Life Cycle Assessment modeling of milk production in Iran - Core

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INFORMATION PROCESSING IN AGRICULTURE 2 (2015) 101–108

journal homepage: www.elsevier.com/locate/inpa

Life Cycle Assessment modeling of milk production in Iran Hamzeh Soltanali a, Bagher Emadi Amin Nikkhah a,b a b

a,* ,

Abbas Rohani a, Mehdi Khojastehpour a,

Department of Biosystems Engineering, Ferdowsi University of Mashhad, Azadi Square, Mashhad, Iran Young Researchers and Elite Club, Rasht Branch, Islamic Azad University, Rasht, Iran

A R T I C L E I N F O

A B S T R A C T

Article history:

Livestock units are known as one of the most influential sectors in the environment pollu-

Received 17 March 2015

tion. Therefore, the aim of this study was to investigate the environmental impacts of milk

Received in revised form

production in Guilan province of Iran through Life Cycle Assessment (LCA) methodology.

12 June 2015

The primary data were collected from 45 units of milk production through a field survey

Accepted 14 June 2015

with the help of a structured questionnaire. The reliability was assessed using Cronbach’s

Available online 17 July 2015

alpha coefficient and was estimated an acceptable value of 0.91. The consumption of resources and emissions were allocated to a functional unit (FU) of one ton of milk. Impacts

Keywords:

of emissions in five impact categories of global warming, acidification, eutrophication, pho-

Acidification

tochemical oxidation and depletion of resources were investigated. The results showed

Dairy farm

that

Environmental impact

kg CO2 eq, 7.97 kg SO2 eq, 3.42 kg PO3 4 eq, 0.21 kg C2H4 eq and 838.39 MJ, respectively. Final

Global warming

indices for these impact categories were calculated as 0.24, 0.28, 0.076, 0.017 and 0.046,

the

characterization

index

for

these

impact

categories

were

1831

respectively. Environmental index (EcoX) and resources depletion index (RDI) were obtained 0.61 and 0.04, respectively. In this study, the highest potential for environmental impacts of production revealed for acidification and followed by global warming impact category. 2015 China Agricultural University. Production and hosting by Elsevier B.V. All rights reserved.

1.

Introduction

Besides securing food for the rising population, according to predictions will be more than 9 billion in 2075, the environment preservation is one of the most important challenges

facing humanities [1]. Agriculture is one of the main sources of greenhouse gas (GHG) emissions such as CO2, CH4 and N2O [2,3]. It is necessary to evaluate environmental impacts of different sectors of agriculture particularly dairy cow breeding units that are one of the main resources of GHG emissions [4]. The FAO report ‘‘Livestock long shadow: environmental issues and options’’ claims that livestock units constitute about 18% of the entire GHG emissions of which 3–5.1% are from dairy cow breeding units [5,6]. Although there are different methods for assessing the environmental impacts associated with food systems, but the appropriate one is the Life Cycle Assessment (LCA),

* Corresponding author. Fax: +98 51 38805838. E-mail addresses: [email protected] (B. Emadi), Farnood. [email protected] (A. Nikkhah). URL: http://orcid.org/0000-0002-3008-2401 (A. Nikkhah). Peer review under the responsibility of China Agricultural University. http://dx.doi.org/10.1016/j.inpa.2015.06.003 2214-3173 2015 China Agricultural University. Production and hosting by Elsevier B.V. All rights reserved.

