A Life Cycle Cost Analysis

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Resources, Conservation & Recycling Advances 21 (2024) 200199

Available online 7 December 2023

Enhancing economic-social sustainability through a closed-loop citrus supply chain: A life cycle cost analysis

Emad Alzubi

^a^,^*

, Ahmed Kassem

^a

, Ani Melkonyan

^b

, Bernd Noche

^a

aTransportssysteme und -logistik, Fakult¨atsingenieurswissenschaften, Universit¨at Duisburg–Essen, Keetmanstr. 3-9, Duisburg 47058, Germany

bZentrum für Logistik und Verkehr, Universit¨at Duisburg–Essen, Oststr. 99, Duisburg 47057, Germany

A R T I C L E I N F O Keywords:

Life cycle costing Food supply chain Closed-loop supply chain Compost, Citrus Sustainability

A B S T R A C T

The focus on food supply chain (FSC) sustainability has grown due to demand, food loss and waste, and environmental impacts. This study aims to quantify citrus life cycle costs (LCC) and determine the main drivers and their contributions. LCC was used to assess the cradle-to-grave cost of 1 kg of citrus sold to consumers at the retailer stage. A comparison was made between an existing citrus supply chain (SC) and a proposed closed-loop structure. In addition to the current citrus SC, four different cases were analyzed and evaluated: the centralized linear citrus SC, the centralized linear citrus SC with a 33 % increase in labor income, the centralized closed-loop citrus SC, and the centralized closed-loop citrus SC with a 33 % increase in labor income. The results showed significant reductions in functional unit’s (FU) costs of 48 %, 38 %, 54 %, and 44 %, respectively, compared to the current citrus SC. Labor accounted for 47–62 % of the FU costs, while agriculture inputs and transportation contributed 15–28 % and 12–16 %, respectively. The study revealed that a centralized citrus closed-loop SC improves economic viability, especially when recycling citrus waste as compost for farms. Transportation currently contributes the most to FU costs (45 %), but in the closed-loop citrus SC, labor becomes the highest contributor (62 %). This cradle-to-grave citrus SC approach identifies drivers and contributions to the FU’s costs, showcasing differences when integrating a circular economy. Future research may explore the impact of other byproducts on FU costs.

1. Introduction

The sustainability of food systems needs greater attention from all stakeholders (Degieter et al., 2022). This is due to challenges such as poverty, hunger, resource scarcity, climate change (Sajid et al., 2023), exacerbated by a projected population increase to 12.3 billion by 2050 (Caat et al., 2022; Pe˜na et al., 2022). This population growth puts immense pressure on all parties within the food supply chain (FSC) to take substantial steps toward FSCs sustainability. In addition, the increasing food loss and waste (FLW) and differences in FSC practices between countries present further obstacles to FSCs’ sustainability (Alzubi and Noche, 2022a).

While (Eriksson et al., 2014) discussed impacts of FLW on FSC competitiveness due to limited natural resources and its environmental impacts, (Alzubi and Akkerman, 2022) highlighted that supply chain (SC) competitiveness directly influences its economic performance.

Hence, reducing the FLW argues the three-bottom line (3BL) of sustainability, potentially enhancing the overall sustainability performance

of FSC (Nicastro and Carillo, 2021). SC structure plays a significant role in the amount of FLW (Chauhan et al., 2021); which has been studied analyzed by several researchers from different point of views (Kurtz et al., 2020; Martin et al., 2022; Qu et al., 2010).

1.1. Sustainable FSC networks

Decentralized SCs have several advantages, such as applying distributed decision models (Qu et al., 2010) and fulfilling customer demands within shorter periods (Martin et al., 2022). Although (Tira- do-Kulieva et al., 2022) found that centralization poses a disadvantage for FSC due to factors related to stability and food security, (Alzubi and Noche, 2022a) considered centralized SC for better stakeholders management aiming to eliminate causes of FLW. Although (Kurtz et al., 2020) has found that having a local marketplace can generate benefits related to food resilience,(Hübner et al., 2016) has have concluded that short FSCs are often associated with crowed logistics, where high operational costs become a disadvantage. Therefore, FLW is an

* Corresponding author.

E-mail address: [email protected] (E. Alzubi).

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important key performance indicator (KPI) affecting FSCs sustainability.

Consequently, the essential redesigning FSCs to integrate the circular economy (CE) is necessary to reduce FLW and enhance FSC sustainability (Nicastro and Carillo, 2021).

The integration of CE with the closed loop supply chain (CLSC) may enhance sustainability goals in FSC (Liu et al., 2021) by setting the overall goal to avoid and decrease FLW through FSC (Despoudi and Dora, 2020), redirecting generated FLW, and by-products to generate value from them (Kyriakopoulos et al., 2019), which improve economic performance and generate social benefits (Lavelli, 2021), such as food security (Kuisma and Kahiluoto, 2017) by reducing food loss. Addi- tionally, the CE creates job opportunities within the SC (Korhonen et al., 2018), employs incentive mechanism to motivate workers (Shekarian, 2020), meets the population demand (G¨obel et al., 2015; Pingali et al., 2017) by offering affordable prices (Nicastro and Carillo, 2021) facili- tated by the reduction of FLW and the integration of CE with by-products.

