Poly-3-hydroxybutyrate (PHB) is a renewable, biodegradable biopolymer that has shown great promise to offset the use of hydrocarbon-derived plastics. The genes encoding the bacterial PHB production pathway have been engineered into several higher order plant species providing an opportunity to produce PHB as a co-product on an industrial, agricultural scale. This study investigates the economic feasibility and estimates the life-cycle greenhouse gas (GHG) emissions produced during the PHB production from hybrid poplar leaves. An established, bench scale extraction procedure was extrapolated upon using SuperPro designer to estimate the product cost, raw materials and energy used during extraction of PHB from poplar leaves on an industrial scale. Assuming an economically feasible concentration of PHB could be produced in the leaf material, a cradle-to-gate life cycle assessment was performed under two of the most likely poplar production scenarios for the Northwest United States where poplar is commonly grown for biomass applications. The cost of PHB production was found to vary greatly with the PHB content in the leaves; from 3.28 per kg at 0.5% PHB to 1.72 per kg at 20% PHB content. Poplar production scenarios varied greatly in their emission of GHGs. An irrigated poplar production scenario is estimated to produce 248.8% more GHGs than production of the displaced polypropylene. An un-irrigated poplar production scenario produced 76.1% less GHGs. Both production scenarios produced significant amounts of volatile organic compounds (VOCs) associated with normal poplar growth that could prove detrimental to local air quality. PHB content of 15% in the poplar was required to bring the PHB production price to 2.26 per kg and make production competitive with petroleum-derived plastics.
ASJC Scopus subject areas
- Renewable Energy, Sustainability and the Environment