A Comparative LCA of ​Cotton, Polyester, and Recycled Polyester ​Woven Shirts
棉、涤纶和再生涤纶梭织衬衫的比较 LCA

ENVR 5340 ​
ENVR 5340

FUNDAMENTALS OF SUSTAINABILITY SCIENCE AND TECHNOLOGY​
可持续发展科学与技术基础

GROUP 4​
第 4 组

CHAN, Hin Man​, 21031375
陈显文， 21031375

CHEN, Yilei​, 21038452
陈一磊 21038452

LAI, Chun Hei​ 21046186
黎俊熙 21046186

LAM, Yuk Chun​ 21048964
林玉珍 21048964

LO, Ka Chun​ 2103671
卢家俊 2103671

CONTENT PAGE
内容页面

Abstract: 3
摘要：3

1. Introduction: 3
1.简介：3

2. Approach: 3
2.进场：3

2.1 Goal and method 3
2.1 目标和方法3

2.2 System boundaries and functional unit 4
2.2 系统边界和功能单元4

2.3 Scenario 4
2.3 场景4

3. Results and Discussion: 4
3.结果与讨论：4

3.1 LCI Life Cycle Inventory 4
3.1生命周期清单4

3.2 LCIA Life Cycle Impact Assessment 5
3.2伦敦国际仲裁院生命周期影响评估5

4. Future Research and Investigation: 7
4.未来研究与调查：7

Reference: 9
编号：9

Appendix 10
附录10

Abstract:
抽象：

This comparative life cycle assessment quantifies and compares the environmental impacts of cotton, virgin polyester (V-PET), and recycled polyester (R-PET) woven shirts. The study reveals cotton has the largest impacts across most categories like global warming potential and toxicity due to its energy-intensive production. R-PET demonstrates substantially lower impacts, highlighting the benefits of recycling PET bottles into fiber instead of extracting and processing virgin materials. To mitigate impacts, the report recommends switching to R-PET, improving production processes, implementing closed-loop recycling, and reducing waste and overproduction. Further research could focus on increasing fiber-to-fiber recycling, determining the environmental break-even point of recycling, and addressing trade-offs like energy use. Overall, recycled polyester emerges as a more sustainable option compared to cotton or V-PET for woven shirts, but its limitations must be addressed through innovation and circular economy principles.
这项生命周期比较评估量化和比较了棉、原生聚酯 （V-PET） 和再生聚酯 （R-PET） 梭织衬衫对环境的影响。该研究表明，棉花由于其能源密集型生产而对全球变暖潜力和毒性等大多数类别的影响最大。R-PET 的环保效果大大降低，凸显了将 PET 瓶回收成纤维而不是提取和加工原生材料的优势。为了减轻影响，该报告建议改用 R-PET，改进生产流程，实施闭环回收，并减少浪费和生产过剩。进一步的研究可以集中在增加纤维到纤维的回收，确定回收的环境收支平衡点，以及解决能源使用等权衡问题。总体而言，与棉或 V-PET 相比，再生聚酯成为一种更可持续的梭织衬衫选择，但其局限性必须通过创新和循环经济原则来解决。

Introduction:
介绍：

Clothing as a necessity plays an important part in the industrial composition and daily consumables around the world. In Turkey, the textile industry accounted for 17.5% of total exports in 2014, totaling US$27.6 billion, providing more than 400,000 jobs, and is an indispensable part of the Turkish economy¹. Globally, it is expected that the global apparel market will provide nearly 194 billion pieces of textiles in 2027². The textile industry is a complex system that includes a variety of processes and raw materials. Like yarn manufacturing, fabric production, bleaching and dying etc. sub-processes among. This may have caused serious emissions problems. In 2018, a research from McKinsey showed that the fashion industry was responsible for 2.1 billion metric tons of greenhouse-gas emissions³. The environmental problems caused by textiles may be worthy of attention.
服装作为一种必需品，在全球的工业构成和日用消耗品中发挥着重要作用。在土耳其，纺织业占 2014 年总出口的 17.5%，总额为 276 亿美元，提供了超过 400,000 个工作岗位，是土耳其经济不可或缺的一部分¹。在全球范围内，预计到 2027 年全球服装市场将提供近 1940 亿件纺织品²。纺织行业是一个复杂的系统，包括各种工艺和原材料。与纱线制造一样，织物生产、漂白和染色等子流程。这可能会导致严重的排放问题。2018 年， 麦肯锡的一项研究表明，时尚行业造成了 21 亿公吨的温室气体排放³。纺织品造成的环境问题可能值得关注。

In this study, we focused on three materials: cotton, virgin polyester (V-PET), and recycled polyester (R-PET). This is because cotton and polyester are the most common textile materials today. Currently, synthetic fibres, such as polyester, nylon dominate in fibre production around 70%⁴. Only polyester production in 2020 is 57.1 million tonnes⁵. Polyester is made from plastic compounds extracted from petroleum, and its source is considered as not environmentally friendly. Recycled polyester comes from a wide range of sources, which can be extracted from plastic water bottles, fishing nets, and used polyester apparel through mechanical or chemical recycling processes and remade into new fibers⁷. This helps reduce waste and reliance on petrochemical materials, but there are still large amounts of contaminants in the recycling process. Cotton is the natural raw material with the highest proportion in the clothing industry, with a market share of about 30%⁶.A lot of pollution is emitted during the cotton planting stage such as the abuse of pesticides, fertilisers, large-scale water consumption, and labour exploitation, etc. Cotton farming contributed to 6.2% pesticide and 14.1% of insecticide of total global usage, and the global average water footprint of seed cotton is 3,644 cubic metres per tonne⁸. Based on the above reasons, we believe that these three types of materials are worth exploring their impact on different environmental impact categories, and to compare making shirts with V-PET and R-PET will have a smaller or to what extent environmental impact than cotton woven shirts.
在这项研究中，我们重点关注三种材料：棉、原生聚酯 （V-PET） 和再生聚酯 （R-PET）。这是因为棉花和涤纶是当今最常见的纺织材料。目前，涤纶、尼龙等合成纤维在纤维生产中占主导地位，约占 70^%4。2020 年仅聚酯产量就为 5710 万吨⁵。聚酯是由从石油中提取的塑料化合物制成的，其来源被认为不环保。再生聚酯的来源很广，可以通过机械或化学回收工艺从塑料水瓶、渔网和旧聚酯服装中提取，并再制成新纤维⁷。这有助于减少浪费和对石化材料的依赖，但回收过程中仍然存在大量污染物。棉花是服装行业中占比最高的天然原料，市场份额约为 30%⁶。 棉花种植阶段会排放大量污染，例如滥用杀虫剂、化肥、大规模用水和劳动剥削等。棉花种植占全球农药总使用量的 6.2% 和 14.1%，全球籽棉的平均水足迹为每吨 3,644 立方米⁸.基于以上原因，我们认为这三类材料值得探讨它们对不同环境影响类别的影响，并比较用 V-PET 和 R-PET 制作衬衫会比棉梭衬衫产生更小或多大的环境影响。

Approach:
方法：

2.1 Goal and method
2.1 目标和方法

The goal of our study is to quantify and compare the environmental impacts of these three textile : virgin cotton, virgin polyester (V-PET), and recycled PET polyester (R-PET). This LCA study has been performed in openLCA 2.0 software using the Ecoinvent 3.9 database. For assessing the environmental impact, we adopted the ReCiPe Midpoint (H) method. In this study, the result only covers the Impact categories of the method ReCiPe Midpoint (H). Due to the lack of data from the literature or industry, we only used data provided in the database for calculations.
我们研究的目的是量化和比较这三种纺织品对环境的影响：原生棉、原生涤纶 （V-PET） 和再生 PET 涤纶 （R-PET）。 该 LCA 研究已在 openLCA 2.0 软件中使用 Ecoinvent 3.9 数据库进行。为了评估环境影响，我们采用了 ReCiPe 中点 （H） 方法。在本研究中，结果仅涵盖方法 ReCiPe 中点 （H） 的影响类别。由于缺乏来自文献或行业的数据，我们只使用数据库中提供的数据进行计算。

2.2 System boundaries and functional unit
2.2 系统边界和功能单元

The scope of this study is cradle to factory gate as system boundary for cotton and V-PET. It includes the production chain from raw material extraction to manufacturing. And excluding the use and disposal processes. The material flow would be like from raw material, for example, polyester resin and cotton fibre, then move to yarn production, weaving, dyeing, garment making. But for R-PET, we set the cradle to cradle as the scope. We assume that V-PET will be recycled into R-PET at the end-of-life. And assuming materials can be recycled safely and infinitely. So, the flow should be like recycle PET from multiple sources, recast into fibre, then move to subsequent processes. Please refer to the chart in Appendix 1 for details.
本研究的范围是从摇篮到工厂大门作为棉花和 V-PET 的系统边界。它包括从原材料提取到制造的生产链。并且不包括使用和处置过程。物料流类似于原材料，例如聚酯树脂和棉纤维，然后转移到纱线生产、织造、染色、服装制造。但对于 R-PET，我们将 cradle to cradle 设置为范围。我们假设 V-PET 将在使用寿命结束时回收成 R-PET。并假设材料可以安全、无限地回收利用。因此，流程应该像从多个来源回收 PET 一样，重新铸造成纤维，然后进入后续流程。详情请参阅附录 1 中的图表。