102

Information Processing in Agriculture

because this method is suitable for determination of inputs, outputs and environmental consequence in a production process [7,8]. A Literature review disclosed that many researchers have reported the valuable application of LCA model in environmental management of agricultural production [9–14]. Some studies have been conducted in terms of environmental impacts assessment during dairy farm activities, for example Van der Werf et al. [15] evaluated the environmental impact of dairy cow breeding in terms of traditional and organic systems. They investigated the impact categories of global warming, acidification, eutrophication, land occupation and fossil resources depletion. They claimed that the impact of land occupation in the organic system was higher in comparison to a traditional system, while the other impact categories had not many differences in the two systems. Castanheira et al. [16] studied environmental impacts of dairy cow breeding units in Portugal. The biggest sources of N2O, NH3 and CH4 were reported to be diesel fuel, manure management and enteric fermentation. McGeough et al. [17] performed a study on LCA in dairy units of Canada and reported that the amount of GHG emission per one liter of milk was 0.92 kg CO2 eq. O’Brien et al. [18] studied environmental impacts of milk production in Ireland. The results indicated that the effective environmental impacts were global warming, acidification, eutrophication, land occupation and fossil resources depletion for each functional unit of milk production. LCA model was also applied to evaluate environmental impacts resulted from global warming potential in milk production units in the United States. The total GHG per liter of milk was equal to 0.20 kg CO2 eq [19]. Guerci et al. [20] analyzed the environmental impacts of dairy farms activities in Denmark, Germany and Italy through LCA and found that the average annual production of milk per cow was between 6275 and 10,964 L. Effective environmental impact categories were acidification, eutrophication, depletion of fossil sources and global warming. The impacts of all of the effective environmental groups in dairy units of Denmark were less than Germany and Italy. In another study, carried out by Zhang et al. [21] they examined the environmental impacts for dairy cow breeding units in Canada using LCA methodology based on an integrated system. The integrated system in the study was for applying an aerobically digested for production of biogas energy and digested slurry. The results indicated that usage of an integrated system in livestock units can decrease fossil recourses and global warming up to 80% and eutrophication and respiratory effects up to 50%. Some other studies which were conducted on environmental impacts through LCA in dairy cow breeding units are also available [14,22,7,23–26]. The sustainable production of milk in Guilan province of Iran requires the consideration of environmental management in the production systems. However, to the best of knowledge of authors, no previous analytical work has been reported on the environmental impacts of milk production in Iran. Therefore, the aim of present study was the environmental impacts assessment of milk production in dairy cow breeding industrial units in Guilan province, Iran based on LCA methodology.

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2.

Materials and methods

2.1.

Site of study and sample selection

The study was carried out in industrial units of dairy cow breeding of Guilan province in northern Iran during agricultural year of 2012–2013. Guilan province is located in the north of Iran on the south of Caspian Sea, within 3634 0 and 3827 0 north latitude and 4853 0 and 5034 0 east longitude. Guilan has a population of approximately 2.5 million people [27]. From 180 industrial units of cow growing in Guilan at the time of the study, 129 of which were dairy cow breeding units [28]. The average numbers of cow in the studied area were ranged 20–200 cows that average was equal to 54.5 head. The most using of machinery were for the process of milking equipment, processing of animal feed, and followed by allocated milk cooling. In addition, many activities such as animal feeding operation were done by human labor. Based on the Cochran formula, 45 active units were selected for this study [29]. n¼

Nðs tÞ2 2

ðN 1Þd þ ðs tÞ2

ts d ¼ pffiffiffi n

ð1Þ

ð2Þ

where, n = sample size, N = number of holdings in the target population, t = the reliability coefficient (1.96), s = the variance, and d = precision. Data were obtained from 45 units of milk production using a face to face questionnaire method during 2012–2013. The instrument used in this research was a questionnaire whose validity was confirmed by university faculty members and agricultural experts. The estimated reliability, using Cronbach’s alpha, was 0.91, which was an acceptable reliability. Each producer was asked to detail activity as inputs to milk production recorded as diesel fuel (lit), electricity (kWh), natural gas (m3), animal feed (kg) and manure (kg), and as the output yield (kg).

2.2.

Life Cycle Assessment

This method comprises four sections as: goal and scope definition, life cycle inventory (LCI), life cycle impact assessment (LCIA) and finally interpretation [8,30,31].

2.2.1.

Goal and scope definition

The purpose of this study was to assess the environmental performance of milk production in dairy farming industries in Guilan province, Iran. The functional unit (FU) is connected to the inputs and outputs and provides a condition for comparison, which is usually equivalent to one ton of milk [16,32]. In the current study, the functional unit was chosen as one ton produced milk.

2.2.2.

System boundary

In first, inputs including fuel, electricity, animal feed and other activities such as animal manure management (transport and accumulation) and enteric fermentation that


potentially have adverse effects on the environment were identified. Then, consumption and emissions for one ton milk production in dairy units were calculated. The system outputs contained all of the pollutants emitted to the environment and were calculated out of using these inputs based on a functional unit. Fig. 1 shows all of the inputs and outputs for milk production in Guilan dairy system.

2.2.2.1. The inputs of the system. Fuels, electricity, animal feed, enteric fermentation and manure for production of one ton of milk are illustrated in the Table 1. 2.2.2.2. The outputs of the system. In this section, the level of the emitted pollutants from potentially pollutant inputs was assessed. Table 2 displays the emission coefficient from inputs consumption in milk production units. 2.2.3.

