When we started Clean Brand, we thought about using glass bottles instead of plastic. One difficulty is that plastic is unavoidable in some of the mechanical components such as the pump or trigger. The only variable was the material of the bottle’s liquid containing body. Let’s consider the question of Glass vs Plastic: Which is Better for the Environment?
The Plastic Problem We Already Know About
It is no secret that plastic gets a bad rep from environmentalist because plastic bottles can take over 450+ years to decompose and less than 9% is recycled. Plastic production directly involves the treatment of crude oil or natural gas in the “cracking process”, where these components are converted into hydrocarbon monomers such as ethylene and propylene. It is obvious the production of plastic takes quite a lot of energy and resourced. Its sizable carbon footprint and greenhouse gas output vary correspondingly. Even after production, the process of disposing plastic—dumping, sorting, incinerating, and recycling all release CO2. As of 2015, emission from plastics was equivalent to 1.8B metric tons of CO2. Given the infamous reputation held by plastic, let’s look at glass at greater detail.
Manufacturing Glass
Making new glass requires sand—ton of sand! Glass is made from all natural resources such as sand, soda ash, and limestone. These resources can be harvested from riverbeds and sea beds. This process disrupts those ecosystems such as disruption of the food chain and erosion / flooding of communities. Worldwide, over 50 billion tons of sand is used every year to manufacturer glass. That is a lot of destruction of various ecosystems!
Once these raw materials are harvested, they’re transported to house for inspection, melting, and heating at 2600-2800 Fahrenheit. Subsequently they undergo conditioning, forming, and finish process for the final product. At this point, it is created, washed, and sterilized for transport and sale. One important consideration is glass is easy to break (than plastic) and there is a high waste consideration during transportation and use.
As you can imagine the process of making glass takes up a ton of virgin material taken from valuable ecosystem and the fossil fuel/ CO2 emissions generated during production. In North America the fossil fuel consumed to make glass averaged 16.6 megajoule per 1kg of glass produced. Plastic, by comparison, is 62 -108 megajoule per 1kg of polymer. Plastic is 3.8-6.75 times more energy intensive to produce than glass!
So where could the benefit come from in using plastic over glass? Consider the relative mass of material used per unit of volume encapsulated. A 9oz glass bottle weighed for this example comes in at 452 grams. A comparable plastic bottle that holds 10oz weighs a mere 64 grams, however. After adjusting for the size difference, the glass bottle requires 7.85 times the mass of glass to enclose the same space due to the much higher density of glass. This means that even the most energy-intensive plastic production produces less net CO2 emissions per bottle – and the more energy-efficient plastic production produces only half as much CO2 as a comparable bottle made of glass. And this calculation doesn’t even get into the added CO2 emissions created when transporting bottles that weight almost 8 times as much.
Recycling Glass
Glass made with all natural resources, it has the greatest theoretical potential of being 100% recycled and not create any additional waste or by-products. Sadly, the good news ends there!
Most glass isn’t made with recycled glass because only 33% of waste glass is a recycled in the US. More than 51M metric tons of plastic is recycled annually vs 10M metric tons for glass. Just like plastic, “wish-cycling” is a real problem where consumers toss nonrecyclable items that contaminate the entire bin. Certain glass such as widows and Pyrex bakeware cannot actually be recycled because of the way its manufactured to withstand high temperatures.
Another problem is that many facilities choose to crush recycled glass than properly recycling them. Therefore, less than 40% of recycled glass actually gets recycled. The remainder gets spread across landfills instead or downcycled, which prevents it from being recycled. The reality is that when glass gets tossed, the vast majority is crushed than recycled. Crushed glass has a practical use in landfills to cover the smells to deter pests, prevent fires, discourage scavenging, and limit rainwater runoff. Given that most glass isn’t recycled, we must evaluate how it decomposes!
Biodegradable Glass
Consumers love the nonporous and impermeable characteristics of glass because there are zero chemical interactions with the ingredients it contains, which sometimes can affect flavor or potency. This virtue is also its greatest drawback. It takes glass bottles one million years to biodegrade under normal environments and even longer in landfills. The 450 years for plastic bottles seem short by comparison.
There is no denying there are real virtues of glass over plastic such as the considerably lower energy used during manufacturing. The biggest problem with glass is the long decomposition time given the highly fragile nature of glass during practical use and handling. It’s useful lifetime is severely handicapped by high breakage rate.
For Clean Brand products, we want to consider the durability of the bottle material during transportation and use. For example, think of how many times you’ve knocked over a bottle onto the floor or counter. How many times can you salvage that bottle if it is made of glass vs plastic? Multi-purpose cleaner bottles are particularly a concern when they do get knocked around the counter or toss across the floor. Or when a young child knocked over the bottle into the sink trying to reach for the soap. The best thing we call all do is eliminate single-use plastics! To do that, we opted for the most durable bottle to be reused again and again.