You have undoubtedly been asked this question: “Paper or plastic?”
What should your answer be? Is one always better than the other? The answer is more complex than you might realize.
Paper is produced from trees. The trees are cut, the bark is stripped off, and the wood is chipped into small cubicle pieces that are about one inch on each side. These wood chips are then “pulped,” which involves cooking the wood at high heat and pressure, and then further digesting it with acid and lime for several hours. To make one ton of pulp requires about 3 tons of wood chips. The pulp is then washed and bleached in a process that requires enormous amounts of water. The pulp is eventually rolled into paper and dried. Overall, the production of paper takes large amounts of water and energy.
The brown paper used to make grocery bags, for example, is relatively unbleached, unlike white letter paper> This is a plus in that fewer chemicals were used in its production.
Paper bags are not very reusable. They break or rip. Brown paper bags can also be composted (best is there is not a lot of ink on the bags) or recycled into other paper products. If the bags are to be recycled, they must go back through the pulping process, which prepares pulp again, this time from the bags, to make paper as before. The re-pulping process requires water and energy and chemical, but new trees are not involved, and less energy is required to pulp paper bags than to pulp wood chips.
Plastic bags are produced from chemical feedstocks that are derived from petroleum. After the petroleum is refined, a fraction is used to produce the chemicals that are the building blocks of plastic bags. Energy is required to produce plastic bags as well. The energy to refine the oil and the energy to run the plant to produce the plastic are the main contributions to energy consumed in making plastic bags..
Plastic bags can be recycled as well. Since the recycling process causes some damage to the polymers used to make the bags, the quality of the recycled plastic bag is not quite as high as that of a new bag.
So, should you use paper or plastic?
The analysis here calculates that even though paper bags hold 1.5 times more per bag, plastic comes out ahead.
Plastic wins because its production is significantly less energy intensive.
Plastic bags require 9.7 million BTUs, per 10,000 bags vs. 16.3 for the equivalent in paper bags, adjusted for the difference in capacity. This analysis assumes at no recycling. Adjusting the analysis for 100% recycling rates, plastic bags still require less energy: 7.0 million BTUs per 10,000 versus 9.1 million BTUs per paper bag equivalent. (Hat-tip to Treehugger for this information)
So, if you have to choose between paper and plastic bags, choose plastic and make sure the bags are reused and/or recycled. Better still is to use a reusable bag made of cloth or canvas, avoiding question of paper or plastic altogether.