Impact assessment

The purpose of this section was to better analyze and interpret outputs and inputs of the system for production of one ton of milk production which was conducted in three phases of characterization, normalization and weighting [36]. In characterization phase, after dividing the impacts into different effective factors, the amount of pollutants resulted from milk production will be calculated regarding its efficiency in different impact categories. This study investigated five impact categories including: depletion of fossil sources, global warming, eutrophication, acidification and photochemical oxidation. The index for characterization of each impact category is calculated through Eq. (2) [36–38]: X ICIi ¼ ½ðEj or Rj Þ CFij ð2Þ i

where ICIi is indicator value per functional unit for impact category i; Ej or Rj, emission of j mixture or consumption of j resource on each functional unit; CFi is the characterization

103

2 ( 2 0 1 5 ) 1 0 1 –1 0 8

Table 1 – The inputs and outputs to produce one ton of milk in Guilan province of Iran. Inputs & outputs Unit Diesel Fuel Electricity Natural Gas Animal feed Manure Milk

lit t1 kWh t1 m3 t1 kg t1 kg t1 t head1 year1

Mean

Standard deviation (std)

9.40 67.13 7.86 1311.42 458.50 7.34

6.60 12.58 6.56 437.88 42.21 1.40

factor for j mixture in impact category of i. The characterization factor in each impact factor shows the mixture potential for creating the impact. The characterization index for each of the impact categories and the efficiency of each mixture are shown in Table 3.

2.2.3.1. Normalization and weighting. In order to have comprehensive understanding of the calculated amounts, characterization index of impact categories get into nondimensions. Normalization factors are shown in Table 4. To better understand the level of damage of each impact categories on the environment, weighting stage was used and higher resulted value in this stage shows more potential risk for damaging the environment. Weighting factors for five impact categories such as global warming, acidification, eutrophication, depletion of fossil sources and photochemical oxidation are mentioned in Table 4. Groups of global warming, acidification, eutrophication and photochemical oxidation affect environmental impacts (EcoX) and depletion of fossil sources affect the depletion of resources (RDI). The difference between the groups of EcoX and RDI index at resource depletion is that the latter affects future generations of human [36–38].

Fig. 1 – Inputs and outputs of milk production in Guilan province, Iran (system boundary).

104


[35] 23.73 21.33 – – – – – –

–

– – –

–

[33] [34] [34] [34] [35] 105 · 147 – 104 – 436.53 105 · 73 105 · 2 104 · 3 105 · 7 – 105 · 217 106 0.04 105 · 56 – 0.70 104 · 187 2.8 104 · 229 – 103 · 5 105 · 21 – 104 – 105 · 112 – 104 · 8 105 · 9 – 0.03112

105 · 27 – – – –

– – 103 · 9

105 · 143 26 · 104 – 105 · 181 7 · 106 – 105 · 132 – 105 · 121 105 – –

Diesel Fuel (kg l1) Natural Gas (kg m31) Electricity (kg kWh1) Feed (kg kg1) Concentrate Silage Straw Alfalfa Enteric Fermentation (Gg Year1) Manure Management (Gg Year1)

– – –

– – –

105 · 34 – 105 · 276

– – 105

2.63 133 · 103 0.580

N2O NH3 SO2 CO NO3 PO4

Emission of pollutants (kg per unit) Inputs

Table 2 – Emission coefficients of contaminants resulting from the use of inputs and activities.

CO2

NOx

CH4

[33] [33]

References

3.