1.2. Sustainable agricultural supply chain

Recycling FW to close the loop within the same agricultural SC (ASC) could positively improve its sustainability (Sadeleer et al., 2020). For instance, (Boccia et al., 2019) analyzed tomato waste, highlighting its high potential for biofuel generation. (Laufenberg et al., 2003) demon- strated that greening the SC of fruit and vegetables (FV) involves minimizing FLW, directing FLW and by-products as animal feeds, or utilizing composting plants to produce fertilizers in a CLSC. This allows FLW to be reintroduced at a specific stage in the same product SC to extract from it. Similarly, (Bas-Bellver et al., 2020) proposed maxi- mizing the benefits from residues of vegetables such as carrots, leeks, and cabbage. Integrating the closed-loop concept into ASC aims minimize the costs of the agricultural inputs (Bas-Bellver et al., 2020).

Globally, fruits and vegetables (FV) constitute the most significant category contributing to food loss and waste (FLW), accounting for 45 – 55 % of the total FLW (Porat et al., 2018), primarily due to their sensitive nature and susceptibility to damage. Citrus products have gained increasing importance in the FV literature as they represent the most abundantly produced fruit occupying the largest cultivation area (Yang et al., 2020). Nevertheless, citrus loss and waste (CLW) accumulate across the citrus SC, with farms contributing at least 20 % of the total production loss (García-Tejero et al., 2012), processors accounting for around 50 % of the total processed weight (Ortiz et al., 2020), transportation contributing approximately 16 % (Adebamiji, 2011; Alzubi et al., 2022), and retailing contributing about 10 % (Hanif and Ashari, 2021). These figures result in a substantial percentage of citrus being discarded within its supply chain (Abbas et al., 2021).

1.3. Sustainable citrus SC

CLW contain valuable components that can be reintroduced for other industrial applications to generate value (Sharma et al., 2022). For instance, CLW is a rich source of pectin, limonene, essential oils (Mamma and Christakopoulos, 2008), vitamins, enzymes, and dietary fibers (Sagar et al., 2018). It can serve as input material for pharma- ceutical or cosmetic applications (Zema et al., 2018). Furthermore, CLW can be recycled and reused in the same citrus SC as fertilizer as mentioned by (Cheraghalipour et al., 2018). Using CLW as fertilizer in the same citrus SC often involves implementing reverse logistics (RL) (Cheraghalipour et al., 2018). Applying RL operations enables the Citrus SC to return packaging crates for reuse and recycling purposes (Borto- lini et al., 2018), leading to reduced operational costs at the farm level (Coelho et al., 2020).

Therefore, returning CLW as fertilizer and closing the loop at the farm can effectively reduce environmental impacts and enhance the economic performance of citrus SC by mitigating costs associated with agricultural inputs (Cheraghalipour et al., 2018). Still, there is a critical

need for a new model that considers collecting AR and FLW scattered along the citrus SC (Al-Hamamre et al., 2017), impeding logistics effi- ciency. To aid the decision process, circularity options and any proposed solution should undergo evaluation using the different sustainability assessment tools such life cycle sustainability assessment tools (St Flour and Bokhoree, 2021).

1.4. Life cycle thinking (LCT) within FSC, ASC, and citrus SC

While LCT is widely considered in the research for sustainability assessment, the literature predominantly focuses on assessing environmental impacts using life cycle assessment (LCA), especially within ASCs (Pena et al., 2022). For instance, (Alzubi et al., 2022) conducted a ˜ comparative LCA on citrus logistics operations, evaluating environmental impacts related to different packaging crates and CLW. In contrast, (Lask et al., 2020) utilized the LCC to find the cost of producing biogas from maize and identified the contributing parameters. Never- theless, (Degieter et al., 2022) reviewed 92 LCC studies on ASCs and concluded that there is a need to adopt an international standard when implementing LCC, often employing mass functional units (FU) for cost calculations. Notably, only one study estimated costs within citrus SC by (Pergola et al., 2013), specifically focusing on the citrus production phase.

1.5. Solar energy as a source of electricity

Although the transition to renewable energy is not a new topic in research, it has garnered increased attention in recent years (Gorjian et al., 2022). Utilizing renewable energy sources can offer several sustainability advantages. For instance, it has the potential to decrease environmental impacts, such as reducing the carbon footprint (Obaideen et al., 2023), as it cuts off the use of fossil fuels, subsequently reducing energy costs (Gielen et al., 2019). Within ASCs, there is a significant demand for electricity (Gorjian et al., 2022) to enhance their reliability due to their complex activities, emphasizing the necessity for a dependable electricity source, such as solar panels (Gorjian et al., 2021).

In a nutshell, LCC studies conducted on ASC lack standardized methodologies, rendering their results challenging to compare (Degi- eter et al., 2022). Therefore, this study followed the standardized procedure of LCA set by the European Commission (Pe˜na et al., 2022), as the initial step toward establishing a similar standard for LCC. Although the effectiveness of returning CLW as fertilizer in a citrus CLSC is acknowledged, there is a gap in assessing the total cost of the FU, crucial for decision-making processes. The novelty of this lies in its evaluation of FU costs and determination of cost factors across all stages of the citrus SC using LCC. Furthermore, the study aims to evaluate an existing citrus supply chain in a Mediterranean country and compare the results with those from a proposed centralized citrus CLSC, aimed at reducing citrus loss, enhancing the Self-sufficiency Index (SSI) (Alzubi et al., 2023), and facilitating a sustainable supply for composting plants by collecting FW and agricultural residues (AR) from various stages.

