From New Trend Natural Gas to Non-Woven Polypropylene Bags: Embodied Energy
Introduction to Non-Woven Polypropylene Bags:
Grocery bags are essential to the modern human lifestyle. They provide a way to efficiently organize and transport groceries, along with many alternative uses. These bags can be produced from a wide variety of materials - oftentimes plastic, paper, fabric, and other alternative materials. A quote from The Australian Bureau of Statistics describes the functionality of traditional grocery bags, “Plastic bags are popular with consumers and retailers because they are a functional, lightweight, strong, cheap, and hygienic way of transporting food and goods. Additionally, the manufacture of plastic bags uses little energy. However, research has shown that energy use and greenhouse gas emissions can be reduced by switching from the commonly used bags to larger, reusable bags, by expanding the Code, and introducing a levy” (Australian Bureau of Statistics, 1). There has been a push in recent years to eliminate plastic bags and replace them with alternative more eco-friendly grocery bags. One type of grocery bag stands out among the rest, reusable non-woven polypropylene (NWPP) grocery bags provide a more environmentally conscious alternative to plastic ones. There are varying types of energy processes that go into the extraction of materials, manufacturing, and transportation of NWPP grocery bags. By looking at the embodied energy during the lifecycle of a non-woven polypropylene reusable grocery bag, it is evident that energy is an integral part of almost every stage of the NWPP bag's lifecycle.
What is Non-Woven Polypropylene?
One of the more popular alternatives to the classic plastic or paper bag is the NWPP bag. Propylene, the raw material base for non-woven polypropylene, was originally discovered by an Italian chemist by the name of Giulio Natta. (The Editors of Encyclopaedia Britannica) To clarify, polypropylene is a material that is made from a plastic-like substance called propylene monomers which is very versatile due to its unique chemical structure. A segment from the article, Everything You Need to Know about Polypropylene (PP) Plastic, defines the nature of polypropylene, “Polypropylene is classified as a “thermoplastic” (as opposed to “thermoset”) material which has to do with the way the plastic responds to heat. Thermoplastic materials become liquid at their melting point (roughly 130 degrees Celsius in the case of polypropylene). A major useful attribute about thermoplastics is that they can be heated to their melting point, cooled, and reheated again without significant degradation.” (Creative Mechanisms Staff, 1) In addition to being used for grocery bags, it is used for packaging, vehicle parts, different types of containers, and many other things.
Energy Necessary in Raw Materials Acquisition of the NWPP bags
Polypropylene is made from propylene gas, a raw material that is found underground. Extraction of the raw materials for NWPP bags requires the use of coal as well as fossil fuels to power the machinery needed to drill into the earth. The use of a vertical drill requires coal and fossil fuels to generate chemical as well as thermal energy. There is also a need for mechanical energy, and human workers, in order to operate the machinery. Chemical energy provides the means of transportation for these raw materials of NWPP grocery bags. Fossil fuels provide the necessary energy to power the trucks, planes, and ships to transport raw materials from overseas to the factories to the manufacturing plants. The manufacturing processes that take place in order to produce NWPP bags create the need for high amounts of primary energy sources which produce chemical and thermal energy. 
Energy in Manufacturing, Processing, and Formulation of the NWPP bags
Non-woven polypropylene requires a more strenuous manufacturing process than that of traditional plastic and paper bags, but in turn, they are much longer functioning because of their chemical structure. As opposed to traditional bags being created with mechanical energy, NWPP uses thermal energy using a high temperature to manipulate the material. (Muthu, 2) An article titled, Woven vs. Non-Woven PP from the website 1 bag at a time describes the manufacturing of NWPP by stating, “Non-woven PP is made by taking polypropylene polymers and spinning them using heat and air into long fluffy threads, like cotton candy, then pressing the threads together between hot rollers to get a flexible but solid fabric with a weave-like texture similar to canvas” (1bagatatime, 1). This quote describes the manufacturing process that occurs when producing NWPP bags, which differs from that of traditional grocery bags. Polypropylene’s high melting point at 130 degrees Celsius requires a high amount of coal and fossil fuels to provide an immense amount of thermal energy necessary to break down the compounds as the first step in the manufacturing process. These threads are then pressed with heated rollers to flatten out the material so that it can be assembled as sort of an alternative fabric. Manufacturing NWPP requires a high amount of thermal energy, to heat the polymers, along with chemical energy in changing the structure of polypropylene. Heating mechanisms, fueled by coal and fossil fuels, use both thermal and chemical energy in order to manipulate the chemical structure of the raw materials of NWPP. There is also a need for mechanical energy, namely human labor, in order to operate the machinery in the NWPP manufacturing factories. Electricity, a secondary energy source, to power factory lights and machinery such as conveyor belts. A life cycle assessment of NWPP describes the variation in the need for energy in manufacturing and production: “The energy demand for these processes is mainly met by grid electricity and this energy consumption depends on the polymer type, density, production equipment, and capacity.” (Kimmel, 1) Since these NWPP manufacturing plants require a high amount of energy, the energy density of fossil fuels is one of the primary fuel sources. Variation in the polymer types requires specialized machinery which in turn results in a fluctuating amount of energy usage. Another segment from an article titled, How are Non-Woven Polypropylene Bags Eco-Friendly (Carrier Bags) describes the physical properties of NWPP, “It is rough and resistant to other chemicals. Polypropylene is tough but also flexible. This makes the material be used easily for chemical and plastic engineering experiments. Polypropylene fabric can be translucent, but because it does not fade very easily, most people use polypropylene as dyed colored fabric.” (Bag Factory, 1) Factories that produce NWPP bags often appear in areas near supermarkets and grocery stores, so the distribution of these goods does not require as much energy as the transportation of raw materials.
