A System Dynamic Model for Polyethylene Terephthalate Supply Chain in the United Arab Emirates—Status, Projections, and Environmental Impacts

Abstract

Polyethylene terephthalate (PET) water bottles are widely used in the United Arab Emirates (UAE); however, their production and disposal adversely affect the environment. In collaboration with the private sector, the UAE government has taken serious steps to reduce these impacts, including (i) encouraging people to stop using PET water bottles and to separate their waste, (ii) establishing material recovery facilities, (iii) constructing facilities for incineration with energy recovery, and (iv) creating business opportunities to downcycle and recycle PET water bottles. This paper models the PET supply chain (PSC) using system dynamics (SD) to simulate the current PSC in the UAE and to project its possible evolution from 2023 to 2050, taking greenhouse gas (GHG) emissions into consideration. For decision-makers, the SD model shows that PET reductions must equal population growth to maintain GHG emissions associated with the PSC for the coming years. In addition, the separation efficiency must exceed 33% of PET consumption to meet the current demand for used PET. Moreover, if PET consumption decreases by more than 1.5%, then businesses relying on used PET will face a supply shortage in the year 2050. As for environmental impacts, it is found that if downcycling and recycling capabilities are fully utilized, GHG emissions will decrease by 35%. Furthermore, if demand for recycled PET reaches 10,000 tons, this reduction will exceed 47%, reaching $177,861MtC{O}_{2}e$.

1. Introduction

Residents of the United Arab Emirates (UAE) are accustomed to drinking bottled water [1], although tap water is potable in all of the UAE’s emirates [2]. UAE residents consume more than 285 liters (L) per capita per year of bottled water, using more than 450 plastic water bottles [3]. Single-use water bottles are manufactured from polyethylene terephthalate (PET). PET is a thermoplastic polymer made from fossil fuels. PET possesses several qualities that make it an ideal material for water bottles. These characteristics include transparency, light weight, durability, and resistance to carbon dioxide [4]. In addition, PET bottles have low production costs. Despite these benefits, PET’s limited useful life, high production volumes, and hundreds of years of decomposition time create several environmental concerns [5]. Furthermore, the production of PET is an energy-intensive process that produces a substantial quantity of greenhouse gases (GHGs) [6].

The UAE population is around 10 million [7] and, as discussed earlier, the per capita consumption of bottled water per year is 285 L; thus, the total bottled water consumed is 2,850,000,000 L/year. An average of 30.89 g of PET are needed for each 1 L of bottled water [8]. Consequently, the amount of PET used to manufacture single-use water bottles in the UAE is around 88,000 tons/year. According to [9], the GHG emissions due to producing and incinerating one ton of PET are $2.01 MtC{O}_{2}e$ and $1.85 MtC{O}_{2}e$, respectively. Thus, the GHG emissions associated with the used PET water bottles in the UAE are $339,680MtC{O}_{2}e$ per year.

To fulfill its targets of satisfying Sustainable Development Goal 13 (SDG-13) [10], the UAE has taken several steps to reduce GHG emissions due to plastic consumption. The UAE has passed a law prohibiting the import, production, and distribution of single-use plastic purchasing bags by 1 January 2024 [11]. However, no comparable legislation prohibiting using single-use water bottles, PET bottles, was enacted. Instead, initiatives were launched, technologies were used, and business opportunities were created to reduce the environmental impacts caused by PET water bottles.

This work gives a holistic overview of the UAE’s PET supply chain (PSC). It starts by listing the current status of all acts taken in the UAE to reduce the impacts of relying on PET water bottles, mitigating its effects, and creating new business opportunities. It then develops a system dynamics (SD) [12] framework to model how these attempts would affect the PSC, starting with PET bottles’ production and ending with incineration. The SD framework calculates the GHG emissions associated with the PSC and is used to project the evolution of the PSC.

