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Renewable energy technologies for irrigation water pumping in India: A preliminary attempt towards potential estimation
ARTICLE IN PRESS
Energy 32 (2007) 861–870 www.elsevier.com/locate/energy
Renewable energy technologies for irrigation water pumping in India: A preliminary attempt towards potential estimation Atul Kumara,, Tara C. Kandpalb a
Policy Analysis Division, The Energy and Resources Institute, Darbari Seth Block, IHC Complex, Lodhi Road, New Delhi 110003, India b Centre for Energy Studies, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India Received 27 September 2004
Abstract Simple frameworks have been developed for estimating the utilization potential of: (a) solar photovoltaic (SPV) pumps; (b) windmill pumps; (c) producer gas based dual fuel engine pumps; and (d) biogas based dual fuel engine pumps for irrigation water pumping in India. The approach takes into account factors such as: solar radiation intensity, wind speed, availability of bovine dung and agriresidues, and their alternative uses, ground water requirements for irrigation and its availability, affordability, and propensity of the users to invest in renewable energy devices, etc. SPV pumps are estimated to have the maximum utilization potential in India, followed by windmill pumps. r 2006 Elsevier Ltd. All rights reserved. Keywords: Potential estimation; Renewable energy technologies; Irrigation water pumping
1. Introduction In view of the increasing global climate change concerns, interest in the development and dissemination of renewable energy technologies (RETs) have again been renewed. In India, a fully-fledged Ministry (Ministry of Non-Conventional Energy Sources) is dedicated to the acceleration of RETs development. However, the reported cumulative numbers of dissemination of most of the RETs are very low, particularly for agricultural applications. Table 1 presents the time trend of the reported growth in the cumulative numbers of solar photovoltaic (SPV) pumps and wind pumps installed in the country as against the corresponding values for electric pumps [1]. Fig. 1 depicts this data in graphical form. It may be noted that, though the numbers of renewable energy based pumps are negligibly small as compared to the number of electric pumps, the rate of growth of their dissemination in the country is much higher than the growth rate in the number of electric pumps. Though the measures taken by the Corresponding author. Tel.: +91 11 24682100; fax: +91 11 24682144.
E-mail addresses: [email protected], [email protected] (A. Kumar). 0360-5442/$ - see front matter r 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.energy.2006.05.004
government of India for promoting renewable energy based pumps have primarily contributed to the apparent high rate of growth in their dissemination, their actual contribution is relatively very small. To find out niche areas for immediate intervention, a realistic assessment of the utilization potential of renewable energy sources in agriculture sector is required. An attempt to estimate the utilization potential of following four RET for irrigation water pumping in India has been made: (i) SPV pumps; (ii) windmill pumps; (iii) producer gas based dual fuel engine pumps; and (iv) biogas based dual fuel engine pumps.
2. Factors affecting the utilization potential The potential of RET based pumps for irrigation depends on several factors such as resource availability, groundwater requirement and its availability, affordability of farmers, and farmers’ propensity to invest in a RET based pump, etc. While the issues relating to the first factor (i.e, the resource availability) may vary considerably from one technology option to another, the issues concerning the remaining three factors are expected to be more or less
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common. A brief discussion on the common factors is presented in the following sub sections. 2.1. Groundwater requirement and its availability Since surface water irrigation is usually the cheapest option for irrigation [2], farmers having access to sufficient surface water for irrigation may not choose any other option(s). Therefore, the areas in the country with surface water availability (a fraction fs of the net sown area) [3–5] have not been included in the potential estimation. It is assumed that the surface water, wherever available, is sufficient to meet the irrigation water requirement. Furthermore, only those areas with groundwater requirement (as a fraction of the total areas requiring ground water) have been considered where the ground water table [6] is within a pre-specific depth (which may vary depending upon the RET being used). For example, a centrifugal surface pump coupled with an SPV array is
Table 1 Time-trend of cumulative number of reported installations of SPV pumps, wind pumps and electric pumps in India SPV pumps
Wind pumps
Electric pumps
1993–94 1994–95 1995–96 1996–97 1997–98 1998–99 1999–2000 2000–01 2001–02 2002–03
54 113 463 1816 2481 2787 3131 3575 4208 5113
56 146 244 449 511 637 714 793 888 945
10276000 10721300 11101100 11565300 11849400 12216700 12514200 12823500 13043900 13792400
Cumulativenumber of SPV and Wind pumps (in number)
Year
usually considered for shallow well water pumping. The maximum suction head for such a surface pump is reported to be 7 m [7]. SPV systems with a submersible pump are reportedly capable of deep well water pumping up to 70 m [7]. However, such deep well irrigation pumping may not always be economical [8]. As a consequence, SPV water pumping for irrigation is preferably carried out in areas with ground water table less than 10 m. Similarly the water output of commonly available windmill pumps is reported to be rather low for a head of more than 20 m. A surface mounted dual fuel engine pump coupled with a biomass gasifier or biogas plant is usually recommended for areas with ground water table up to 5 m [9]. Central ground water board (CGWB) monitors the ground water table in India from a network of about 15 000 stations. Measurements of ground water tables are taken at these stations four times in a year. It is observed that during pre monsoon period (May month) with maximum irrigation water demand the ground water table is deepest [6]. Therefore, the ground water table for the month of May (pre-monsoon period) has been considered in this study [6]. Table 2 presents the state wise net sown area, its fraction of area under surface irrigation (fs) and the area with different ground water table in India (as a fraction of total area requiring ground water) [3,4,6]. 2.2. Affordability of the user To make a preliminary assessment of the affordability of a farmer to invest in a RET based water pumping system a comparison of the total annual cost likely to be incurred by the farmer with his annual income from agriculture can be made. The following assumptions are made to estimate the total annual cost of RET based water pumping system.
6000
15.0
5000
12.5
10.0
4000 SPV pumps
Wind pumps
Electric pumps
3000
7.5
2000
5.0
1000
2.5
Cumulative number of electric pumps (in millions)
862
0 0.0 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 Year Fig. 1. Time-trend of cumulative number of reported installations of SPV pumps, wind pumps and electric pumps in India.
ARTICLE IN PRESS A. Kumar, T.C. Kandpal / Energy 32 (2007) 861–870 Table 2 State wise net sown area (As), its fraction irrigated by surface water (fs) and area with different ground water table in India State
Andhra Pradesh Arunachal Pradesh Assam Biharb Goa Gujarat Haryana Himachal Pradesh Karnataka Kerala Madhya Pradeshc Maharashtra Orissa Punjab Rajasthan Tamil Nadu Uttar Pradeshd West Bengal
As (thousand hectare)
fs (fraction)
Area with different ground water table (as a fraction of the total area requiring ground water) Up to 5 m
Up to 10 m
14460 350
0.1710 —a
0.3153 0.4444
0.8054 1.0000
3205 10743 67 10292 3711 1010
0.1129 0.1107 0.1045 0.0624 0.3697 0.0040
0.7424 0.4850 0.7456 0.1958 0.3763 0.2817
0.9694 0.9621 1.0000 0.5602 0.7025 0.6056
12321 1796 22111
0.0941 0.0863 0.0943
0.2153 0.3823 0.1367
0.6615 0.8242 0.6709
20925 5296 4033 20971 7474 17986 5656
0.0433 0.2368 0.3362 0.0830 0.2015 0.1764 0.1733
0.2116 0.4901 0.3439 0.1577 0.4678 0.4387 0.3473
0.7376 0.9517 0.7549 0.3963 0.8377 0.8457 0.8069
863
Haryana is assumed to be applicable for other states of India as well in the example case(s) presented in the paper. The framework presented in this study can be used with better realistic value as and when available. On the basis of farm size, the farmers in India are classified in five categories (marginal, small, semi-medium, medium, and large) [4]. The willingness to pay for irrigation of farmers of respective categories have been estimated on the bases of an all India average land holding size of different categories of farmers [4]. 2.3. Propensity of the user to invest in a renewable energy technology based pump The propensity of the user to invest in a RET based pump will depend on the awareness and knowledge of the user about the technology for water pumping and also on the availability, reliability, and economics of conventional options to him. A factor (varying from 0 to 1) named propensity factor can be used to express the same. In this study the value of propensity factor for marginal, small, and semi-medium farmers has been assumed at 0.2 while it is assumed to be 0.8 for medium and large farmers. As mentioned earlier, a large variation is expected in the case of resource availability for the technology options for water pumping considered in this study. The following section presents the resource availability related issues for all the four RET options for irrigation water pumping.
a
Negligible area. Including Jharkhand. c Including Chattisgarh. d Including Uttaranchal. b
3. Resource availability for renewable energy technology options
A fraction fcs of the capital cost (C0) of the system may be provided as capital subsidy to the user by the government. A fraction fis of the balance of the cost (after capital subsidy) may be provided as loan to the farmer for a period of t years at an interest rate r (in fraction). The remaining fraction of the capital cost is assumed to be paid by the user out of his savings. This fraction is not considered for the estimation of annual expenses of the system. The annual operation, repair and maintenance cost of the system can be expressed as a fraction m of its capital cost. Mathematically, the annual expenses (Ca) can be expressed as rð1 þ rÞt C a ¼ C 0 ð1 f cs Þf is þ m , ð1 þ rÞt 1
3.1. SPV pumps It is recommended that for installing SPV pumps, the average daily solar radiation in the least sunny month should be greater than 3.5 kW/m2 on a horizontal surface [10]. Ideally, detailed solar radiation data for each location should be used in evaluating the potential of using an SPV pump. However, to make an initial macrolevel assessment, broad solar radiation availability characteristics readily available in the literature [11] are used. On a macrolevel, seven north-eastern sates and the northern states of Jammu and Kashmir, Himachal Pradesh and Uttranchal in India can be given low priority in the process of identification of niche areas for installation of SPV pumps. 3.2. Windmill pumps
(1) 1
A study carried out by World Bank for the state of Haryana has estimated the gross agricultural income and farmers’ willingness to pay for irrigation [2]. Since data for all states of India is not available, the per hectare value for 1 India is divided into following main administrative units arranged hierarchically: state, division, district, block, and village.