Our functional unit is defined as 1 woven shirt, free size, with 300 grams with no raw material loss. We focused on a standard type of woven shirt without considering variations accessories, trims. Etc
我们的功能单元定义为 1 件梭织衬衫，自由尺寸，300 克，无原材料损失。我们专注于标准类型的梭织衬衫，而不考虑各种配饰、饰边。等.

2.3 Scenario
2.3 场景

In our scenario setting, we focus on Guangdong, China, where the manufacturing process unfolds. The product journey starts at the resin factory or cotton fibre factory and travels 100 km to the vertical set-up garment factory, handling yarn production, weaving, dyeing, and garment making.
在我们的情景设置中，我们专注于中国广东，那里的制造过程正在展开。产品旅程从树脂厂或棉纤维厂开始，行驶 100 公里到垂直设置的服装厂，处理纱线生产、织造、染色和服装制作。

Results and Discussion:
结果与讨论：

3.1 LCI Life Cycle Inventory
3.1 生命周期清单

Having defined the scope and the flow of system boundary, a Life Cycle Inventory (LCI) is required for documenting the inputs and outputs of the specific products in an environmental context. Normally the inputs and outputs cover the raw materials, modes of energy, resource consumptions such as water, as well as the emissions to air, water and land. The inputs and outputs are collected from different stages of the manufacturing processes. (Ecochain)
在定义了系统边界的范围和流程后，需要生命周期清单 （LCI） 来记录环境背景下特定产品的输入和输出。通常，输入和输出包括原材料、能源方式、资源消耗（如水）以及向空气、水和土地的排放。输入和输出是从制造过程的不同阶段收集的。（生态链）

Manufacturing Processes of Cotton Woven Shirt
棉梭衬衫的制造工艺
As the scope is defined from a starting point as the cradle, the life cycle inventory of the cotton woven shirt will start from the cultivation of seed cotton. The cotton is then harvested and processed to become cotton fibre. The cotton fibre is transported to a factory for further processing into yarn. We adopted the process named as “yarn production, cotton, ring spinning, for weaving” in the Ecoinvent 3.9 database. The yarn will be weaved to form the woven fabric. Bleaching and dyeing will be followed as the last step for finishing the fabric. Cutting and sewing is needed to form the final product as a woven shirt. The model graph and LCI of the cotton woven shirt is depicted in (Fig 3.1.1 and Fig 3.1.2)
由于范围从摇篮这个起点开始定义，棉织衬衫的生命周期盘点将从籽棉的种植开始。然后，棉花被收获并加工成棉纤维。棉纤维被运送到工厂进一步加工成纱线。我们在 Ecoinvent 3.9 数据库中采用了名为“纱线生产、棉花、环锭纺纱、织造”的工艺 。纱线将被编织成机织织物。漂白和染色将作为整理织物的最后一步。需要裁剪和缝纫才能将最终产品形成梭织衬衫。棉织衬衫的模型图和 LCI 如图 3.1.1 和图 3.1.2 所示。