Several researchers have used SD to predict waste generation; for example, to predict the municipal solid waste (MSW) for Newark in the USA and the associated costs [13]. Similarly, MSW generation and management assuming different demographic and economic policies in Shanghai, China, were studied using SD in [14]. Moreover, SD was used to study municipal plastic waste generation and management in Dubai, UAE [15]. This research borrows the assumptions used in these works to predict the amounts of PET consumed from 2023 to 2050. However, this work studies a single type of plastic, PET, due to its high usage in the UAE.

From a practical perspective, decision-makers can use the developed SD model to comprehend the causal relationship between the various PSC stages and their respective acts. Furthermore, evaluating the expected volumes of GHG emissions along each stage would help decision-makers optimize their efforts to satisfy SDG-13 [16]. Decision-makers can also use the SD’s projections to benchmark their expectations from their current PSC interventions and to determine if they require additional involvement, such as enacting laws prohibiting the use of PET bottles or offering incentives to companies that recycle plastics.

Besides the work’s practical perspective, it has scientific contributions, since it can be used for benchmarking purposes. Benchmarking is about identifying the highest standards of excellence for products, services, or processes, and then making the improvements necessary to reach those standards, commonly called “best practices” [17]. Thus, by developing an SD model for the UAE’s PSC, researchers in other countries can use this study to benchmark other countries’ attempts to reduce GHG emissions and create business opportunities related to PSC. The UAE has the world’s largest per capita consumption of bottled water [2], and other neighboring countries share this behavior in the Gulf Council Countries. For example, European countries are trying hard to combat the negative impacts of plastics used in packaging because (i) the packaging industry is the largest consumer of plastics [18,19] and (ii) plastic is a major contributor to fossil fuel consumption [20]. Thus, several researchers have analyzed and modeled attempts to manage plastic packaging wastes in several European countries, such as Austria [19], Italy [21], and the Netherlands [22]. These studies did not focus on PET alone, since the most common plastic packaging materials are polyethylene (PE) and polypropylene (PP) [22]. The extensive use of PET water bottles is more specific to Middle Eastern countries; however, combating climate changes is a global effort.

2. Current Status

Figure 1 shows the different PSC stages. The PSC, as depicted in Figure 1, starts with bottle production, 1. Producing PET bottles is based on the market demand, reflecting the UAE’s water drinking habits. Sold PET bottles are then source-separated, 2A, or separated from the waste mainstream in material recovery facilities (MRFs), 2B. Separated PET bottles can then be either recycled to rPET to be used again to manufacture water bottles, 2C, or downcycled to manufacture other products, 2D. PET bottles that are not separated reach their end-of-life (EOL). Unseparated PET bottles are disposed of in landfills, 3A, or incinerated, 3B. Incinerators with energy recovery (IwER) are the preferable option for incinerating waste.

The UAE is comprised of seven Emirates. These Emirates, ordered based on their population, are Dubai, 3,551,734; Sharjah, 1,831,000; Abu Dhabi, 1,567,000; Ajman, 504,846; Ras Al-Khaimah, 345,000; Al Fujairah, 256,256; and Umm Al Quwain, 49,159 [7]. The population of the first three emirates represents 88.6% of the total UAE population. Thus, this work focuses on these three Emirates. Moreover, it is assumed that good practices in one of the Emirates will be repeated by others.

Waste in the three major Emirates is managed by different entities. Abu Dhabi Waste Management Centre, TADWEER [23], in coordination with the Environment Agency in Abu Dhabi, is Abu Dhabi’s lead entity responsible for managing solid waste throughout the Emirate. Founded in 2007, the BEEAH Group began its journey as a Sharjah-based, public–private partnership company responsible for waste management in Sharjah [24]. In Dubai, Dubai Municipality’s Waste Management Department is responsible for managing waste in Dubai [25]. The private sector can be authorized by the appropriate entities to manage waste in the three emirates.

2.1. Generation, Step 1

PET water bottles are manufactured to meet consumer demand like any other product. The majority of people would not rely solely on PET water bottles. For instance, a person may use a water dispenser with refillable water containers at home or the office, but purchase PET bottles when visiting a park or ordering food in a restaurant.