According to the mentioned studies, the implementation of a centralized structure would significantly impact economic and social sustainability, particularly when integrated with a CLSC. Therefore, this paper aims to address the following research questions (RQ):

RQ1: How might a centralized SC structure affect the economic performance of citrus SC?

RQ2: How might recycling CLW influence citrus SC’s economic performance?

RQ3: How would CLSC influences the social performance of citrus SC?

To address the RQs, the citrus SC in Jordan will be selected and evaluated. A proposed centralized structure will be assessed through

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four different cases: the centralized linear citrus SC, the centralized linear citrus SC with increase in labor income, the centralized citrus CLSC, and the centralized citrus CLSC with increase in labor income.

Additionally, to reduce energy costs within the stages of the proposed citrus SC, solar energy will be evaluated with the aim of eliminating electricity expenses in all cases.

2. Material and methods

This section outlines the steps taken to conduct the LCC analysis.

Firstly, the case study has been described. Secondly, the LCC procedure is outlined and explained. Data necessary for the analysis was collected through various sources, including observations of the harvesting practices on farms, tracking transportation trucks, and gathering sec- ondary data from reports and databases published by agencies in Jor- dan, such as the Department of Statistics (DoS) and the Ministry of Agriculture (MoA), as well as interviews with multiple stakeholders. The steps undertaken are illustrated in Fig. 1. A summary of the interviewees’ profiles can be found in Table 1.

2.1. Description of the case study

The case study concerns the citrus SC in Jordan, a Mediterranean country (Papirio et al., 2022), where citrus is planted and grown in Jordan Valley (JV). The region yields an average citrus production of approximately 145,000 tons (Alzubi and Noche, 2022b). Fig. 2 illustrates the overall flow of citrus products, originating from farms and progressing through the central market of fruits and vegetables (CM), retailers, and ultimately reaching consumers.

The planted area dedicated to citrus in Jordan covers approximately 5773 ha, with about 89 % situated in the JV and divided into 1977

agricultural units, each ranging from 3 to 4 ha (DoS, 2021). Citrus va- rieties cultivated in the JV includes oranges, lemons, grapefruit, lime, pomelo, mandarin, clementine, tangerine, and Kumquat. (Alzubi and Noche, 2022b) identified various causes contributing to CLW on farms.

One of these factors is linked to the availability of workers, who tend to work only when there are no alternative employment opportunities, as the income from citrus cultivation is perceived as low relative to the effort required.

In addition, individual farmers are responsible for cultivating and transporting their yield to CM, where they can sell it to retailers.

Moreover, retailers independently transport their goods from CM to their stores (Alzubi and Noche, 2022a; 2022b), resulting in a consider- able number of trucks facilitating fruit transportation. This extensive movement impacts the sustainability of citrus SC due to the high costs of harvesting, packaging, and transporting citrus. The high CLW on farm and during transportation activities, owing to shortage workers and a lack of handling facilities, exacerbates these challenges.

The cost of a 5 kg box is estimated at USD 2.68, inclusive of taxes and commissions. Farmers pay a tax of USD 0.14 for each box entering the CM, along with a commission of USD 0.07 (Alzubi et al., 2023). A fully loaded truck from the JV to the CM costs USD 140, where the truck capacity is 110 boxes. The cost breakdown for the current citrus SC, which includes production, harvesting, packaging, transportation costs of harvested citrus, as well as taxes and commissions at the CM, was collected from farmers and is presented in Table 2. According the website of the CM, the selling price of 1 kg citrus varies from USD 0.73 to 1.15 (Central Market of Fruits and Vegetables, 2023).

Considering the amount of CLW generated in the SC, which is around 20 % is sourced solely from farms (Alzubi et al., 2023), while 12 % sourced from transportation from the farms to the CM, and in the CM (Alzubi et al., 2022). However, based on semi-structured interviews with

Fig. 1.Analysis steps conducted in this research.

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nine owners of FV stores from different cities, they estimated the citrus waste in their stores at 12 %, among which around 7 % come from transportation from the CM to the stores. Thus, the total CLW generated within the citrus SC is around 48 %. Farmers reported that they need around 300 kg N-fertilizer annually for their farms in JV. The CLW generated at the farm only can produce around 2000 kg of organic fertilizer, which is rich in nitrogen (Ng et al., 2019).

During the interviews with farmers and farmworkers, farmworkers earn a daily income of USD 35.00, but this income proves insufficient due to their long working hours and the low compensation relative to their effort (Alzubi et al., 2023). They need to collect at least 50 boxes, each weighing 5 kg. Their expressed motivation aligns with a desire for a minimum income increment of USD 11.00, aimed at fulfilling their family’s needs.

2.2. Proposed structure for citrus SC

The necessity for a redesign of the citrus SC arises from the substantial levels of CLW and the imperative to enhance the social impacts

of the citrus SC by generating employment opportunities and aug- menting labor income. The proposed structure replaces the CM with two new nodes responsible for collecting, packaging, storing, and distributing citrus throughout Jordan and transportation trucks must return to their starting points. As proposed in (Alzubi and Noche, 2022a), the new citrus SC advocates the integration of collection points (CP) gathering citrus from farms and transporting it to two citrus hubs (CH). These hubs will undertake processing, packaging, storage, and distribution to 12 distribution centers (DC), aiming to diminish CLW and reduce the overall costs per kilogram of citrus at the retailing stage. In addition, the centralized citrus SC offers an infrastructure to integrate the cold SC starting from the farm, which can reduce the effect of perishability on citrus products and would lead to improving the SSI, which measures the ability to cover the domestic demand from the local produce. Notably, the SSI was found for citrus products to be 82 % in Jordan (Alzubi et al., 2023).

(Alzubi and Noche, 2022a) conducted a mathematical model to determine the optimal number of CPs. The model was resolved using the resource location-allocation algorithm. The distribution of these CPs spans the JV, situated at one-kilometer intervals along the main street of the JV. According to the analysis, the proposed citrus SC should incor- porate 52 CPs and two CHs. Moreover, the proposed structure allows for the integration of CE practices by collecting empty crates and CLW from all SC stages, returning them to the CPs. Their analysis identified optimal locations based on transportation costs and diesel consumption. The collected CLW will be used to produce compost and returned to the farm, while the crates can be reused to diminish the environmental impacts of packaging crates (Alzubi et al., 2022). A summary of the proposed citrus SC is illustrated in Fig. 3. Returning the compost to the farm reduces farmers’ costs and contributes to lowering the cost per 1 kg of citrus.

The study examines the costs of the proposed citrus SC across two Table 1

Interviewees profiles for data collection to redesign citrus SC.

Position Number of

interviewees Location Meeting Extracted data Grading line

provider Sales Director 1 China Online Machine costs, space needed, layout, required workers, required energy, life span.

Regional sales

manager 1 Egypt Online Machine costs, space needed, layout, required workers, required energy, life span Technical support

Engineer 1 Egypt Online Machine costs, space needed, layout, required workers, required energy, life span Compost machine

provider Regional sales

manager 1 China Online Machine costs, space needed, layout, required workers, required energy, life span, input/

output ratio

Citrus farms Farmer 6 Jordan Onsite Agricultural inputs and their costs, selling price, farm area, number of trees, amount of waste, agricultural residue, number of workers, transportation costs, CLW.

Farmworkers 15 Jordan Onsite Income, working hours, cultivation rate per day, their expenses, number of family members, distance to work.

Retailers Store owner 9 Jordan Onsite Demand, CLW, selling price, purchasing costs, purchasing quantities, purchasing frequency, distance from market, labor.

Solar panels

providers Sales Engineers 2 Jordan Onsite Selling price, space requirement, labor requirement, generated electricity per panel.

Bank Loan officer 1 Jordan Online Loan types, amount allowed, interest rate, loan period, monthly payment.

Fig. 2. Current CSC in Jordan.

Table 2

The average cost of citrus production per FU.

Cost item USD

Labor 0.141

Pesticide

Fertilizer 0.051

0.034

Packaging box 0.056

Transportation 0.254

Taxes 0.028

Commissions at the CM 0.014

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cases. The first case involves analyzing the costs from cradle to grave, excluding consideration of CLW. The second case evaluates the costs from cradle to cradle, incorporating the return of CLW for use as farm compost. Additionally, each case assesses two scenarios: (i) the costs associated with the new structure, and (ii) the costs when workers’ income is increased by 33 %, as outlined in (Alzubi and Noche, 2022b).

Both scenarios undergo analysis within the cradle-to-grave scope and are then compared against the costs of the current citrus SC. In the proposed citrus SC, CPs and CHs will be supplied with the required electricity from the solar panels, therefore, all analysis will consider the solar panels as a source of energy. However, the effect of utilizing the soler energy on the FU costs is evaluated.

As CPs and CHs represent new nodes, they will necessitate the acquisition of new machines and equipment for operation. Furthermore, it’s essential to conduct an analysis of the ongoing operational costs associated with the new structure. Data pertaining to packing house machines, including energy requirements, labor needs, and other relevant details, were gathered through interviews with representatives from grading lines, as outlined in Table 1.

2.3. Life cycle costing (LCC)

The LCC approach is utilized in this study to quantify all costs required to switch to the proposed structure by (Alzubi and Noche, 2022a) and to identify cost contributors to the FU. The analyses adhered to the ISO (2017) guidelines. (ISO, 2017) guidelines. Each CP will be equipped with three composting machines to process the CLW generated in the allocated farms. Moreover, CLW generated downstream in the SC will be collected at the DCs and prepared to be returned to the CHs with the same trucks, that transport citrus from the hub to the DCs, and then to CPs to be fed into the composting machines. The RL is depicted by green arrows in Fig. 3.

2.3.1. Goal and scope

The study aims to provide a thorough cost analysis when implementing the proposed structure, achieved by measuring the following objectives: (i) Quantifying the costs associated with the citrus life cycle across various cost categories. (ii) Identifying the cost drivers and their contributions to the total costs. (iii) Comparing the costs of the FU within five cases: the current citrus SC, the centralized linear citrus SC (Alzubi and Noche, 2022a), the centralized linear citrus SC with a 33 % increase in labor income, the centralized citrus CLSC (Alzubi and Noche, 2022a), and the centralized citrus CLSC with a 33 % increase in labor income (Alzubi and Noche, 2022b). (iv) Re-evaluating all cases in point (iii) when closing the loop and returning compost to farms.

The relevant variable and fixed costs were presented, and cost items were identified through interviews conducted with experts, machine providers, farmers, and farmworkers. The analysis covered stages in the proposed structure, adopting a cradle-to-grave approach. Maintenance activities were excluded since the proposed structure has not undergone any replacements or maintenance yet. Additionally, costs related to end- of-life machines, equipment decommissioning, or recycling, following Pe˜na et al. (2022), were not included. The overall lifespan of the project is 25 years, while machines, electric tricycle trucks (ETT), and solar energy systems were considered to have a lifespan of 10 – 15 years.

Following Alzubi et al. (2022), the FU was defined as 1 kg of citrus sold to consumers at the retailing stage. Furthermore, the scope of this study is illustrated in Figs. 4 and 5 for the current citrus SC and proposed one, respectively.

2.3.2. LCC calculation

The total LCC cost in US dollar (USD) of citrus production, harvesting, packaging, transporting, and distributing 1 kg of citrus from farm to retailer can be calculated according to Eq. (1):

LCC(USD/kg citrus) =Cp+Ch+Cpc+Ct+Cd (1) Where: Cp =Production cost, Ch =harvesting cost, Cpc =packaging cost, Ct =transportation cost, and Cd=distribution cost.

To save companies’ privacy, the name of the companies will not be mentioned unless they agree to publish their names. The analysis followed the European Commission’s guide to Cost-Benefit Analysis (Eu- ropean Commission, 2015). In addition, the Straight-Line Method of Depreciation Calculation (SLMDC) was applied since it is a proposed concept. SLMDC considers the amount of depreciation decreases steadily over the years. Therefore, the depreciation expense was calculated using Eq. (2) (Cotter, 2022).

Depreciation rate = initial costs of assets − Salvage value

lifespan(years) (2)

2.3.3. Life cycle inventory

Based on the interviews with stakeholders and machine and services providers, the required equipment, and machines to operate the concept were identified and summarized in Table 3, divided into subsections related to CPs and CHs. Accordingly, the initial capital investment was calculated. The proposed structure found that the optimum number of CPs required to collect the citrus from all farms in JV is fifty-two, while CHs required are two hubs. Therefore, cost items related to CP in Table 2 were multiplied by fifty-two, while items related to CHs were multiplied by two.

Fig. 3. Proposed citrus SC of the case study.

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2.3.3.1. Feasibility analysis of installing solar panels. Due to the high electricity costs in Table 3, an analysis was conducted to evaluate the feasibility of installing solar panels, which are expected to cut energy expenses. The findings of this analysis are summarized in Table 4. For ease of calculations, all data listed in Table 4 are for one CP and one CH, and these figures will be multiplied by fifty-two for CP and by two for CH. To collect data about the solar panels’ requirements, specifications and costs, interviews were conducted with two sales engineers repre- senting two different companies in Jordan (though they preferred not to disclose company details). Both companies concurred on the following specifications: each panel can generate up to 0.56 kWh, covering an area of 1.6 m2, and is priced at USD 169.25.

The payback period and the rate of return (ROR) over 25 years were calculated to evaluate how worthy the use of electricity generated from a solar system for the CPs and CHs is. The payback period is the time needed to recover the investment, while ROR is the net gain or loss that might occur on an investment over a specific period. The payback period and ROR were calculated using Eqs. (3) and (4). Here it was assumed that the compounded interest rate of 5 %.

Payback period= initial investment

annual payback (3)

ROR= final investment− initial investment

initial investment .100% (4)

2.3.3.2. End-of-life assets. Calculating the depreciation depends on the salvage value of assets by the end of their life span. Therefore, this sub- section aims to evaluate the salvage value of the assets based on the data related to the scrap market in Jordan. The required data obtained from the Jordan local market states the scrap price as USD 705.22 / (kg steel).

Based on the cost items listed in Table 5, by the end of the investment, the total assets are USD 405,387.87. However, the End-of-Life value of any item not listed in Table 5 is considered zero in the depreciation calculation.

2.3.3.3. Covering initial investment using a loan. Assuming the new citrus SC structure’s initial investment costs will be covered with a loan. The average interest rate found in Jordan over 25 years is 6.5 %. Table 6 calculates the annual payments required when covering all fixed costs using loans with an interest rate of 6.5 % over 25 years, which is the assumed life span for investing in the new citrus SC.

Fig. 4. System boundaries of citrus SC adopted to implement LCC for the current citrus SC.

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3. Results and discussion

The results of the LCC calculations are presented and discussed in this section. The proposed design for citrus SC impacted the total costs of cultivating, transporting, and handling one kg of citrus from the farm to the retailer. Considering the costs listed in Table 2, the total cost per kg of citrus from the farm to the CM is USD 0.40. Following Alzubi and Noche (2022a), an assumption on transportation costs from the CM to the retailer stating that the transportation costs is USD 0.17. Comparatively, the total cost of the current situation is USD 0.57 per kg. The proposed citrus SC could result in a minimum 48 % reduction in the total cost of cultivating, transporting, and handling citrus from the farm to the retailer. Data listed in Table 3 was utilized in the analysis to specify the FU’s costs for all cases.

However, the issue concerning labor shortage on farms, as workers are avoiding employment due to long working hours and low income.

Therefore, (Alzubi and Noche, 2022b) proposed increasing their income by at least 33 %, leading to a 38 % reduction in the total cost/kg of citrus.