Manufacturing Process of Virgin Polyester and Recycled Polyester Woven Shirt
原生涤纶和再生涤纶梭织衬衫的制造工艺
Polyester production will be the starting point for both virgin and recycled polyester in this study since the scope begins from the cradle. The material of polyester is predominantly Polyethylene Terephthalate (PET), which is manufactured by the polymerization of terephthalic acid and ethylene glycol. These two ingredients are derived from fossil fuel. In this project, the process of “polyester resin, unsaturated” in OpenLCA Ecoinvent 3.9 database is deployed as the input to start the life cycle inventory. This polyester resin manufacturing process will depict the first life of the polyester resin. When we consider the recycled material, we have modelled the second life of the recycled PET by taking the inputs and outputs within the recycling process into consideration. The recycling model starts with taking back the PET bottles and generating them to PET granulate for further processing. As shown in Fig 3.1.3, we have also used “Avoided Product” function to prevent duplicated counting of the impacts brought by the manufacturing process of the virgin PET materials. Therefore, a comprehensive picture of the impacts brought by the recycled PET can be achieved. Once the fibre made of virgin and recycled polyester is made, subsequent processes such as yarn production, weaving, bleaching and dyeing will be followed. Cutting and sewing is the last stage to complete a woven shirt. Model graphs and LCI for both virgin and recycled polyester are shown in Figure 3.1.4 to 3.1.7.
在本研究中，聚酯生产将是原生聚酯和再生聚酯的起点，因为范围从摇篮开始。聚酯材料主要是聚对苯二甲酸乙二醇酯 （PET），它是通过对苯二甲酸和乙二醇聚合而成的。这两种成分来自化石燃料。在本项目中，将 OpenLCAEcoinvent 3.9 数据库中的“聚酯树脂，未饱和”过程部署为启动生命周期盘点的输入。该聚酯树脂制造过程将描绘聚酯树脂的第一次生命。在考虑回收材料时，我们通过考虑回收过程中的输入和输出，对回收 PET 的第二次生命进行了建模。回收模式从回收 PET 瓶开始，并将其生产成 PET 颗粒进行进一步加工。如图 3.1.3 所示，我们还使用了“避免的产品”功能，以防止重复计算原生 PET 材料制造过程带来的影响。因此，可以全面了解回收 PET 带来的影响。一旦制造出由原生和再生聚酯制成的纤维，将进行后续过程，如纱线生产、编织、漂白和染色。裁剪和缝纫是完成一件梭织衬衫的最后阶段。原始聚酯和再生聚酯的模型图表和 LCI 如图 3.1.4 至 3.1.7 所示。

3.2 LCIA Life Cycle Impact Assessment
3.2 伦敦国际仲裁院生命周期影响评估

Global Warming GWP
全球变暖 GWP,

Global Warming Potential (GWP) is a metric to measure the impact on the Earth’s climate. According to this study, the cotton woven shirt contributes 8.02582 kg CO2-eq, which is the biggest contributor to global warming, followed by the V-PET woven shirt. The R-PET shirt has the least impact.
全球变暖潜能值 （GWP） 是衡量对地球气候影响的指标。根据这项研究，棉梭织衬衫贡献了 8.02582 公斤 CO2-eq，这是导致全球变暖的最大贡献者，其次是 V-PET 梭织衬衫。R-PET 衬衫的影响最小。

In addition, looking at the contribution of life cycle stages tables (Fig. 3.2.1 & Fig. 3.2.2), the graphs show that yarn production and weaving are the main contributing factors. They account for 28.95% and 44.18% respectively of the total GWP contribution for a cotton shirt, equivalent to about 3.546 kg CO2-eq and 2.323 kg CO2-eq.
此外，从生命周期阶段表的贡献来看（图3.2.1和图3.2.2），图表显示纱线生产和织造是主要的贡献因素。它们分别占一件棉衬衫总 GWP 贡献的 28.95% 和 44.18%，相当于约 3.546 千克二氧化碳当量和 2.323 千克二氧化碳当量。

Turning raw cotton up to fabric involves energy-intensive processes like carding, combing, drawing, spinning, and mercerization for yarn production, as well as warping and drawing into the loom for weaving, exceeding the energy used in virgin polyester production and eventually increasing the global warming impact.
将原棉转化为织物涉及能源密集型过程，如用于纱线生产的梳理、精梳、牵伸、纺纱和丝光，以及用于织机的整经和牵伸到织机上进行织造，超过了原生涤纶生产中使用的能源，并最终加剧了全球变暖的影响。

In contrast, since RPET is recycled material from disposed bottles, it reduces the need for new raw materials and can save energy consumption. Thus, RPET emits only 2.327 kg CO2-eq, which is about 30% of the GHG emissions from cotton (Fig. 3.2.3). R-PET can result in significant GHG emission savings compared to other materials.
相比之下，由于 RPET 是从废弃瓶子中回收的材料，因此它减少了对新原材料的需求并可以节省能源消耗。因此，RPET 仅排放 2.327 公斤二氧化碳当量，约占棉花温室气体排放量的 30%（图 3.2.3）。与其他材料相比，R-PET 可以显著减少温室气体排放。

Ecotoxicity Potential in different perspectives (FETP; METP; TETP )
不同角度的生态毒性潜在 （FETP;METP;TETP ）

