cake, 90% efficiency of mechanical extraction, Calorific
value of the oil obtained as 40 MJ/litre and specific grav-
ity of the oil as 0.913 g/cm3 [5], the total energy obtained
from the plant is calculated as:


3
0.380.940 100.913
14.983
outputprimary
EX
X
MJ ofenergyhayr
 

(7)
Table 1. Yield of jetropha due to irri gation.
Year after
planting
Expected
yield–Rain fed
(kg seeds/ha/yr)
Expected
yield–Irrigated
(kg seeds/ha/yr)
Change in yield
(kg seeds/ha/yr)
1st - 250 250
2nd 250 1000 750
3rd 1000 2500 1500
4th 2000 5000 3000
5th 3000 8000 5000
6th and
onwards 4000 12000 8000
Table 2. Total yield of jetropha without irrigation (MT
seeds/ha).
Low Normal High
Year 1 0.10 0.25 0.40
Year 2 0.50 1.00 1.50
Year 3 0.75 1.25 1.75
Year 4 0.90 1.75 2.25
Year 5 1.10 2.00 2.75
Table 3. Total yield of jetropha with irrigation (MT seeds/
ha).
Low Normal High
Year 1 0.75 1.25 2.50
Year 2 1.00 1.50 3.00
Year 3 4.25 5.00 5.00
Year 4 5.25 6.25 8.00
Year 5 5.25 8.00 12.50
Table 4. Energy balance for jetropha plantation with 20 m water table depth.
Year Yield Without Irrigation
(MT seeds/ha/yr)
Yield with
irrigation
(MT seeds/ha/yr)
Increase in Yield
(MT seeds/ha/yr)
Energy Output
due to increase in
Yield (kJ)
Energy required
for irrigation
(kJ)
Energy Balance
(Out–In) (kJ)
Cumulative
Energy Balance
(kJ)
Low rainfall and 20 m depth
1 0.1 0.75 0.65 9737 13942 −4205 −4205
2 0.5 1.0 0.5 7490 13942 −6452 −10657
3 0.75 4.25 3.5 52430 13942 38488 27831
4 0.9 5.25 4.35 65163 13942 51221 79052
5 1.1 5.25 4.11 61567 13942 47625 126677
Normal Rainfall and 20 m Depth
1 0.25 1.25 1.0 14980 13942 1038 1038
2 1.0 1.5 0.5 7490 13942 −6452 −5414
3 1.25 5.0 3.75 56175 13942 42233 36819
4 1.75 6.25 4.5 67410 13942 53468 90287
5 2.0 8.0 6.0 89880 13942 75938 166225
High Rainfall and 20 m Depth
1 0.4 2.5 2.1 31458 13942 17516 17516
2 1.5 3.0 1.5 22470 13942 8528 26044
3 1.75 5.0 3.25 48685 13942 34743 60787
4 2.25 8.0 5.75 86135 13942 72193 132980
5 2.75 12.5 9.75 146055 13942 132113 265093