3.1. LCC of the citrus CLSC

The returning CLW to the farm as fertilizer is expected to eliminate the fertilizer costs, which will decrease the costs of the FU in LCC from cradle-to-grave by USD 0.034/kg citrus. However, it is expected that the CLW will be reduced by at least 65 % when implementing the proposed citrus SC (Alzubi and Noche, 2022a) . Considering this scenario, the amount of CLW used for fertilizer production is 40.50 tons, producing up to 12.15 tons of organic fertilizer daily during the season. The total amount of organic fertilizer is 24,396.5 tons, which covers the fertilizer requirement for all citrus farms in JV.

Based on the amount of fertilizer produced, it is expected that the fertilizer costs will be USD 0.00. Therefore, the CLSC cost analysis was conducted to assess the total costs of producing, harvesting, and transporting 1 kg of citrus from farm to retailer, including the RL. Fig. 6 compares the cradle-to-grave costs of 1 kg of citrus in three cases: the current citrus SC, the new citrus SC, and the new citrus SC with increased labor income. The analysis also incorporates the effect of depreciation. With the CLSC, the FU’s cost is estimated for the new citrus SC at USD 0.25 kg citrus with a 55.8 % decrease compared to the current citrus SC. Similarly, motivating the worker and increasing their income Fig. 5. System boundaries of citrus SC adopted to implement LCC for the proposed citrus SC.

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by 33 % will result in around USD 0.32 kg-citrus with a 43.5 % decrease.

The relative contribution of each factor to the FU for all cases, including the current citrus SC (Fig. 7).

Fig. 7 indicates that labor costs constitute the highest contribution to the FU, especially in the case of increasing workers’ income in the citrus CLSC. This is due to the more workers required to operate the compost machines in the CPs and the 33 % income increase to motivate them to come and work in the citrus farms. However, this will enhance social performance by providing more job opportunities for RLs activities and CLW recycling.

However, adopting motivation mechanisms such as increasing workers’ income enhances their purchasing ability to meet their fam- ilies’ needs (Shekarian, 2020). Similar discussions were conducted by (Barrett et al., 2012; Pena et al., 2022; ˜ Sany´e-Mengual et al., 2015).

Additionally, ASCs are labor intensive, which is one of the causes to make this cost category the highest contributor to FU’s cost (Alzubi and Noche, 2022b; CIR, 2018; Pena et al., 2022). The second contributor is ˜ pesticide practices (D’Onghia and Lacirignola, 2009; Ferreira et al., 2016; Pe˜na et al., 2022). Reusing the crates for agricultural products would cut the farmer’s costs and enhance their profits (Alzubi et al., 2022; Alzubi and Noche, 2022b; Wasala et al., 2015).

3.2. Covering initial investment using a loan

The analysis of using a loan to cover the initial investment indicates that the total annual expenses are USD 8134,163.78, and the monthly payment is USD 46,140.804, at an effective rate of 4.1 %. However, when distributing the annual expenses over the annual citrus production, which is 171,000 tons (DoS, 2021), each tone must generate at least USD 47.08 to cover the annual expenses.

3.3. Installing solar panels

The results from Eqs. (3) and (4) show promising benefits from installing solar panels, especially at the CH, since the investment re- covery is much faster than in a CP. It is expected to take 13.01 years to recover the investment paid to install a solar system for the CHs with a Table 3

Life cycle inventory of equipping 52 CPs and 2 CHs according to the proposed model.

Life Cycle stage

Fixed or variable cost

Cost item Lifespan

(years) Quantity Cost (USD)

CP Fixed ETT 10 156 220,028.21

Fixed Forklift

trolley 15 52 29,337.09

Fixed Compost

machine 15 156 4070,521.86

Fixed Office tables 15 52 73,334.27

Fixed Air

conditioner 10 52 57,827.93

Fixed Euro pallet 15 3120 22,002.82

Fixed Heavy-duty platform scale

15 52 36,671.37

Fixed Heavy-duty

plastic crates 15 156 378,448.52

variable Rent 52 293,370.94

variable Labor 312 1848,236.95

variable Electricity 1407,744

kWh 1436,637.52

CH Fixed Floor

isolation (refrigerated room)

25 400 m² 5641.749

Fixed Wall isolation (refrigerated room)

25 760 m² 28,942.17

Fixed Cooling unit (refrigerated room)

15 2 47,954.87

Fixed Plumbing and electrical works

25 23,413.26

Fixed Hangar

facility 25 2100 m² 148,095.91

Fixed Packing and

sizing line 25 2 310,296.19

Fixed Euro pallet 15 1320 9308.89

Fixed Forklift 15 4 50,775.74

Fixed Container

lifter 15 2 70,521.86

Fixed 40 ft refrigerated container

15 22 186,177.72

Fixed 40 ft

container 15 20 84,626.23

variable Labor 270 1787,306.06

variable Water 240 m³ 20,310.30

variable Electricity 411,600

kWh 36,768.69

variable Diesel (with

factor 2.5) 1438,577 L 3500,063.47

Table 4

Data required for the payback period and ROR to install a solar system.

Life Cycle stage Variable Value

CP Total electricity required (kWh/ month) 2256.00 Electricity generated (kWh/ panel) 0.56

Cost /panel (USD) 169.25

Solar panel area (m²) 1.60

Number of panels required 135.00

Total costs of solar panels (USD) 22,849.08

Interest rate 0.05

CH Total electricity required (kWh/ month) 17,150.05 Electricity generated (kWh/ panel) 0.56

Cost /panel (USD) 169.25

Solar panel area (m²) 1.60

Number of panels required 1021

Total costs of solar panels (USD) 172,806.77

Interest rate 0.05

Table 5

End-of-life assets (salvage value).

