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PetroProzac, Dasani-style

I was on Prozac for a long time. It may have helped me out of a jam for a little bit, but people stay on it forever. I had to get off at a certain point because I realized that, you know, everything's just OK.
     — comedian Jim Carrey

When the Wall Street Journal published Message in the Drink Bottle: Recycle on August 30, 2007, the words "petroleum", "oil" and "natural gas" did not appear in the text. Branded-Water Craze Adds to Piles of Plastic, Spurring Innovation at Coke, Pepsi, the sub-headline read. Peak oil is usually thought of as a liquid fuels crisis, but all of the other uses mankind has found for hydrocarbons should not be left out of the equation. As with gasoline, we consume plastic water bottles (pictured below left) as if there were no tomorrow.

The plastic in water bottles is polyethylene terephthalate (PET or PETE). Where does this magical substance come from?

PET is a polymer, a substance consisting of a chain of repeating organic molecules with great molecular weight. Like most plastics, PET is ultimately derived from petroleum hydrocarbons. It is created by a reaction between terephthalic acid (C8H604) and ethylene glycol (C2H602).

Terephthalic acid is an acid formed by the oxidation of para-xylene (C8H10), an aromatic hydrocarbon, using just air or nitric acid. Para-xylene is derived from coal tar and petroleum using fractional distillation, a process that utilizes the different boiling points of compounds to cause them to "fall out" at different points of the process.

Ethylene glycol is derived from ethylene (C2H4) indirectly through ethylene oxide (C2H40), a substance also found in antifreeze. Ethylene is a gaseous hydrocarbon that is present in petroleum and natural gas, but is usually derived industrially by heating ethane or an ethane-propane mixture.

Plastic Water Bottle Ethane and propane are common components1 of natural gas liquids, and serve as the primary feedstock to ethylene(-propylene) crackers, which accounts for this part of PET. Naphtha, which is produced during crude oil refining, is a common feedstock for an aromatics complex that derives the para-xylene. The"petro" in petrochemicals is there for a reason.

What is the energy cost to produce a plastic PET bottle? This is a hard question to answer because boundaries must be put on the calculation. The Pacific Institute cites a PlasticsEurope study (click on PET Bottles in this graph to download it) to make a rough calculation which we will follow here. According to the Wall Street Journal, a half-liter Dasani (Coca Cola) bottle now weighs 16.0 grams, a reduction of 5 grams off the older weight. The study indicates that it requires 103.94 megajoules (MJ) to produce 1 kilogram of PET bottles. A simple calculation reveals that it takes 3.326 MJ to produce a one liter Dasani bottle weighing 16 grams, excluding the cap and packaging. This is equivalent to 0.00052 barrels of fuel oil. According to the Beverage Marketing Corporation, Americans consumed 31.2 billion liters of bottled water in 2006. If all of this water had been Dasani served up in PET bottles, the oil equivalent would be 16.224 million barrels. This amounts to about three-quarters of one day's oil consumption in the United States.

PlasticsEurope extols the virtues of plastics. The library page is especially illuminating. "Plastics are fantastic ... today's lifestyles simply wouldn't be possible without plastics." One can't help but agree. People in the 19th and most of the 20th century got by without them somehow, but they didn't have a computer, nifty bicycles, etc. Under Facts and Figures, we learn "that plastics consume just 4% of the annual consumption of oil and gas, yet they are one of the most resource-efficient materials around." No argument. It is the Resource Efficiency section that matters—

Plastics are much too valuable to throw away, and putting plastics waste into landfill is like throwing oil away! PlasticsEurope supports eco-efficient solutions such as the diversion of ‘calorie rich’ plastics waste from landfill and end-of-life management of this material through recycling or recovery.

Pet Recycling Waste Water, Water Everywhere, a report from the Container Recycling Institute (CRI), describes the growth of non-carbonated beverage consumption in the United States and its attendant problems. CRI estimates that "approximately 18 million barrels of crude oil equivalent were consumed in 2005 to replace the 2 million tons of PET bottles that were wasted instead of recycled."

The provenance of the CRI number is unknown2, but a precise calculation can be carried out using CRI's data source for their graph (left) and the conversion factors introduced above. The National Association for PET Container Resources indicates that 3.905 billion pounds of PET plastic bottles available on store shelves were thrown out in 2005, as opposed to the 1.170 billion pounds that were recycled. The total includes all PET bottles, e.g. for carbonated beverages, not just water. Doing the conversions, it appears that 95.735 million barrels of fuel oil equivalent was "thrown away" when these PET bottles were put in the garbage, which is a little less than 5 days of United States consumption. PET water bottles make up 17% of the total. (This calculation does not include possible energy recovery—see below.)

After the PET bottle is manufactured, energy is expended for the cap, the label and packaging. The bottles must be filled with filtered water, perhaps with some flavoring and minerals added, and transported to a retail destination where someone buys it and drinks it. At that point, "the empty PET packaging is discarded by the consumer after use and becomes PET waste. In the recycling industry, this is referred to as post-consumer PET." If the consumer recycles it, the plastic is subject to mechanical recycling

Once collected, the plastics are delivered to a material recovery facility (MRF) or handler for sorting into single resin streams to increase product value. The sorted plastics are then baled to reduce shipping costs to reclaimers.

Reclamation is the next step where the plastics are chopped into flakes, washed  to remove contaminants and sold to end users to manufacture new products such as bottles [e.g. more PET water bottles], containers, clothing, carpet, plastic, etc.

If the PET bottle is thrown into the garbage, it either ends up in a landfill, or is converted to heat and electricity in a waste-to-energy (WtE) process, usually through incineration. PET plastic is composed of complex hydrocarbons, and thus has a high calorific value. Efficiency in WtE processes vary, but must be improved. This is called "energy recovery" in the post-consumer disposal world.

Pet Recycling SymbolWe have followed the life of the PET water bottle from the cradle to the grave. In the best case, some small fraction of the total energy expended will be recovered at the end via WtE. Otherwise, the plastic will be recycled or in the worst case, the entire process is a dead loss. All of this energy was used up so that a thirsty "consumer" could drink bottled water instead of tap water, and in the case of Dasani, for the profitability of the Coca Cola Company and any non-subsidiary corporate entities participating in the PET bottle life cycle. All of this economic activity boosts growth which adds to various countries' Gross Domestic Products, provides jobs and gives economists a warm fuzzy feeling. That's the plus side.

On the negative side of the ledger, much of the energy expended to make PET bottles is just thrown away, especially in the United States. (Energy recovery and recycling is far more prevalent in Europe than it is in the U.S.) The author has not been able to find a study that calculates the net energy loss—up to the point of reuse in the recycling case—for each possible outcome over the entire PET life cycle. Garbage dumps continue to fill up, but a lot of the PET plastic ends up in the oceans—see Polymers Are Forever (Orion Magazine, May/June 2007). The North Pacific gyre is a troublesome destination. The plastic, which breaks down into durable tiny particles a few millimeters or less in size, is ingested by open ocean filter feeders, which eventually kills them. There are the usual carbon dioxide emissions associated with making PET bottles, which contributes to global warming.

Pet Weight and RecyclingUnder pressure from municipalities and environmentalists, the bottled water manufacturers are reducing the amount PET in their product and acknowledging their obligation to encourage recycling according to the Wall Street Journal (graphic left, link op. cit.). The issues presented are clogged landfills and carbon dioxide emissions that contribute to global warming. The bottling companies are only now "starting to warm up to financial incentives for recycling", which they have consistently opposed in the past. Eleven states, including California and New York, have deposit laws. Like the Coca Cola Company, Pepsi—Aquafina, which is also filtered tap water—has reduced the weight of their bottles but only 10% of them are made from recycled PET.

Us Bottled Water Sales Does the world need PET water bottles? No. Many of us were born during a time when they didn't exist, but we managed to muddle through somehow. Why do "consumers" think they need them? There is a perception "that municipal water is not as safe as it could be" and sometimes that's true, but "New York City’s water is every bit as good as bottled Evian" according to Walt Boyes, principal of Spitzer and Boyes, consultants in water treatment and distribution. This is not the real reason people drink bottled water, however. It is marketing that drives the consumption, and consumption is growing briskly (graph left, from CRI).

“Branding is extremely important for water,” says Chiranjeev Kohil, professor of marketing at California State University at Fullerton. “In a lot of categories, you can duplicate products and get an edge on quality or attributes, but that edge can be shaved off very quickly by competitors. In the water category, there is no technological superiority. The only thing that differentiates one water from the next is the brand.”

As with wanton3 consumption of liquid transportation fuels, it does not seem to have occurred anyone that throwing oil away is a more fundamental problem than clogged waste dumps or recycling efforts. It is the availability of tap water filtered by reverse osmosis delivered in a PET bottle that's at issue in the case of Pepsi or Coca-Cola. Exotic products like Fiji Water have even higher energy costs than those cited here. Petrochemicals are taken for granted. Our society is taking PetroProzac again. Recycling is better than not recycling, and lighter bottles reduce the volumes of fossil fuels feedstock required. The real problem, however, is the way the world does business. We need to stop all this foolishness now.

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1. Refining and petrochemical feedstocks are obviously very complex subjects. If you want to learn more, there are many excellent books, e.g. Petroleum Refining: Technology and Economics by Glenn E. Handwerk and James H. Gary.

2. There is a large discrepancy between the CRI figure and the numbers derived here, but the difference is less than an order of magnitude. CRI's only note on their methodology reads—

Factors used: 5.78 MBtu/barrel crude oil. Source for average annual residential energy consumption (94.6 MBtu per household): U.S. Department of Energy, Energy Information Administration, Look at Residential Energy Consumption in 2001.

It is not clear what 5.78 Mbtu/barrel crude oil (equivalent) applies to. As noted, the boundary conditions used for these kinds of calculations vary from study to study.

3. I did not mean to pick on Dasani (Coca-Cola) in this article. I could have used Nestle, Pepsi, Evian or any of the others. Using one example made things easier.

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