Wednesday, April 18, 2007

Paper or Plastic?

Analysis of the energy usage and loss connected to both types of retail bags. Very interesting.

Vol. 2 No.5: April 17, 2007
Cleaner environment not in the bag for San Francisco
by Amy Kaleita, Public Policy Fellow, Environmental Studies

In late March, the San Francisco Board of Supervisors voted 10-1 to become the first American city to ban the use of non-biodegradable plastic bags by larger retailers, including supermarkets and drug stores. Alternatives include bags made of recycled paper or biodegradable plastic. But neither of these options is without problems.

Critics of plastic bags argue that the petroleum products required to produce them make these types of bags an environmental problem. The feedstocks for paper bags, on the other hand, are renewable wood products. But this is only part of the story.

According to the Institute for Lifecycle Environmental Assessment, total production of a single plastic bag uses 120 kJ (kilojoules) of petroleum, but a single paper bag uses 500 kJ of petroleum.

When all elements are considered, the total amount of energy used by a single paper bag is 1,680 kJ, compared to 735 kJ for a single plastic bag. In other words, a paper bag is, in effect, a double bag requiring more than twice the amount of energy. Plastic is also the winner from the standpoint of pollutant production.