Packaging for food products is a $12 billion industry dominated by variations on paper and plastic foam products. For 10 years, the company EarthShell has been trying to green the industry and get a lucrative piece of the pie. In place of Styrofoam containers or cardboard egg cartons, EarthShell sells products made of a mixture of limestone, sand, and starch from plants like corn and potatoes. The products decompose in a matter of weeks and take up negligible space in landfills. Enviros love the idea and the company has even designed packaging for McDonald’s, but EarthShell is facing an uphill battle. “Efforts to distinguish products by environmental packaging have been kind of a bust,” said J. Winston Porter, president of the Waste Policy Center, an environmental management research center, who noted that consumers generally care far more about what’s in a package than about the package itself. So far, the company has sunk $270 million and more than a decade of work into trying to carve its own niche, but things continue to look bleak in the green-packaging industry.