I first learned about LCA at the very beginning of my Masters at Western. Our TA had us use a statistics software to analyze the environmental impact of different products.
This is where I learned that a plastic bag is a better environmental choice than a paper bag.
It’s true. And the reason I’m writing about it today is because I’m finding that many of us are missing this key technique when trying to solve our key environmental issues. The harm in ignoring this information is that we take a generalized approach to a given issue without considering all the facts, i.e. all plastics are bad. Even worse, we can blindly choose an alternative that may be more damaging that the first problem we are trying to solve. Yikes.
So, what is LCA exactly?
To conduct an LCA, you need to account for all the inputs and output of a particular product during every stage of its life. From raw material extraction to design, material and part production, assembly, transportation, retail storage, use, and finally disposal.
In the case of the paper bag vs. plastic bag, we need to consider the following:
- How much energy is used to make the bag during manufacturing?
- How durable is the bag?
- What is the carbon footprint of shipping bags from producer to supplier?
- How easy is it to recycle?
- How quickly does it decompose if thrown away?
When you consider all of these, the plastic bag comes up as the green winner. If my memory serves me right, it is because the paper bag consumes much more resources in manufacturing, it is not as durable, it is heavier and bulkier- making transportation costly and takes up more space in the landfill.
Same idea is applied to the bio-plastics or plant-based plastics. They take much more resources to produce and cannot be recycled with non-bio plastic, thereby creating a new waste stream.
Of course, there are limitations with this technique. The software makes assumptions based on consumer behaviour regarding re-use. Ease of recycling is affected by geography and processing availability. The other limitation is due to the data lag which may slow down the momentum needed to address the biggest environmental challenges of our time.
However, LCAs are a key tool to be used, at least considered when making key decisions. It is a critical resource now more than ever in the wake of single-use plastic bans. We cannot forget that the items we are banning do serve a purpose for consumers. What will be the alternative that consumers are forced to use and what is the overall environmental impact of those? Let's take the science-based approach and look at the LCA before making decisions.