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The current trend of using plastic material in the manufacturing of packaging products raises serious environmental concerns due to waste disposal on land and in oceans and other environmental pollution. Natural polymers such as cellulose, starch, chitosan, and protein extracted from renewable resources are extensively explored as alternatives to plastics due to their biodegradability, biocompatibility, nontoxic properties, and abundant availability. The tensile and water vapor barrier properties and the environmental impacts of natural polymers played key roles in determining the eligibility of these materials for packaging applications. The brittle behavior and hydrophilic nature of natural polymers reduced the tensile and water vapor barrier properties. However, the addition of plasticizer, crosslinker, and reinforcement agents substantially improved the mechanical and water vapor resistance properties. The dispersion abilities and strong interfacial adhesion of nanocellulose with natural polymers improved the tensile strength and water vapor barrier properties of natural polymer-based packaging films. The maximum tensile stress of these composite films was about 38 to 200% more than that of films without reinforcement. The water vapor barrier properties of composite films also reduced up to 60% with nanocellulose reinforcement. The strong hydrogen bonding between natural polymer and nanocellulose reduced the polymer chain movement and decreased the percent elongation at break up to 100%. This review aims to present an overview of the mechanical and water vapor barrier properties of natural polymers and their composites along with the life cycle environmental impacts to elucidate their potential for packaging applications. [ABSTRACT FROM AUTHOR]

Abstract Torrefaction is a thermal pretreatment method to increase the energy density and to decrease the grinding energy of biomass. In this study, the torrefaction of two types of commercially available wood pellets was carried out in the temperature range of 230–290 °C for 30 min residence time. Torrefaction produces both the solid fuel known as torrefied pellets and the volatile stream known as torgas. The torgas was further separated into condensable liquids, known as tor-liquid and non-condensable gases. The products yield, its compositions and fuel properties at various torrefaction temperatures were also determined. The increase in temperature reduced the torrefied pellet yield from 89 to 52%, while increased the condensable liquid yield from 5 to 23% within the torrefaction study condition. The heating value (24 MJ kg−1) and the volumetric energy density (12.5 GJ m−3) of torrefied pellets at 270 °C were comparable to that of coal for biopower. The increase in torrefaction temperature improved the hydrophobicity (resistance to water uptake), but adversely reduced the pellet density, hardness, and durability of torrefied pellets causing high susceptibility to breakage and fine generation during handling, transport, and storage. Further research is required to improve the quality of torrefied pellets for safe handling and storage. The non-condensable fraction of torgas was mainly composed of carbon dioxide, carbon monoxide, and traces of methane. The condensable liquid was rich in organic acids, ketones, furfural, and levoglucosan, which could be potentially transformed into high-value chemicals and other commercially viable products. Highlights • Torrefied pellet yield reduced from 89 to 52% between 230 and 290 °C. • Torrefied pellets produced at 270 °C had similar fuel properties as coal. • TAP pathway improved the hydrophobicity of wood pellets. • Pellet hardness and durability decreased with increased torrefaction temperature. • Tor-liquid was rich in organic acids, and levoglucosan and can be a co-product. [ABSTRACT FROM AUTHOR]

The assessment of biomass at high spatial resolution is critical to manage supply risks and to identify optimal plant sites for producing sustainable biofuels and co-products. The spatial variabilities in soil type, topography, climate, and crop management practices further require vast computational time and resources to estimate the availability of sustainable biomass for a large study area. In this study, we developed a GIS-based integrated predictive modeling platform to assess the availability of sustainable crop residues at high spatial (30 m) and temporal (2010–2022) scales. A GIS-based multi-criteria inclusion-exclusion analysis and facility location-allocation models were used to identify suitable sites, and optimal siting of biogas plants respectively with biomass delivered cost. The Artificial Neural Network (ANN) based predictive models were well suited to predict sustainability indicators (soil erosion SE- R 2 = 0.96, soil conditioning index, SCI R 2 = 0.98 and organic matter factor, OMF- R 2 = 0.83) for assessing sustainable removal rates of crop residues (corn stover and wheat straw). The GIS-based integrated model was applied to the State of Ohio and found that about 4–13 dry Tg of crop residues can be sustainably available to build 1–25 regional biogas plants. A typical optimal biogas plant with a feedstock capacity of up to 500 dry Gg could be drawn from a transport radius of about 19–35 km with a delivered cost of 40–46 $ dry Mg −1 . The temporal and spatial variations in assessing the availability of biomass largely affected the supply chain decisions and its delivered costs. [ABSTRACT FROM AUTHOR]

