The Environmental Protection Agency (EPA) in the US provides some information on the paper vs plastic debate:
- Paper sacks generate 70 percent more air and 50 times more water pollutants than plastic bags.
- 2000 plastic bags weigh 30 pounds, 2000 paper bags weigh 280 pounds. The latter takes up a lot more landfill space.
- It takes 91 percent less energy to recycle a pound of plastic than it takes to recycle a pound of paper. It takes more than four times as much energy to manufacture a paper bag as it does to manufacture a plastic bag. Energy to produce the bags (in British thermal units): Safeway plastic bags: 594 BTU; Safeway paper bags: 2511 BTU.
- Current research demonstrates that paper in today's landfills does not degrade or break down at a substantially faster rate than plastic does. In fact, nothing completely degrades in modern landfills due to the lack of water, light, oxygen, and other important elements that are necessary for the degradation process to be completed.
A study done in 1990 by Franklin Associates came to similar conclusions:
Plastic bags, having less mass than paper, produce less solid waste. At current recycling rates two plastic bags produces 14 g of solid waste while one paper creates 50 g. Two plastic bags produce 72% less solid waste than their paper bag equivalent. As the recycling rate increases, postconsumer waste decreases accordingly, so if 25% more bags are recycled, the solid waste decreases by 25%. Every recycled bag avoids contributing to postconsumer solid waste. However when recycling rates increase, pre-consumer solid waste increases for plastic though it decreases for paper. Still because paper creates substantially greater quantities of solid waste, two plastic bags never surpass a third of the solid waste from one paper bag.
For atmospheric waste, again plastic produce substantially less pollutants. In comparing the bags, two plastic bags produce 1.1 kg while one paper bag produces 2.6 kg. As the recycling rate improves, paper bags produce half as much atmospheric waste, but never better than two plastics. At best a paper bag still produces 35% more atmospheric waste. Again, despite the recycling rate, two plastic bags always create less airborne pollution.
Waterborne pollutants are high for a paper bag. Waterborne waste consists of pollutants which harm ecosystems. Two plastic bags account for only seven percent of the waterborne waste of one paper sack. Where paper produces 1.5 g, plastic produces 0.1g. Furthermore, as recycling increases, a paper bag's waterborne waste increases. The additional waste is from reprocessing paper product. Because of this, in terms of waterborne waste, plastic will always be preferred regardless of the recycling rate.
The study's main conclusion:
Plastic bags do have problems - namely, they are made from non-renewable petroleum products and are recycled at a considerably lower rate in blue box programs than paper bags are. However counter-intuitive it may sound, though, banning plastic bags is not necessarily a solution to the perceived problem. This won't stop scientifically illiterate politicians from making this decision for us in order to score "green points".
Through a lifecycle energy analysis, plastic is the better bag. At current recycling rates two plastic bags use less energy and produce less solid, atmospheric, and waterborne waste than a single paper bag. Moreover future improvements only increase preference in plastic bags. Increasing recycling rates and reducing the 2-to-1 ratio through proper bagging techniques would further the energy preference for plastic bags.