Twenty individuals at the University of Sharjah (UOS) were asked to participate in a brainstorming session to identify locations or situations where they would utilize PET water bottles. The group members were chosen to represent a range of demographic characteristics, like age, gender, income, and level of education. Students, professors, administrators, and others comprised the group. Moreover, Participants varied in age from 18 to 67, and the group included twelve females and eight males. Before the sessions, all participants were informed of the purpose of the brainstorming sessions so that they could have their ideas prepared and not be influenced by others.

Participants identified over 15 locations or occasions where PET water bottles would be utilized. However, some locations, such as hospitals, were disregarded because of the low consumption volume. In addition, to facilitate the analysis, especially given that the SD framework is a strategic tool, the aforementioned locations were clustered based on the anticipated amounts of PET bottles used and the reasons for using PET bottles. The following is a list of these clusters:

• Daily: in homes and workplaces;
• Outing: in parks, malls, and recreational areas;
• Hospitality: in restaurants and hotels;
• Education: in schools and universities;
• Others: gyms, sports events, and outdoor recreational activities.

The Dubai Can initiative, which targets single-use plastic water bottles in Dubai, was launched in February 2022 [26]. “One Small Change, One Big Impact” is the initiative’s slogan. The initiative concentrates on three fronts to accomplish this goal:

• Encourage everyone to stop using PET water bottles and replace them with refillable ones;
• Install water stations in Dubai;
• Raising environmental awareness about the harmful effects of plastics.

In one year, the initiative has cut the consumption of over 10 million 500 mL single-use plastic water bottles.

Alternatives to drinking PET-bottled water at homes and workplaces are available, like the 5 gallon refillable water containers with dispensers or tap water [2]. Moreover, the cost of installing a filter and using tap water is found to be the cheapest alternative [1]. However, some people still rely on PET water bottles at home. The Dubai Can initiative tries to raise the environmental awareness of its residents about problems associated with PET bottles and enforce the idea that tap water is potable. The initiative is expected to convince people to switch to water filters or dispensers at homes and workplaces.

As part of the Dubai Can initiative, the government of Dubai has dedicated several locations to install drinking water stations in major tourist attractions, such as beaches and parks [27]. In response, private companies sponsored these drinking water stations [26]. Moreover, several mall management companies have responded to the initiative by installing water drinking stations [28]. This number of water drinking stations is expected to increase, and this practice is anticipated to roll out to the rest of the UAE. With time, visitors to these locations are expected to bring their own refillable water bottles, instead of buying PET water bottles.

Several hotels and restaurants have also responded to Dubai Can initiative by abolishing PET bottles [29]. For example, the ACCOR hotel management group was one of the first to abolish PET bottles in two of the five-star hotels it managed in February 2022 [30]. ACCOR manages 59 properties, and plans to phase out PET bottles from all its managed properties. The IHG Hotels and Resorts group has also discontinued the use of PET bottles in two of the hotels it manages, namely (1) a new hotel in December 2022 [31], and (2) a cluster of hotels it manages in May 2023 [32], with plans to extend this practice to all of the hotels it manages in Dubai. This response is expected to continue such that more hotels and restaurants will stop using PET bottles. Unlike malls and parks, hotels and restaurants offer water as part of a service or a total bill.

The gyms, sports events, and outdoor recreational activities cluster is removed from further consideration, since a limited number of people participate in such activities; additionally, it is only for a few days per year. Thus, this cluster is excluded from any further analysis.

2.2. Source Sorting, Step 2A

Different tools are used to improve source separation:

• Using classical waste separation bins in malls and workplaces. These bins would directly separate plastic bins.
• Having separation bins in some neighborhoods. However, these bins would have mixed types of plastics that would require additional processing to isolate PET bottles.
• Using a mobile application (app) to collect recyclable waste. Recapp, a free door-to-door recycling service, started in Abu Dhabi in November 2020 and expanded its work to cover Dubai in February 2022 [33]. Using a mobile application, 15,000 registered users in Abu Dhabi can schedule pick-ups for plastic bottles and aluminum cans.
• Reverse vending machines to sell used PET bottles in Dubai and Abu Dhabi [34]. Similarly, people can get free bus rides for their recycled PET bottles [35].
• Private companies organizing the collection of PET bottles from places like schools and workplaces to downcycle PET into other products [36].

