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Electrolyzers and fuel cells will be crucial for achieving global clean hydrogen and industrial decarbonization goals. However, the nascent clean hydrogen sector faces uncertainties around material supply chains and technology end‐of‐life management. This work aims to guide the transition to a circular hydrogen economy by using process modeling, techno‐economic analysis, and life cycle assessment to evaluate the material cost, energy use, greenhouse gas (GHG) emissions, toxicity, and water use of five potential recycling strategies for proton exchange membrane electrolyzers (PEMWE) and fuel cells (PEMFC). Hydrometallurgy, acid dissolution, and electrochemical dissolution are shown to offer 2–7 times improvement across all assessed metrics relative to the manufacturing of PEMWE and PEMFC from raw materials. Recycling can also lower the raw material demand, material cost, energy use, and GHG emissions associated with PEMWE and PEMFC deployment in the United States in 2050 by 23%, 19%, 21%, and 16%, respectively. This study provides key insights into the costs, benefits, and complexities of recycling strategies for PEMWE and PEMFC, aiding the development of a circular economy that is synergistic with clean hydrogen deployment. [ABSTRACT FROM AUTHOR]

This study assessed the long‐term annual biofuel production capacity potential and price in the United States and shed light on the prospect of biofuel adoption for marine propulsion. A linear programming model was developed to assist the projections and provide insightful analyses. The projected long‐term (2040) maximum annual capacity of biofuels in the United States is 245 million metric tons (Mt) or 65 billion gallons of heavy fuel oil gallon equivalent (HFOGE) when based on the median feedstock availability. Between 2022 (near‐term) and 2040, the potential biofuel capacity increases by over 40%, attributed to increased feedstock availability. At a price range up to $500/t, biodiesel is the main product, and the annual capacity (12 Mt) is limited to feedstock availability constraints. Biodiesel and corn ethanol are the main biofuels at a price range up to $750/t. At a higher price point (above $750/t), the biofuel types and annual capacities increase substantially (218 Mt per year). Biofuels above this price include gasoline‐, jet‐, and diesel‐range blendstocks, as well as bio‐methanol, bio‐propane, and biogas. This study concludes that the US domestic feedstock availability coupled with advanced conversion technologies can produce substantial amounts of biofuels to achieve a critical mass and be impactful as alternative marine fuels. There is also a need to improve the biofuel price for marine shipping adoption. Policies and economic incentives that provide temporary financial support would help facilitate maritime biofuel adoption. © 2022 Alliance for Sustainable Energy, LLC. Biofuels, Bioproducts and Biorefining published by Society of Industrial Chemistry and John Wiley & Sons Ltd. [ABSTRACT FROM AUTHOR]

Methane pyrolysis has emerged as a promising low-carbon hydrogen production method, serving as a bridge from conventional fossil fuels to renewable energies (REs). A recent technique for sustainable hydrogen production involves the process of methane pyrolysis in molten salt. To better understand the potential of sustainable turquoise hydrogen production, this paper presents a techno-economic assessment of methane pyrolysis in molten salt combined with a high-temperature heliostat solar field. In addition, a high-temperature thermal energy storage (HTES) unit is utilized to ensure uninterrupted hydrogen production during periods of solar unavailability, thereby contributing to the economic viability of the overall system. The proposed system can produce about 9 tons of H 2 /day and 27 tons of solid carbon/day with a round-trip efficiency of 49.8 % and a levelized cost of hydrogen (LCOH) of 1.93 $/kg. To further decarbonize the process, the feasibility of utilizing REs as the source of electricity for the HTES was analyzed, yielding a synergistic achievement of clean and economic hydrogen production. This configuration resulted in a LCOH of 1.25 $/kg, after including the United States (US) clean hydrogen production tax incentives. The proposed system shows the potential to achieve the US Department of Energy target of 1 $/kg of hydrogen with a 20 % reduction in the cost of RE infrastructure. • Proposing a novel design for methane pyrolysis in molten salt based on heliostat solar field. • Utilizing high-temperature thermal energy storage for continuous hydrogen production. • Performing a comprehensive techno-economic analysis by including clean hydrogen tax incentives. • Reaching a hydrogen cost of 1.25 $/kg by incorporating the US clean hydrogen tax incentives. • Achieving the target of hydrogen shot (1 $/kg of H 2) through a 20 % reduction in the cost of RE infrastructure. [ABSTRACT FROM AUTHOR]