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Results and discussion

Table 5 illustrates the amount of emitted pollutants from the consumption of inputs and activities for production of one ton of milk in Guilan province, Iran. Inputs of animal feed, electricity and diesel fuel were the key factors in environmental hazards in most impact categories. In a similar study in Portugal, Castanheira et al. [16] showed that animal feed in that concentrate was the main sources of pollutants emission in milk production. Given study in the USA, animal feed and management of animal manure were introduced as the main factor of weather pollution [42]. As shown in Table 5, enteric fermentation and management of manure were the next pollutants of dairy units in Guilan province. Fig. 2 shows the total emissions of pollutants in industrial dairies in Guilan province. The total emissions of pollutants CH4, N2O, NOx, CO2, NH3, SO2, CO, NO3 and PO3 4 for one ton of milk production were obtained 28.06, 1.60, 4.82, 744.71, 2.80, 0.90, 0.77, 16.80 and 0.14 kg eq, respectively. Among the pollutants CO2, CH4 and NO3 had the most roles in environment pollution, respectively. The prime factor for CO2 emission in dairy farms were animal feed, electricity and diesel fuel which were 676.3, 38.93 and 24.98 kg for one ton of milk, respectively. Among animal feed, concentrate was identified as the main factor for the emission of CO2. Enteric fermentation was the main factor of the emission of CH4 that was equal to 26.57 kg eq for one ton of milk. The reason for high level of methane emission was related to the animal feed consumed. Grainger et al. [43] showed that using appropriate strategies such as: the increase of oil substances in livestock diet in the management of animal feed can minimize the emission of methane gas due to enteric fermentation, 1% increase in oil substances in livestock would lead to 6% decrease in methane emission. In a similar study carried out in dairy farms of Portugal N2O, NH3 and CH4 were introduced as the biggest pollutants. Enteric fermentation was the main source of CH4 emission [16] in another study carried out in Canada 56% of CH4 emission was reported as enteric fermentation [44] Conclusion of study in Guilan farms indicated that concentrate was the main reason for emission of NO3, which was equal to 16.8 kg for one ton of milk production. Table 6 displays the indices of characterization, normalization and the final index of environmental impact categories of milk production in Guilan province, Iran. The characterization indices of global warming, acidification, eutrophication, photochemical oxidation and depletion of resources for each ton of milk production were computed 7.97 kg SO2 eq, 3.42 kg PO3 0.21 1831 kg CO2 eq, 4 eq, kg C2H4 eq and 838.39 MJ, respectively. The characterization index of global warming in the studies in Portugal, Ireland, France, Japan, and the average of Germany, Italy and Denmark for one ton of milk were reported to be equal to 1021, 951, 1060, 980 and 1230 kg CO2 eq, respectively. This impact category contained three important GHG such as CH4, CO2 and N2O. In most studies, the main reasons for its emission were enteric fermentation, diesel fuel and the management of manure


105

2 ( 2 0 1 5 ) 1 0 1 –1 0 8

Table 3 – Characterization factor of environmental impacts. Impact category

Potential of compounds

References

Global warming potential (kg CO2 eq) Acidification (kg SO2 eq) Eutrophication (kg PO43 eq) Depletion of fossil resources (MJ) Photochemical oxidation (kg C2H4 eq)

CO2 = 1, CH4 = 21, N2O = 310 SO2 = 1.2, NOX = 0.5, NH3 = 1.6 NOX = 0.13, NH3 = 0.35, NO3 = 0.1, PO4 = 1 42.86 CH4 = 0.006, SO2 = 0.048, CO = 0.027

[37,39] [36] [36] [36] [40]

Table 4 – Normalization and weighting factors. Impact category

Normalization factor (unit)

Weighting factor

References

Global warming potential (kg CO2 eq) Acidification (kg SO2 eq) Eutrophication (kg PO3 4 eq) Depletion of fossil resources (MJ) Photochemical oxidation (kg C2H4 eq)

8143 52 63 39167 9.69

1.05 1.8 1.4 1.14 0.8

[37,41] [37,41] [37,41] [36] [8]

Table 5 – The emissions of contaminants resulting from the consumption of inputs and activities for each ton of milk production. Inputs

Pollutions (kg per one ton of milk)

Diesel fuel Electricity Natural gas Animal feed: - Concentrate - Silage - Straw - Alfalfa Enteric fermentation Manure management

CH4

N2O

0.013

0.017

0.020

0.000023

0.79

0.39 0.009 0.034 0.014

0.008 26.57 0.66

CO

SO2

NH3

CO2

NOX

NO3

0.032 0.18

24.98 38.93 1.04

0.012 0.08

0.0066

106 · 6.7

378.18 8.87 241.10 48.15

1.17 0.005 3.44 0.11

16.80

0.60 0.77

0.068 0.020

2.70 0.1

1.14

Fig. 2 – The total emissions of pollutants (kg) in industrial dairies in Guilan province, Iran.

