This is a guide discussing whether glass is more sustainable than plastic, and vice versa.
We compare some of the key factors involved in the production, usage and waste management of each.
Summary – Is Glass More Sustainable Than Plastic?
There’s a few main points to consider when is comes to comparing the sustainability of paper and plastic …
1. Glass tends to come from renewable and abundant resources like limestone, sand, soda ash, and other source materials, compared to plastic which comes from mainly non renewable petrochemicals and other additives
2. Plastic is probably cheaper and has less of an eco footprint to produce, transport and sell/buy overall for businesses and consumers because of factors like how light plastic is, how flexible and durable it is as a material, and less energy and resources required to produce single use plastic compared to glass which tends to be heavier and needs to be melted at high temperatures in a furnace (using recycled glass/waste glass/broken glass/glass cullet can reduce the environmental impact of producing glass – but there are challenges and costs involved with obtaining suitable and reasonably priced recycled glass, along with glass recycling presenting other issues to do with mixing glass, contamination, and so on)
3. Plastic is recycled at a lower rate in general than glass (but it depends on the country, and type of glass or plastic item in question), and plastic also seems to be littered and inadequately disposed of into the environment in greater quantities than glass. Plastic, once in the environment, seems to be less eco and wild life friendly than glass. Glass can be recycled infinitely whilst plastic can only be recycled a certain amount of times before it loses integrity and quality. Plastic though, can sometimes be more eco friendly to send to landfill or incinerate. Both materials take an extremely long time to break down, but plastic can break into micro and nano plastics that get into food and water supplies, and plastic can absorb and transport organic pollutants as litter or ocean debris.
From an environmental perspective, how sustainable glass and plastic are might depend on the exact environmental indicator you are measuring (greenhouse emissions, energy use, water use, waste generated, etc), what stage of the product or material lifecycle you are referring to, the item you are talking about (a bottle, a container, etc.), the country you are referring to (the US, UK, a european country, and so on), and other variables. Food and beverage type glass especially probably has more potential to be a material that is part of a circular economy compared to plastic, but in some countries, the recycling and waste management systems aren’t set up to optimise glass recycling.
Outside of environmental indicators and measurements of sustainability, plastic tends to cost less and be easier in general for businesses to produce and transport as part of their products. Plastic is probably the more profitable material for most businesses to use.
Plastic may present issues to human health in terms of leaching of BPA and other chemicals when used in plastic bottles, containers, etc., plus potential issues with micro and nano plastics. Glass presents less of these issues.
Plastic may also lead to ingestion by, and entanglement for wild life and marine life. Whereas, glass doesn’t seem to lead to as many problems for wild life
Specifically with drink bottles, a high quality glass bottle that is re-used hundreds of times and can be recycled effectively and in a cost effective manner might be more sustainable in some ways than a single use plastic bottle
Glass vs Plastic: Comparison
What They Are Made Of – Glass is sourced from sand, soda ash, limestone and other additives. Recycled glass can also be used in the form of glass waste/broken glass/cullet. Glass is therefore mostly made from renewable and natural source materials. Plastic on the other hand mostly comes from non-renewable petrochemical feed stock such as crude oil and natural gas (recyclenow.com, and bettermeetsreality.com). It should be noted though that limestone usually has to be quarried, which has some environmental concerns
Energy Used, & Greenhouse Gas Emissions In Production – Glass can be energy intensive because of a high heat furnace used to melt glass, and fossil fuels that can be used to provide energy for heating and melting. Some sources indicate glass is more energy intensive – ‘Glass takes twice as much energy to produce [compared to plastic]’ (blog.theplasticbottlescompany.com). Using cullet can reduce energy requirements for glass production significantly (recyclenow.com via bettermeetsreality.com). Despite the melting process for glass, some studies indicate ‘manufacturing [a] low weight PET bottle is [the] equivalent to manufacturing a glass bottle, which is heavier, causing carbon emission that’s similar to a PET plastic bottle’ (drkarenslee.com via bettermeetsreality.com)
Weight – Glass is a heavier material than plastic
Transport & Delivery – because of the weight and properties of glass, glass may be more expensive, use more fuel, emit more GHGs, and be less efficient with packing and transport space – all leading to a higher environmental footprint for the transport of glass products and containers than lighter materials like plastic