The water output of a windmill pump is very sensitive to any variation in wind speed. Wind speed at any location depends upon a variety of site specific factors and large variations in annual monthly mean wind speeds have been reported at different locations in a state [12–15]. Therefore, analysis for the estimation of potential of windmill pumps for irrigation water pumping in India has been carried out using district wise data on resource availability, net sown
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area, surface water irrigation, and ground water table, etc. [5,6,12–15]. The wind speed at any location increases with an increase in height from the ground level. In most of the prevailing windmill pump designs rotor is fixed on a tower at about 10 meters height from the ground. From the available data on measured values of annual monthly mean wind speed at different locations [12–15], the annual monthly mean wind speeds at the 10 m height from the ground level (v10) have been estimated by using the following relation [15,16]: a 10 , (2) v10 ¼ vh h
available as feedstock for large-scale dissemination of producer gas based dual fuel engine pumps. Agro-processing residues such as rice husk, groundnut shells and bagasse, etc. also may not be available for the use as feedstocks for agricultural water pumping systems, as these may be used by the respective agro-processing units for meeting their own thermal/electrical energy requirement. Some crop residues may find use as fodder and/or fertilizer. Hence, the following non-fodder, non-fertilizer crop residues have been considered as potential feedstocks: (a) arhar stalks; (b) cotton stalks; (c) jute sticks; (d) maize cobs and stalks; and (e) mustard stalks. These residues are available in substantial amounts in the country and have also been found suitable as feedstocks in biomass gasifiers [4,19]. The annual amount of crop residue produced depends on the annual crop production and the corresponding residue to crop ratio (Rj) [20]. A fraction (fl) of the total amount of crop residues produced may be lost during collection. A fraction (fou) of the collected crop residues may be used in other applications [21]. The amount (Qr,j) of jth crop residue available per hectare of sown area can be estimated as
where vh represents the annual monthly mean wind speed measured at a reference height of h meters from the ground level and a the ground surface friction coefficient. Though the value of a varies from 0.1 to 0.5 depending upon the terrain of the location, a value of 0.2 as reported for crops and shrubs type terrain has been used in the study [16]. As the reported water output of commercially available windmill designs at wind speeds below 10 km/h is very low [17], the areas with annual monthly mean wind speeds greater than 10 km/h (as a fraction, fw, of the net sown area in the district) only have been considered in this study for windmill pump based irrigation.
Qr;j ¼ Y j Rj ð1 f l Þð1 f ou Þ,
(3)
where Yj represents the yield of jth crop in the state and Rj the residue to crop ratio for jth crop. It is assumed that producer gas based dual fuel engine pumps for irrigation can only be used in those states where the crop(s) considered in this study are produced in
3.3. Producer gas based dual fuel engine pumps In view of decreasing availability of fuel wood from forests in India [18], it is assumed that the same is not
Table 3 State wise sown area and yield of selected crops in India (for the year 2000–01) State
Arhar Sown area (thousand hectares)
Andhra Pradesh Assam Biharb Gujarat Haryana Himachal Pradesh Jammu and Kashmir Karnataka Madhya Pradeshc Maharashtra Orissa Punjab Rajasthan Tamil Nadu Uttar Pradeshd West Bengal a
510 —a 60 320 — — — 580 350 1100 150 — — 80 400 —
Very small. Including Jharkhand. c Including Chattisgarh. d Including Uttaranchal. b
Cotton Yield (kg/ha)
426 1280 337
441 665 602 503
710 1254
Jute
Maize
Mustard
Sown area (thousand hectares)
Yield (kg/ha)
Sown area (thousand hectares)
Yield (kg/ha)
Sown area (thousand hectares)
Yield (kg/ha)
Sown area (thousand hectares)
1020 — — 1620 560 — — 560 510 3080 — 470 510 190 — —
277
80 70 170 — — — — — — 30 30 — — — — 620
1586 1674 1410
520 — 730 400 — 300 330 670 820 260 — 160 970 120 910 40
2727
— 270 110 190 400 — — — 450 — — 50 1430 — 910 440
122 424
298 80 100 430 268 285
266 908
2167
2159 1550 2293 1592 3157 1468 850 2793 1047 1619 1632 2501
Yield (kg/ ha)
514 933 1236 1371
804
1222 918 987 956
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substantial amounts. In fact, in this study, only those state and crop combinations are considered, where the crop yield is enough to provide the amount of residue that is required as feedstock for irrigating at least one crop in a year. The sown areas of different crops considered in this study along with their respective yields for various states are presented in Table 3 [4]. To avoid ambiguity it is assumed that a farmer with surplus availability of the crop residue is not trading the surplus amount with any other farmer. 3.4. Biogas based dual fuel engine pumps It has been reported that households having less than four bovines cannot normally install family size biogas plants [22]. Therefore, in this study it is assumed that households owning 1–3 bovines may contribute dung for operation of community type biogas plants for supplying biogas to a dual fuel engine pump for irrigation water pumping (besides other end uses). Based on the 1991 census data on the livestock holding and its distribution in 16 states of India (Table 4), number of households owning 1–3 bovines have been estimated [23]. An average value of 10.88 kg of dung availability per bovine is assumed in this study [24]. It is also assumed that only 75% of the available dung is finally collected. It is also assumed that 25 kg of raw dung has to be fed daily to the biogas plant per m3 of rated capacity of the biogas plant [24].
Table 4 Pattern of bovine ownership in different states of India (for the year 1991) State
Andhra Pradesh Assam Bihara Gujarat Haryana Himachal Pradesh Karnataka Kerala Madhya Pradeshb Maharashtra Orissa Punjab Rajasthan Tamil Nadu Uttar Pradeshd West Bengal a
Number of rural households (thousand)
n¼1
n¼2
10327 3364 12175 4804 1882 861
12 12 17 14 14 8
11 11 17 13 13 8
7 7 8 12 12 11
5552 4102 8945
12 14 10
11 14 9
9 5 8
4. Framework used for potential estimation 4.1. SPV pumps On the basis of assumptions made in earlier section, net sown area in a state with requirement for ground water and also its availability (Ag) can be estimated as Ag ¼ As ð1 f s Þf g10 ,
(4)
where As represents the net sown area in the state, fs the areas in the state with surface water availability (as a fraction of the net sown area in the state), and fg10 the area with ground water table up to 10 m (as a fraction of the total area requiring ground water in the state). As discussed earlier, the factors pertaining to affordability of the users and their propensity to invest in an SPV pump are quite different for farmers of different categories. Therefore, a category wise break-up of the above estimated area has been used for further analysis. The net sown area with requirement and availability of ground water for ith category of farmers (Ag,i) can be expressed as Asg;i ¼ As ð1 f s Þf g10 f lh;i ,
(5)
where flh,i represents the net sown area operated by ith category of farmers (on the basis of land holding size) as a fraction of net sown area in the state (i ¼ 1; 2; 3; 4, and 5 correspond to marginal, small, semi-medium, medium, and large, respectively) [4]. Using average size of land holding of different categories of farmers in the state [4], the number of farmers of ith category (Nsg,i) that own the above estimated area (Eq. (5)) can be determined as N sg;i ¼
n¼3
As ð1 f s Þf g10 f lh;i , Si
(6)
where Si represents the average size of land holding of ith category of farmers in the state. Finally, using correction factors for the affordability of the ith category of farmers (fa,i) and their propensity to invest in SPV pumps (fp,i) the potential number of SPV pump users (Nspv) in the state can be estimated as N spv ¼
5 X ðN g;i f a;i f p;i Þ.
(7)
i¼1
9259 5168 2355 5574 8435 18024 8910
Including Jharkhand. Including Chattisgarh. c Very small (negligible). d Including Uttaranchal. b
Rural households owning n bovines as a % of all rural households
865
10 14 14 10 12 20 13
9 14 13 10 11 19 13
6 7 12 —c 5 13 7
Two sizes of SPV pumps (0.9 and 1.8 kWp) are commercially available in India. The financial incentives provided by government are available for purchasing only one pump. Therefore, in the initial phase of dissemination it is assumed that the farmer will install either of the two pumps depending upon his need and affordability. In this study it is assumed that the farmers with large land holdings will continue to use other conventional pumps for satisfying their balance water requirement for irrigation.
