Comparison between glass and r-PET bottle (0.5 liters)
Water consumption
Glass bottle
Manufacturing of glass
- Raw material handling: Production of glass requires raw materials such as sand, soda, and limestone, where water can be used in mining operations and to purify the raw materials (Bergdala glastekniska museum, n.d.)
- Production process: Water is used to cool down equipment and sometimes in the melting process itself (Bergdala glastekniska museum, n.d.).
- Cleaning and shaping: Water is used to clean and shape the glass (Bergdala glastekniska museum, n.d.).
rPET Bottle
For rPET bottles, the biggest advantage is using recycled material, which often means that the total resource consumption is lower than for new PET production (Tomra, 2022). Water usage includes:
- Cleaning and preparation of recycled material: Water is used to clean the recycled plastic bottles and to process the plastic into new bottles (Tomra, 2022).
- Production and shaping: Although water is used, it is often in smaller quantities than in the production of glass (Tomra, 2022).
Comparison in water consumption
According to some studies and estimates, much more water is required to produce a glass bottle compared to an rPET bottle. One of the most important reasons is that glass is a heavier material, which means that more energy and resources, including water, are used in production and processing.
General estimate
- Glass bottle: To produce a 0.5-liter glass bottle, it can take up to 15 liters of water or more, depending on production technology and efficiency (Learn Glassblowing, 2022).
- rPET Bottle: Production of a 0.5-liter PET can require about 0.75 to 1 liter of water (The Energy Footprint of Bottled Water | Live Science, 2009).
For a 0.5-liter glass bottle, water consumption can be 10-15 liters (adjusted for the bottle's weight and production requirements), while for a 0.5-liter rPET bottle, it can be 0.75 to 1 liter of water. This means that the glass bottle can require about 10-15 times more water than an rPET bottle.
Note that these figures are rough estimates and that exact values may vary depending on production techniques, geographical location, and specific factory routines. For a more accurate comparison, detailed information from specific manufacturers or a complete life cycle analysis is needed.
Energy consumption
The comparison of energy consumption between the production of a 0.5-liter glass bottle and a 0.5-liter bottle of 100% recycled PET (rPET) shows significant differences due to the different processes and materials used. Here is an overview of the energy requirements commonly associated with each type of bottle:
Glass bottle
The production of glass is very energy-intensive, mainly due to the melting process:
rPET Bottle
The production of rPET bottles is significantly less energy-intensive because they use recycled plastic:
Energy consumption comparison
Glass bottle
Production process: The production of a 0.5-liter glass bottle can require approximately 1.11 to 1.67 kWh of energy, depending on the efficiency of the production facility and the recycling rate of the glass (Livescience, 2009).
rPET Bottle
Production process: The energy consumption for a 0.5-liter rPET bottle is often in the range of 0.139 to 0.417 kWh, depending on the quality and degree of purity of the recycled material and the production process (A. Yu. Sanzharovskii, et al., 2022).
Summary
A 0.5-liter glass bottle thus requires approximately 4 to 6 times more energy to produce compared to a 0.5-liter rPET bottle that is made of 100% recycled material. These estimates may vary depending on specific production processes and techniques used, but they provide a general indication of the significant energy advantage that rPET has over glass from an environmental perspective.
Carbon dioxide emissions
The production of glass bottles and rPET bottles (bottles made from 100% recycled PET plastic) has different carbon dioxide footprints. Generally, glass bottles have a higher carbon dioxide footprint than rPET bottles.
Glass bottles:
- The production of glass is energy-intensive, especially in the melting of the raw material at high temperatures (International Aluminium, 2023).
- Glass bottles are heavier than plastic bottles, which means higher transport emissions per unit if the same volume is to be transported (International Aluminium, 2023).
rPET bottles:
- The use of 100% recycled PET reduces the need for new raw materials and energy-intensive processes required to produce new plastic (Annarita Paiano, 2021). rPET has a significantly lower carbon footprint compared to both new PET and glass (Shaini A. et al 2014).
According to estimates, carbon dioxide emissions for a 0.5-liter glass bottle are approximately 500-800 grams of CO2 equivalents (International Aluminium, 2023). For a 0.5-liter bottle of 100% rPET, emissions are usually between 100-200 grams of CO2 equivalents, depending on the production process and the energy sources used (Annarita Paiano, 2021).
This means that the glass bottle can have up to four times higher carbon dioxide emissions than an rPET bottle. However, this is a generalization, and actual values may vary depending on specific production conditions and the efficiency of recycling systems.
Transport efficiency
- rPET: rPET bottles are lighter than glass bottles, which results in lower transport emissions and reduced shipping costs. This reduces the overall environmental impact from transport (A. Yu. Sanzharovskii, et al., 2022).
- Glass: Glass bottles are heavier and more fragile, which leads to higher transport emissions and an increased risk of damage during shipping, which can result in more waste (International Aluminium, 2023).
Recyclability
- rPET: Recycled PET can be recycled multiple times, although it may be necessary to mix with new PET to maintain quality. Recycling PET reduces the need for new raw materials and can reduce the overall environmental impact (A. Yu. Sanzharovskii, et al., 2022).
- Glass: Glass can be recycled almost indefinitely without loss of quality, which is a major advantage. However, the recycling process is energy-intensive and can be less efficient in terms of transport and handling (International Aluminium, 2023).
Waste management and sustainability
- rPET: rPET bottles contribute to reduced waste by using recycled material, which can reduce the total amount of waste and pressure on landfills (A. Yu. Sanzharovskii, et al., 2022).
- Glass: Glass bottles are biodegradable but can take a very long time to break down in the environment if they are not recycled. In addition, the risk of broken glass and related waste is greater during transport (International Aluminium, 2023).
Reference
Learn Glassblowing. (2022). The Water Footprint Of A Glass Bottle. https://learnglassblowing.com/the-water-footprint-of-a-glass-bottle/
ISSUU. (2022). Renewable glass manufacturing. https://issuu.com/quartzbusinessmedia/docs/glass_international_december_january_2022/s/14571836
Livescience. (2009). The energy footprint of bottled water. The energy footprint of bottled water.
International Aluminium. (2023). Comparing the carbon footprints of beverage containers. https://international-aluminium.org/wp-content/uploads/2023/01/Comparing-the-carbon-footprints-of-beverage-containers.pdf#:~:text=URL%3A%20https%3A%2F%2Finternational
Tomra. (2022). What is rPET plastic? https://www.tomra.com/en/reverse-vending/media-center/feature-articles/what-is-rpet-plastic
Annarita Paiano, (2021). The environmental performance of glass and PET mineral water bottles in Italy. https://link.springer.com/chapter/10.1007/978-981-16-4609-6_1
A. Yu. Sanzharovskii, et al., (2022). Carbon Footprint of the Life cycle of glass contai. https://link.springer.com/article/10.1007/s10717-022-00505-1