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Analysis of plastics recovery and regeneration by life cycle assessment What is life cycle assessment?

Analysis of plastics recovery and regeneration by life cycle assessment

What is life cycle assessment?

 

LCA

Life cycle assessment (LCA) is a method tool, which is used to assess the environmental impact related to all stages of the product life cycle, including the whole process from raw material acquisition, production, use, recycling to product final disposal (namely “from cradle to grave”). As an important tool for product assessment and environmental management, life cycle assessment (LCA) has been widely used both at home and abroad. More and more LCA reports appear in the public view to provide basis for policy-making.

For one-time packaging, the assumption of end of life may be the most decisive aspect, regardless of its upstream impact on raw materials, production and transportation. This includes whether the product is reused, whether it is recycled (and where it is recovered), or is ultimately landfill or burned. However, the assumption about the end of one-time packaging life cycle is usually an ideal scenario, which is based on national average and national published recycling statistics, but rarely really explore what actually happens at the end of the life cycle.

In terms of plastics, it is also very important to study the end of product life cycle. For example, a large number of plastics are exported to countries with loose regulation, and the fate of plastics is unknown in many cases. With the export of plastics identified as a major source of marine plastic pollution, many people began to question: even recyclable plastic products, are they really recycled?

Waste treatment: how to compare the environmental impact of landfill and incineration?

01

Landfill

In life cycle evaluation, plastics seem to perform better. One of the reasons is that until recently, landfill is still a practical waste treatment method in most parts of the world. The impact of plastics in landfills is usually only related to the transport and maintenance of landfills, and there is no “direct discharge” problem, as they are largely inert in landfills. But there is evidence that plastics may not be completely inert, but the transition from scientific assumptions to embedded life cycle lists takes time and its emissions may still be small [2]. In addition, it is difficult to develop a landfill GHG emission list for each material, because the reactions occurring in the landfill will vary depending on the composition of the landfill or other factors.

Overall, from a climate perspective, landfills have a smaller impact than burning plastic (all of which will be released).

02

waste incineration

Most modern incinerators are a little like coal-fired power plants, which use energy from waste (EFW) to generate electricity. Life cycle assessment usually includes the “benefits” (or “avoidable burden”) from the incineration of plastic waste, because the electricity generated (sometimes heat) means less energy needs to be generated from other sources.

In the United States, landfill remains dominant despite a slow shift to incineration. EPA waste data for 2010 show that only 18 percent of the waste is sent to incineration. However, the latest data for 2017 show that this proportion has risen to 20% [3].

Although the difference is relatively small, it is important to use the latest waste statistics in the research area, even to assume the future scenarios based on current policy commitments, which is particularly important when using life cycle assessment to support or evaluate long-term decisions. In addition, the application of the results of this study to countries with very different waste treatment infrastructure will lead to inaccurate conclusions.

In the EU, landfill is marginalized and waste to energy plants are growing (from 38% in 2010 to 55% in 2017). Therefore, the research based on the waste data a few years ago may not reflect the current reality. But as people gradually realize that “addicted” to incineration actually limits the high recovery rate, this reality may change again. At the same time, due to the differences between the waste treatment systems in the United States and the EU, the research on the two systems is not comparable.

Even within the EU, waste treatment systems vary widely. In Sweden, for example, landfill plastics are banned and they are committed to completely preventing plastic from entering incinerators; In Wales, their goal is to eliminate plastic from landfills, but incineration is considered acceptable. This is also a reason why the explanation of time and region should be clear in this study.

It is worth noting that for countries that rely more on waste incineration, research often shows that the environmental impact of non recycled plastics is becoming more and more serious. This is due to the trend of decarbonization of energy systems – which would be incompatible with future decarbonization targets if energy generated by burning plastics replaces renewable energy rather than polluting more heavily fossil fuels. Looking at the scenarios that could be seen in 2030 and in the future, life cycle assessment will find that burning plastics are becoming increasingly unsustainable.

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How to use life cycle evaluation to analyze the recycling and recycling of plastics?

In addition to landfill and incineration, recycling and recycling play an important role in the end of the life cycle. However, in the study, the recycling rates are not accurate and difficult to compare. Life cycle assessment studies usually use the recovery rate reported by the state and assume a closed cycle process. However, in fact, there are many losses to the material from collection to recovery. That is why the EU recently adjusted its recovery measurement methods – only materials that have become recycled products (rather than assuming that all collected materials for recycling will eventually be recycled) [5]. This could lead to a significant reduction in the recovery reported by the EU, especially for plastics.

The details of the recovery rate are noteworthy. There are often studies using the current reported recovery rate to demonstrate future decisions. Given the potential for future recovery to change, the system may also be further optimized, which will not reflect the best results.

An example of this is a 2017 study of a composite packaging box manufacturer that compares milk containers in Nordic countries with composite packaging boxes [6]. The results clearly show that what life end point the product has and plays a key role in determining which packaging system has the lowest overall impact, but the study does not carry out sensitivity analysis focusing on future scenarios. If such scenario analysis is not available, the research will have a very limited role in policy-making, and will be used more as a marketing tool for manufacturers, and the results of the study are often taken out of context. This is why comparative research in enterprises often has problems, not because they lack the correct methodology, but because they can adopt a narrow view, which is difficult to find and understand for ordinary readers who are not experts.

Most comparative studies use the method of “cradle to grave” (from raw materials to disposal at the end of the life cycle), i.e. product evaluation based on the life cycle. The end of a product’s life cycle may be a certain number of reuse or recycling. For a product put into the market, if it performs well in the traditional linear system model, it is very good for life cycle evaluation. However, if we consider that the tomb of one product is the cradle of another, system modeling will become more complex and difficult to understand.

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