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4.2. Windmill pumps
producer gas based dual fuel engine pump. Xcr,j can be estimated as
On the basis of assumptions made in Section 3.2, net sown area (Awg) with requirement for ground water and also its availability in a district where annual monthly mean wind speed is greater than 10 km/h can be estimated as Awg ¼ As;d f w ð1 f s;d Þf g20 ,
(8)
where As,d, fs,d and fg20, respectively, represent the net sown area, fraction of sown area under surface irrigation and the fraction of total area requiring ground water with ground water table up to 20 m in the district [5,6,12–15]. As discussed earlier the factors pertaining to affordability of the users and their propensity to invest in a windmill pump is different for farmers of different categories. Therefore, the category wise numbers of farmers owning the area as estimated by Eq. (8) need to be obtained. Since district level data on sizes of land holdings and land holdings distribution among different categories of farmers are not available, it is assumed that the values pertaining to a state [4] are applicable for each district of that state. Thus, the number of farmers of ith category (Nwg,i) that own the above estimated area (Eq. (8)) can be estimated as N wg;i ¼
As;d f w ð1 f s;d Þf g20 f lh;i . Si
(9)
As in the case of SPV pumps, by introducing correction factors for affordability of the farmers and their propensity to invest in windmill pumps the potential number of windmill pump users (Nwp) in the district can be estimated as N wp ¼
5 X ðN wg;i f a;i f p;i Þ.
(10)
X cr;j ¼
3:6ðPpg rd;pg Þ , CV cr;j Zgas Zdfe
where j ¼ 1; 2; 3; 4; 5 correspond to arhar stalk, cotton stalk, jute sticks, maize cobs and stalk, and mustard stalk respectively. Therefore, the annual hours of operation (tav;j ) of a producer gas based dual fuel engine pump using the crop residue available from one hectare sown area of jth crop can be estimated as tav;j ¼
Qr;j . X cr;j
Ag;j ¼ As;j ð1 f s Þf g5 ,
trq ¼
rw gHV w , 3:6 106 ðPpg Zdp Þ
(11)
where rw represents the density of water, g the acceleration due to gravity, H the total head, Vw the volume of water required for irrigating one hectare land during a single cropping season, Ppg the size of producer gas based dual fuel engine pump (in kW) and, Zdp the efficiency of the pump used with the dual fuel engine. The rate of consumption (Xcr,j) of jth crop residue in a producer gas based dual fuel engine pump of rated capacity, Ppg, would also depend upon its calorific value (CV cr;j ), efficiency of gasifier (Zgas), efficiency of dual fuel engine (Zdfe), and diesel replacement factor (rd,pg) of the
(14)
where As,j represents the sown area of jth crop in the state, fg5 the area with 5 m ground water table (as a fraction of area requiring ground water). This exercise has been undertaken only for those state and crop combinations for which the value of tav,j is greater than the required hours of operation (trq) as estimated from Eq. (11). Similarly, as in pervious cases, using distribution of land holdings among different categories of farmers and their average size of land holdings, the number of ith category of farmers (N pg;j;i ) growing the jth crop and owning the area as estimated by Eq. (14) can be estimated as N pg;j;i ¼
The required hours of operation (trq) of a producer gas based dual fuel engine pump for irrigating one hectare land can be estimated as
(13)
For each of the crop considered in this study, it is assumed that the prevailing situation pertaining to the surface water availability, land holding sizes, land holding distribution among farmers, and the ground water table is the same over the entire state. Thus, the sown area of a crop with ground water requirement and its availability (Ag,j) can be estimated as
i¼1
4.3. Producer gas based dual fuel engine pumps
(12)
As;j ð1 f s Þf g5 f lh;i . Si
(15)
Once again, using correction factors for the affordability of farmers and their propensity to invest in a producer gas based dual fuel engine pump the potential number of producer gas based dual fuel engine pump users (Npg) in the state can be estimated as N pg ¼
5 X 5 X ðN pg;j;i Þf a;i f p;i .
(16)
i¼1 j¼1
4.4. Biogas based dual fuel engine pumps A 20 m3 daily biogas production capacity community biogas plant has been chosen as it can provide sufficient volume of biogas for operating a 7.46 kW (10 hp) dual fuel engine pump with reasonable capacity utilization factor. In the case of community biogas plants (being considered in this study for providing biogas to the dual fuel engine pump) the affordability criteria can be somewhat relaxed.
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Moreover, due to economy of scale, the unit cost of community biogas plant (per m3 biogas production capacity) would be much lower than that for family size biogas plants. Thus, it is possible for the participating users to share equity funds for the installation of the biogas plant and other equipment for the system. However, an index of community participation (l) has been introduced to take into account the practical problems faced in such a participatory programme. In fact, a low value (0.10) has been assigned to the index of participation in this study to obtain rather conservative estimates. It may be noted that the index of community participation would also take into account the propensity of the individuals to invest in a community biogas plant based water pumping system. Further, the value of l can only be estimated through detailed field survey based studies. In the absence of such studies, in the present work, the value is assumed on the basis of discussion with the experts in the relevant areas. Considering all the above mentioned factors the potential number of community biogas plants (Nbg) that can be used for irrigation water pumping in a state can be estimated by the following relation: 1 lðN h1 þ 2N h2 þ 3N h3 Þð10:88 0:75Þ N bg ¼ 20 25 ð1 f s Þf g5 ,
ð17Þ
where Nh1, Nh2 and Nh3 represent the number of households owning 1, 2 and 3 bovines, respectively, in a state. As in the cases of other three technological options the product ‘(1fs)fg5’ is used to consider the area with ground water requirement and its availability. 5. Results and discussion The use of the framework presented in the earlier section requires detailed data on a variety of input parameters. However, due to unavailability of required data an initial exercise towards estimation of potential numbers and identification of niche areas has been undertaken on the basis of the proposed framework. Table 5 presents the state wise average sizes of land holding of different categories of farmers in India [4]. The fractional distribution of net sown area among different categories of farmers in various states of India is presented in Table 6 [4]. Other input parameters used in calculations are presented in Table 7 [9]. Using the base values of various input parameters, as presented earlier some exemplifying calculations have been made and the results obtained are briefly presented in this section. On the basis of assumptions made in Sections 2, 3 and 4, and the values of input parameters as listed in Table 7, the categories of farmers who can afford to invest in SPV pump, windmill pump and producer gas based dual fuel engine pump are indicated in Table 8. It may be noted that only for these combinations of category of farmers and RET based pumps, the affordability factor (fa,i) is assigned a value of one (1) while for others it is assumed to be zero.
867
Table 5 State wise average sizes of land holdings of different categories of farmers (for the year 1990–91) State
Marginal farmers (ha)
Small farmers (ha)
Semimedium farmers (ha)
Medium farmers (ha)
Large farmers (ha)
Andhra Pradesh Arunachal Pradesh Assam Bihara Goa Gujarat Haryana Himachal Pradesh Karnataka Kerala Madhya Pradeshb Maharashtra Orissa Punjab Rajasthan Tamil Nadu Uttar Pradeshc West Bengal All India Average
0.45 0.63
1.43 1.53
2.71 2.80
5.86 5.65
15.66 16.40
0.40 0.35 0.33 0.53 0.47 0.40
1.40 1.36 1.54 1.47 1.52 1.42
2.68 2.73 2.25 2.83 2.81 2.74
5.18 5.65 4.50 5.99 5.86 5.69
80.80 16.41 19.00 16.45 15.41 16.17
0.47 0.17 0.45
1.46 1.37 1.45
2.75 2.60 2.78
5.93 5.43 6.04
15.28 59.33 16.44
0.49 0.49 0.55 0.48 0.36 0.38 0.44 0.39
1.46 1.38 1.61 1.44 1.41 1.41 1.53 1.43
2.77 2.63 2.91 2.85 2.73 2.73 2.78 2.76
5.86 5.40 6.21 6.23 5.71 5.55 5.39 5.90
15.13 16.80 16.07 19.11 18.52 15.42 203.00 17.33
a
Including Jharkhand. Including Chattisgarh. c Including Uttaranchal. b
Table 9 presents the estimated potential of four RET options considered for irrigation water pumping in this study. Potential number of SPV pumps are estimated at 6.03 million (out of which 4.29 million are of capacity of 1.8 kWp and the balance 1.74 million of capacity of 0.9 kWp). With 1.06 million SPV pumps the state of Maharashtra in India has highest utilization potential closely followed by Madhya Pradesh (0.99 million). Since the percentage share of marginal and small farmers is very high in the states of Kerala and West Bengal, in spite of large area with ground water table of less than 10 m in these states, the estimated potential of SPV pumps is very low as compared to the total number of farmers. Moreover, due to larger number of smaller land holdings in Kerala and West Bengal, the potential number of 0.9 kWp SPV pumps is much higher than that of 1.8 kWp SPV pumps. In other states it is just the reverse as the land holding are larger. The potential number of windmill pumps for irrigation is estimated at 2.39 million. In view of long coastal area, large number of farmers with small or higher land holdings, and substantial area under 20 m ground water table the state of Maharashtra has highest utilization potential of windmill pumps (0.64 million), followed by another coastal state
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Table 6 State wise fractional distribution of net sown area among different categories of farmers in India (for the year 1990–91) State
