5 research outputs found

    Exploring Comparative Energy and Environmental Benefits of Virgin, Recycled, and Bio-Derived PET Bottles

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    Polyethylene terephthalate (PET) is a common plastic resin used to produce packaging, notably plastic bottles. Most PET bottles are produced from fossil fuel-derived feedstocks. Bio-derived and recycling-based pathways to PET bottles, however, could offer lower greenhouse gas (GHG) emissions than the conventional route. In this paper, we use life-cycle analysis to evaluate the GHG emissions, fossil fuel consumption, and water consumption of producing one PET bottle from virgin fossil resources, recycled plastic, and biomass, considering each supply chain stage. We considered two routes to produce bottles from biomass: one in which all PET precursors (ethylene glycol and teraphthalic acid) are bio-derived and one in which only ethylene glycol is bio-derived. Bio-derived and recycled PET bottles offer both GHG emissions and fossil fuel consumption reductions ranging from 12% to 82% and 13% to 56%, respectively, on a cradle-to-grave basis compared to fossil fuel-derived PET bottles assuming PET bottles are landfilled. However, water consumption is lower in the conventional pathway to PET bottles. Water demand is high during feedstock production and conversion in the case of biomass-derived PET and during recycling in the case of bottles made from recycled PET

    Techno-Economic Analysis and Life-Cycle Analysis of Two Light-Duty Bioblendstocks: Isobutanol and Aromatic-Rich Hydrocarbons

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    Isobutanol and aromatic-rich hydrocarbons (ARHC) are two biomass-derived high-octane blendstocks that could be blended with petroleum gasoline for use in optimized spark-ignition engines in light-duty vehicles, potentially increasing engine efficiency. To evaluate technology readiness, economic viability, and environmental impacts of these technologies, we use detailed techno-economic analysis (TEA) and life-cycle analysis (LCA). We assumed isobutanol is produced via biochemical conversion of an herbaceous feedstock blend while ARHC is produced via thermochemical conversion of a woody feedstock blend. The minimum estimated fuel selling price (MFSP) of isobutanol ranged from 5.57/gasolinegallonequivalent(GGE)(5.57/gasoline gallon equivalent (GGE) (0.045/MJ) based on today’s technology to 4.22/GGE(4.22/GGE (0.034/MJ) with technology advancements. The MFSP of ARHC could decline from 5.20/GGE(5.20/GGE (0.042/MJ) based on today’s technology to 4.20/GGE(4.20/GGE (0.034/MJ) as technology improves. Both isobutanol and ARHC offer about 73% greenhouse gas (GHG) emission reduction relative to petroleum gasoline per LCA of these two bioblendstocks. On the other hand, water consumption in the production of both bioblendstocks exceeds that of conventional gasoline although process engineering offers routes to cutting water consumption. Over their life-cycles, both isobutanol and ARHC emit more NO<sub><i>x</i></sub> and PM<sub>2.5</sub> than petroleum gasoline. Improving the energy efficiency and lowering air emissions from agricultural equipment will reduce the life-cycle air pollutant emissions of these bioblendstocks

    Current and Future United States Light-Duty Vehicle Pathways: Cradle-to-Grave Lifecycle Greenhouse Gas Emissions and Economic Assessment

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    This article presents a cradle-to-grave (C2G) assessment of greenhouse gas (GHG) emissions and costs for current (2015) and future (2025–2030) light-duty vehicles. The analysis addressed both fuel cycle and vehicle manufacturing cycle for the following vehicle types: gasoline and diesel internal combustion engine vehicles (ICEVs), flex fuel vehicles, compressed natural gas (CNG) vehicles, hybrid electric vehicles (HEVs), hydrogen fuel cell electric vehicles (FCEVs), battery electric vehicles (BEVs), and plug-in hybrid electric vehicles (PHEVs). Gasoline ICEVs using current technology have C2G emissions of ∼450 gCO<sub>2</sub>e/mi (grams of carbon dioxide equivalents per mile), while C2G emissions from HEVs, PHEVs, H<sub>2</sub> FCEVs, and BEVs range from 300–350 gCO<sub>2</sub>e/mi. Future vehicle efficiency gains are expected to reduce emissions to ∼350 gCO<sub>2</sub>/mi for ICEVs and ∼250 gCO<sub>2e</sub>/mi for HEVs, PHEVs, FCEVs, and BEVs. Utilizing low-carbon fuel pathways yields GHG reductions more than double those achieved by vehicle efficiency gains alone. Levelized costs of driving (LCDs) are in the range 0.250.25–1.00/mi depending on time frame and vehicle-fuel technology. In all cases, vehicle cost represents the major (60–90%) contribution to LCDs. Currently, HEV and PHEV petroleum-fueled vehicles provide the most attractive cost in terms of avoided carbon emissions, although they offer lower potential GHG reductions. The ranges of LCD and cost of avoided carbon are narrower for the future technology pathways, reflecting the expected economic competitiveness of these alternative vehicles and fuels

    Environmental, Economic, and Scalability Considerations and Trends of Selected Fuel Economy-Enhancing Biomass-Derived Blendstocks

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    Twenty-four biomass-derived compounds and mixtures, identified based on their physical properties, which could be blended into fuels to improve spark ignition engine fuel economy, were assessed for their economic, technology readiness, and environmental viability. These bio-blendstocks were modeled to be produced biochemically, thermochemically, or through hybrid processes. To carry out the assessment, 17 metrics were developed for which each bio-blendstock was determined to be favorable, neutral, or unfavorable. Cellulosic ethanol was included as a reference case. Overall economic and, to some extent, environmental viability is driven by projected yields for each of these processes. The metrics used in this analysis methodology highlight the near-term potential to achieve these targeted yield estimates when considering data quality and current technical readiness for these conversion strategies. Key knowledge gaps included the degree of purity needed for use as a bio-blendstock. Less stringent purification requirements for fuels could cut processing costs and environmental impacts. Additionally, more information is needed on the blending behavior of many of these bio-blendstocks with gasoline to support the technology readiness evaluation. Overall, the technology to produce many of these blendstocks from biomass is emerging, and as it matures, these assessments must be revisited. Importantly, considering economic, environmental, and technology readiness factors, in addition to physical properties of blendstocks that could be used to boost engine efficiency and fuel economy, in the early stages of project research and development can help spotlight those most likely to be viable in the near term
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