Recycling Rate – Glass has a higher recycling rate at around an average of 33% for all types of glass containers and bottles in the US in 2015 (cen.acs.org, and gpi.org), compared to plastic which had a recycling rate of 9.1% in 2015 in the US (thebalancesmb.com). In the UK, different glass types are recycled at different rates – soda lime silica glass is recycled at a far higher rate than other glass types like borosilicate glass, lead glass and glass fibre, that aren’t widely recycled (recyclenow.com via bettermeetsreality.com). Windows, ovenware, Pyrex, crystal and other types of glass can’t be cross contaminated with food and beverage glass for recycling (gpi.org). In some countries, glass has an average 90% recycling rate, and the turnaround for putting a glass container or bottle from the recycling bin back on the shelf as a new glass product can be as little as 1 month (several sources via bettermeetsreality.com)
How Many Times Each Can Be Recycled – plastic can only be recycled a finite number of times before needing to be downcycled, or sent to landfill, or incinerated. Plastic loses it’s economic value and quality after being recycled a certain amount of times. Glass in comparison, can be recycled an infinite amount of times
Ease Of, Efficiency Of, & Value Of Recycling – different types of both glass and plastic can be difficult to recycle, can be inefficient to recycle, and both tend to have lower value as recycled material compared to other recycled materials like metal in current waste management systems with current facilities and technology. The US in particular faces several challenges if it wants to increase the rate of glass recycling
Secondary Uses – Both plastic and glass, if not able to be recycled, can have secondary uses across a range of applications. Plastic can also be incinerated (with technology that captures CO2 and air pollutants preferably)
Environmental Impact Of Recycling & Other Disposal Options – glass has the advantage of using cullet to significantly cut the raw and natural resources used, energy used and emissions in the glass production process (glassallianceeurope.eu via bettermeetsreality.com). Plastic on the other hand has different environmental and economic benefits for different disposal options (recycling, incineration, landfill) depending on different factors and variables
Durability – Glass is more fragile and brittle than plastic, and is more prone to breaking. Hard plastic may last longer than most types of glass, and increase it’s sustainability footprint from re-use (but, it depends on the type of glass and type of product or item in question)
Safety – Broken glass can be a health and safety issue in general, where as plastic tends not to be as much of a safety issue in general use (unless leaching, or even micro plastics is/are an issue)
Pollution Waste Created – More pollution is created in the manufacture, shipping and recycling of glass [than plastic] (blog.theplasticbottlescompany.com via bettermeetsreality.com)
Litter & Pollution In The Environment – Plastic items are some of the most commonly littered and inadequately disposed of items found on cleanups, and found in the ocean, in rivers, and even in the soil as micro plastic
Break Down & Degradation – Both materials take a very long time to break down compared to other materials – up to millions of years for glass, and even never for plastic (scientists are unsure is plastic ever fully goes away)
Carbon Footprint – several publications indicate glass has a higher footprint than plastic – ‘Glass creates more than 6 times the global warming gases than plastic’ (blog.theplasticbottlescompany.com). But that footprint can be lowered with re-use of the glass item and the use of recycled glass partially replacing virgin glass (blog.theplasticbottlescompany.com and tappwater.co, via bettermeetsreality.com). One source indicates ‘for every six tons of recycled glass used, the carbon dioxide emissions drop a ton’ (inquirer.com)
Eco Impact Per Gram – glass has a lower eco impact per gram for abiotic materials, water use, and GHG emissions indicators during production. But, glass is heavier, so the totals for final glass bottles compared to plastic bottles for example tend to favor plastic (giynow.com)
Eco Impact For Reusable Materials – reusable glass is better environmentally across abiotic materials, water use, and GHG emissions during manufacturing compared to reusable plastic (giynow.com)
Plastic vs Glass Bottles – when looking at bottles as an example, the more sustainable material can come down to several factors such as the types of glass and plastic used, how many times the bottle is re-used, what is used to make the bottle, how the bottle is disposed of, and other factors
Improvements In Each Material – both materials have been getting lighter over the past few decades, as well as more eco friendly across various measurements. So, there could be further improvements in the future environmentally for each material based on this trend continuing
The Sustainability Of Plastic
Read more about the sustainability of plastic in this guide
Other Factors To Consider
Just as there is different types of plastic, there are different types of glass. Each different type of glass can have a different sustainability footprint
Using recycled glass like cullet makes a difference to sustainability compared to using glass purely from virgin resources
The waste management systems, facilities and technology in a given country or State make a difference to the sustainability not just of different materials, but different waste items and products (because of how different waste materials and items are processed among the different disposal options at different rates)
How long a glass product or item lasts, or how many times it can be used/re-used before being thrown out, impacts it’s sustainability footprint