Paper Bags VS Plastic Bags, Which Is More Environmentally Friendly?

What is LCA?

LCA is a method used to assess the environmental impact of a product, process, or service, and typically consists of four phases:

1. Determine the goals and scope of the LCA

2. Write a list of energy, material inputs, and environmental outputs for all relevant lifecycle phases

3. Evaluate environmental impacts related to life cycle inputs and outputs

4. Interpret the results and lead to more informed decisions

What is Life Cycle Stages?

The life cycle is generally divided into five phases. Take a plastic bag as an example:

1. Access to raw materials, including processes related to raw material extraction and refining. For plastic bags, the acquisition of raw high-density polyethylene (HDPE) includes obtaining natural gas and transporting it to chemical plants;

2. Manufacturing, including the process of converting raw materials into finished products. In this example, the plastic bag is obtained by melting a plastic pellet into a sheet and then forming a bag;

3. Distribution, which is for the final consumption and transportation and storage of goods. For example, plastic bags will be distributed from the manufacturer to the hands of various grocers;

4. Use/reuse, at this stage the product provides useful services to consumers. For example, with a plastic bag, we can take home the vegetables we bought from the market. Some consumers may use the previous bag to buy food or use the bag as a garbage bag, so we will also use this part of the reuse cycle in this life cycle;

5. The end of the life cycle, in which the product enters the waste management system. For example, plastic bags may be recycled, buried or incinerated to generate electricity.

So why using paper bags may be less environmentally friendly?

In order to reduce waste, there are many places where legislation restricts or prohibits the use of plastic bags by grocers. However, some LCA studies have shown that if consumers switch to paper bags, it may lead to the use of more diesel. Because paper bags take up more space than plastic bags, so the same number of bags can be shipped to grocers, and paper bags may require more truck mileage. So, in this case, one of the pros and cons of switching from plastic bags to paper bags is that while the plastic waste is reduced, the use of diesel fuel and the resulting emissions have increased.

The importance of LCA

Through this example, you can know the two effects of LCA:

1. LCA allows us to know that sometimes we feel that we have made an environmental decision, but the actual impact on the environment may change due to the intervention of this decision on consumer behavior. Therefore, it is necessary to consider all relevant effects in the LCA;

2. Consideration of all life cycles allows us to discover unexpected results. As mentioned earlier, reducing plastic waste at the end of the life cycle may result in increased costs for diesel fuel use. If we are only limited to non-biodegradable waste, paper bags are an environmentally friendly alternative to plastic bags. However, only by looking at the full life cycle can we find that the use of paper bags has worsened the environment during the distribution phase. Proper use of the LCA method can reveal these pros and cons and allow us to make better decisions.