Andhra Pradesh Arunachal Pradesh Assam Bihara Goa Gujarat Haryana Himachal Pradesh Karnataka Kerala Madhya Pradeshb Maharashtra Orissa Punjab Rajasthan Tamil Nadu Uttar Pradeshc West Bengal Lakshdweep A& N island
Marginal farmers
Small farmers
Semimedium farmers
Medium farmers
Large farmers
0.1638 0.0286
0.1955 0.0743
0.2517 0.2400
0.2612 0.4200
0.1278 0.2343
0.1894 0.3343 0.2836 0.0475 0.0795 0.2129
0.2446 0.1819 0.1642 0.1305 0.1248 0.2327
0.2864 0.2398 0.1343 0.2444 0.2544 0.2554
0.1535 0.1845 0.1343 0.3891 0.3503 0.2030
0.1261 0.0596 0.2836 0.1886 0.1911 0.0960
0.0870 0.4816 0.0637
0.1873 0.2133 0.1259
0.2597 0.1420 0.2188
0.3061 0.0635 0.3515
0.1600 0.0991 0.2401
0.0773 0.1973 0.0407 0.0346 0.2834 0.3143 0.3649 1.0000 0.0370
0.1903 0.2693 0.0813 0.0700 0.2400 0.2441 0.2995 0.0000 0.1111
0.2810 0.2948 0.2088 0.1441 0.2257 0.2338 0.2244 0.0000 0.2963
0.3276 0.1911 0.4022 0.3020 0.1741 0.1691 0.0753 0.0000 0.3333
0.1237 0.0476 0.2670 0.4493 0.0768 0.0386 0.0359 0.0000 0.1852
a
Including Jharkhand. Including Chattisgarh. c Including Uttaranchal. b
Karnataka. Once again due to dominance of marginal land holdings (unable to satisfy affordability criteria) the estimated potential of windmill pump utilization for the state of Kerala is rather low. Owing to a variation in the calorific value of different crop residues and the corresponding values of residue to crop ratios, yields of the respective crops in the state, etc., the number of feasible hours of operation of a 3.73 kW (5 hp) producer gas based dual fuel engine pumps would vary considerably for different combinations of residues and states. The potential of producer gas based dual fuel engine pumps for irrigation pumping in India is estimated at 0.46 million with highest potential in the state of Maharashtra. It is estimated that around 36 thousand community biogas plants of 20 m3 daily biogas production capacity can be installed for irrigation pumping in India. Since a dual fuel engine pump can be used with a community type biogas plant, the potential number of biogas based dual fuel engine pumps is essentially equal to the potential number of community biogas plants. Uttar Pradesh has the highest potential (approximately 10,000 plants) of community biogas plants for irrigation pumping. It may be noted that the number of SPV pumps users (Nspv) or windmill pumps users (Nwp) also correspond to
Table 7 List of input parameters used in calculations
Capital cost of the system
Parameter
Symbol
Unit
Value
SPV pump (0.9 kWp) SPV pump (1.8 kWp) Windmill pump Producer gas based dual fuel engine pump (5 hp) SPV pump (0.9 kWp) SPV pump (1.8 kWp) Windmill pump Producer gas based dual fuel engine pump (5 hp)
C0
Rs Rs Rs Rs
170 000 328 000 104166 75000
m
Fraction Fraction Fraction Fraction
0.01 0.01 0.02 0.05
fcs
Fraction
0.50
fis
Fraction
0.80
r t CVar,j
fl
Fraction Years MJ/kg MJ/kg MJ/kg MJ/kg MJ/kg Fraction Fraction Fraction Fraction Fraction Fraction
0.10 10 14.88 17.88 19.04 14.53 18.84 1.32 3.00 2.30 1.86 1.85 0.10
fou
Fraction
0.20
H
m
5
Vw
m3
6000
Zgas Zdfe Zdp
Fraction Fraction Fraction
0.80 0.23 0.40
rd,pg
Fraction
0.80
Annual operation, repair and maintenance cost (as a fraction of capital cost) Capital subsidy (as a fraction of the capital cost) Amount of low interest loan (as a fraction of the balance of the cost) Interest rate on loan Loan repayment period Calorific Arhar stalks value of Cotton stalks agricultural Jute and sticks residues Maize cobs and stalks Mustard stalks Residue to Arhar stalks crop ratio Cotton stalks Jute and sticks Maize cobs and stalks Mustard stalks Fraction of the total amount of crop residues produced that may be lost during collection. Fraction of the collected crop residues that may be used in other applications Total pumping head Volume of water required for irrigating one hectare land during a single cropping season Efficiency of gasifier Efficiency of dual fuel engine Efficiency of the pump used with the dual fuel engine Diesel replacement factor of the producer gas based dual fuel engine pump
Rj
the area of land that one SPV pump or windmill pump can effectively irrigate. However, this study assumes that one farmer can not own more than on SPV pump or other renewable energy based pump. Though the size(s) of the same may vary. 6. Concluding remarks Though the compounded annual rate of growth in the number of electric pumps in the country is merely 3%
ARTICLE IN PRESS A. Kumar, T.C. Kandpal / Energy 32 (2007) 861–870 Table 8 Categories of farmers who can afford to invest in SPV pump, windmill pump, and producer gas based dual fuel engine pump Renewable energy option for water pumping
Size
Categories of farmers who can afford to invest in the renewable energy option
SPV pump
0.9 kWp 1.8 kWp —
Semi medium Medium, large Small, semi medium, medium, large Small, semi medium, medium, large
Windmill pump Producer gas based dual fuel engine pump
3.73 kW (5 hp)
SPV pumps
Windmill Producer gas pumps based dual fuel engine pumps
Biogas based dual fuel engine pumps
0.9 kWp 1.8 kWp Andhra Pradesh Assam Biharb Gujarat Haryana Himachal Pradesh Karnataka Kerala Madhya Pradeshc Maharashtra Orissa Punjab Rajasthan Tamil Nadu Uttar Pradeshd West Bengal Goa Andmand and Nicobar Island All India
Even with rather conservative values of relevant input parameters the estimates indicate that, there is a vast potential of renewable energy utilization for irrigation water pumping in India. Out of four renewable energy technologies considered in this study, the estimated utilization potential of SPV pumps is highest followed by windmill pumps. The potential is estimated considering the prevailing conditions such as cost and technical specification of renewable energy based devices, income of farmers, etc. The future potential of renewable energy use may increase due to cost reductions and/or technology advancement, as well as increase in income of farmer. References
Table 9 Potential of different renewable energy technologies for irrigation pumping in India (thousands) State
869
179 59 161 93 30 —
407 68 267 331 95 —
274 —a — 442 — —
49 18 34 45 21 7
2.42 1.99 6.43 0.91 0.55 0.22
139 15 211 300 86 29 77 83 215 61 1 —
367 14 783 757 118 132 439 139 330 43 2 —
549 38 81 643 90 — 123 132 3 — 9 6
33 — 18 88 6 14 33 12 63 21 — —
1.08 1.33 0.94 1.41 1.99 0.67 0.39 2.52 10.31 2.51 — —
6031
2390
462
35.67
a
Negligible or not estimated. Including Jharkhand. c Including Chattisgarh. d Including Uttaranchal. b
(primarily due to increasing uncertainty in the availability of electricity) the incremental annual number of new electric pumps is far more than the reported cumulative number of renewable energy based pumps disseminated so far. It is therefore, extremely important to develop appropriate technologies for this purpose beside formulating and implementing suitable dissemination strategies for renewable energy based options for water pumping.
[1] The Energy and Resources Institute. TERI energy data directory and yearbook 2003/04. New Delhi, India: TERI Press; 2004. [2] World Bank. Power supply to agriculture, vol. 1. Report no. 22171IN. Washington, DC: Energy Sector Unit, South Asia Regional Office World Bank, 2001. [3] The Fertilizer Association of India. Fertilizer statistics 1999–2000. 10, New Delhi, India: FAI, Shaheed Jit Singh Marg; 2000. [4] Ministry of Agriculture. Agricultural statistics at a glance. New Delhi, India: MOA, Government of India, Krishi Bhavan, Dr. Rajendra Prasad Road; 2002. [5] Ministry of Agriculture. Indian agricultural statistics 1992–1993. vols. I, II, all India, state-wise and district-wise. New Delhi, India: MOA, Government of India, Krishi Bhavan, Dr. Rajendra Prasad Road; 1993. [6] Central Ground Water Board. Ground water year book. Reports of various states in India. New Delhi, India: CGWB, Government of India, Jamnagar House, Mansingh Road, 2001. [7] Central Electronics Limited. Solar powered water pumping system. Product brochure. Sahibabad (UP), India: CEL, 4, Industrial Area; 2003. [8] Bhattacharya T. Terrestrial solar photovoltaics. New Delhi, India: Narosa Publishing House; 1998. [9] Kumar A. CO2 emissions mitigation by using renewable energy technologies for irrigation water pumping and crop drying in India, Doctoral thesis. New Delhi, India: Indian Institute of Technology Delhi; 2004. [10] United Nations Economic and Social Commission for Asia and Pacific. Solar powered water pumping in Asia and the Pacific. Bangkok, Thailand: UNESCAP, The United Nations Building, Rajadamnern Nok Avenue; 1991. [11] Mani A, Rangarajan S. Solar radiation over India. New Delhi, India: Allied Publishers Private Limited; 1982. [12] Mani A, Mooley DA. Wind energy data for India. New Delhi, India: Allied Publishers Private Limited; 1983. [13] Mani A. Wind energy resources survey for India—I. New Delhi, India: Allied Publishers Private Limited; 1990. [14] Mani A. Wind energy resources survey for India—II. New Delhi, India: Allied Publishers Private Limited; 1992. [15] Mani A. Wind energy resources survey for India—III. New Delhi, India: Allied Publishers Private Limited; 1994. [16] Patel MR. Wind and solar power systems. New York: CRC Press; 1999. [17] Ministry of Non-Conventional Energy Sources. Global windpump evaluation programme, preparatory phase: country study on India. New Delhi, India: MNES, Government of India, 14 CGO Complex. Lodhi Road, 1987. [18] Rai SN, Chkrabarty SK. Demand and supply of fuelwood and timber in India. Ind Forest 2001;3:263–79. [19] Grover PD. Thermochemical characterization of biomass residues for gasification. New Delhi, India: Biomass Research Laboratory,
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Chemical Engineering Department, Indian Institute of Technology Delhi; 1989. [20] National Productivity Council. A report on improvement of agricultural residues and agro-by-products utilisation. New Delhi, India: NPC, Utpadakta Bhavan, 5-6 Institutional Area, Lodhi Road; 1987. [21] Tripathi AK, Iyer PVR, Kandpal TC, Singh KK. Assessment of availability and costs of some agricultural residues used as feedstocks for biomass gasification and briquetting in India. Energy Conver Manag 1998;39(15):1611–8.
