Site Suitability and Air Pollution Impacts of Composting Infrastructure for California's Organic Waste Diversion Law.

California's organic waste diversion law, SB 1383, mandates a 75% reduction in organics disposal by 2025 to reduce landfill methane emissions. Composting will likely be the primary alternative to landfilling, and 75-100 new large-scale composting facilities must be sited in the state to meet its diversion goal. We developed a strategy for evaluating site suitability for commercial composting by incorporating land-use, economic, and environmental justice criteria.

Engineered reduction of S-adenosylmethionine alters lignin in sorghum.

Background: Lignin is an aromatic polymer deposited in secondary cell walls of higher plants to provide strength, rigidity, and hydrophobicity to vascular tissues. Due to its interconnections with cell wall polysaccharides, lignin plays important roles during plant growth and defense, but also has a negative impact on industrial processes aimed at obtaining monosaccharides from plant biomass. Engineering lignin offers a solution to this issue.

Recommendations for life-cycle assessment of recyclable plastics in a circular economy.

Technologies that enable plastic circularity offer a path to reducing waste generation, improving environmental quality, and reducing reliance on fossil feedstocks. However, life-cycle assessment (LCA) methods commonly applied to these systems fall far short of capturing the full suite of advantages and tradeoffs. This perspective highlights inconsistencies in both the research questions and methodological choices across the growing body of LCA literature for plastics recycling.

Shaping the future US bioeconomy through safety, security, sustainability, and social responsibility.

Biomanufacturing practitioners and researchers describe the norms that should govern the growing, global field, to include safety, security, sustainability, and social responsibility. These '4S Principles' should be broadly adopted so that the future of the field may provide the greatest benefits to society.

Corridor-Level Impacts of Battery-Electric Heavy-Duty Trucks and the Effects of Policy in the United States.

Electrifying freight trucks will be key to alleviating air pollution burdens on disadvantaged communities and mitigating climate change. The United States plans to pursue this aim by adding vehicle charging infrastructure along specific freight corridors. This study explores the coevolution of the electricity grid and freight trucking landscape using an integrated assessment framework to identify when each interstate and drayage corridor becomes advantageous to electrify from a climate and human health standpoint.

Impact of bioenergy feedstock carbon farming on sustainable aviation fuel viability in the United States.

Biomass-derived sustainable aviation fuel holds significant potential for decarbonizing the aviation sector. Its long-term viability depends on crop choice, longevity of soil organic carbon (SOC) sequestration, and the biomass-to-biojet fuel conversion efficiency. We explored the impact of fuel price and SOC value on viable biojet fuel production scale by integrating an agroecosystem model with a field-to-biojet fuel production process model for 1,4-dimethylcyclooctane (DMCO), a representative high-performance biojet fuel molecule, from Miscanthus, sorghum, and switchgrass.

Increased drought and extreme events over continental United States under high emissions scenario.

The frequency, severity, and extent of climate extremes in future will have an impact on human well-being, ecosystems, and the effectiveness of emissions mitigation and carbon sequestration strategies. The specific objectives of this study were to downscale climate data for US weather stations and analyze future trends in meteorological drought and temperature extremes over continental United States (CONUS). We used data from 4161 weather stations across the CONUS to downscale future precipitation projections from three Earth System Models (ESMs) participating in the Coupled Model Intercomparison Project Phase Six (CMIP6), specifically for the high emission scenario SSP5 8.

Matching diverse feedstocks to conversion processes for the future bioeconomy.

A wide variety of wasted or underutilized organic feedstocks can be leveraged to build a sustainable bioeconomy, ranging from crop residues to food processor residues and municipal wastes. Leveraging these feedstocks is both high-risk and high-reward. Converting mixed, variable, and/or highly contaminated feedstocks can pose engineering and economic challenges.

Complementary roles for mechanical and solvent-based recycling in low-carbon, circular polypropylene.

Plastic recycling presents a vexing challenge. Mechanical recycling offers substantial greenhouse gas emissions savings relative to virgin plastic production but suffers from degraded aesthetic and mechanical properties. Polypropylene, one of the most widely used and lowest-cost plastics, features methyl pendants along the polymer backbone, rendering it particularly susceptible to declining properties, performance, and aesthetics across a succession of mechanical recycles.

Field performance of switchgrass plants engineered for reduced recalcitrance.

Switchgrass ( L.) is a promising perennial bioenergy crop that achieves high yields with relatively low nutrient and energy inputs. Modification of cell wall composition for reduced recalcitrance can lower the costs of deconstructing biomass to fermentable sugars and other intermediates.

Private and External Costs and Benefits of Replacing High-Emitting Peaker Plants with Batteries.

Falling costs of lithium-ion (Li-ion) batteries have made them attractive for grid-scale energy storage applications. Energy storage will become increasingly important as intermittent renewable generation and more frequent extreme weather events put stress on the electricity grid. Environmental groups across the United States are advocating for the replacement of the highest-emitting power plants, which run only at times of peak demand, with Li-ion battery systems.

Co-Processing Agricultural Residues and Wet Organic Waste Can Produce Lower-Cost Carbon-Negative Fuels and Bioplastics.

Scalable, low-cost biofuel and biochemical production can accelerate progress on the path to a more circular carbon economy and reduced dependence on crude oil. Rather than producing a single fuel product, lignocellulosic biorefineries have the potential to serve as hubs for the production of fuels, production of petrochemical replacements, and treatment of high-moisture organic waste. A detailed techno-economic analysis and life-cycle greenhouse gas assessment are developed to explore the cost and emission impacts of integrated corn stover-to-ethanol biorefineries that incorporate both codigestion of organic wastes and different strategies for utilizing biogas, including onsite energy generation, upgrading to bio-compressed natural gas (bioCNG), conversion to poly(3-hydroxybutyrate) (PHB) bioplastic, and conversion to single-cell protein (SCP).

