Jan. 21, 2022
There's more to plastic water bottles than meets the eye. Understanding its environmental impact may make a person think twice about grabbing a bottled water from the grocery store shelf. The Pacific Institute, a nonprofit research organization, estimates that the production and use of plastic bottles consumes as much energy as filling a quarter of all bottles with oil. (Oil produces a lot of greenhouse gases when it's burned, which contributes to global warming.) Here's a more in-depth look at the carbon footprint of plastic water bottles.
The production of one pound of PET (polyethylene terephthalate) plastic can produce up to three pounds of carbon dioxide. The processing of the plastic resin and the transportation of the plastic bottle largely affect the carbon footprint of the bottle. Estimates show that the total carbon footprint of a 500 ml (0.53 quart) plastic bottle of water equals 82.8 grams (about 3 ounces) of carbon dioxide.
Plastic bottles are made from resins derived from petroleum or refined oil and natural gas. Oil and natural gas are sometimes transported long distances to plastic manufacturers, using fossil fuels and producing greenhouse gas emissions. The size of the carbon footprint depends on the mode of transportation and the distance the raw materials must be transported. For example, trucking causes more CO2 emissions than rail transport. When long distances are involved, transportation energy consumption can account for up to 29% of the carbon footprint of plastic bottles.
The manufacture of plastic resins accounts for the highest percentage of the carbon footprint of plastic bottles. During the process, hydrocarbons from oil and natural gas are heated to extremely high temperatures to break down the larger hydrocarbon molecules into smaller molecules. The small hydrocarbons are then combined in different ways to form various types of plastics. PET resin, shaped like rice grains, is the raw material for plastic PET bottles. The energy used to produce PET resin accounts for approximately 30% of the total carbon footprint of a 500 ml plastic bottle.
Converting plastic resin into plastic bottles requires energy. The plastic resin is melted and injected into a mold, which is then heated and molded into a bottle. This final process accounts for about 8% of the carbon footprint of plastic bottles.
Energy is also required to clean, fill, store and package plastic bottles. Waste generation, including transporting plastic bottles to landfills, adds to the carbon footprint of the bottles. The sum of these processes can represent 33% of the carbon footprint of plastic bottles.
Carbon footprint calculators for individuals, children and businesses are available online; some are free. Personal calculators typically deal with general lifestyle activities and their estimated greenhouse gas emissions. Results may vary from calculator to calculator, but they can help consumers figure out what they can keep in their daily habits.
Given that the production of plastic resins is typically a major contributor to the carbon footprint of plastic bottles, recycling can reduce carbon dioxide and other greenhouse gases by about 30 to 70 percent. Other environmentally friendly alternatives include using fewer plastic bottles, making lighter bottles, reducing transportation distances and other energy-intensive processes. Research into other types of non-fossil fuel plastics and materials can significantly reduce the carbon footprint of plastic bottles.
