Molecular Dynamics Simulation of Zeolite-Assisted Pyrolysis of Polystyrene: Material Selection and Mechanistic Insights.

Polystyrene (PS) presents a significant environmental challenge due to its durability and resistance to degradation. A major issue in addressing this challenge is optimizing the pyrolysis process to selectively convert PS into valuable products, such as styrene, while minimizing unwanted byproducts. Existing studies on PS pyrolysis have primarily focused on general reaction yields and kinetics, with limited molecular-level insight into how zeolites can enhance product selectivity.

Understanding Rapid PET Degradation via Reactive Molecular Dynamics Simulation and Kinetic Modeling.

As the demand for PET plastic products continues to grow, developing effective processes to reduce their pollution is of critical importance. Pyrolysis, a promising technology to produce lighter and recyclable components from wasted plastic products, has therefore received considerable attention. In this work, the rapid pyrolysis of PET was studied by using reactive molecular dynamics (MD) simulations.

Techno-economic and life cycle analysis of circular phosphorus systems in agriculture.

Fertilizer runoff is a global nuisance that disrupts biogeochemical cycles of nitrogen and phosphorus. We perform techno-economic and life cycle analyses of selected approaches for enabling a circular economy of phosphorus. We consider four schemes: capturing P with ion-exchange resins followed by precipitation, interception by wetland and recovery in char after biomass pyrolysis, removal by bioreactor and recovery in char after bioreactor substrate pyrolysis, and using legacy phosphorus accumulated in a saturated wetland to grow crops by wetlaculture.

Metrics for a nature-positive world: A multiscale approach for absolute environmental sustainability assessment.

Absolute environmental sustainability (AES) metrics include nature's carrying capacity as a reference to provide insight into the extent to which human activities exceed ecosystem limits, and to encourage actions toward restoration and protection of nature. Existing methods for determining AES metrics rely on the frameworks of Planetary boundaries (PB) and Ecosystem Services. This work provides new insight into the relationship between these methods and demonstrates that AES metrics based on the framework of techno-ecological synergy (TES) are better suited to encouraging nature-positive decisions.

Quantification and valuation of ecosystem services in life cycle assessment: Application of the cascade framework to rice farming systems.

The integration of ecosystem service (ES) assessment with life cycle assessment (LCA) is important for developing decision support tools for environmental sustainability. A prequel study has proposed a 4-step methodology that integrates the ES cascade framework within the cause-effect chain of life cycle impact assessment (LCIA) to characterize the physical and monetary impacts on ES provisioning due to human interventions. We here follow the suggested steps in the abovementioned study, to demonstrate the first application of the integrated ES-LCIA methodology and the added value for LCA studies, using a case study of rice farming in the United States, China, and India.

Nature-Based Solutions Can Compete with Technology for Mitigating Air Emissions Across the United States.

Despite the proliferation of control technologies, air pollution remains a major concern across the United States, suggesting the need for a paradigm shift in methods for mitigating emissions. Based on data about annual emissions in U.S.

Toward Sustainable Chemical Engineering: The Role of Process Systems Engineering.

Products from chemical engineering are essential for human well-being, but they also contribute to the degradation of ecosystem goods and services that are essential for sustaining all human activities. To contribute to sustainability, chemical engineering needs to address this paradox by developing chemical products and processes that meet the needs of present and future generations. Unintended harm of chemical engineering has usually appeared outside the discipline's traditional system boundary due to shifting of impacts across space, time, flows, or disciplines, and exceeding nature's capacity to supply goods and services.

A Water-Withdrawal Input-Output Model of the Indian Economy.

Managing freshwater allocation for a highly populated and growing economy like India can benefit from knowledge about the effect of economic activities. This study transforms the 2003-2004 economic input-output (IO) table of India into a water withdrawal input-output model to quantify direct and indirect flows. This unique model is based on a comprehensive database compiled from diverse public sources, and estimates direct and indirect water withdrawal of all economic sectors.

Economic Dependence of U.S. Industrial Sectors on Animal-Mediated Pollination Service.

Declining animal pollinator health and diversity in the U.S. is a matter of growing concern and has particularly gained attention since the emergence of colony collapse disorder (CCD) in 2006.

Allocation Games: Addressing the Ill-Posed Nature of Allocation in Life-Cycle Inventories.

Allocation is required when a life cycle contains multi-functional processes. One approach to allocation is to partition the embodied resources in proportion to a criterion, such as product mass or cost. Many practitioners apply multiple partitioning criteria to avoid choosing one arbitrarily.

Techno-ecological synergy: a framework for sustainable engineering.

Even though the importance of ecosystems in sustaining all human activities is well-known, methods for sustainable engineering fail to fully account for this role of nature. Most methods account for the demand for ecosystem services, but almost none account for the supply. Incomplete accounting of the very foundation of human well-being can result in perverse outcomes from decisions meant to enhance sustainability and lost opportunities for benefiting from the ability of nature to satisfy human needs in an economically and environmentally superior manner.

Accounting for the biogeochemical cycle of nitrogen in input-output life cycle assessment.

Nitrogen is indispensable for sustaining human activities through its role in the production of food, animal feed, and synthetic chemicals. This has encouraged significant anthropogenic mobilization of reactive nitrogen and its emissions into the environment resulting in severe disruption of the nitrogen cycle. This paper incorporates the biogeochemical cycle of nitrogen into the 2002 input-output model of the U.

Multi-scale modeling for sustainable chemical production.