Energy in the Distribution and Transportation of the NWPP bags
Transportation and distribution of the NWPP bags is the next step in the lifecycle. After being manufactured, NWPP grocery bags are distributed to grocery stores such as Trader Joe’s, Walmart, and FoodMaxx. There is a need for varying amounts of fossil fuels, namely petroleum, in order to provide the chemical energy necessary to power the semi-trucks and distribution facilities. In addition to this, mechanical energy or human power is needed just as before to operate the vehicles to distribute NWPP grocery bags to stores. More human labor is also necessary in unloading the bags from distributors and stocking them in stores. At this point, the NWPP bags have reached the stage where they can finally be used.
Energy in Use, Re-Use, and Maintenance PP Bags
Grocery stores often offer alternatives to the traditional plastic bag in the form of paper bags, canvas totes, and of course non-woven polypropylene bags. Non-woven polypropylene bags often range between 99 cents to 5 dollars and are reusable for many years. This eliminates the need to purchase paper or plastic for 10 cents every time while purchasing groceries. Primarily, these NWPP bags are used for to carry groceries but they can be used to carry and organize many different items. The energy that goes into using these bags is predominantly mechanical because of the people that use the non-woven propylene bags. A human exerts on average about 100 watts a day. Lifting a bag full of groceries exerts about 10 watts of energy but it can vary depending on how heavy the contents are in the bags. When reusing these non-woven polypropylene bags, it is easy to wipe them down and clean them because of the waterproof and durable material. (Thompson, 1) A segment from NRDC’s article, NRDC Lauds Passage of New York City Council Legislation Requiring Groceries, Retails to Provide Plastic Bag Recycling for Consumers, describes the magnitude of the plastic bag epidemic, “’ The average American family takes home almost 1,500 plastic shopping bags a year, clogging our cabinets, kitchen drawers and landfills. They’re hanging from trees, and littering our beaches,’” said NRDC Urban Program co-director, Eric A. Goldstein. (NRDC, 1) Plastic bag usage and consumption is detrimental to the environment because of the fact they are difficult to recycle without the correct resources. When comparing plastic bags to non-woven polypropylene bags there is a difference in the reusability and sustainability of the product. Traditional plastic bags are oftentimes used only once before being discarded, on the other hand, non-woven polypropylene reusable can sustain many years of use if maintained properly thus reducing the need to purchase new grocery bags all the time.
Energy in Recycling
Recycling these bags is also an important part of the life cycle as well. In terms of reuse and recycling, non-woven polypropylene bags can be used for many other things. They can be used to carry toys, books, clothes, shoes, along with many other supplies. When comparing the potential for recycling plastic bags, paper bags, and NWPP bags, non-woven polypropylene stands out among the rest. The most important form of energy for recycling in this case would be mechanical, or human energy. Mechanical energy is used to physically move these bags to the correct recycling facilities as opposed to discarding them in the trash which will inevitably end up in a landfill. (Greene,1) In addition, polypropylene can be broken down into its original raw materials, and approximately the same amount of energy can be put into recycling the NWPP bags. This requires thermal, chemical, and mechanical energy as well, just like before. Non-woven polypropylene bags are entirely recyclable so there is no need for energy in waste management as opposed to plastic and paper bags which oftentimes end up in landfills.
Why Choose Non-Woven Polypropylene?
Energy is an essential part of the life cycle of any product. For reusable non-woven polypropylene grocery bags, most of the energy goes into the acquisition of raw materials, manufacturing processes, and transportation of the materials to and from one place to another. Embodied energy sources for the life cycle of non-woven polypropylene include thermal, chemical, and mechanical energy. The amount of energy saved by using reusable non-woven polypropylene grocery bags outweighs the cost and potential waste caused by traditional plastic and paper bags. NWPP bags are much more efficient and sustainable because they are much more durable and require less energy in the long run.
TLPPACKAGING FOR SHOPPING BAGS