[22] Purohit P, Kumar A, Rana S, Kandpal TC. Using renewable energy technologies for domestic cooking in India: a methodology for potential estimation. Renew Energy 2002;26(2):235–46. [23] Centre for Monitoring Indian Economy. Basic statistics relating to the Indian economy. Bombay, India: Centre for Monitoring Indian Economy Private Ltd.; 1993. [24] Rubab S, Kandpal TC. A methodology for financial evaluation of biogas technology in India using cost functions. Biomass Bioenergy 1996;10(1):11–23.
Energy 32 (2007) 861–870 www.elsevier.com/locate/energy
Renewable energy technologies for irrigation water pumping in India: A preliminary attempt towards potential estimation Atul Kumara,, Tara C. Kandpalb a
Policy Analysis Division, The Energy and Resources Institute, Darbari Seth Block, IHC Complex, Lodhi Road, New Delhi 110003, India b Centre for Energy Studies, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India Received 27 September 2004
Abstract Simple frameworks have been developed for estimating the utilization potential of: (a) solar photovoltaic (SPV) pumps; (b) windmill pumps; (c) producer gas based dual fuel engine pumps; and (d) biogas based dual fuel engine pumps for irrigation water pumping in India. The approach takes into account factors such as: solar radiation intensity, wind speed, availability of bovine dung and agriresidues, and their alternative uses, ground water requirements for irrigation and its availability, affordability, and propensity of the users to invest in renewable energy devices, etc. SPV pumps are estimated to have the maximum utilization potential in India, followed by windmill pumps. r 2006 Elsevier Ltd. All rights reserved. Keywords: Potential estimation; Renewable energy technologies; Irrigation water pumping
1. Introduction In view of the increasing global climate change concerns, interest in the development and dissemination of renewable energy technologies (RETs) have again been renewed. In India, a fully-fledged Ministry (Ministry of Non-Conventional Energy Sources) is dedicated to the acceleration of RETs development. However, the reported cumulative numbers of dissemination of most of the RETs are very low, particularly for agricultural applications. Table 1 presents the time trend of the reported growth in the cumulative numbers of solar photovoltaic (SPV) pumps and wind pumps installed in the country as against the corresponding values for electric pumps [1]. Fig. 1 depicts this data in graphical form. It may be noted that, though the numbers of renewable energy based pumps are negligibly small as compared to the number of electric pumps, the rate of growth of their dissemination in the country is much higher than the growth rate in the number of electric pumps. Though the measures taken by the Corresponding author. Tel.: +91 11 24682100; fax: +91 11 24682144.
E-mail addresses: [email protected], [email protected] (A. Kumar). 0360-5442/$ - see front matter r 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.energy.2006.05.004
government of India for promoting renewable energy based pumps have primarily contributed to the apparent high rate of growth in their dissemination, their actual contribution is relatively very small. To find out niche areas for immediate intervention, a realistic assessment of the utilization potential of renewable energy sources in agriculture sector is required. An attempt to estimate the utilization potential of following four RET for irrigation water pumping in India has been made: (i) SPV pumps; (ii) windmill pumps; (iii) producer gas based dual fuel engine pumps; and (iv) biogas based dual fuel engine pumps.
2. Factors affecting the utilization potential The potential of RET based pumps for irrigation depends on several factors such as resource availability, groundwater requirement and its availability, affordability of farmers, and farmers’ propensity to invest in a RET based pump, etc. While the issues relating to the first factor (i.e, the resource availability) may vary considerably from one technology option to another, the issues concerning the remaining three factors are expected to be more or less
ARTICLE IN PRESS A. Kumar, T.C. Kandpal / Energy 32 (2007) 861–870
common. A brief discussion on the common factors is presented in the following sub sections. 2.1. Groundwater requirement and its availability Since surface water irrigation is usually the cheapest option for irrigation [2], farmers having access to sufficient surface water for irrigation may not choose any other option(s). Therefore, the areas in the country with surface water availability (a fraction fs of the net sown area) [3–5] have not been included in the potential estimation. It is assumed that the surface water, wherever available, is sufficient to meet the irrigation water requirement. Furthermore, only those areas with groundwater requirement (as a fraction of the total areas requiring ground water) have been considered where the ground water table [6] is within a pre-specific depth (which may vary depending upon the RET being used). For example, a centrifugal surface pump coupled with an SPV array is
Table 1 Time-trend of cumulative number of reported installations of SPV pumps, wind pumps and electric pumps in India SPV pumps
Wind pumps
Electric pumps
1993–94 1994–95 1995–96 1996–97 1997–98 1998–99 1999–2000 2000–01 2001–02 2002–03
54 113 463 1816 2481 2787 3131 3575 4208 5113
56 146 244 449 511 637 714 793 888 945
10276000 10721300 11101100 11565300 11849400 12216700 12514200 12823500 13043900 13792400
Cumulativenumber of SPV and Wind pumps (in number)
Year
usually considered for shallow well water pumping. The maximum suction head for such a surface pump is reported to be 7 m [7]. SPV systems with a submersible pump are reportedly capable of deep well water pumping up to 70 m [7]. However, such deep well irrigation pumping may not always be economical [8]. As a consequence, SPV water pumping for irrigation is preferably carried out in areas with ground water table less than 10 m. Similarly the water output of commonly available windmill pumps is reported to be rather low for a head of more than 20 m. A surface mounted dual fuel engine pump coupled with a biomass gasifier or biogas plant is usually recommended for areas with ground water table up to 5 m [9]. Central ground water board (CGWB) monitors the ground water table in India from a network of about 15 000 stations. Measurements of ground water tables are taken at these stations four times in a year. It is observed that during pre monsoon period (May month) with maximum irrigation water demand the ground water table is deepest [6]. Therefore, the ground water table for the month of May (pre-monsoon period) has been considered in this study [6]. Table 2 presents the state wise net sown area, its fraction of area under surface irrigation (fs) and the area with different ground water table in India (as a fraction of total area requiring ground water) [3,4,6]. 2.2. Affordability of the user To make a preliminary assessment of the affordability of a farmer to invest in a RET based water pumping system a comparison of the total annual cost likely to be incurred by the farmer with his annual income from agriculture can be made. The following assumptions are made to estimate the total annual cost of RET based water pumping system.
6000
15.0
5000
12.5
10.0
4000 SPV pumps
Wind pumps
Electric pumps
3000
7.5
2000
5.0
1000
2.5
Cumulative number of electric pumps (in millions)
862
0 0.0 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 Year Fig. 1. Time-trend of cumulative number of reported installations of SPV pumps, wind pumps and electric pumps in India.