Purpose: Producing biochar from forest residues can help resolve environmental issues by reducing forest fires and mitigating climate change. However, transportation and storage of biomass to a centralized facility are often cost-prohibitive and a major hurdle for the economic feasibility of producing biobased products, including biochar. The purpose of this study was to evaluate the environmental impacts and economic feasibility of manufacturing biochar from forest residues with small-scale portable production systems. Methods: This study evaluated the environmental performance and economic feasibility of biochar produced through three portable systems (biochar solutions incorporated (BSI), Oregon Kiln (OK), and air curtain burner (ACB)) using forest residues in the United States (US). Cradle-to-grave life-cycle assessment (LCA) and techno-economic analysis (TEA) were used to quantify environmental impacts and minimal selling price (MSP) of biochar respectively considering different power sources, production sites, and feedstock qualities. Results and discussions: The results illustrated that the global warming (GW) impact of biochar production through BSI, OK, and ACB was 0.25–1.0, 0.55, and 0.61-t CO2eq/t biochar applied to the field, respectively. Considering carbon-sequestration, 1-t of biochar produced with the portable system at a near-forest site and applied to the field reduced the GW impact by 0.89–2.6 t CO2eq. For biochar production, the environmental performance of the BSI system improved substantially (60–70%) when it was powered by a gasifier-based generator instead of a diesel generator. Similarly, near-forest(off-grid) biochar production operations performed better environmentally than the operations at in-town sites due to the reduction in the forest residues transportation emissions. Overall, the net GW impact of biochar produced from forest residues can reduce environmental impacts (i.e., 1–10 times lower CO2eq emissions) compared with slash-pile burning. The MSP per tonne of biochar produced through BSI, OK, and ACB was $3,000–$5,000, $1,600, and $580 respectively considering 100 working days per year. However, with improved BSI systems when allowed to operate throughout the year, the MSP can be reduced to below $1000/t of biochar. Furthermore, considering current government grants and subsidies (i.e.,$12,600/ha for making biochar production from forest residues), the MSP of biochar can be reduced substantially (30–387%) depending on the type of portable system used. Conclusion: The portable small-scale production systems could be environmentally beneficial and economically feasible options to make biochar from forest residues at competitive prices given current government incentives in the US where excess forest biomass and forest residues left in the forest increase the risk of forest fires. [ABSTRACT FROM AUTHOR]

This study performs techno‐economic analysis and Monte Carlo simulations (MCS) to explore the effects that variations in biomass feedstock quality have on the economic feasibility of fast pyrolysis biorefineries using decentralized preprocessing sites (i.e., depots that produce pellets). Two biomass resources in the Southeastern United States, that is, pine residues and switchgrass, were examined as feedstocks. A scenario analysis was conducted for an array of different combinations, including different pellet ash control levels, feedstock blending ratios, different biorefinery capacities, and different biorefinery on‐stream capacities, followed by a comparison with the traditional centralized system. MCS results show that, with depot preprocessing, variations in the feedstock moisture and feedstock ash content can be significantly reduced compared with a traditional centralized system. For a biorefinery operating at 100% of its designed capacity, the minimum fuel selling price (MFSP) of the decentralized system is $3.97–$4.39 per gallon gasoline equivalent (GGE) based on the mean value across all scenarios, whereas the mean MFSP for the traditional centralized system was $3.79–$4.12/GGE. To understand the potential benefits of highly flowable pellets in decreasing biorefinery downtime due to feedstock handling and plugging problems, this study also compares the MFSP of the decentralized system at 90% of its designed capacity with a traditional system at 80%. The analysis illustrates that using low ash pellets mixed with switchgrass and pine residues generates a more competitive MFSP. Specifically, for a biorefinery designed for 2,000 oven dry metric ton per day, running a blended pellet made from 75% switchgrass and 25% pine residues with 2% ash level, and operating at 90% of designed capacity could make an MFSP between $4.49 and $4.71/GGE. In contrast, a traditional centralized biorefinery operating at 80% of designed capacity marks an MFSP between $4.72 and $5.28. [ABSTRACT FROM AUTHOR]