Abstract: Mechanical properties of wheat straw, barley straw, corn stover and switchgrass were determined at different compressive forces, particle sizes and moisture contents. Ground biomass samples were compressed with five levels of compressive forces (1000, 2000, 3000, 4000 and 4400N) and three levels of particle sizes (3.2, 1.6 and 0.8mm) at two levels of moisture contents (12% and 15% (wet basis)) to establish compression and relaxation data. Compressed sample dimensions and mass were measured to calculate pellet density. Corn stover produced the highest pellet density at low pressure during compression. Compressive force, particle size and moisture content significantly affected the pellet density of barley straw, corn stover and switchgrass. However, different particle sizes of wheat straw did not produce any significant difference on pellet density. The relaxation data were analyzed to determine the asymptotic modulus of biomass pellets. Barley straw had the highest asymptotic modulus among all biomass indicating that pellets made from barley straw were more rigid than those of other pellets. Asymptotic modulus increased linearly with an increase in compressive pressure. A simple linear model was developed to relate asymptotic modulus and maximum compressive pressure. [Copyright &y& Elsevier]

Wheat and barley straws, corn stover and switchgrass at two moisture contents were ground using a hammer mill with three different screen sizes (3.2, 1.6 and 0.8 mm). Energy required for grinding these materials was measured. Among the four materials, switchgrass had the highest specific energy consumption (27.6 kW h t-1), and corn stover had the least specific energy consumption (11.0 kW h t-1) at 3.2 mm screen size. Physical properties of grinds such as moisture content, geometric mean diameter of grind particles, particle size distribution, and bulk and particle densities were determined. Second- or third-order polynomial models were developed relating bulk and particle densities of grinds to geometric mean diameter within the range of 0.18–1.43 mm. Switchgrass had the highest calorific value and the lowest ash content among the biomass species tested. [Copyright &y& Elsevier]

In recent years, the demand for environmental sustainability has caused a great interest in finding novel polymer materials from natural resources that are both biodegradable and eco-friendly. Natural biodegradable polymers can displace the usage of petroleum-based synthetic polymers due to their renewability, low toxicity, low costs, biocompatibility, and biodegradability. The development of novel starch-based bionanocomposites with improved properties has drawn specific attention recently in many applications, including food, agriculture, packaging, environmental remediation, textile, cosmetic, pharmaceutical, and biomedical fields. This paper discusses starch-based nanocomposites, mainly with nanocellulose, chitin nanoparticles, nanoclay, and carbon-based materials, and their applications in the agriculture, packaging, biomedical, and environment fields. This paper also focused on the lifecycle analysis and degradation of various starch-based nanocomposites. [ABSTRACT FROM AUTHOR]

Localized carbon reduction strategies are especially critical in states and regions that lack top-down climate leadership. This paper illustrates the use of coupled systems in assessments of subnational climate solutions with a case study of Georgia, a state located in the southeastern United States that does not have statewide climate goals or plans. The paper illustrates how robust place-specific plans for climate action could be derived from foundational global and national work and by embedding that research into the context of socio-ecological-technological systems. Our replicable methodology advances the traditional additive sectoral wedge analysis of carbon abatement potential by incorporating solution interdependencies and by spanning both carbon sources and sinks. We estimate that a system of 20 solutions could cut Georgia's carbon footprint by 35% in 2030 relative to a business-as-usual forecast and by 50% relative to Georgia's emissions in 2005. We also produce a carbon abatement cost curve that aligns private and social costs as well as benefits with units of avoided CO2-e. The solutions are affiliated with various social cocosts and co-benefits that highlight societal concerns extending beyond climate impacts, including public health, environmental quality, employment, and equity. [ABSTRACT FROM AUTHOR]

Highlights • Economic feasibility of portable systems to utilize forest residues was investigated. • Forest residues were processed into raw and torrefied briquettes and biochar. • Minimum selling price (MSP) of biochar was estimated to $1044/ODMT. • MSP of raw and torrefied-briquettes were $162 and $274/ODMT respectively. • MSPs could be reduced by at least 50% with improved portable systems. Abstract Wildfires are getting extreme and more frequent because of increased fuel loads in the forest and extended dry conditions. Prevention of wildfire by fuel treatment methods will generate forest residues in large volumes, which in addition to available logging residues, can be used to produce biofuels and bioproducts. In this study, the techno-economic assessment of three portable systems to produce woodchips briquettes (WCB), torrefied-woodchips briquettes (TWCB) and biochar from forest residues were evaluated using pilot-scale experimental data. A discounted cash flow rate of return method was used to estimate minimum selling prices (MSPs) for each product, to conduct sensitivity analyses, and to identify potential cost-reduction strategies. Using a before-finance-and-tax 16.5% nominal required return on investment, and a mean transport distance of 200 km, the estimated delivered MSPs per oven-dry metric ton (ODMT) of WCB, TWCB, and biochar were $162, $274, and $1044 respectively. The capital investment (16–30%), labor cost (23–28%), and feedstock cost (10–13%) without stumpage cost were the major factors influencing the MSP of solid biofuels and biochar. However, the MSPs of WCB, TWCB, and biochar could be reduced to $65, $145, and $470/ODMT respectively with technologically improved portable systems. In addition, the MSPs of solid biofuels and biochar could be further reduced by renewable energy and carbon credits, if the greenhouse gas (GHG) reduction potentials are quantified and remunerated. In conclusion, portable systems could be economically feasible to use forest residues and make useful products at current market prices while simultaneously reducing potential wildfires and GHG emissions. [ABSTRACT FROM AUTHOR]

