Search

Static life cycle assessment (LCA) methodologies fail to consider the temporal profiles of system inputs and outputs (including emission timing), such that they underestimate the benefits of temporarily stored biogenic carbon in bioproducts, such as cotton. This research focuses on greenhouse gas emission timing and applies dynamic emission accounting to the life cycle of cotton woven pants. The significance of temporary biogenic carbon storage and emission timing is illustrated by converting the 2017 Cotton Incorporated static LCA to a dynamic model using the Dynamic Carbon Footprinter (baseline scenario). A reduction in cumulative radiative forcing for dynamic relative to static modeling of 22%, 5%, and 2% are observed at 10-years, 30-years, and 100-years, respectively. Alternative scenarios analyzed include converting cotton woven pants at end of life to bioenergy, to compost, or to building insulation, an alternative cotton production scenario using regenerative agricultural practices, and two pants extended lifetime scenarios. The regenerative agricultural practice scenario provides reductions in cumulative impacts compared to the baseline scenario of 96%, 69%, and 105% after 10, 30, and 100-years, respectively. A 3x extension in the lifetime of pants provides a benefit in reduced cumulative impacts of 31%, 40%, and 41%, after 10, 30, and 100-years, respectively. This case study with cotton demonstrates that dynamic LCA is a useful tool for assessing the benefits of biobased products, and it allows for more nuanced analysis of reductions in climate impacts in both the short- and long-term time horizons. [ABSTRACT FROM AUTHOR]

Microfibers and microplastics originating from wastewater treatment plant (WWTP) effluents are significant pollutants in freshwater sources and marine environments. This research investigated the biodegradation of cotton microfibers generated from bleached cotton jersey knit fabric and commercially available flushable wipes, polypropylene-based (PP) nonwoven wipes containing a cellulose component, and tissue paper. Biodegradation was tested in wastewater treatment plants (WWTP) solids, seawater, and lakewater according to the ISO 14852 and ASTM D6691 standard methods in an ECHO respirometer. Degradation experiments continued until a plateau in CO2 emissions was reached, and the final biodegradation extent was calculated relative to the theoretical CO2 produced based on elemental analysis. The results showed that the cotton and other cellulosic materials/components biodegrade to a great extent, as expected for all conditions, whereas the PP did not degrade. In general, for the cellulose polypropylene composite wipes, the cellulose biodegraded readily; the presence of the PP did not hinder the cellulose biodegradation. [ABSTRACT FROM AUTHOR]

The consumer use phase of a product life cycle often creates a significant portion of the environmental burdens and in many cases the consumer use environmental impacts can be reduced with small behavioral changes. Due to hot water washing and mechanical drying, the apparel consumer use phase has been recognized as an environmental hotspot significantly contributing to multiple impact categories. Despite the importance of this phase, there is a lack of data describing apparel consumer use behavior that is fundamental to perform comprehensive LCAs. To address this need, consumer data was collected from over 6,000 global respondents spanning China, Germany, Italy, Japan, the United Kingdom and the United States characterizing the use of Tshirts, knit collared shirts and woven pants. A particularly significant variable required for LCA is the total washes per lifetime, for which global averages were determined to be 17.3 washes, 22.2 washes and 23.5 washes for T-shirts, knit collared shirts and woven pants, respectively, with substantial inter-country variation. In addition, clothing lifetime was examined and respondents reported an average first-life use period of 37 months, 40 months and 42 months for T-shirts, knit collared shirts and pants, respectively. Washing water temperature and machine technologies are reported and vary by country. Clothes drying methods were also examined and respondents reported high machine drying rates in the United States (73%) and less than 13% in all other nations. For garment end-of-life fate, Asian countries reported higher values of clothing disposal while European countries and the United States reported more donations to charity. This publication provides robust consumer use data by country and on global levels that can be used in future LCAs and other apparel research. Additionally, these data can be used to benchmark current laundering technologies and identify consumer use behavior changes that could reduce the environmental impacts of apparel. [ABSTRACT FROM AUTHOR]

Cotton is a natural fiber that takes up carbon dioxide from the environment when grown; however, it requires various resources to be cultivated in a financially viable way. Resources such as fertilizer, pesticides, herbicides, and irrigation water can create environmental impacts as well as present significant costs to the grower. Understanding the efficacy of technologies and grower practices is an important aspect of developing best practices and guiding future research. To better understand the grower needs, practices, and resource use efficiency, a survey was conducted in 2015 with 925 U.S. cotton grower respondents. This survey gathered data on field performance, pest pressures, growing practices, and other parameters that were used to examine the resources used per pound of cotton lint as well as estimate the greenhouse gas emissions and energy use from cotton cultivation. In general, growers who used various precision agricultural technologies reported higher performing fields with higher resource use efficiencies than non-precision technology adopters. [ABSTRACT FROM AUTHOR]

The production of six regionally important cellulosic biomass feedstocks, including pine, eucalyptus, unmanaged hardwoods, forest residues, switchgrass, and sweet sorghum, was analyzed using consistent life cycle methodologies and system boundaries to identify feedstocks with the lowest cost and environmental impacts. Supply chain analysis was performed for each feedstock, calculating costs and supply requirements for the production of 453,592 dry tonnes of biomass per year. Cradle-togate environmental impacts from these modeled supply systems were quantified for nine mid-point indicators using SimaPro 7.2 LCA software. Conversion of grassland to managed forest for bioenergy resulted in large reductions in GHG emissions due to carbon uptake associated with direct land use change. By contrast, converting forests to cropland resulted in large increases in GHG emissions. Production of forest-based feedstocks for biofuels resulted in lower delivered cost, lower greenhouse gas (GHG) emissions, and lower overall environmental impacts than the agricultural feedstocks studied. Forest residues had the lowest environmental impact and delivered cost per dry tonne. Using forest-based biomass feedstocks instead of agricultural feedstocks would result in lower cradle-to-gate environmental impacts and delivered biomass costs for biofuel production in the southern U.S. [ABSTRACT FROM AUTHOR]