Synthetic natural gas (SNG) is of great interest in reducing fossil energy consumption while maintaining compatibility with existing NG infrastructure and end-use applications equipment. SNG can be produced using clean H 2 generated from renewable or nuclear energy and CO 2 captured from stationary sources or the atmosphere. In this study, we develop an engineering process model of SNG production using Aspen Plus® and production scales reported by the industry. We examine the levelized cost and life cycle greenhouse gas (GHG) emissions of SNG production under various CO 2 supply scenarios. Considering the higher cost of H 2 transportation compared with CO 2 transportation, we assume that CO 2 feedstock is transported via pipeline to the H 2 production location, which is collocated with the SNG plant. We also evaluate the cost of CO 2 captured from the atmosphere, assuming the direct air capture process can occur near the SNG facility. Depending on the CO 2 supply chain, the levelized cost of SNG is estimated to be in the range of $45–76 per million British thermal units (MMBtu) on a higher heating value (HHV) basis. The SNG production cost may be reduced to $27–57/MMBtu-HHV by applying a tax credit available in the United States for low-carbon H 2 production (45 V). With a lower electricity price of 3ȼ/kWh for water electrolysis and accounting for a 45 V tax credit, the SNG cost reaches parity with the cost of fossil NG. Depending on the CO 2 supply chain, SNG can reduce life cycle GHG emissions by 52–88 % compared with fossil NG. • A process model of synthetic natural gas production is developed using Aspen Plus. • SNG is produced from low-carbon/zero-carbon H 2 and point-source/atmospheric CO 2. • Levelized production cost and life cycle GHG emissions of SNG are evaluated. • SNG cost can be reduced with a tax credit in the U.S. for low-carbon H 2 production. • SNG can reduce life cycle GHG emissions by 52–88 % compared to fossil NG. [ABSTRACT FROM AUTHOR]

Electrification and clean hydrogen are promising low-carbon options for decarbonizing industrial process heat, which is an essential target for reducing sector-wide emissions. However, industrial processes with heat demand vary significantly across industries in terms of temperature requirements, capacities, and equipment, making it challenging to determine applications for low-carbon technologies that are technically and economically feasible. In this analysis, we develop a framework for evaluating life cycle emissions, water use, and cost impacts of electric and clean hydrogen process heat technologies and apply it in several case studies for plastics and petrochemical manufacturing industries in the United States. Our results show that industrial heat pumps could reduce emissions by 12-17% in a typical poly(vinyl chloride) (PVC) facility in certain locations currently, compared to conventional natural gas combustion, and that other electric technologies in PVC and ethylene production could reduce emissions by nearly 90% with a sufficiently decarbonized electric grid. Life cycle water use increases significantly in all low-carbon technology cases. The levelized cost of heat of viable low-carbon technologies ranges from 15 to 100% higher than conventional heating systems, primarily due to energy costs. We discuss results in the context of relevant policies that could be useful to manufacturing facilities and policymakers for aiding the transition to low-carbon process heat technologies.

The revised Renewable Fuel Standard's cellulosic biofuels mandate requires the USA to consume 16 000 million gallons of cellulosic biofuel per year by 2022. The cellulosic biofuels industry has fallen far short of reaching the production targets needed to achieve this volume, and it has even struggled to achieve the greatly reduced revised volumes that were created by the US Environmental Protection Agency despite the subsequent inclusion of landfill gas within the mandate. This article examines the underlying causes of this shortfall from the perspectives of markets and policy. It examines how the cellulosic biofuels production environment has not been conducive to the cost‐competitiveness of pioneer, first‐of‐their‐kind facilities and pathway buildout, and how recent techno‐economic analyses have used uncertainty to quantify the impacts of this environment. It further examines how the cellulosic biofuels mandate has actually hindered commercialization despite being intended to support it. © 2019 Society of Chemical Industry and John Wiley & Sons, Ltd [ABSTRACT FROM AUTHOR]