ARTICLE IN PRESS A. Kumar, T.C. Kandpal / Energy 32 (2007) 861–870 Table 2 State wise net sown area (As), its fraction irrigated by surface water (fs) and area with different ground water table in India State
Andhra Pradesh Arunachal Pradesh Assam Biharb Goa Gujarat Haryana Himachal Pradesh Karnataka Kerala Madhya Pradeshc Maharashtra Orissa Punjab Rajasthan Tamil Nadu Uttar Pradeshd West Bengal
As (thousand hectare)
fs (fraction)
Area with different ground water table (as a fraction of the total area requiring ground water) Up to 5 m
Up to 10 m
14460 350
0.1710 —a
0.3153 0.4444
0.8054 1.0000
3205 10743 67 10292 3711 1010
0.1129 0.1107 0.1045 0.0624 0.3697 0.0040
0.7424 0.4850 0.7456 0.1958 0.3763 0.2817
0.9694 0.9621 1.0000 0.5602 0.7025 0.6056
12321 1796 22111
0.0941 0.0863 0.0943
0.2153 0.3823 0.1367
0.6615 0.8242 0.6709
20925 5296 4033 20971 7474 17986 5656
0.0433 0.2368 0.3362 0.0830 0.2015 0.1764 0.1733
0.2116 0.4901 0.3439 0.1577 0.4678 0.4387 0.3473
0.7376 0.9517 0.7549 0.3963 0.8377 0.8457 0.8069
863
Haryana is assumed to be applicable for other states of India as well in the example case(s) presented in the paper. The framework presented in this study can be used with better realistic value as and when available. On the basis of farm size, the farmers in India are classified in five categories (marginal, small, semi-medium, medium, and large) [4]. The willingness to pay for irrigation of farmers of respective categories have been estimated on the bases of an all India average land holding size of different categories of farmers [4]. 2.3. Propensity of the user to invest in a renewable energy technology based pump The propensity of the user to invest in a RET based pump will depend on the awareness and knowledge of the user about the technology for water pumping and also on the availability, reliability, and economics of conventional options to him. A factor (varying from 0 to 1) named propensity factor can be used to express the same. In this study the value of propensity factor for marginal, small, and semi-medium farmers has been assumed at 0.2 while it is assumed to be 0.8 for medium and large farmers. As mentioned earlier, a large variation is expected in the case of resource availability for the technology options for water pumping considered in this study. The following section presents the resource availability related issues for all the four RET options for irrigation water pumping.
a
Negligible area. Including Jharkhand. c Including Chattisgarh. d Including Uttaranchal. b
3. Resource availability for renewable energy technology options
A fraction fcs of the capital cost (C0) of the system may be provided as capital subsidy to the user by the government. A fraction fis of the balance of the cost (after capital subsidy) may be provided as loan to the farmer for a period of t years at an interest rate r (in fraction). The remaining fraction of the capital cost is assumed to be paid by the user out of his savings. This fraction is not considered for the estimation of annual expenses of the system. The annual operation, repair and maintenance cost of the system can be expressed as a fraction m of its capital cost. Mathematically, the annual expenses (Ca) can be expressed as rð1 þ rÞt C a ¼ C 0 ð1 f cs Þf is þ m , ð1 þ rÞt 1
3.1. SPV pumps It is recommended that for installing SPV pumps, the average daily solar radiation in the least sunny month should be greater than 3.5 kW/m2 on a horizontal surface [10]. Ideally, detailed solar radiation data for each location should be used in evaluating the potential of using an SPV pump. However, to make an initial macrolevel assessment, broad solar radiation availability characteristics readily available in the literature [11] are used. On a macrolevel, seven north-eastern sates and the northern states of Jammu and Kashmir, Himachal Pradesh and Uttranchal in India can be given low priority in the process of identification of niche areas for installation of SPV pumps. 3.2. Windmill pumps
(1) 1
A study carried out by World Bank for the state of Haryana has estimated the gross agricultural income and farmers’ willingness to pay for irrigation [2]. Since data for all states of India is not available, the per hectare value for 1 India is divided into following main administrative units arranged hierarchically: state, division, district, block, and village.
The water output of a windmill pump is very sensitive to any variation in wind speed. Wind speed at any location depends upon a variety of site specific factors and large variations in annual monthly mean wind speeds have been reported at different locations in a state [12–15]. Therefore, analysis for the estimation of potential of windmill pumps for irrigation water pumping in India has been carried out using district wise data on resource availability, net sown
ARTICLE IN PRESS A. Kumar, T.C. Kandpal / Energy 32 (2007) 861–870
864
area, surface water irrigation, and ground water table, etc. [5,6,12–15]. The wind speed at any location increases with an increase in height from the ground level. In most of the prevailing windmill pump designs rotor is fixed on a tower at about 10 meters height from the ground. From the available data on measured values of annual monthly mean wind speed at different locations [12–15], the annual monthly mean wind speeds at the 10 m height from the ground level (v10) have been estimated by using the following relation [15,16]: a 10 , (2) v10 ¼ vh h
available as feedstock for large-scale dissemination of producer gas based dual fuel engine pumps. Agro-processing residues such as rice husk, groundnut shells and bagasse, etc. also may not be available for the use as feedstocks for agricultural water pumping systems, as these may be used by the respective agro-processing units for meeting their own thermal/electrical energy requirement. Some crop residues may find use as fodder and/or fertilizer. Hence, the following non-fodder, non-fertilizer crop residues have been considered as potential feedstocks: (a) arhar stalks; (b) cotton stalks; (c) jute sticks; (d) maize cobs and stalks; and (e) mustard stalks. These residues are available in substantial amounts in the country and have also been found suitable as feedstocks in biomass gasifiers [4,19]. The annual amount of crop residue produced depends on the annual crop production and the corresponding residue to crop ratio (Rj) [20]. A fraction (fl) of the total amount of crop residues produced may be lost during collection. A fraction (fou) of the collected crop residues may be used in other applications [21]. The amount (Qr,j) of jth crop residue available per hectare of sown area can be estimated as
where vh represents the annual monthly mean wind speed measured at a reference height of h meters from the ground level and a the ground surface friction coefficient. Though the value of a varies from 0.1 to 0.5 depending upon the terrain of the location, a value of 0.2 as reported for crops and shrubs type terrain has been used in the study [16]. As the reported water output of commercially available windmill designs at wind speeds below 10 km/h is very low [17], the areas with annual monthly mean wind speeds greater than 10 km/h (as a fraction, fw, of the net sown area in the district) only have been considered in this study for windmill pump based irrigation.
Qr;j ¼ Y j Rj ð1 f l Þð1 f ou Þ,
(3)
where Yj represents the yield of jth crop in the state and Rj the residue to crop ratio for jth crop. It is assumed that producer gas based dual fuel engine pumps for irrigation can only be used in those states where the crop(s) considered in this study are produced in
3.3. Producer gas based dual fuel engine pumps In view of decreasing availability of fuel wood from forests in India [18], it is assumed that the same is not
Table 3 State wise sown area and yield of selected crops in India (for the year 2000–01) State
Arhar Sown area (thousand hectares)
Andhra Pradesh Assam Biharb Gujarat Haryana Himachal Pradesh Jammu and Kashmir Karnataka Madhya Pradeshc Maharashtra Orissa Punjab Rajasthan Tamil Nadu Uttar Pradeshd West Bengal a
510 —a 60 320 — — — 580 350 1100 150 — — 80 400 —
Very small. Including Jharkhand. c Including Chattisgarh. d Including Uttaranchal. b
Cotton Yield (kg/ha)
426 1280 337
441 665 602 503
710 1254
Jute
Maize
Mustard
Sown area (thousand hectares)
Yield (kg/ha)
Sown area (thousand hectares)
Yield (kg/ha)
Sown area (thousand hectares)
Yield (kg/ha)
Sown area (thousand hectares)
1020 — — 1620 560 — — 560 510 3080 — 470 510 190 — —
277
80 70 170 — — — — — — 30 30 — — — — 620
1586 1674 1410
520 — 730 400 — 300 330 670 820 260 — 160 970 120 910 40
2727
— 270 110 190 400 — — — 450 — — 50 1430 — 910 440
122 424
298 80 100 430 268 285
266 908
2167
2159 1550 2293 1592 3157 1468 850 2793 1047 1619 1632 2501
Yield (kg/ ha)
514 933 1236 1371
804
1222 918 987 956
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substantial amounts. In fact, in this study, only those state and crop combinations are considered, where the crop yield is enough to provide the amount of residue that is required as feedstock for irrigating at least one crop in a year. The sown areas of different crops considered in this study along with their respective yields for various states are presented in Table 3 [4]. To avoid ambiguity it is assumed that a farmer with surplus availability of the crop residue is not trading the surplus amount with any other farmer. 3.4. Biogas based dual fuel engine pumps It has been reported that households having less than four bovines cannot normally install family size biogas plants [22]. Therefore, in this study it is assumed that households owning 1–3 bovines may contribute dung for operation of community type biogas plants for supplying biogas to a dual fuel engine pump for irrigation water pumping (besides other end uses). Based on the 1991 census data on the livestock holding and its distribution in 16 states of India (Table 4), number of households owning 1–3 bovines have been estimated [23]. An average value of 10.88 kg of dung availability per bovine is assumed in this study [24]. It is also assumed that only 75% of the available dung is finally collected. It is also assumed that 25 kg of raw dung has to be fed daily to the biogas plant per m3 of rated capacity of the biogas plant [24].