2.3. MRF Sorting, Step 2B

Each of the three largest Emirates has MRFs. All the solid waste MRFs are capable of segregating PET bottles. Dubai has four MRFs capable of processing 5200 tons/day [37,38]. BEEAH has an MRF facility in Sharjah, capable of processing 2000 tons/day [39].

2.4. Recycling, Step 2C

Bottle-to-bottle recycling means producing rPET that can be used again to produce water bottles or food containers [40], i.e., satisfy health and safety requirements. A PET recycling facility in Fujairah was granted a Food Grade Certification of Conformity from the Ministry of Industry and Advanced Technology (MoIAT) for its recycled PET granules [41]. The facility recycles between 11,000 and 12,000 tonnes of used plastic bottles per year, accounting for 10% to 12% of all PET bottles used in the UAE. In 2023, the UAE has set up a recycling facility with a capacity of 12,000 tonnes per year to produce rPET [42]. Thus, the UAE can recycle over 24% of its PET consumption.

To create a fully circular economy, companies need to produce new water bottles from rPEt; however, this is not currently the case. In 2023, the Al Ain Water Company started a production line of rPET-based water bottles [43]. However, rPET water bottles are not common in the market.

2.5. Downcycling, Step 2D

DGRADE is a manufacturer of eco-friendly clothes. DGRADE converts PET bottles to yarn that is used to manufacture clothes and non-food packaging products [36]. DGRADE cooperates with schools, universities, and others to collect their used PET bottles, as discussed earlier when we spoke about source separation. According to [44], the new DGRADE facility in Abu Dhabi can process 1 billion PET bottles per year, around 30,000 tonnes of PET.

2.6. IwER, Step 3A

Four IwER facilities are being built, and are expected to incinerate almost two-thirds of the solid household waste produced in the UAE [45]. Two of these projects are in Abu Dhabi, one in Sharjah, and another one in Dubai [45]. Dubai’s IwER facility is a USD 1.1 billion facility, one of the largest in the world [46].

2.7. Landfilling, Step 3B

Dubai has increased the cost of landfilling in 2022 and targets zero landfilling in 2030 [47]. The target of Abu Dhabi is to reach zero landfilling in 2070 [48], while BEEAH in Sharjah is targeting 2050 [49].

3. SD Models

SD models support studying policy tests and “what-if” scenarios [50]. Consequently, SD is commonly utilized to examine how the system’s behaviors over time are linked to its underlying decision rules and structure [51]. According to [52], SD uses a holistic approach to complex problems by considering causalities among actors and variables in these systems. Thus, SD was used to study waste management [53,54] and circular economy [55,56] problems.

The steps recommended in Sterman [57] are followed, and a conceptual model using Vensim^® was iteratively built to facilitate its validation by experts from the three primary entities managing waste in the UAE [58]. Experts have validated the logic and input parameters used in building the SD models, in addition to the SD results. The first model studies the growth in PET demand based on population growth. The second model extends the first model and considers the entire PSC in the UAE.

The variables in the SD model are classified as stocks, flows, and auxiliary variables. To form the SD model for the application, a Causal Loop Diagram (CLD) and a Stock and Flow Diagram (SFD) are required to be constructed [12].

3.1. PET Consumption SD Model

Figure 2 shows the first SD model that studies the effects of all efforts to replace PET water bottles with other alternatives; whereas

Table 1. Equations used in developing the PET consumption SD model.

Variable/Flow	Equation/Value	Unit
Growth rate	Uniform (0.65–1%)	person/year
Population	Growth rate × Population	person
Behavior change	PET users × Awareness success	%
Bottled water/year	PET users × Default: bottled water/person year	L
PET	Bottled water/year × PET g/L	tonne

shows the main equations used in the SD model.