PO4

0.14

106


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Table 6 – Life Cycle Assessment of Guilan dairy farms for the production of one ton of milk. Impact category

Characterization index (t1)

Normalization index (t1)

Final index (t1)

Global Warming Potential Acidification Eutrophication Depletion of fossil resources Photochemical oxidation

1831(kg CO2 eq) 7.97 (kg SO2 eq) 3.42 (kg PO3 4 eq) 838.39 (in MJ) 0.21 (kg C2H4 eq)

0.22 0.15 0.054 0.040 0.022

0.24 0.28 0.076 0.046 0.017

[15,16,18,20,34]. The characterization index of acidification for one ton of milk in countries including Portugal, Ireland, France, Japan, and Germany, Italy and Denmark were reported 20, 9.40, 7.20, 7.13, 16.93 kg SO2 eq, respectively. Similar results were found in the current study which showed that SO2 and N2 emitted from concentrate were the main reasons for the emission of this impact category [15,16,18,20,34]. The results revealed that the amount of acidification (5.95 kg SO2 eq) in Guilan province of Iran, was relatively lower than the European countries. One of the main reasons for low amount of this impact category was the limited lands in Guilan. In the other hand, it is not possible to production of plant grass and grain products for animal feed in large scale. In the present study, the highest factor for emission of was concentrate which was equal to 0.14 kg for one PO3 4 ton of milk. Other inputs and activities lacked PO3 4 . In some studies, the main reason for emission of this impact category was the emitted N2 from concentrate, corn silage and grass silage [16,20]. Nowadays, there are many solutions to decrease environmental impacts in milk production farms namely: animal feed management. To decrease and control GHG on dairy farms in the Netherlands, it was suggested to replace grass silage with corn silage for feed management. Applying this strategy can decrease negative environmental impacts resulted from enteric fermentation and also can decrease greenhouse gases as 12.8 kg CO2 eq yearly for one ton of milk production [45]. There are some other studies in which adopting the best management strategy in animal feed has been introduced as an appropriate way to decrease negative environmental impacts in dairy farms [24,26]. The index

of characterization for photochemical oxidation in this study was 0.21 kg C2H4 eq which was less than the index of dairy farms of Ireland and Japan [34,18]. The main elements of this group were CH4, SO2 and CO and the main reasons of their emission were enteric fermentation, concentrate, wheat and rice straw. The amount of fossil fuel depletion which contained the energy provided from the consumption of diesel fuel and electricity in Guilan’s milk production units was 838.39 MJ which was less than the other countries [15,16,18,20,34]. The reason for the low amount of this impact category is inadequate number of cows in livestock units due to high price of animal feed. This has led to reduction of fuel consumption in livestock units. In most of the developed countries biogas technology is used to manage the pollutions of emission from fossil fuels in dairy farms more efficiently. This is one of the basic methods to control and decrease the GHG emission and it has an economic benefit [21,46]. Fig. 3 shows the final indices for each impact category; global warming, acidification, eutrophication, fossil fuel depletion and photochemical oxidation which were 0.24, 0.28, 0.076, 0.046 and 0.017 respectively. Acidification and global warming in environmental impact categories (ExoX), had the most disastrous impacts on the environment. The impact of acidification in this study was high due to high consumption of concentrate and electricity which were mostly consumed for heating water and pumps in milk equipment. In addition, animal feed, enteric fermentation, electricity and diesel fuel for tractors were introduced as the main reasons for high global warming.

Fig. 3 – The final indices of the environmental impacts of milk production in Guilan province, Iran.


4.

Conclusion

Results revealed that CO2, CH4 and NO3 caused the most environmental pollutions in most impact categories. The main potential inputs for high CO2 emission in dairy farms was animal feed, electricity and diesel fuel which were respectively 676.3, 38.93 and 24.98 kg for one ton of milk production. Among animal feed, concentrate was selected as the main factor of GHG emissions. Acidification and global warming caused the most amount of damage to the environment. The main point of these environmental impacts were animal feed particularly concentrate, electricity, enteric fermentation and diesel fuel. Other impact categories were not significantly different from each other in case of pollution. In this study, to better environmental management of milk production in Guilan province of Iran, implementation of animal feed management programs and use of biogas systems have been proposed. These systems have not been used widely in Iran due to high costs and lack of adequate knowledge. In addition, it is recommended to take major steps through facilitate livestock units establishment and also encouraging the managers to be familiarize with new technologies like biogas.

Acknowledgment This research was supported by Ferdowsi University of Mashhad, Iran. Further, we are indebted to Surur Khorramdel (Department of Agronomy, Ferdowsi University of Mashhad, Iran) for her critical comments on the manuscript.

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2 ( 2 0 1 5 ) 1 0 1 –1 0 8

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