Energy Analysis of Irrigated Jetropha Cultivation for Producing Biodiesel 57
Table 5. Energy balance for jetropha plantation with 40 m water table depth.
Year Yield Without
Irrigation
(MT seeds/ha/yr)
Yield with
irrigation
(MT seeds/ha/yr)
Increase in Yield
(MT seeds/ha/yr)
Energy Output
due to increase in
Yield (kJ)
Energy required
for irrigation
(kJ)
Energy Balance
(Out–In) (kJ)
Cumulative
Energy Balance
(kJ)
Low Rainfall and 40 m Depth
1 0.1 0.75 0.65 9737 27884 −18147 −18147
2 0.5 1.0 0.5 7490 27884 −20394 −38541
3 0.75 4.25 3.5 52430 27884 24546 −13995
4 0.9 5.25 4.35 65163 27884 37279 23284
5 1.1 5.25 4.11 61567 27884 33683 56967
Normal Rainfall and 40 m Depth
1 0.25 1.25 1.0 14980 27884 −12904 −12904
2 1.0 1.5 0.5 7490 27884 −20394 −33298
3 1.25 5.0 3.75 56175 27884 28291 −5007
4 1.75 6.25 4.5 67410 27884 39526 34519
5 2.0 8.0 6.0 89880 27884 61996 96515
High Rainfall and 40 m Depth
1 0.4 2.5 2.1 31458 27884 3574 3574
2 1.5 3.0 1.5 22470 27884 −5414 −1840
3 1.75 5.0 3.25 48685 27884 20801 18961
4 2.25 8.0 5.75 86135 27884 58251 77212
5 2.75 12.5 9.75 146055 27884 118171 195383
Table 6. Energy balance for jetropha plantation with 60 m water table depth.
Year Yield Without
Irrigation
(MT seeds/ha/yr)
Yield with
irrigation
(MT seeds/ha/yr)
Increase in Yield
(MT seeds/ha/yr)
Energy Output
due to increase in
Yield (kJ)
Energy required
for irrigation
(kJ)
Energy Balance
(Out–In) (kJ)
Cumulative
Energy Balance
(kJ)
Low Rainfall and 60 m Depth
1 0.1 0.75 0.65 9737 41826 −32089 −32089
2 0.5 1.0 0.5 7490 41826 −34336 −66425
3 0.75 4.25 3.5 52430 41826 10604 −55821
4 0.9 5.25 4.35 65163 41826 23337 −32484
5 1.1 5.25 4.11 61567 41826 19741 −12743
Normal Rainfall and 60 m Depth
1 0.25 1.25 1.0 14980 41826 −26846 −26846
2 1.0 1.5 0.5 7490 41826 −34336 −61182
3 1.25 5.0 3.75 56175 41826 14349 −46833
4 1.75 6.25 4.5 67410 41826 25584 −21249
5 2.0 8.0 6.0 89880 41826 48054 26805
High Rainfall and 60 m Depth
1 0.4 2.5 2.1 31458 41826 −10368 −10368
2 1.5 3.0 1.5 22470 41826 −19356 −29724
3 1.75 5.0 3.25 48685 41826 6859 −22865
4 2.25 8.0 5.75 86135 41826 44309 21444
5 2.75 12.5 9.75 146055 41826 104229 125673

Energy Analysis of Irrigated Jetropha Cultivation for Producing Biodiesel 58
Figure 1. Cumulative energy vs. number of years (low rainfall).
Figure 2. Cumulative energy vs. number of years (normal rainfall).
Figure 3. Cumulative energy vs. number of years (high rainfall).

Energy Analysis of Irrigated Jetropha Cultivation for Producing Biodiesel 59
Figure 4. Energy yield stabilization.
4. Energy Balance of Irrigated Jetropha
Cultivation
Due to variation of depth of water table and rainfall, cas-
es for three different values of depth of water tables have
been considered, 20 m, 40 m and 60 m. Each of the three
depths has been examined with different annual rainfall
denoted as low, average and high rainfall conditions.
Thus nine combinations were made for the analysis. Re-
sults of the year wise energy balance for these combina-
tions are presented in Tables 4-6. The graphical repre-
sentation of the energy balance is provided in Figures 1,
2 and 3.
5. Energy Matrix
When we correlate the data obtained from the 3 tables
above, an “Energy Yield Stabilization” matrix can be
created with Depth of the water table on the vertical axis
and the Degree of rainfall on the horizontal axis. The
number of years it takes to pay back the primary energy
used for irrigation (termed as year of stabilization in this
paper) can be indicated as shown in Table 7 below. The
graphical representation of the matrix is provided in
Figure 4.
If we consider the case of Jaipur, the average amount
of rainfall is 500 mm per annum with the average depth
of water table being 40 m [2]. From the above data, if
anyone plans to invest in Jatropha plantation, he/she
would start obtaining profits from the 4th year onwards.
6. Conclusions
From the results shown in Tables 4-6, it can be con-
cluded that areas having low rainfall and water table be
Table 7. Energy yield stabilization matrix.
Depth of Water
Table (m) Low Rainfall Normal Rainfall High Rainfall
20 (m) 3rd year 3rd year 1st year
40 (m) 4th year 4th year 3rd year
60 (m) - 5th year 4th year
low 60 m, irrigated cultivation of bio-diesel will always
have negative energy balance due to high energy re-
quirement for pumping underground water. Whereas, in
areas having normal rainfall and 60 m deep water table,
the energy balance becomes positive only in the fifth
year. In cases of high rainfall, irrigated cultivation of
bio-diesel becomes energy positive in the fourth year.
Low rainfall areas having high water table at 20 m depth,
have neutral energy balance in the third year. Therefore,
irrigated farming of Jetropha in low rainfall and deep
water table areas should be discouraged. Further, if the
energy requirement for oil extraction from seeds, trans-
esterification of oil and other stages is accounted, even
areas having normal rainfall and deep water table would
also become unattractive for irrigated cultivation of bio-
diesel.
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Energy Analysis of Irrigated Jetropha Cultivation for Producing Biodiesel 60
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