The SD model starts by finding the expected UAE population for the simulated years, as shown by rows 2 and 3 of Table 1 and the population stock of Figure 2. Since it is expected that people might abandon the use of PET water bottles, the SD model also forecasts the percentage of residents who would still use PET water bottles, as shown by row 4 of Table 1 and the PET users and non-PET users stock of Figure 2. The volume of bottled water depends on the population and percentage of UAE residents who will keep using PET water bottles, as shown by row 5 of Table 1 and the “Bottled water/year” variable of Figure 2, from which the used PET can be calculated, as shown by row 6 of Table 1.

Data and assumptions used in developing the model can be described as follows:

• Population growth. The UAE population estimates in 2023 range between 9.48 and 10.67 million inhabitants [7]. Thus, 10 million is taken as the starting population in 2023. The population growth rate before 2010 was above 5%; however, it slowed down from 2011 to 2023, and growth rates during this period were below 1%. Thus, the growth rate is a uniform random number between 0.65% and 1%. The green arrows in Figure 2 show the SD model of the population calculations.
• Bottled water consumption. Two stocks are used to study the effects of all efforts to replace PET water bottles with other alternatives: PET users with an initial value of 1 and non-PET users with an initial value of 0, where these values represent population percentages, i.e., one means 100%. An awareness success variable shows how these efforts will convince people to stop using PET bottles, i.e., moving from the PET users’ stock to non-PET users.
  As stated earlier, the average percentage of bottled water consumed per capita per year is 285 L in the UAE. This number is multiplied by the percentage of people who still use PET bottles to find the volume of water drunk from PET bottles per year.
• GHG emission calculations. Knowing the volume of water consumed using PET bottles per year, the weight of PET produced is calculated. The weight of PET is then multiplied by the sum of GHG emissions generated due to PET production and incineration.

Table 2. Average weight of PET bottles per capacity based on [8], and a generic PET bottle used for calculations.

Bottle Size (mL)	Average Weight (g)	PET g/L
250	6.41	25.64 g
330	14.31	43.36 g
600	19.71	32.85 g
1500	32.6	21.73 g
Generic (1000)	30.89	30.89 g

shows the average PET weight per PET bottle volume [8]. The last row of Table 2 shows the PET weight for a generic PET bottle, assuming equal consumption of the four types of water bottles. This value, 30.89 g/L, is used to calculate the weight of manufactured PET.

Table 3. 2050 Metrics assuming different reduction scenarios.

Awareness Success	Bottled Water Volume	PET	GHG
%	(Million L)	(Tonnes)	${\mathit{MtCO}}_{\mathbf{2}}\mathit{e}$	% Dev.
0	2814.0	109,454	422,491	0
0.85	2543.3	86,922	335,522	−20.6
5	887.1	27,401	105,768	−75.9
10	206.0	6365	24,568	−94.2
15	44.0	1360	5250	−98.8
20	8.6	265	1022	−99.8

shows the volumes of water consumed using PET water bottles, PET manufactured, and GHG emissions in the year 2050, assuming different awareness success rates. Moreover, Figure 3 shows the amounts of GHG emissions for the years 2023–2025 for different awareness success rates. It is clear from Table 3 that the higher the awareness success rate is, the more reductions in the three metrics are. The default value for the awareness success is 0%, i.e., the UAE does not try to convince people to abandon their current consumption pattern of PET water bottles. Row 2 of Table 3 shows that around 3 billion liters of bottled water would be consumed in the year 2050 for a 0% awareness success rate. For the 0% awareness success rate, the associated GHG emissions due to producing PET water are expected to reach 442,491 $MtC{O}_{2}e$. If the UAE government succeeds in convincing 5% of PET users to switch to a new alternative each year, the GHG emissions reduction in the year 2050 will be 75.9%.To maintain the same values of the three metrics for 2023–2050, the awareness success rate must be equivalent to the average population growth rate, as shown by the 0.85% awareness success rate in Figure 3.