Mountain pine beetle (MPB) (Dendroctonus ponderosae Hopkins) has become a serious infestation problem in Western Canada. The infested lodgepole pine (Pinus concorta Douglas) becomes host to blue staining fungi and the infested trees die in 4-6 years. The dead trees gradually lose their suitability for dimension lumber and pulp chips due to excessive cracking and spoilage. Recovering the killed wood and proces- sing it to pellets for bioenergy and other applications could partially avert the economic loss, and reduce overloading of the forest floor and potential for forest fires. In this study, heating value, density, and chemical composition of pellets made from MPB-infested Pine wood were measured and compared with those measured for pellets made from uninfested pine. Chemical analysis showed minor decrease in lignin and sugar contents of pellets made from MPB wood. The mean density of pellets manufactured from MPB (about 975 kg m-3) was slightly higher than the density of pellets from uninfested wood (934 kg m-3). This difference was not statistically significant (α =0.05) due to a large variation in the measured data. The high heating value (HHV) of MBP at a mean 19.20 MJ kg-1 was not significantly different from 19.05 MJ kg-1 measured for pellets made from uninfested pine. Biologically cultured MPB pellets did not show any staining fungi growth. The overall conclusion is that MBP infested wood can be used to produce comparable pellets to non-infested wood pellets. [ABSTRACT FROM AUTHOR]

Mountain pine beetle (MPB) (Dendroctonus ponderosae Hopkins) has become a serious infestation problem in Western Canada. The infested lodgepole pine (Pinus concorta Douglas) becomes host to blue staining fungi and the infested trees die in 4-6 years. The dead trees gradually lose their suitability for dimension lumber and pulp chips due to excessive cracking and spoilage. Recovering the killed wood and processing it to pellets for bioenergy and other applications could partially avert the economic loss, and reduce overloading ofthe forest floor and potential for forest fires. In this study, heating value, density, and chemical composition ofpellets made from MPB-infested Pine wood were measured and compared with those measured for pellets made from uninfested pine. Chemical analysis showed minor decrease in lignin and sugar contents of pellets made from MPB wood. The mean density of pellets manufactured from MPB (about 975 kg m-3) was slightly higher than the density of pellets from uninfested wood (934 kg m-3).' This difference was not statistically significant (α=0.05) due to a large variation in the measured data. The high heating value (HHV) ofMBP at a mean 19.20 MJ kg-1 was not significantly different from 19.05 MJ kg-1 measured for pellets made from uninfested pine. Biologically cultured MPB pellets did not show any staining fungi growth. The overall conclusion is that MBP infested wood can be used to produce comparable pellets to noninfested wood pellets. [ABSTRACT FROM AUTHOR]

Climate change induced by greenhouse gas emissions from the extraction and use of fossil fuels has raised global concerns and needs to develop alternative and environmentally friendly transportation fuels from biomass and other organic carbon sources. In this study, a cradle to grave attributional life cycle assessment (LCA) was conducted to produce drop-in renewable diesel from biogas (via solid-state anaerobic digestion) derived from energy crop, i.e. miscanthus cultivated in strip-mined lands. The analysis included miscanthus cultivation, harvesting, and transportation to the biorefinery, conversion of the biomass to Fischer-Tropsch diesel, and combustion of the drop-in renewable diesel for a passenger vehicle. Results showed that the miscanthus derived drop-in renewable diesel could reduce greenhouse gas emissions by up to 73% when compared with that of the conventional fossil-derived diesel. Similarly, the proposed design consumes 4.91 MJ/GGE of fossil fuel compared to the conventional diesel with fossil fuel depletion of 18.98 MJ/GGE. Although the respiratory effects, smog formation, acidification, and eutrophication potentials of the miscanthus to drop-in renewable diesel process are relatively higher than the conventional process, the proposed technology still represents a sustainable liquid fuels pathway that is less dependent on fossil fuel, can substantially reduce greenhouse gas emissions, and help attain the renewable transportation fuels standard. Image 1 • Renewable diesel derived from miscanthus by anaerobic digestion and F-T synthesis. • GHG emissions of renewable diesel reduced by 73% when displacing fossil diesel. • Use of digestate as chemical fertilizer further reduced the GHG emissions by 24%. • Renewable diesel qualifies for the U.S. Renewable Fuel Standard credits. • Ten other environmental impacts of renewable diesel compared with fossil diesel. [ABSTRACT FROM AUTHOR]