With recent advances in metabolic engineering, it is now technically possible to produce a wide portfolio of existing petrochemical products from biomass feedstock. In recent years, a number of modeling approaches have been developed to support the engineering and decision-making processes associated with the development and implementation of a sustainable biochemical industry. The temporal and spatial scales of modeling approaches for sustainable chemical production vary greatly, ranging from metabolic models that aid the design of fermentative microbial strains to material and monetary flow models that explore the ecological impacts of all economic activities.

Techno-ecological synergy as a path toward sustainability of a North American residential system.

For any human-designed system to be sustainable, ecosystem services that support it must be readily available. This work explicitly accounts for this dependence by designing synergies between technological and ecological systems. The resulting techno-ecological network mimics nature at the systems level, can stay within ecological constraints, and can identify novel designs that are economically and environmentally attractive that may not be found by the traditional design focus on technological options.

Reinforced wind turbine blades--an environmental life cycle evaluation.

A fiberglass composite reinforced with carbon nanofibers (CNF) at the resin-fiber interface is being developed for potential use in wind turbine blades. An energy and midpoint impact assessment was performed to gauge impacts of scaling production to blades 40 m and longer. Higher loadings force trade-offs in energy return on investment and midpoint impacts relative to the base case while remaining superior to thermoelectric power generation in these indicators.

Assessing resource intensity and renewability of cellulosic ethanol technologies using eco-LCA.

Recognizing the contributions of ecosystem services and the lack of their comprehensive accounting in life cycle assessment (LCA), an in-depth analysis of their contribution in the life cycle of cellulosic ethanol derived from five different feedstocks was conducted, with gasoline and corn ethanol as reference fuels. The relative use intensity of natural resources encompassing land and ecosystem goods and services by cellulosic ethanol was estimated using the Eco-LCA framework. Despite being resource intensive compared to gasoline, cellulosic ethanol offers the possibility of a reduction in crude oil consumption by as much as 96%.

Appreciating the role of thermodynamics in LCA improvement analysis via an application to titanium dioxide nanoparticles.

Although many regard it as the most important step of life cycle assessment, improvement analysis is given relatively little attention in the literature. Most available improvement approaches are highly subjective, and traditional LCA methods often do not account for resources other than fossil fuels. In this work exergy is evaluated as a thermodynamically rigorous way of identifying process improvement opportunities.

Accounting for ecosystem services in Life Cycle Assessment, Part II: toward an ecologically based LCA.

Despite the essential role of ecosystem goods and services in sustaining all human activities, they are often ignored in engineering decision making, even in methods that are meant to encourage sustainability. For example, conventional Life Cycle Assessment focuses on the impact of emissions and consumption of some resources. While aggregation and interpretation methods are quite advanced for emissions, similar methods for resources have been lagging, and most ignore the role of nature.

Accounting for ecosystem services in life cycle assessment, Part I: a critical review.

If life cycle oriented methods are to encourage sustainable development, they must account for the role of ecosystem goods and services, since these form the basis of planetary activities and human well-being. This article reviews methods that are relevant to accounting for the role of nature and that could be integrated into life cycle oriented approaches. These include methods developed by ecologists for quantifying ecosystem services, by ecological economists for monetary valuation, and life cycle methods such as conventional life cycle assessment, thermodynamic methods for resource accounting such as exergy and emergy analysis, variations of the ecological footprint approach, and human appropriation of net primary productivity.

Thermodynamic metrics for aggregation of natural resources in life cycle analysis: insight via application to some transportation fuels.

While methods for aggregating emissions are widely used and standardized in life cycle assessment (LCA), there is little agreement about methods for aggregating natural resources for obtaining interpretable metrics. Thermodynamic methods have been suggested including energy, exergy, and emergy analyses. This work provides insight into the nature of thermodynamic aggregation, including assumptions about substitutability between resources and loss of detailed information about the data being combined.

Carbon nanofiber polymer composites: evaluation of life cycle energy use.

Holistic evaluation of emerging nanotechnologies using systems analysis is pivotal for guiding their safe and sustainable development. While toxicity studies of engineered nanomaterials are essential, understanding of the potential large scale impacts of nanotechnology is also critical for developing sustainable nanoproducts. This work evaluates the life cycle energetic impact associated with the production and use of carbon nanofiber (CNF) reinforced polymer nanocomposites (PNC).

Exergy: its potential and limitations in environmental science and technology.

New technologies, either renewables-based or not, are confronted with both economic and technical constraints. Their development takes advantage of considering the basic laws of economics and thermodynamics. With respect to the latter, the exergy concept pops up.

Life cycle assessment of an ionic liquid versus molecular solvents and their applications.

Ionic liquids (ILs) have been claimed as "greener" replacements to molecular solvents. However, the environmental impacts of the life cycle phases and comparison with alternative methods have not been studied. Such a life cycle assessment (LCA) is essential before any legitimate claims of "greenness" can be made and is the subject of this paper.

Toward Bayesian chemometrics--a tutorial on some recent advances.

Chemometrics is increasingly being perceived as a maturing science. While this perception seems to be true with regards to the traditional methods and applications of chemometrics, this article argues that advances in instrumentation, computation, and statistical theory may combine to drive a resurgence in chemometrics research. Previous surges in chemometrics research activity were driven by the development of new ways of making better use of available information.

Flow of natural versus economic capital in industrial supply networks and its implications to sustainability.

Appreciating the reliance of industrial networks on natural capital is a necessary step toward their sustainable design and operation. However, most contemporary accounting techniques, including engineering economics, life cycle assessment, and full cost accounting, fail in this regard, as they take natural capital for granted and concentrate mainly on the economic aspects and emissions. The recently developed "thermodynamic input-output analysis" (TIOA) includes the contribution of ecological goods, ecosystem services, human resources, and impact of emissions in an economic input-output model.