The life cycle assessment reveals concerning ecotoxicity impacts on freshwater, marine, and terrestrial ecosystems from cotton production and manufacturing.
生命周期评估揭示了棉花生产和制造对淡水、海洋和陆地生态系统的生态毒性影响。

According to the study result (fig. 3.2.1, Fig 3.2.2), below highlight related to FETP; METP & TEP
根据研究结果（图 3.2.1、图 3.2.2），下面突出显示与 FETP 相关的内容;METP & TEP

Upon closer examination of the study results, the yarn production and weaving stages of the cotton life cycle are the major contributors, responsible for 70-80% of these substantial ecotoxicity potentials (Fig. 3.2.5 – 3.2.7). Carding, combing, spinning, and mercerization process release toxins into ecosystems, leading to bioaccumulation, aquatic disruption, and broader ecological impact through biomagnification.
仔细研究结果后，棉花生命周期的纱线生产和织造阶段是主要贡献者，占这些潜在生态毒性的 70-80%（图 3.2.5 – 3.2.7）。梳理、精梳、纺纱和丝光过程将毒素释放到生态系统中，导致生物积累、水生破坏，并通过生物放大产生更广泛的生态影响。

On the other hand, this study’s results reveal RPET material is more sustainable, having the least impact in terms of toxicity on freshwater, marine and terrestrial ecosystems.
另一方面，这项研究的结果表明，RPET材料更具可持续性，对淡水、海洋和陆地生态系统的毒性影响最小。

Given that cotton's outsized contribution across all three ecotoxicity categories, transitioning to less impactful materials such as r-PET recycled polyester and implementing cleaner production processes are imperative.
鉴于棉花在所有三个生态毒性类别中都做出了巨大贡献，因此必须过渡到影响较小的材料，如 r-PET 再生聚酯，并实施更清洁的生产流程。

Human Toxicity: Carcinogenic & non-carcinogenic
人类毒性：致癌和非致癌 

Human toxicity from carcinogens can lead to cancer and genetic defects, while non-carcinogenic toxins might cause various health issues and environmental harm, disrupting ecosystems and food chains. In this study, figures 3.2.1, 3.2.2, 3.2.8, and 3.2.9 clearly show the results, and the table below highlights specific results on HTPc and HTPnc
致癌物对人类的毒性会导致癌症和遗传缺陷，而非致癌毒素可能会导致各种健康问题和环境危害，破坏生态系统和食物链。在这项研究中，图 3.2.1、3.2.2、3.2.8 和 3.2.9 清楚地显示了结果，下表突出显示了 HTPc 和 HTPnc 的具体结果:

Cotton material is the biggest contributor to HTPc and HTPnc. On the other hand, R-PET material shows significant improvement; having the least impact on these two impact categories.
棉材料是 HTPc 和 HTPnc 的最大贡献者。另一方面，R-PET 材料显示出显着的改进; 对这两个影响类别的影响最小。

In the HTPc results, R-PET shows 0.11287 kg 1,4 DCB-Eq, while cotton registers 0.3481 kg 1,4-DCB-Eq. Comparing these two materials, R-PET can achieve about 60% saving compared to cotton material. As well as, in the HTPnc result, R-Pet shows 1.77132 kg 1,4 DCB-Eq, that is about 9% of the total of HTPnc. R-PET can have the lowest environmental impact.
在 HTPc 结果中，R-PET 显示 0.11287 公斤 1,4 DCB-当量，而棉花显示 0.3481 公斤 1,4-DCB-当量。比较这两种材料，R-PET 比棉材料可以节省约 60% 的成本。此外，在 HTPnc 结果中，R-Pet 显示 1.77132 kg 1,4 DCB-Eq，约占 HTPnc 总量的 9%。 R-PET 对环境的影响最小。

However, in view of each production stage of R-PET woven shirts, yarn production and bleaching & dyeing are the stages that account for 84%- 86% of total HTPc and HTPnc of a cotton woven shirt.
然而，鉴于R-PET编织衬衫的每个生产阶段，纱线生产和漂染是占 棉编织衬衫总HTPc和HTPnc的84%- 86%的阶段。

To mitigate this, it's recommended to adopt less toxic materials, employ advanced, water-efficient dyeing technologies, and treat all dyeing wastewater effectively.
为了缓解这种情况，建议采用毒性较小的材料，采用先进的节水染色技术，并有效处理所有染色废水。

