• Energy Research

To prevent the chance of unintended environmental harm, engineering decisions need to consider an expanded boundary that captures all relevant connected systems. Comprehensive models for sustainable engineering may be developed by combining models at multiple scales. Models at the finest “equipment” scale are engineering models based on fundamental knowledge. At the intermediate “value chain” scale, empirical models represent average production technologies, and at the coarsest “economy” scale, models represent monetary and environmental exchanges for industrial sectors in a national or global economy. However, existing methods for sustainable engineering design ignore the economy scale, while existing methods for life cycle assessment do not consider the equipment scale. This work proposes an integrated, multiscale modeling framework for connecting models from process to planet and using them for sustainable engineering applications. The proposed framework is demonstrated with a toy problem, and potential applications of the framework including current and future work are discussed. © 2015 American Institute of Chemical Engineers AIChE J, 61: 3332–3352, 2015

La primera biorrefinación con lignina del álamo nórdico para producir fibras de celulosa podría desplazar la producción de algodón en tierras agrícolas Al cruzar Populus trichocarpa 3 P. trichocarpa de una población distante, se obtuvieron álamos híbridos que pueden crecer rápidamente en tierras marginales en climas del norte. Estos híbridos pueden transformarse mediante fraccionamiento catalítico reductor para producir una fibra textil deslignificada que puede ser un sustituto del algodón, así como un biocombustible alimentado con lignina en el rango de gasolina-aviación-diesel. La sostenibilidad de esta cadena de valor fue evaluada por LCA y mostró beneficios sustanciales en términos de uso de agua en comparación con la producción de algodón. Le bioraffinage en lignine du peuplier nordique pour produire des fibres de cellulose pourrait déplacer la production de coton sur les terres agricoles En croisant Populus trichocarpa 3 P. trichocarpa d'une population éloignée, des peupliers hybrides ont été obtenus qui peuvent croître rapidement sur des terres marginales dans les climats nordiques. Ces hybrides peuvent être transformés par fractionnement catalytique réducteur pour donner une fibre textile délignifiée qui peut remplacer le coton ainsi qu'un biocarburant ligninérisé dans la gamme essence-aviation-diesel. La durabilité de cette chaîne de valeur a été évaluée par LCA et a montré des avantages substantiels en termes d'utilisation de l'eau par rapport à la production de coton. Lignin-first biorefining of Nordic poplar to produce cellulose fibers could displace cotton production on agricultural lands By crossing Populus trichocarpa 3 P. trichocarpa from a distant population, hybrid poplar trees were obtained that can grow rapidly on marginal lands in northern climates.These hybrids can be transformed by reductive catalytic fractionation to yield a delignified textile fiber that can be a substitute for cotton as well as a ligninderived biofuel in the gasoline-aviation-diesel range.The sustainability of this value chain was evaluated by LCA and showed substantial benefits in terms of water use compared with cotton production. يمكن للتكرير الحيوي الأول لليجنين للحور الشمالي لإنتاج ألياف السليلوز أن يحل محل إنتاج القطن في الأراضي الزراعية من خلال عبور Populus trichocarpa 3 P. trichocarpa من مجموعة سكانية بعيدة، تم الحصول على أشجار الحور الهجينة التي يمكن أن تنمو بسرعة على الأراضي الهامشية في المناخات الشمالية. يمكن تحويل هذه الهجينة عن طريق التجزئة التحفيزية المختزلة لإنتاج ألياف نسيج منزوعة الكرامة يمكن أن تكون بديلاً عن القطن بالإضافة إلى وقود حيوي خفيف في نطاق البنزين والطيران والديزل. تم تقييم استدامة سلسلة القيمة هذه من قبل LCA وأظهرت فوائد كبيرة من حيث استخدام المياه مقارنة بإنتاج القطن.

Analysis of a promising lignin-first biorefining technique, reductive catalytic fractionation, provides useful metrics for cost and sustainability to guide researchers toward critical areas for improvement.

When excess base is required to drive desired reactions, such as in lignin alkaline oxidation, Sr(OH)2 can offer a reversibly-soluble alternative to NaOH that allows simple recycle of the excess base with concomitant cost and environmental benefits.

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. However, life cycle results from different allocation methods frequently contradict each other, making it difficult or impossible for the practitioner to draw any meaningful conclusions from the study. Using the matrix notation for life-cycle inventory data, we show that an inventory that requires allocation leads to an ill-posed problem: an inventory based on allocation is one of an infinite number of inventories that are highly dependent upon allocation methods. This insight is applied to comparative life-cycle assessment (LCA), in which products with the same function but different life cycles are compared. Recently, there have been several studies that applied multiple allocation methods and found that different products were preferred under different methods. We develop the Comprehensive Allocation Investigation Strategy (CAIS) to examine any given inventory under all possible allocation decisions, enabling us to detect comparisons that are not robust to allocation, even when the comparison appears robust under conventional partitioning methods. While CAIS does not solve the ill-posed problem, it provides a systematic way to parametrize and examine the effects of partitioning allocation. The practical usefulness of this approach is demonstrated with two case studies. The first compares ethanol produced from corn stover hydrolysis, corn stover gasification, and corn grain fermentation. This comparison was not robust to allocation. The second case study compares 1,3-propanediol (PDO) produced from fossil fuels and from biomass, which was found to be a robust comparison.

Abstract Sustainable design methods focus on reducing or minimizing the demand for ecosystem goods and services, quantified as natural resources and pollutant mitigation. However, the capacity of ecosystems to supply these demands is routinely ignored, leading to decisions that overburden ecological processes and cause environmental damage. This work develops a techno-ecological synergy (TES) design methodology that balances the ecosystem services that can be provided by nature with the ecosystem service demands created by human activities. The methodology includes the design of technological processes that require ecosystem services as well as the ecological processes that supply those services. The TES Design methodology is demonstrated by application to a renewable energy production system that includes both land use activities, such as agriculture and wind turbines, and biomass conversion activities such as corn ethanol and soybean biodiesel. Under TES Design, the system is optimized to balance the demand and supply of ecosystem services, within constraints imposed on energy production and system economics. The system is also optimized under a more conventional approach that reduces ecosystem service demand while neglecting ecosystem service supply and the relevant ecological processes. Results show that only the TES methodology produces system designs in which ecosystem service supply meets or exceeds the demand. TES system designs produce the same amount of energy as conventional designs, have similar system economics, and use land both for energy production and for ecosystem service supply. The additional supply enables the use of intensive agricultural practices with higher ecosystem service demands and higher biomass yields. These results encourage further efforts toward TES Design with additional ecosystem services.

Sustainable process design (SPD) problems combine a process design problem with life cycle assessment (LCA) to optimize process economics and life cycle environmental impacts. While SPD makes use of recent advances in process systems engineering and optimization, its use of LCA has stagnated. Currently, only process LCA is utilized in SPD, resulting in designs based on incomplete and potentially inaccurate life cycle information. To address these shortcomings, the multiscale process to planet (P2P) modeling framework is applied to formulate and solve the SPD problem. The P2P framework offers a more comprehensive analysis boundary than conventional SPD and greater modeling detail than advanced LCA methodologies. Benefits of applying this framework to SPD are demonstrated with an ethanol process design case study. Results show that current methods shift emissions outside the analysis boundary, while applying the P2P modeling framework results in environmentally superior process designs. Future extensions of the P2P framework are discussed. © 2015 American Institute of Chemical Engineers AIChE J, 61: 3320–3331, 2015