In Singapore, when it comes to single-use materials, plastic is a much better choice than glass.
- Glass is far more energy and carbon intensive than its plastic substitutes.
- It requires significant energy to make (the melting point of glass is around 1500C)
- It is heavy so takes more energy to transport
- When recycling glass, it has to be reheated to those same high temperatures
- It cannot be incinerated in Waste-to-Energy ("WTE") plants (100% of the mass of glass ends up as bottom ash)
- Plastic can definitely can pose a menace to marine life and food chains when it enters the ocean.
- However, when waste is properly managed, this concern is mitigated.
- Singapore has an excellent waste management system, ensuring there is virtually no leakage of plastic into waterways.
- Plastic is better than glass in a number of ways:
- It requires far less energy to produce, say, one 500ml plastic bottle than its glass counterpart
- Its lightweight nature reduces the energy needed for transportation
- It releases a lot of energy when incinerated delivering more power to the electricity grid
- It produces virtually no bottom ash and has negligible impact on Semakau. Materials like metals, glass, sand, rock, and other minerals form the vast majority of bottom ash at WTE plants and are the culprits in the demise of Semakau. It's not plastic.
In short, single-use glass is a much worse choice for climate change than single-use plastic.
Plastic is often touted as the ultimate environmental villain, but in Singapore, the recommendation is quite the opposite. When it comes to choosing between glass and plastic for single-use materials, the sustainable choice is to opt for plastic.
At first, it might sound counterintuitive. You've been told the opposite your entire life. Glass is infinitely recyclable! There are straws in the noses of turtles!
But the reality is far more complex.
Bear in mind that this analysis is specific to Singapore which has the following attributes:
- little domestic packaged food production: most packaged foods and drinks get shipped in from long distances
- virtually no domestic glass or plastic recycling: these materials must be shipped long distances to get recycled
- an excellent waste management infrastructure with almost no leakage of waste materials into the ocean
- all waste is incinerated in WTE plants: no consumer waste is sent straight to landfill and do not sit around for 500 years waiting to degrade
With this context, lets look at the two materials:
Glass production requires substantial energy input, and its heavy weight results in significant transportation costs merely to move it from one place to another. Transport alone releases a lot of carbon.
Recycling glass is no easy task either. The process demands a great deal of energy as it must be reheated to an astounding 1500°C to create new bottles and jars from recycled glass. Moreover, unlike plastic, glass cannot be incinerated in local WTE plants, where temperatures range from 850°C to 1000°C - far below the melting point.
This means that any glass put into an incinerator remains intact, leading it straight to Semakau.
The exorbitant expense of transporting glass becomes an additional deterrent to recycling efforts in Singapore. Companies involved in recycling glass have to bear heavy transport costs, and as a consequence, glass waste in the blue bins is also subject to these charges. This makes it financially unviable to recycle glass unless someone is willing to foot the transportation bill.
Plastic can be a menace, particularly when it ends up in waterways and oceans, causing harm to marine life and the ecosystem. However, Singapore has an excellent waste management system, resulting in minimal leakage into surrounding bodies of water. Thus, the risk of plastics becoming hazardous to sea creatures is considerably reduced in Singapore.
Then there's incineration: plastic has a “high calorific burn” meaning it releases a lot of energy when incinerated. This increses electricity generation at WTE plants which in turn means that we are (slightly) less reliant on other fossil fuels (mostly natural gas) for energy generation. Moreover, the toxins released during plastic incineration are effectively removed through chemical scrubbers in WTE plants, ensuring that the air emitted meets health and safety standards.
About Bottom Ash & Semakau
This story is not complete without addressing the misconception surrounding plastic's contribution to bottom ash at WTE plants. Contrary to popular belief, plastic incineration results in virtually no bottom ash.
So what is filling up Semakau?
The bottom ash that heads to Semakau is composed of materials that cannot be incinerated at temperatures achieved in WTE plants. 850C is more than enough to destroy plastic but many material will remain intact: this includes metals, glass, sand, rock, and other minerals.
Plastic, much like paper and other chemically organic materials, makes a negligible contribution to the bottom ash at WTE plants.
Let's dispel the notion that plastic is a major contributor to Semakau and instead acknowledge that it is the other materials that are the main problem.
While glass might be the sustainable choice for long-term use, it falls short when considered for single-use materials. In such cases, choosing plastic over glass is the responsible decision in Singapore.
Nevertheless, remember that the best choice depends on the local conditions and waste management infrastructure of a particular region.
Let's make informed decisions, prioritizing sustainability based on our specific circumstances. Think local to act global.
Oh and: none of this is an endorsement that we should be consuming tons of plastic. The best choice is to not consume any single-use items. Duh.