Energy Resources
能源资源

Fig 3.2.1, 3.2.2, and 3.2.10 illustrate the study result. Cotton is the highest energy consumer in textile production, accounting for 45% of total energy use (1.625 kg oil-Eq). Virgin PET (VPET) follows, consuming 35% (1.502 kg oil-Eq), mainly due to petroleum extraction and processing. Recycled PET (RPET) is the most energy-efficient, using only 20% (0.8402 kg oil-Eq), highlighting the energy-saving benefits of recycling over virgin material production or cotton cultivation.
图 3.2.1、3.2.2 和 3.2.10 说明了研究结果。棉花是纺织品生产中能耗最高的产品，占总能源使用量的 45%（1.625 公斤油当量）。原生 PET （VPET） 紧随其后，消耗 35%（1.502 千克油当量），主要是由于石油开采和加工。回收 PET （RPET） 是最节能的，仅使用 20%（0.8402 公斤油当量），突出了回收利用相对于原生材料生产或棉花种植的节能优势。

To reduce the energy footprint in textile production, adopt sustainable and precision farming for cotton, invest in energy-efficient technologies and alternative materials for VPET production, and promote RPET use. Enhancing recycling processes and implementing energy management systems across the supply chain, along with investing in renewable energy sources like solar or wind, are crucial for optimising energy use and advancing sustainable practices in the industry.
为了减少纺织品生产中的能源足迹，采用可持续和精准的棉花种植，投资于用于 VPET 生产的节能技术和替代材料，并促进 RPET 的使用。加强回收流程并在整个供应链中实施能源管理系统，以及投资太阳能或风能等可再生能源，对于优化能源使用和推进行业的可持续实践至关重要。

Water consumption
耗水量

The LCA analysis reveals that cotton has the highest overall water consumption potential, with a result of 3.48454 m3, especially during the yarn production and weaving stages, accounting for 44.96% and 47.67% of the total contribution for a cotton woven shirt respectively.
LCA 分析表明，棉花的总耗水潜力最高，为 3.48454 m3，尤其是在纱线生产和织造阶段，分别占棉梭织衬衫总贡献的 44.96% 和 47.67%。

V-PET's water consumption is notably high during resin/fibre production, at 52.56% of the total contribution for a VPET woven shirt, reflecting the water used in the petrochemical processes to create virgin polyester fibres.
V-PET 在树脂/纤维生产过程中的耗水量非常高，占 VPET 机织衬衫总耗水量的 52.56%，这反映了石化过程中用于制造原生聚酯纤维的水。

R-PET shows the least water consumption overall, with a particularly low result of 0.02362 cubic metres. The low WCP of R-PET is attributed to bypassing the initial polymerization stage that requires significant water usage, showcasing the benefits of recycling in terms of water conservation. All study results of water consumption are listed on Fig. 3.2.1, 3.2.2, and 3.2.11.
R-PET 的总体耗水量最少，仅为 0.02362 立方米。R-PET 的低 WCP 归因于绕过了需要大量用水的初始聚合阶段，展示了回收利用在节水方面的好处。所有用水量的研究结果均列于图 3.2.1、3.2.2 和 3.2.11 中。

Future Research and Investigation:
未来的研究和调查：

According to the Swiss Federal Office for the Environment, recycled polyester has roughly the same quality as virgin polyester, while its production only uses 41% of the energy required for virgin polyester⁹. Consequently, developing a recycled polyester supply chain can have a massive positive impact on global energy and resource requirements. However, there are some challenges that need to be addressed to fully realise the potential of recycled polyester.
根据瑞士联邦环境局的数据，再生聚酯的质量与原生聚酯大致相同，而其生产仅使用原生聚酯所需能源的 41%⁹。因此，发展再生聚酯供应链可以对全球能源和资源需求产生巨大的积极影响。然而，要充分发挥再生聚酯的潜力，还需要解决一些挑战。