Table 4 Pattern of bovine ownership in different states of India (for the year 1991) State
Andhra Pradesh Assam Bihara Gujarat Haryana Himachal Pradesh Karnataka Kerala Madhya Pradeshb Maharashtra Orissa Punjab Rajasthan Tamil Nadu Uttar Pradeshd West Bengal a
Number of rural households (thousand)
n¼1
n¼2
10327 3364 12175 4804 1882 861
12 12 17 14 14 8
11 11 17 13 13 8
7 7 8 12 12 11
5552 4102 8945
12 14 10
11 14 9
9 5 8
4. Framework used for potential estimation 4.1. SPV pumps On the basis of assumptions made in earlier section, net sown area in a state with requirement for ground water and also its availability (Ag) can be estimated as Ag ¼ As ð1 f s Þf g10 ,
(4)
where As represents the net sown area in the state, fs the areas in the state with surface water availability (as a fraction of the net sown area in the state), and fg10 the area with ground water table up to 10 m (as a fraction of the total area requiring ground water in the state). As discussed earlier, the factors pertaining to affordability of the users and their propensity to invest in an SPV pump are quite different for farmers of different categories. Therefore, a category wise break-up of the above estimated area has been used for further analysis. The net sown area with requirement and availability of ground water for ith category of farmers (Ag,i) can be expressed as Asg;i ¼ As ð1 f s Þf g10 f lh;i ,
(5)
where flh,i represents the net sown area operated by ith category of farmers (on the basis of land holding size) as a fraction of net sown area in the state (i ¼ 1; 2; 3; 4, and 5 correspond to marginal, small, semi-medium, medium, and large, respectively) [4]. Using average size of land holding of different categories of farmers in the state [4], the number of farmers of ith category (Nsg,i) that own the above estimated area (Eq. (5)) can be determined as N sg;i ¼
n¼3
As ð1 f s Þf g10 f lh;i , Si
(6)
where Si represents the average size of land holding of ith category of farmers in the state. Finally, using correction factors for the affordability of the ith category of farmers (fa,i) and their propensity to invest in SPV pumps (fp,i) the potential number of SPV pump users (Nspv) in the state can be estimated as N spv ¼
5 X ðN g;i f a;i f p;i Þ.
(7)
i¼1
9259 5168 2355 5574 8435 18024 8910
Including Jharkhand. Including Chattisgarh. c Very small (negligible). d Including Uttaranchal. b
Rural households owning n bovines as a % of all rural households
865
10 14 14 10 12 20 13
9 14 13 10 11 19 13
6 7 12 —c 5 13 7
Two sizes of SPV pumps (0.9 and 1.8 kWp) are commercially available in India. The financial incentives provided by government are available for purchasing only one pump. Therefore, in the initial phase of dissemination it is assumed that the farmer will install either of the two pumps depending upon his need and affordability. In this study it is assumed that the farmers with large land holdings will continue to use other conventional pumps for satisfying their balance water requirement for irrigation.
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4.2. Windmill pumps
producer gas based dual fuel engine pump. Xcr,j can be estimated as
On the basis of assumptions made in Section 3.2, net sown area (Awg) with requirement for ground water and also its availability in a district where annual monthly mean wind speed is greater than 10 km/h can be estimated as Awg ¼ As;d f w ð1 f s;d Þf g20 ,
(8)
where As,d, fs,d and fg20, respectively, represent the net sown area, fraction of sown area under surface irrigation and the fraction of total area requiring ground water with ground water table up to 20 m in the district [5,6,12–15]. As discussed earlier the factors pertaining to affordability of the users and their propensity to invest in a windmill pump is different for farmers of different categories. Therefore, the category wise numbers of farmers owning the area as estimated by Eq. (8) need to be obtained. Since district level data on sizes of land holdings and land holdings distribution among different categories of farmers are not available, it is assumed that the values pertaining to a state [4] are applicable for each district of that state. Thus, the number of farmers of ith category (Nwg,i) that own the above estimated area (Eq. (8)) can be estimated as N wg;i ¼
As;d f w ð1 f s;d Þf g20 f lh;i . Si
(9)
As in the case of SPV pumps, by introducing correction factors for affordability of the farmers and their propensity to invest in windmill pumps the potential number of windmill pump users (Nwp) in the district can be estimated as N wp ¼
5 X ðN wg;i f a;i f p;i Þ.
(10)
X cr;j ¼
3:6ðPpg rd;pg Þ , CV cr;j Zgas Zdfe
where j ¼ 1; 2; 3; 4; 5 correspond to arhar stalk, cotton stalk, jute sticks, maize cobs and stalk, and mustard stalk respectively. Therefore, the annual hours of operation (tav;j ) of a producer gas based dual fuel engine pump using the crop residue available from one hectare sown area of jth crop can be estimated as tav;j ¼
Qr;j . X cr;j
Ag;j ¼ As;j ð1 f s Þf g5 ,
trq ¼
rw gHV w , 3:6 106 ðPpg Zdp Þ
(11)
where rw represents the density of water, g the acceleration due to gravity, H the total head, Vw the volume of water required for irrigating one hectare land during a single cropping season, Ppg the size of producer gas based dual fuel engine pump (in kW) and, Zdp the efficiency of the pump used with the dual fuel engine. The rate of consumption (Xcr,j) of jth crop residue in a producer gas based dual fuel engine pump of rated capacity, Ppg, would also depend upon its calorific value (CV cr;j ), efficiency of gasifier (Zgas), efficiency of dual fuel engine (Zdfe), and diesel replacement factor (rd,pg) of the
(14)
where As,j represents the sown area of jth crop in the state, fg5 the area with 5 m ground water table (as a fraction of area requiring ground water). This exercise has been undertaken only for those state and crop combinations for which the value of tav,j is greater than the required hours of operation (trq) as estimated from Eq. (11). Similarly, as in pervious cases, using distribution of land holdings among different categories of farmers and their average size of land holdings, the number of ith category of farmers (N pg;j;i ) growing the jth crop and owning the area as estimated by Eq. (14) can be estimated as N pg;j;i ¼
The required hours of operation (trq) of a producer gas based dual fuel engine pump for irrigating one hectare land can be estimated as
(13)
For each of the crop considered in this study, it is assumed that the prevailing situation pertaining to the surface water availability, land holding sizes, land holding distribution among farmers, and the ground water table is the same over the entire state. Thus, the sown area of a crop with ground water requirement and its availability (Ag,j) can be estimated as
i¼1
4.3. Producer gas based dual fuel engine pumps
(12)
As;j ð1 f s Þf g5 f lh;i . Si
(15)
Once again, using correction factors for the affordability of farmers and their propensity to invest in a producer gas based dual fuel engine pump the potential number of producer gas based dual fuel engine pump users (Npg) in the state can be estimated as N pg ¼
5 X 5 X ðN pg;j;i Þf a;i f p;i .
(16)
i¼1 j¼1
4.4. Biogas based dual fuel engine pumps A 20 m3 daily biogas production capacity community biogas plant has been chosen as it can provide sufficient volume of biogas for operating a 7.46 kW (10 hp) dual fuel engine pump with reasonable capacity utilization factor. In the case of community biogas plants (being considered in this study for providing biogas to the dual fuel engine pump) the affordability criteria can be somewhat relaxed.
ARTICLE IN PRESS A. Kumar, T.C. Kandpal / Energy 32 (2007) 861–870
Moreover, due to economy of scale, the unit cost of community biogas plant (per m3 biogas production capacity) would be much lower than that for family size biogas plants. Thus, it is possible for the participating users to share equity funds for the installation of the biogas plant and other equipment for the system. However, an index of community participation (l) has been introduced to take into account the practical problems faced in such a participatory programme. In fact, a low value (0.10) has been assigned to the index of participation in this study to obtain rather conservative estimates. It may be noted that the index of community participation would also take into account the propensity of the individuals to invest in a community biogas plant based water pumping system. Further, the value of l can only be estimated through detailed field survey based studies. In the absence of such studies, in the present work, the value is assumed on the basis of discussion with the experts in the relevant areas. Considering all the above mentioned factors the potential number of community biogas plants (Nbg) that can be used for irrigation water pumping in a state can be estimated by the following relation: 1 lðN h1 þ 2N h2 þ 3N h3 Þð10:88 0:75Þ N bg ¼ 20 25 ð1 f s Þf g5 ,
ð17Þ
where Nh1, Nh2 and Nh3 represent the number of households owning 1, 2 and 3 bovines, respectively, in a state. As in the cases of other three technological options the product ‘(1fs)fg5’ is used to consider the area with ground water requirement and its availability. 5. Results and discussion The use of the framework presented in the earlier section requires detailed data on a variety of input parameters. However, due to unavailability of required data an initial exercise towards estimation of potential numbers and identification of niche areas has been undertaken on the basis of the proposed framework. Table 5 presents the state wise average sizes of land holding of different categories of farmers in India [4]. The fractional distribution of net sown area among different categories of farmers in various states of India is presented in Table 6 [4]. Other input parameters used in calculations are presented in Table 7 [9]. Using the base values of various input parameters, as presented earlier some exemplifying calculations have been made and the results obtained are briefly presented in this section. On the basis of assumptions made in Sections 2, 3 and 4, and the values of input parameters as listed in Table 7, the categories of farmers who can afford to invest in SPV pump, windmill pump and producer gas based dual fuel engine pump are indicated in Table 8. It may be noted that only for these combinations of category of farmers and RET based pumps, the affordability factor (fa,i) is assigned a value of one (1) while for others it is assumed to be zero.
