In terms of an easy mark for environmentalists, few packaging products catch the flak that polystyrene (PS) foam does, but a new study comparing the energy consumption, water use, solid waste (by weight and volume), and greenhouse gas emissions for PS, paper, and bioplastic PLA (polylactic acid) found that PS uses less energy and water than its "green" competitors over its lifecycle from production to transportation to disposal.

The peer-reviewed study was commissioned by the Plastics Foodservice Packaging Group of the American Chemistry Council, with the researchers declaring that PS's light weight, it is 90% air after all, was the primary reason that it uses "significantly" less energy and water than comparable paper-based or corn-based alternatives.

Polystyrene foam clamshell container.

In terms of solid waste by volume, PS foam products create less, similar, or more waste than alternatives, depending on the product and its weight. Greenhouse gas emission comparisons varied widely in the study, based on uncertainties over whether paper-based products degrade after disposal. If paperboard products do degrade to the maximum extent, they would generate more greenhouse gas emissions than PS foam products, according to the report.

The life-cycle inventory and greenhouse gas emissions study compared average-weight PS foam, paperboard, and PLA cups used for hot (16-oz) and cold (32-oz) drinks, 9-inch dinner plates, and clamshell sandwich containers. The peer-reviewed paper updated a 2006 study with some additional data, including greenhouse gas emissions following disposal.  

Key findings: