Monday, March 28, 2011

USA - polystyrene foam cups and plates use less energy, water than paper or corn-based alternatives

A new peer-reviewed study finds that commonly used cups, plates and sandwich containers made of polystyrene foam use significantly less energy and water than comparable paper-based or corn-based (polylactic: PLA) alternatives, primarily due to polystyrene foam's much lower weight.

The life-cycle inventory and greenhouse gas emissions study compares average-weight polystyrene foam, paperboard and PLA cups used for hot (16 ounce) and cold (32 ounce) drinks, 9-inch dinner plates and "clamshell" sandwich containers. 2 Researchers modelled energy consumption, water use, solid waste (by weight and volume) and greenhouse gas emissions for each product resulting ! from production, transportation and disposal. Some key findings:

Energy use: Polystyrene foam products consume significantly less energy than the alternatives-half as much as wax-coated paperboard cups and one-third as much as PLA clamshells. Water use: Polystyrene foam products use significantly less water than the alternatives-up to four times less than PLA clamshells.

Solid waste: Polystyrene foam products create significantly less solid waste by weight than the alternatives-up to five times less than paperboard and PLA products.

Polystyrene foam cups for hot drinks create less waste by volume than the alternatives-significantly less than paperboard cups with corrugated sleeves used for insulation.

Greenhouse gases: Polystyrene foam products generate slightly more greenhouse gas emissions than PLA products, expressed as net CO2 equivalents. If paperboard products do not degrade after disposal, they store carbon and generate fewer greenhouse gas emissions than polystyrene foam products; however, if paperboard products degrade to the maximum extent, they generate more greenhouse gas emissions than polystyrene foam products, so comparisons of greenhouse gas emissions vary widely depending on assumptions about the degradation of paperboard products.

The study's authors found that lower weight products with similar functionality-such as polystyrene foam products composed of more than 90% air-generally produce smaller environmental burdens.Although PLA is corn-based, the study notes: "According to the [PLA producer] NatureWorks LLC website, PLA does not biodegrade in landfills."Copies of the report on the study Life cycle inventory of foam polystyrene, paper-based, and PLA foodservice products (0.8 MB) can be downloaded from:!%20tp:/

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