|Fig. 1: Recycling bins that require paper to be separated from plastic and metal. (Source: Wikimedia Commons)|
Municipal programs to recycle materials such as paper, glass, plastic, and metal are one way to decrease the amount of resources (especially non-renewable ones) needed to produce a given amount of products, but it may not be obvious whether such programs save more money than they cost, or more energy than they consume. The financial and energetic costs of collecting, sorting, and processing the recyclables need to be considered in addition to the cost of producing final products from the recycled material. The sections below argue that recycling programs can in fact be worth their cost, but only if the programs are run efficiently, with sufficient public education and effective technology for sorting and processing, and for cases where reuse is not a practical alternative.
One of the main alternatives to which recycling is compared is the disposal of the recyclable waste in landfills. Since no sorting or processing is required beyond transporting the waste to the landfill, it appears at first glance that landfill disposal is cheaper: it requires less money for human labor and less energy for work done by machines. It's for this reason that Mayor Michael Bloomberg put a moratorium on recycling programs in New York City in 2002, and the diversion of recyclables to landfills for those 18 months was estimated to save the city $57 million.  The cost of picking up and transporting recyclables can range from $20 to $70 per ton, depending on the length and difficulty of the recycling truck routes, and the budget also has to consider the energy cost of the fossil fuels burned to run these trucks, as well as labor and fuel costs to sort, process, and market the recycled material.  The average mix of recyclables collected by a homeowner are estimated to be worth about $125 per ton when the recycled materials are sold to manufacturers, so there is a possibility for recycling programs to make a net profit, but only if transportation, sorting, and processing costs are kept lower than this value per ton.  This is a requirement that some but not all current recycling programs may be able to meet. Cities fare better in terms of net profit and energy savings when people recycle more (so that there's more recyclable material per truck trip), when residents sort recyclables themselves (for free) rather than requiring the city to sort them, when the population is dense (more recyclables collected per mile in the collection truck), and when efficient sorting and/or processing technologies are in place. [1,3,4]
The metric discussed above - revenue generated by selling recycled materials minus the costs of producing recycled materials - doesn't tell the whole story, since it doesn't account for the energy saved by manufacturing from recycled instead of virgin materials. A metric that attempts to account for all these factors, as well as other effects like new jobs in recycling and increased lifespans for landfills, is the GPI (Genuine Progress Index) developed by the GPI Atlantic research group.  According to the metric in the previous section, recycling programs cost Nova Scotia $18 million more per year than landfill disposal, but the GPI Atlantic report says that Nova Scotia saves $25 million - 125 million per year by recycling, depending on which additional factors are included.  Clearly the energy savings of manufacturing from recycled material rather than virgin material is worth consideration, and there are in fact energy savings for all the typical recyclable materials considered below, although more for some than others.  Aluminum offers the most savings, with cans from recycled material requiring as little as 4% of the energy required to make the same cans from bauxite ore.  Metals don't degrade as they're recycled in the same way plastics and paper do, fibers shortening every cycle, so many metals are prime candidates for recycling, especially considering their high value per ton compared to other recyclables.  Polystyrene from recycled material costs 88% less than without recycling, but a negligible amount of polystyrene is recycled in the United States because of the difficulty sorting it from other plastics. Infrared sorting can help, and soon more cities may be able to take advantage of these savings as the technology develops.  Other plastic products like polyethylene terephthalate soft drink bottles cost 76% less to manufacture form recycled materials, and this percentage as well as the variety of plastics that can be recycled is expected to increase with new separation technologies such as froth floatation and skin flotation. [3,6] Nonetheless, plastic degrades every time it's recycled, so some plastic will always need to come directly from fossil oils if such products are to continue to be produced.  Paper (in particular newspaper) and glass have lower energy savings than the previous materials, with recycled products costing 45% and 21% less energy respectively. Recycled paper has a large market in China, although work still needs to be done to facilitate mixed paper recycling as opposed to newspaper-only recycling. Glass, on the other hand, may not be worthwhile to recycle, since the energy saved is only about a fifth of the energy to produce glass from sand, and sand is not a resource that is running low. [1,6] For the materials considered here, greater energy savings corresponds to a higher monetary value per ton, creating an even greater incentive for cities to recycle at least aluminum and higher-grade plastics. 
An alternative to recycling that almost always appears to be the cheaper option (at least in cases where it applies) is reuse. Reusable containers only have to be manufactured once for hundreds or thousands of uses (such as a water bottle used every day for years), and the energy cost between uses is approximately that of cleaning the container with soap and water, a negligible expense compared to sorting, melting down, and pouring the material into a mold again, for example. For products with glass containers, a deposit-refund system to encourage people to return the containers to the store for reuse seems more useful than recycling, given glass's durability and the small energy savings for recycling it.  If individuals own their own containers made of durable material, or return such containers to the store to be cleaned and refilled, reuse could in theory replace all disposable and recyclable containers, although this method does require a greater time commitment from consumers to clean these containers, and/or the inconvenience of carrying empty containers around, collecting them, and returning them. Reuse doesn't work as well for printed paper, or for non-container metal or plastic items such as electronics or packing material, so recycling may still be the best option in these cases.
One of the most popular reasons for recycling is that the virgin materials are running out and will run out faster with every product not made from recycled material, but this reasoning doesn't apply to the same extent (if at all) to all types of recyclable material. There is only so much metal ore in the Earth's crust, and similarly there is only so much fossil oil to produce plastic, so it makes sense to slow the rate at which we use up these resources, and reusing and recycling the resources we have already harvested is one way to do that. Particularly in the case of plastic, scarcity is becoming an increasingly strong motivator for recycling as the price of fossil oils increases. However, sand for glass is a finite but hardly scarce resource, and paper is in theory a renewable resource. [1,6] Commercial tree farms turn organic waste, water, and sunlight into wood for paper, and the used paper can then become organic waste to complete the cycle, as long as the paper is free of toxic additives like certain inks.  However, if the demand for paper exceeds the output of the finite acreage available for tree farms, paper recycling can supplement tree farm output so that that there is less incentive for paper manufacturers to harvest (non-renewably) from natural forests.
With a well-designed program and the right technology, recycling can be more efficient in terms of energy, money, and natural resources when compared to a system that manufactures everything from virgin materials and sends it all to landfills when consumers discard it. Recycling is not always the cheapest alternative, however, especially when reuse is an option, as in the case of glass jars or drink containers. Reuse, recycling, and even landfills have materials for which they are the least wasteful disposal method, but as technology finds new ways to sort and recycle waste, the fraction of waste going to landfills can certainly decrease.
© Ashley Micks. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
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