Greenhouse Gas and Air Pollutant Emissions from Composting.

Composting can divert organic waste from landfills, reduce landfill methane emissions, and recycle nutrients back to soils. However, the composting process is also a source of greenhouse gas and air pollutant emissions. Researchers, regulators, and policy decision-makers all rely on emissions estimates to develop local emissions inventories and weigh competing waste diversion options, yet reported emission factors are difficult to interpret and highly variable.

Machine learning for surrogate process models of bioproduction pathways.

Technoeconomic analysis and life-cycle assessment are critical to guiding and prioritizing bench-scale experiments and to evaluating economic and environmental performance of biofuel or biochemical production processes at scale. Traditionally, commercial process simulation tools have been used to develop detailed models for these purposes. However, developing and running such models can be costly and computationally intensive, which limits the degree to which they can be shared and reproduced in the broader research community.

Environmental and Economic Impacts of Managing Nutrients in Digestate Derived from Sewage Sludge and High-Strength Organic Waste.

Increasingly stringent limits on nutrient discharges are motivating water resource recovery facilities (WRRFs) to consider the implementation of sidestream nutrient removal or recovery technologies. To further increase biogas production and reduce landfilled waste, WRRFs with excess anaerobic digestion capacity can accept other high-strength organic waste (HSOW) streams. The goal of this study was to characterize and evaluate the life-cycle global warming potential (GWP), eutrophication potential, and economic costs and benefits of sidestream nutrient management and biosolid management strategies following digestion of sewage sludge augmented by HSOW.

Correction to "Expression of Dehydroshikimate Dehydratase in Sorghum Improves Biomass Yield, Accumulation of Protocatechuate, and Biorefinery Economics".

[This corrects the article DOI: 10.1021/acssuschemeng.2c01160.

Prospects for carbon-negative biomanufacturing.

Biomanufacturing has the potential to reduce demand for petrochemicals and mitigate climate change. Recent studies have also suggested that some of these products can be net carbon negative, effectively removing CO from the atmosphere and locking it up in products. This review explores the magnitude of carbon removal achievable through biomanufacturing and discusses the likely fate of carbon in a range of target molecules.

Engineering sorghum for higher 4-hydroxybenzoic acid content.

Engineering bioenergy crops to accumulate coproducts can increase the value of lignocellulosic biomass and enable a sustainable bioeconomy. In this study, we engineered sorghum with a bacterial gene encoding a chorismate pyruvate-lyase () to reroute the plastidial pool of chorismate from the shikimate pathway into the valuable compound 4-hydroxybenzoic acid (4-HBA). A gene encoding a feedback-resistant version of 3-deoxy-d-arabino-heptulonate-7-phosphate synthase () was also introduced in an attempt to increase the carbon flux through the shikimate pathway.

Comparing accumulation with microbial routes to set targets for a cost-competitive bioeconomy.

Plants and microbes share common metabolic pathways for producing a range of bioproducts that are potentially foundational to the future bioeconomy. However, accumulation and microbial production of bioproducts have never been systematically compared on an economic basis to identify optimal routes of production. A detailed technoeconomic analysis of four exemplar compounds (4-hydroxybenzoic acid [4-HBA], catechol, muconic acid, and 2-pyrone-4,6-dicarboxylic acid [PDC]) is conducted with the highest reported yields and accumulation rates to identify economically advantaged platforms and breakeven targets for plants and microbes.

Circularity in mixed-plastic chemical recycling enabled by variable rates of polydiketoenamine hydrolysis.

Footwear, carpet, automotive interiors, and multilayer packaging are examples of products manufactured from several types of polymers whose inextricability poses substantial challenges for recycling at the end of life. Here, we show that chemical circularity in mixed-polymer recycling becomes possible by controlling the rates of depolymerization of polydiketoenamines (PDK) over several orders of magnitude through molecular engineering. Stepwise deconstruction of mixed-PDK composites, laminates, and assemblies is chemospecific, allowing a prescribed subset of monomers, fillers, and additives to be recovered under pristine condition at each stage of the recycling process.

Fertilizer demand and potential supply through nutrient recovery from organic waste digestate in California.

Diversion of organic waste from landfills offers an opportunity to recover valuable nutrients such as nitrogen and phosphorus that are typically discarded. Although prior research has explored the potential for buildout of anaerobic digestion (AD) infrastructure to treat organic waste and generate energy, a better understanding is needed of the nutrient recovery potential from the solid and liquid byproducts (digestate) resulting from AD of these waste streams. We quantified the system-wide mass of nutrients that can potentially be recovered in California by integrating current and potential future AD facilities with existing nutrient recovery technologies.

Health and Climate Impacts from Long-Haul Truck Electrification.

Long-haul truck electrification has attracted nascent policy support, but the potential health and climate impacts remain uncertain. Here, we developed an integrated assessment approach with high spatial-temporal (km and hourly) resolution to characterize the causal chain from truck operation to charging loads, electricity grid response, changes in emissions and atmospheric concentrations, and the resulting health and climate impacts across the United States. Compared to future diesel trucks, electrified trucking's net health benefits are concentrated only along the West Coast with a business-as-usual electricity grid.