Category Life span (Years) Future value

(USD)

Containers 15 29,619.18

ETT 10 15,401.98

Hangar facility 25 56,417.49

Compost machines 15 275,035.26

Hubs machines 25 23,977.43

Forklifts 15 4936.53

Total assets by the End-of-life 405,387.87

Table 6

Total annual expenses by covering fixed costs using a loan, interest rate of 6.5 %, 25 years.

Life cycle stage Fixed costs Annual operating

costs

Collection points $

4261,920.00 $ 1518,400.00

Citrus hub $

1036,560.00 $ 3763,145.02

Totals $

5298,480.00 $ 5281,545.02 Annual loan payment over 25 years at a 6.5

% interest rate $ 485,577.10 -

Depreciation rate $ 200,442.00 -

Total annual expenses, including fixed

costs - $ 5767,122.12

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ROR of 9.55 %. While it was found for the CPs to be 14.15 years with a ROR of 8.81 %. In addition to the economic benefits, as discussed by (Guno and Agaton, 2022), consuming the required electricity generated using solar panels has environmental benefits since it uses a renewable energy resource, which also cuts the energy cost.

3.3.1. Effect of installing solar panels on costs

The analysis in the previous sections accounted for costs associated with utilizing solar panels. However, to demonstrate the impact of using solar energy in the proposed citrus SC, the costs attributed to the solar panels were excluded from the fixed costs, while the electricity costs listed in Table 3 were incorporated into the operational expenses.

Fig. 6. Total costs of cultivating, transporting, and handling the FU from cradle-to-grave.

Fig. 7. Life cycle stages contribution to the cost of 1 kg citrus from cradle-to-grave.

Fig. 8. Total costs of cultivating, transporting, and handling the FU from cradle-to-grave, when solar energy is not considered.

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Consequently, a comprehensive re-evaluation of all costs was per- formed. The analysis revealed an increase varies from 18.4 % to 23.5 % in the total costs of FU within the proposed citrus SC when solar panels were not utilized for electricity. Fig. 8 illustrates the FU costs in scenarios where the solar panels were not considered in the proposed structure. Nevertheless, in all cases, the total FU costs demonstrate a reduction compared to the current citrus SC.

The optimum decision at this stage is to have a solar system because it increases profit and keeps the environmental impacts low (Guno and Agaton, 2022; Kumar et al., 2022). Accordingly, the utilization of solar panels to generate the required electricity is highly recommended. This action will yield economic benefits while also positively impacting the environmental performance of citrus SC.

3.4. Economic performance

The closed-loop concept was integrated into citrus SC, in which the return trips of transportation trucks can be improved by being loaded with empty packaging crates and the collected CLW in the DCs. The costs related to the packaging crates listed are considered reusing those crates.

Reusable packaging leads to environmental benefits (Alzubi and Akkerman, 2022; Del Borghi et al., 2018). However, selecting the appropriate packaging crates to transport agricultural products, like citrus, is crucial to reduce the CLW (Alzubi et al., 2022; Chen et al., 2019; Fernando et al., 2018; Zheng et al., 2022).

Based on the general outcomes discussed above, a centralized citrus SC would improve its overall sustainability performance and enhance the opportunity to close the loop. Referring to the RQ1, it has been found that citrus CLSC improved its economic performance by reducing the FU’s cost for several reasons, such as more citrus will be supplied to the market due to less CLW, which was also concluded by (Weidner et al., 2019). Referring to the RQ2, the loss and waste could be used as compost, which would minimize the agricultural inputs’ costs.

3.5. Social performance

Several social benefits could be generated from the citrus CLSC. For instance, more returning packaging crates for the reuse can reduce the packaging costs (Alzubi et al., 2023). Similarly, the returned CLW to reused as compost can eliminate the fertilizer costs (Cheraghalipour et al., 2018). These enhance the potential to improve stakeholders’

profitability, which in return should be reflected in the selling price for the consumer.

Nevertheless, for RQ3, the social dimension would also be improved in many directions. Firstly, increasing labor income, as suggested by Alzubi and Noche (2022b), helps in improving their purchasing abilities to meet their needs. Secondly, the model creates additional job opportunities, which is particularly significant given Jordan’s high unem- ployment rate of 24.7 % as of the end of 2021 (DoS, 2021; MoA, 2021).

The proposed structure is expected to generate approximately 582 Job opportunities. Furthermore, reducing CLW in farms and transportation has positive social implications.

Focusing on the 20 % of CLW originating from farms and addressing its causes to reduce this percentage would significantly augment the supply of citrus to meet market demand (Alzubi et al., 2023). As they highlighted, this substantial CLW portion stems from the inadequate hiring of workers on the farm, who would work only when no other job opportunities are available. T Addressing this issue could potentially decrease CLW at this stage by 65 %, resulting in an approximate increase of 26,000 tons of citrus supplied to the market. Consequently, enhancing the SSI by about 18 % to meet domestic demand (Alzubi et al., 2023).

This improvement suggests potential increased profits for stakeholders.