While recycled polyester brings positive benefits to the ecology, there are some limitations to the recycled polyester as well. Firstly, Textile Exchange states that in 2020, 99% of recycled polyester was from PET bottles, meaning that less than 0.5% of the global fibre market came from pre- and post-consumer recycled textiles. In the US, just over 13% of clothes were recycled in 2018, with 11 million tonnes of clothes dumped or incinerated⁹. To help the supply of fibre recycled polyester, clothing manufacturers or recyclers can invest in innovation, such as technology to separate composite materials to avoid dumping, such as polyester blended with cotton, elastics, metal zips, and plastic buttons. It is necessary to create a closed-loop system of fibre-to-fibre production, so that at the end of each garment's life, it should be the input for a new garment. This will reduce the dependence on virgin polyester and increase the amount of recycled clothes.. In addition, companies should also focus on circular solutions and supply chain engagement such as partnership with key suppliers. More education and promotion should be done to spread the benefits of recycled polyester among the customers to increase demand.
虽然再生聚酯为生态带来了积极的好处，但再生聚酯也存在一些局限性。首先，Textile Exchange 指出，到 2020 年，99% 的再生聚酯来自 PET 瓶，这意味着全球纤维市场只有不到 0.5% 来自消费前和消费后的回收纺织品。在美国，2018 年略高于 13% 的衣服被回收利用，有 1100 万吨衣服被倾倒或焚烧⁹。为了帮助供应纤维再生聚酯，服装制造商或回收商可以投资于创新，例如分离复合材料以避免倾倒的技术，例如与棉、松紧带、金属拉链和塑料纽扣混纺的聚酯。有必要创建一个纤维到纤维生产的闭环系统，以便在每件服装的使用寿命结束时，它应该成为新服装的原料。这将减少对原生聚酯的依赖，并增加回收衣物的数量.. 此外，公司还应关注循环解决方案和供应链参与，例如与主要供应商建立合作伙伴关系。应该进行更多的教育和推广，在客户中传播再生聚酯的好处，以增加需求。

Secondly, there are trade-offs to consider. Despite its contribution to reducing certain indicators in the figures 3.2.1, 3.2.2, 3.2.10, the production of recycled polyester is still energy-intensive than wool, cotton and other materials according to the Stockholm Environment Institute⁹. Meanwhile, mechanical recycling, which is cheaper than chemical recycling, can lose the fibre strength, and it may need to be mixed with virgin fibre. The biggest advantage of chemical recycling is that the fibre is 100% recycled without loss, but requires high temperatures and chemicals may cause damage to the environment and workers without proper management. The principles of sustainable engineering are applicable here. According to Principle 1, all material and energy inputs and outputs should be inherently non-hazardous as much as possible. However, the production of recycled polyester under high temperature can release carcinogenic antimony compounds into the environment as a harmful component. Recyclers are suggested to modify their manufacturing processes, use alternative chemicals, and acquire third-party verification to prove their responsible recycling practices. For example, The Global Recycled Content Standard monitors waste management and prohibits the use of hazardous chemicals based on the ZDHC Manufacturing Restricted Substances List¹⁰
其次，需要考虑权衡取舍。根据斯德哥尔摩环境研究所的数据，尽管再生聚酯的生产对降低图 3.2.1、3.2.2、3.2.10 中的某些指标做出了贡献，但再生聚酯的生产仍然比羊毛、棉花和其他材料耗能 ⁹。同时，比化学回收更便宜的机械回收可能会失去纤维强度，并且可能需要与原生纤维混合。化学回收的最大优点是纤维 100% 回收无损失，但需要高温和化学品可能会对环境造成破坏，如果没有适当的管理，工人可能会造成破坏。可持续工程的原则在这里适用。根据原则 1，所有材料和能源的输入和输出都应尽可能在本质上是无害的。然而，在高温下生产再生聚酯会作为有害成分将致癌的锑化合物释放到环境中。建议回收商修改其制造工艺，使用替代化学品，并获得第三方验证，以证明其负责任的回收做法。例如，全球回收内容标准监控废物管理，并根据 ZDHC 生产限用物质清单¹⁰ 禁止使用危险化学品.

Lastly, recycling itself is only part of the components in the circular economy model. It is insufficient to solve the fundamental problem of the fashion industry: overproduction. According to the principles of sustainable engineering, Principle 2 and 4 mentions to prevent waste and maximize mass and energy efficiency. Hence, fabric companies need to rethink, repair, remanufacture, and recover, while customers need to reduce and reuse to prevent fabric waste generation and energy consumption.
最后，回收本身只是 循环经济模式的一部分。它不足以解决时尚行业的根本问题：生产过剩。根据可持续工程的原则，原则 2 和 4 提到要防止浪费并最大限度地提高质量和能源效率。因此，面料公司需要重新思考、修复、再制造和恢复，而客户需要减少和再利用，以防止面料废物的产生和能源消耗。