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Table 5 State wise average sizes of land holdings of different categories of farmers (for the year 1990–91) State
Marginal farmers (ha)
Small farmers (ha)
Semimedium farmers (ha)
Medium farmers (ha)
Large farmers (ha)
Andhra Pradesh Arunachal Pradesh Assam Bihara Goa Gujarat Haryana Himachal Pradesh Karnataka Kerala Madhya Pradeshb Maharashtra Orissa Punjab Rajasthan Tamil Nadu Uttar Pradeshc West Bengal All India Average
0.45 0.63
1.43 1.53
2.71 2.80
5.86 5.65
15.66 16.40
0.40 0.35 0.33 0.53 0.47 0.40
1.40 1.36 1.54 1.47 1.52 1.42
2.68 2.73 2.25 2.83 2.81 2.74
5.18 5.65 4.50 5.99 5.86 5.69
80.80 16.41 19.00 16.45 15.41 16.17
0.47 0.17 0.45
1.46 1.37 1.45
2.75 2.60 2.78
5.93 5.43 6.04
15.28 59.33 16.44
0.49 0.49 0.55 0.48 0.36 0.38 0.44 0.39
1.46 1.38 1.61 1.44 1.41 1.41 1.53 1.43
2.77 2.63 2.91 2.85 2.73 2.73 2.78 2.76
5.86 5.40 6.21 6.23 5.71 5.55 5.39 5.90
15.13 16.80 16.07 19.11 18.52 15.42 203.00 17.33
a
Including Jharkhand. Including Chattisgarh. c Including Uttaranchal. b
Table 9 presents the estimated potential of four RET options considered for irrigation water pumping in this study. Potential number of SPV pumps are estimated at 6.03 million (out of which 4.29 million are of capacity of 1.8 kWp and the balance 1.74 million of capacity of 0.9 kWp). With 1.06 million SPV pumps the state of Maharashtra in India has highest utilization potential closely followed by Madhya Pradesh (0.99 million). Since the percentage share of marginal and small farmers is very high in the states of Kerala and West Bengal, in spite of large area with ground water table of less than 10 m in these states, the estimated potential of SPV pumps is very low as compared to the total number of farmers. Moreover, due to larger number of smaller land holdings in Kerala and West Bengal, the potential number of 0.9 kWp SPV pumps is much higher than that of 1.8 kWp SPV pumps. In other states it is just the reverse as the land holding are larger. The potential number of windmill pumps for irrigation is estimated at 2.39 million. In view of long coastal area, large number of farmers with small or higher land holdings, and substantial area under 20 m ground water table the state of Maharashtra has highest utilization potential of windmill pumps (0.64 million), followed by another coastal state
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Table 6 State wise fractional distribution of net sown area among different categories of farmers in India (for the year 1990–91) State
Andhra Pradesh Arunachal Pradesh Assam Bihara Goa Gujarat Haryana Himachal Pradesh Karnataka Kerala Madhya Pradeshb Maharashtra Orissa Punjab Rajasthan Tamil Nadu Uttar Pradeshc West Bengal Lakshdweep A& N island
Marginal farmers
Small farmers
Semimedium farmers
Medium farmers
Large farmers
0.1638 0.0286
0.1955 0.0743
0.2517 0.2400
0.2612 0.4200
0.1278 0.2343
0.1894 0.3343 0.2836 0.0475 0.0795 0.2129
0.2446 0.1819 0.1642 0.1305 0.1248 0.2327
0.2864 0.2398 0.1343 0.2444 0.2544 0.2554
0.1535 0.1845 0.1343 0.3891 0.3503 0.2030
0.1261 0.0596 0.2836 0.1886 0.1911 0.0960
0.0870 0.4816 0.0637
0.1873 0.2133 0.1259
0.2597 0.1420 0.2188
0.3061 0.0635 0.3515
0.1600 0.0991 0.2401
0.0773 0.1973 0.0407 0.0346 0.2834 0.3143 0.3649 1.0000 0.0370
0.1903 0.2693 0.0813 0.0700 0.2400 0.2441 0.2995 0.0000 0.1111
0.2810 0.2948 0.2088 0.1441 0.2257 0.2338 0.2244 0.0000 0.2963
0.3276 0.1911 0.4022 0.3020 0.1741 0.1691 0.0753 0.0000 0.3333
0.1237 0.0476 0.2670 0.4493 0.0768 0.0386 0.0359 0.0000 0.1852
a
Including Jharkhand. Including Chattisgarh. c Including Uttaranchal. b
Karnataka. Once again due to dominance of marginal land holdings (unable to satisfy affordability criteria) the estimated potential of windmill pump utilization for the state of Kerala is rather low. Owing to a variation in the calorific value of different crop residues and the corresponding values of residue to crop ratios, yields of the respective crops in the state, etc., the number of feasible hours of operation of a 3.73 kW (5 hp) producer gas based dual fuel engine pumps would vary considerably for different combinations of residues and states. The potential of producer gas based dual fuel engine pumps for irrigation pumping in India is estimated at 0.46 million with highest potential in the state of Maharashtra. It is estimated that around 36 thousand community biogas plants of 20 m3 daily biogas production capacity can be installed for irrigation pumping in India. Since a dual fuel engine pump can be used with a community type biogas plant, the potential number of biogas based dual fuel engine pumps is essentially equal to the potential number of community biogas plants. Uttar Pradesh has the highest potential (approximately 10,000 plants) of community biogas plants for irrigation pumping. It may be noted that the number of SPV pumps users (Nspv) or windmill pumps users (Nwp) also correspond to
Table 7 List of input parameters used in calculations
Capital cost of the system
Parameter
Symbol
Unit
Value
SPV pump (0.9 kWp) SPV pump (1.8 kWp) Windmill pump Producer gas based dual fuel engine pump (5 hp) SPV pump (0.9 kWp) SPV pump (1.8 kWp) Windmill pump Producer gas based dual fuel engine pump (5 hp)
C0
Rs Rs Rs Rs
170 000 328 000 104166 75000
m
Fraction Fraction Fraction Fraction
0.01 0.01 0.02 0.05
fcs
Fraction
0.50
fis
Fraction
0.80
r t CVar,j
fl
Fraction Years MJ/kg MJ/kg MJ/kg MJ/kg MJ/kg Fraction Fraction Fraction Fraction Fraction Fraction
0.10 10 14.88 17.88 19.04 14.53 18.84 1.32 3.00 2.30 1.86 1.85 0.10
fou
Fraction
0.20
H
m
5
Vw
m3
6000
Zgas Zdfe Zdp
Fraction Fraction Fraction
0.80 0.23 0.40
rd,pg
Fraction
0.80
Annual operation, repair and maintenance cost (as a fraction of capital cost) Capital subsidy (as a fraction of the capital cost) Amount of low interest loan (as a fraction of the balance of the cost) Interest rate on loan Loan repayment period Calorific Arhar stalks value of Cotton stalks agricultural Jute and sticks residues Maize cobs and stalks Mustard stalks Residue to Arhar stalks crop ratio Cotton stalks Jute and sticks Maize cobs and stalks Mustard stalks Fraction of the total amount of crop residues produced that may be lost during collection. Fraction of the collected crop residues that may be used in other applications Total pumping head Volume of water required for irrigating one hectare land during a single cropping season Efficiency of gasifier Efficiency of dual fuel engine Efficiency of the pump used with the dual fuel engine Diesel replacement factor of the producer gas based dual fuel engine pump
Rj
the area of land that one SPV pump or windmill pump can effectively irrigate. However, this study assumes that one farmer can not own more than on SPV pump or other renewable energy based pump. Though the size(s) of the same may vary. 6. Concluding remarks Though the compounded annual rate of growth in the number of electric pumps in the country is merely 3%
ARTICLE IN PRESS A. Kumar, T.C. Kandpal / Energy 32 (2007) 861–870 Table 8 Categories of farmers who can afford to invest in SPV pump, windmill pump, and producer gas based dual fuel engine pump Renewable energy option for water pumping
Size
Categories of farmers who can afford to invest in the renewable energy option
SPV pump
0.9 kWp 1.8 kWp —
Semi medium Medium, large Small, semi medium, medium, large Small, semi medium, medium, large
Windmill pump Producer gas based dual fuel engine pump
3.73 kW (5 hp)
SPV pumps
Windmill Producer gas pumps based dual fuel engine pumps
Biogas based dual fuel engine pumps
0.9 kWp 1.8 kWp Andhra Pradesh Assam Biharb Gujarat Haryana Himachal Pradesh Karnataka Kerala Madhya Pradeshc Maharashtra Orissa Punjab Rajasthan Tamil Nadu Uttar Pradeshd West Bengal Goa Andmand and Nicobar Island All India
Even with rather conservative values of relevant input parameters the estimates indicate that, there is a vast potential of renewable energy utilization for irrigation water pumping in India. Out of four renewable energy technologies considered in this study, the estimated utilization potential of SPV pumps is highest followed by windmill pumps. The potential is estimated considering the prevailing conditions such as cost and technical specification of renewable energy based devices, income of farmers, etc. The future potential of renewable energy use may increase due to cost reductions and/or technology advancement, as well as increase in income of farmer. References
Table 9 Potential of different renewable energy technologies for irrigation pumping in India (thousands) State
869
179 59 161 93 30 —
407 68 267 331 95 —
274 —a — 442 — —
49 18 34 45 21 7
2.42 1.99 6.43 0.91 0.55 0.22
139 15 211 300 86 29 77 83 215 61 1 —
367 14 783 757 118 132 439 139 330 43 2 —
549 38 81 643 90 — 123 132 3 — 9 6
33 — 18 88 6 14 33 12 63 21 — —
1.08 1.33 0.94 1.41 1.99 0.67 0.39 2.52 10.31 2.51 — —
6031
2390
462
35.67
a
Negligible or not estimated. Including Jharkhand. c Including Chattisgarh. d Including Uttaranchal. b
(primarily due to increasing uncertainty in the availability of electricity) the incremental annual number of new electric pumps is far more than the reported cumulative number of renewable energy based pumps disseminated so far. It is therefore, extremely important to develop appropriate technologies for this purpose beside formulating and implementing suitable dissemination strategies for renewable energy based options for water pumping.
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