Greenhouse Gas Profile of a Plastic Material Derived from a Genetically Modified Plant

Abstract

This article reports an assessment of the global warming potential associated with the life cycle of a biopolymer (poly(hydroxyalkanoate) or PHA) produced in genetically engineered corn developed by Monsanto. The grain corn is harvested in a conventional manner, and the polymer is extracted from the corn stover (i.e., residues such as stalks, leaves and cobs), which would be otherwise left on the field. While corn farming was assessed based on current practice, four different hypothetical PHA production scenarios were tested for the extraction process. Each scenario differed in the energy source used for polymer extraction and compounding, and the results were compared to polyethylene (PE). The first scenario involved burning of the residual biomass (primarily cellulose) remaining after the polymer was extracted from the stover. In the three other scenarios, the use of conventional energy sources of coal, oil, and natural gas were investigated. This study indicates that an integrated system, wherein biomass energy from corn stover provides energy for polymer processing, would result in a better greenhouse gas profile for PHA than for PE. However, plant‐based PHA production using fossil fuel sources provides no greenhouse gas advantage over PE, in fact scoring worse than PE. These results are based on a “cradle‐to‐pellet” modeling as the PHA end‐of‐life was not quantitatively studied due to complex issues surrounding the actual fate of postconsumer PHA.

Making Plastics from Garbage

“…A similar result was found for polyhydroxyalkanoate (PHA) produced using biomass power (Kurdikar et al 2000). This seems quite possible because PLLA production requires substantially more process energy than many comparable petrochemical polymers.…”

“…Consequently, nearly all materials are converted to valuable resources or recycled in the process. Production of plastics worldwide consumes around 270 MMT of fossil fuel each year (Gerngross and Slater 2000), with around 45% of this used as feedstock; the balance is used as process energy (Kurdikar et al 2000). Because petroleum resources are limited and the combustion of fossil fuels releases greenhouse gases with the potential to change our environment, the use of fossil energy resources is a global issue.…”

Production of renewable polymers from crop plants

“…Lifecycle assessments have indicated that biopolymers produced in plants may offer considerable savings in terms of energy use and greenhouse gas emissions over petrochemical equivalents and biopolymers produced from white biotechnology if the product concentration in the plant is high enough and the remaining biomass available after extraction of all other potentially valuable components is used to generate energy (Kurdikar et al, 2001). Furthermore, agricultural crops offer the possibility of producing biopolymers on a larger scale than is possible by microbial biotechnology, which is an important factor for biopolymers used in commodity products.…”

Hydrophobic Polymers from Food Waste: Resources and Synthesis

“…The development of this technology has three major disadvantages, the current high cost of industrial production, the greenhouse gas emission from the overall production process 246 and the lack of public acceptance for genetically modified plants. The overall cost of discovery, research and development, breeding, production, admission, and regulatory clearance for each country can, under present circumstances be prohibitive.…”