3.2. PSC SD Model

The SD model that captures the UAE’s PSC is shown in Figure 4, while

Table 4. Major equations or variables used in developing the SD model in Figure 4.

Variable/Flow	Equation/Value	Unit
new PET	PET-rPET used	tons/year
to mainstream waste	New PET × (1 − Source separation effectiveness)	tons
Separated PET	New PET × Source separation effectiveness + Main-stream waste × MRF separation effectiveness	tons
PET-based yarn demand	RANDOM UNIFORM (25,000, 30,000)	tons/year
rPET demand	RANDOM UNIFORM (1000, 3000)	tons/year
to incineration	Main-stream waste × (1 − MRF separation effectiveness)	tons
to rPET	IF (Separated PET (tons) > rPET and downcycle demand (tons)) Then (rPET demand) Else (Separated PET (tons) × $\frac{rPETdemand}{rPET\&downcycledemand\left(tons\right)})$	tons/year
to downcycle	IF (Separated PET (tons) > rPET and downcycle demand (tons)) Then (PET-based yarn demand (tons)) Else (Separated PET (tons) × $\frac{PET-basedyarndemand\left(tons\right)}{rPET\&downcycledemand\left(tons\right)})$	tons/year

lists the major equations or variables used in developing this model. The PET consumption model represents step 1 of Figure 1, while the PSC SD model shows the rest of the steps in Figure 1. Thus, the PET generation step in Figure 4 is the same as the one shown in the previous model. The first stock variable in Figure 4 shows the amount of virgin PET that is used to manufacture new PET water bottles. The rest of the stock variables shows the amounts of PET at the different PSC stages. Used PET needed for downcycling and recycling is found by contacting the two companies that consume these types of PET. The variable named balance, in yellow, shows the extra or shortage in used PET amounts.

For GHG calculations, we use data provided by [9] about recycling when calculating GHG emissions due to both recycling and downcycling. However, by downcycling PET bottles to yarns, GHG savings are obtained by replacing cotton and other natural fabrics with plastic ones. According to [59], $2.81 MtC{O}_{2}e$ are needed to produce one ton of cotton yarn. Thus, we assume that this amount is GHG savings due to downcycling. Thus, GHG calculations are composed of:

• Producing PET water bottles from virgin PET, $2.01MtC{O}_{2}e$;
• Recycling PET to rPET, $0.95MtC{O}_{2}e$;
• Downcycling PET to yarn, $0.95MtC{O}_{2}e$;
• Incinerating PET, $1.85MtC{O}_{2}e$;
• Savings due to replacing cotton yarn with plastic, $-2.81MtC{O}_{2}e$.

Through the developed SD model, decision-makers were interested in answering the below questions. In answering these questions, it is assumed that the consumption for PET water bottles will remain constant, i.e., a reduction in PET consumption is equal to the population increase, as discussed earlier.

• Q1: What is the least separation percentage that needs to be maintained to satisfy the recycling and downcycling demands?
  A1: Measures taken and technologies used need to separate 33% of the consumed PET. If this separation value is maintained, then the expected GHG emissions are 228,568.9643 $MtC{O}_{2}e$, which is a 31% saving compared to the default situation shows no increase or decrease in PET consumption. It is intuitive to assume that source-separation is cheaper than waste mainstream separation, which should be the focus of decision-makers.
• Q2: If a tax is imposed on virgin PET and consumers start to prefer rPET, what will happen to GHG emissions?
  A2: The current situation assumes that around 2000 PET tons are recycled into water bottles, around 64 million bottles. Figure 5 shows the decrease in GHG emissions for using rPET instead of virgin PET. For 10,000 tons of rPET water bottles, and assuming the same volume of downcycled used PET, GHG emissions would be $177,861MtC{O}_{2}e$; however, the sum of separation percentages needs to be around 45% to satisfy the market demand for used PET.
• Q3: How much can the demand for virgin PET drop before the downcycling and recycling industries face a shortage in used PET, assuming 40% separation rate?
  A3: If measures are taken to reduce PET usage by 1.5% per year, then the UAE will face a shortage of used PET in 2050. In this case, it is necessary to increase separation percentages.

4. Discussion

To meet the current demand in the UAE, approximately 88,000 tons of virgin PET are required annually. Using this quantity of PET to produce PET water bottles that are subsequently incinerated generates 335,522 $MtC{O}_{2}e$ in GHG emissions. To prevent PET consumption from increasing, the annual demand for PET should be decreased by 0.85%, which is equivalent to the expected average population growth.

Used PET can be downcycled into clothing or recycled into rPET, which can be used to produce rPET water bottles. DGRADE, a private company in the UAE, can recycle 30,000 tons of PET, but the demand for rPET water bottles is still in its infancy. Assuming (i) full capacity of downcycling is utilized, (ii) 2000 tons/year of PET are recycled to rPET, and (iii) PET consumption remains unchanged, the GHG emissions would decrease to 226,455 $MtC{O}_{2}e$, a $-35.2\%$ decrease in GHG emissions. However, separated PET must account for at least 33% of used PET to meet this demand.

If the demand for rPET increases to 10,000 tons per year, the GHG emissions would be 177,861 $MtC{O}_{2}e$, a decrease of 47%, compared to the do-nothing scenario. To reach this objective, the waste management system must be able to separate approximately 45% of used PET, 40,000 tons per year. Lastly, if PET consumption decreased by 1.5% per year, the PET recycling and downcycling industries would experience a shortage of used PET.

The accuracy of the insights gained from the SD model depends on the assumption adopted to build the model. For example, it is assumed that the population growth rate is randomly and uniformly distributed between 0.65% and 1.0%; however, this assumption needs to be regularly revised due to (i) its domino effect on all other factors in the SD model and (ii) instability of data used where the population growth rate was more than 5% before 2011 and suddenly became less than 1%. Another major assumption affecting the model results is the GHG emissions associated with PET production, recycling, and incineration [9]. These GHG emissions were measured in the United States; however, these values might be different in the UAE context, for which it is not available.

5. Conclusions

This work is a compilation of the UAE’s PET water bottle management efforts. The production, incineration, and disposal of PET water bottles generates substantial greenhouse gas (GHG) emissions, which have a negative impact on the environment. As a result, an SD model is created to represent the UAE’s efforts to reduce, separate, recycle, and incinerate PET as a PET supply chain (PSC). The SD model considers the PSC’s GHG emissions from 2023 to 2050. The SD model attempts to answer several questions posed by decision-makers regarding possible projections.

Simulating the PSC’s SD model reveals that, to prevent the current PET consumption in the UAE from increasing, it is found that the percentage of PET usage reduction must be equal to the population growth. Moreover, given the UAE’s current recycling and downcycling capabilities, at least 33% of the consumed PET must be separated, preferably through source separation. Increasing the demand for water bottles made from recycled PET (rPET) is also necessary. If the consumption of rPET bottles reaches 10,000 tons, GHG emissions could be reduced by an additional 21%. Lastly, if using PET water bottles is reduced by 1.5% per year, the UAE will reach an equilibrium between demand and supply of used PET in 2050.

The SD model can be used by decision-makers to evaluate their sustainability efforts, particularly those related to SDG-13. In addition, decision-makers can determine where to invest money and resources to mitigate the PSC’s environmental impacts and how to create business opportunities from this supply chain. The SD model is unique in that it focuses on a country rather than a factory or specific business, and can be applied to other countries.

The economic and social impacts of reducing, recycling, downcycling, and incinerating PET bottles were not considered in this work. Thus, future research should consider these impacts, not only the environmental ones. However, researchers should better analyze the stages where PET water bottles are mixed with other waste, e.g., incinerators and MRFs, where the costs and revenues are shared by many plastic and non-plastic waste. By considering plastic packaging material, the UAE can benchmark its policies to European countries. Moreover, each source of PET consumption should be further analyzed, e.g., daily or hospitality consumption.