The future research in the area of recycled polyester could focus on fibre-to-fibre recycling. Research could be conducted to determine the extent to which the environmental impact can be reduced by increasing the use of fibre-recycled polyester in the fashion industry Hence, there might be the possibility of achieving an environmental break-even point. However, it should be noted that the break-even point may not completely resolve the waste generation issue since recycling itself has environmental impacts. If possible, society shall transit from recycling to prevent overwhelming fabric waste generation. Overall, further research in these areas could help to accelerate the adoption of fibre recycled polyester in the fashion industry and contribute to a more sustainable future.
再生聚酯领域的未来研究可能集中在纤维到纤维的回收上。可以进行研究，以确定通过增加纤维回收聚酯在时尚行业中的使用，可以在多大程度上减少对环境的影响。因此，有可能达到环境收支平衡点。但是，应该注意的是，盈亏平衡点可能无法完全解决废物产生问题，因为回收本身对环境有影响。如果可能，社会应该从回收中过渡，以防止产生压倒性的织物废料。总体而言，这些领域的进一步研究有助于加速纤维再生聚酯在时尚行业的采用，并为更可持续的未来做出贡献。

Reference:
参考：

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3. Berg A, Magnus K-H, Granskog A, Lee L (2020, Aug 26) Fashion on climate: report. McKinsey & Company. Retrieved from https://www.mckinsey.com/industries/retail/our-insights/fashion-on-climate
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4. Konina, N. Y. (2023). Smart Digital Innovations in the Global Fashion Industry and a Climate Change Action Plan. In Smart Green Innovations in Industry 4.0 for Climate Change Risk Management (pp. 255-263). Cham: Springer International Publishing.
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5. Production of Polyester Fibers Worldwide from 1975 to 2021(in Million Metric Tons). (n.d.). Statista. https://www.statista.com/statistics/912301/polyester-fiber-production-worldwide/
5. 1975 年至 2021 年全球聚酯纤维产量（单位：百万吨）。（日期不详）。统计。https://www.statista.com/statistics/912301/polyester-fiber-production-worldwide/

6. Kazan, H., Akgul, D., & Kerc, A. (2020). Life cycle assessment of cotton woven shirts and alternative manufacturing techniques. Clean Technologies and Environmental Policy, 22, 849-864.
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7. Leonas, K. K. (2017). The use of recycled fibers in fashion and home products. Textiles and clothing sustainability: Recycled and Upcycled textiles and fashion, 55-77.
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Appendix
附录

Annex 1. Flow of the system boundary
附件 1.系统边界的流程

Fig 3.1.1 Model Graph of Cotton Woven Shirt
图 3.1.1 棉织衬衫的模型图

Fig 3.1.2 LCI of Cotton Woven Shirt
图 3.1.2 棉织衬衫的 LCI

Fig 3.1.3 Use of “Avoided Product” Function in OpenLCA
图 3.1.3 OpenLCA 中“避免的乘积”功能的使用

Fig 3.1.4 Model Graph of Virgin Polyester Woven Shirt
图 3.1.4 初剪涤纶梭织衬衫模型图

Fig 3.1.5 Model Graph of Recycled Polyester Woven Shirt
图 3.1.5 再生涤纶梭织衬衫的模型图

Fig 3.1.6 LCI of Virgin Polyester Woven Shirt
图 3.1.6 Virgin 涤纶梭织衬衫的 LCI

Fig. 3.2.1
图 3.2.1

Fig. 3.2.2
图 3.2.2

Fig. 3.2.3
图 3.2.3

Global Warming (GWP100)
G肺叶增温 （GWP100）

Fig.  3.2.4
无花果。 3.2.4

Ecotoxicity – Freshwater ecotoxicity potent (FETP)
生态毒性 – 淡水生态毒性强效 （FETP）

Fig. 3.2.5
图 3.2.5

Ecotoxicity - Marine ecotoxicity potential (METP)
生态毒性 - 海洋生态毒性潜能值 （METP）

Ecotoxicity - Terrestrial ecotoxicity potential (TETP)
生态毒性 - 陆地生态毒性潜能值 （TETP）

Fig. 3.2.7
图 3.2.7

Human Toxicity Potential – Carcinogenic (HTPc)
人类毒性潜力 – 致癌性 （HTPc）

Fig. 3.2.8
图 3.2.8

Human Toxicity Potential – Non-Carcinogenic (HTPnc)
人类毒性潜力 – 非致癌性 （HTPnc）

Fig. 3.2.9
图 3.2.9

Energy consumption
能量消耗

Fig. 3.2.10
图 3.2.10

Water Consumption Potential (WCP)
耗水潜力 （WCP）

Fig. 3.2.11
图 3.2.11