3.6. Managerial and practical implications

The study analyzed various factors contributing to the FU’s cost, and

from this analysis, significant implications can be derived for stakeholders and policymakers. Implementing the proposed citrus SC can enhance its economic-social sustainability. In addition to adopting solar systems to generate the required electricity for both CPs and CHs; a unified transportation model will reduce the total costs per FU. Recy- cling CLW and returning it as compost will reduce the costs of the FU by around 40 %.

Reducing CLW will increase citrus supply to the market, positively impacting the SSI (Alzubi et al., 2023). This aligns with sustainability development goals and serves as a valuable reference for policymakers.

Additionally, more working opportunities will be offered to run the packinghouse, compost machines, and associated logistics operations (Friedman and Ormiston, 2022). Moreover, Managers can take advan- tage of the model and apply it to other ASCs to improve their sustainability. Additionally, FLW consumes natural resources, especially water;

therefore, any reduction in the FLW contributes to a reduction in resource depletion (Alzubi et al., 2022; Ortiz et al., 2020). Al-Hamamre et al. (2017) conducted an analysis of agricultural residues in Jordan and explored various valorization options for this waste. Additionally, they discussed the significant quantity of FLW scattered across various stages in FSCs and farms throughout the country. An important challenge they identified was the absence of collection facilities, hindering the consis- tent supply necessary for circularity, such as reuse as compost or for biogas production. This challenge can potentially be addressed within the centralized CLSC model.

FSC managers would benefit from this study by being proactive in adopting the centralized CLSC for many reasons. For instance, the closed loop SC would aid to adopt CE options or upcycling the collected FLW.

The centralized SC would help to eliminate the various causes to FLW, which lead to enhance competitiveness of their SCs, as discussed by Eriksson et al. (2014). Additionally, CLSC maximizes the utilization of return trips instead of the being empty, which would cut the costs of transportation Bortolini et al. (2018) and input materials to their operations Coelho et al. (2020). Finally, the centralized CLSC would aid the managers by providing a stable infrastructure to implement new tech- nologies such as Block Chain or internet of things trace and reduce FLW in the different stages if FSC, as also discussed by (Chauhan et al., 2021).

4. Conclusions

The paper investigated and analyzed the economic feasibility of a proposed citrus SC model that could enhance the overall sustainability performance of citrus SC by integrating the CLSC to collect and return CLW and packaging crates from the downstream SC to the farm stage.

The LCC was applied to quantify the total costs of the new model and then to compare five different cases: The current citrus SC, the centralized linear citrus SC, the centralized linear citrus SC with a 33 % increase in labor income, the centralized citrus CLSC, and the centralized citrus CLSC with a 33 % increase in labor income. Furthermore, the paper also identified the most contributor to the total FU’s costs.

The results indicated that the costs of the FU in the centralized liner citrus SC could reduce the cradle-to-grave cost of 1 kg of citrus in the linear citrus SC and the linear citrus SC with a 33 % increase in labor cost by 48 % and 38 %, respectively. However, the cost of the FU in the centralized citrus CLSC and the centralized citrus CLSC with a 33 % increase in the labor cost could be reduced by 54 % and 44 %, respectively. Nevertheless, the relative contributions of all cost factors have been calculated. It has been found that in the centralized citrus SC; the labor cost became most contributing to the total cost of 1 kg citrus in all cases because of the increase in the number of workers and the 33 % increase in the labor cost to motivate workers. Moreover, agricultural inputs reserved second place. An interesting result is that the contribution of transportation was reduced from 45 % in the current citrus SC to 16 % in the proposed model because of the increased amount of citrus that could be transported in the same trip.

Utilizing solar panels to generate the required electricity in CPs and

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CHs has resulted in an additional reduction varies from 18.4 % to 23.5 % in the costs of the FU for the proposed citrus SC. Moreover, the centralized citrus CLSC can positively influence the economic and social dimensions within citrus SC. Furthermore, it can potentially improve the SSI by reducing CLW in the initial stage and transportation by 18 % and cover the domestic demand for citrus (Alzubi and Noche, 2022b). The analysis showed that the proposed citrus SC could generate 582 working opportunities in all CPs and CHs.

The limitation of the study is that the study was conducted based on a proposed structure and compared to an existing citrus SC, which might lead to not considering some of the required cost items related to new nodes within the SC. In addition, the analysis considers citrus SC only and the waste generated from it, and therefore, future research might be directed to cover other agricultural products, study other CE practices to the CLW. However, since the study covers the LCC considering social impacts, the LCA of citrus SC might be conducted in future research to provide a full analysis of sustainability within citrus SC.

CRediT authorship contribution statement

Emad Alzubi: Conceptualization, Data curation, Formal analysis, Funding acquisition, Investigation, Methodology, Validation, Visuali- zation, Writing – original draft, Writing – review & editing. Ahmed Kassem: Validation, Writing – original draft, Writing – review & editing.

Ani Melkonyan: Writing – review & editing. Bernd Noche: Supervi- sion, Writing – original draft, Writing – review & editing.

Declaration of Competing Interest

The authors declare the following financial interests/personal re- lationships which may be considered as potential competing interests:

Emad Alzubi reports financial support was provided by Deutscher Akademischer Austauschdienst - DAAD.

Data availability

data used is listed in the manuscript.

Acknowledgment

The authors would like to thank the interviewees for their time, re- marks and information provided.

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