Carbon capture (CC) technology is receiving increasing attention as a critical technology for climate change mitigation. Most previous studies focus on the application of CC technology in the power generation sector, while fewer studies have analyzed applications in the refining industry, which is one of the largest greenhouse gas (GHG) emissions sources in the U.S. industrial sector. Unlike the power generation sector, the refining industry has highly distributed CO 2 emission sources. In this paper, bottom-up modeling and techno-economic analysis approaches are integrated to quantify the national CO 2 emission reduction potential and costs of three types of CC technologies applied to U.S. refineries: (1) pre-combustion, (2) post-combustion, and (3) oxyfuel-combustion. Two scenarios are developed to compare different design strategies for CC systems; one is a distributed design scenario for post-combustion technology, the other is a centralized design scenario for pre-combustion and oxyfuel-combustion technology. The results of the two scenarios are compared, and the trade-offs between different design strategies are highlighted. The results shown in this study provide an intuitive and quantitative understanding of the potential of CC technology to reduce CO 2 emissions from the U.S. refining industry. Such information is helpful to policymakers, oil companies, and energy/environmental analysts for strategic planning and systems design to manage future CO 2 emissions of refineries. [ABSTRACT FROM AUTHOR]

The United States is the largest broiler producer in the world, and Americans consume about 45 kg of chicken per capita per year, which generates substantial economic and environmental footprints. We conduct techno-economic analysis and life cycle assessment (TEA / LCA) to evaluate the sustainability performance of the U.S. broiler industry and quantify the cost, greenhouse gas (GHG) emissions, energy, water, land, fertilizer, and respiratory impacts of 7 broiler production scenarios for a contract Grower, Integrator, and Combined control volume. The assessment is a farm-gate to farm-gate analysis that includes capital cost of chicken houses, labor, chicks brought into the farm, feeds, on-site fuels, and on-site emissions. We found that economics for the Integrator are profitable and dominated by the cost of corn and soybean meal feeds, payments to the Grower, and revenue from live broilers. Additionally, we found that economics for the Grower generate modest return on investment (ROI) largely based on the cost of houses and labor when compared to contract revenue from the Integrator. Environmental impacts for GHG, energy, and respiratory effects are primarily associated with upstream feed production (roughly 65%–80% of total impacts) and on-site fuel consumption (∼20%–35% of total impacts), while those for water, land, and eutrophication are almost entirely attributable to upstream feed production (litter spreading has a low economic allocation factor). Tradeoffs among sustainability metrics are further explored with a sensitivity analysis and by evaluating cost/environmental benefit scenarios. [ABSTRACT FROM AUTHOR]

• Six BF-BOF and four EAF decarbonization options are evaluated for their CO 2 reduction and associated costs against a consistent baseline. • Improved energy efficiency, carbon capture and storage, and low-carbon energy switching have been evaluated for CO 2 reduction and associated cost. • Deep decarbonization can be achieved by combining various CO 2 reduction options. • The avoidance cost of CO 2 is impacted mainly by fuel prices. • CO 2 capture and storage provides highest CO 2 reduction and lowest CO 2 avoidance cost. Iron and steel manufacturing is the largest contributor to CO 2 emissions among heavy industries worldwide. This is mostly due to the use of coal in blast furnace-basic oxygen furnace (BF-BOF) process for virgin (primary) steel production. The electricity generation mix used in the electric arc furnace (EAF) process to recycle scrap steel also contributes to the CO 2 emission associated with secondary steel production. To decarbonize iron and steel sector, we investigated decarbonization options for BF-BOF and EAF processes, including energy efficiency, carbon capture and storage, and the use of clean energy sources, in various BF-BOF and EAF process configurations. For each decarbonization approach, we evaluated the CO 2 reduction potential via life cycle analysis (LCA) and estimated the associated cost through techno-economic analysis (TEA). A typical U.S. BF-BOF for virgin steel production has a cradle-to-gate (CTG) CO 2 emissions of 1,990 kg/MT steel with a levelized cost of steel (LCOS) of $439/MT steel, while a typical U.S. EAF process for secondary steel production in the United States has a CTG CO 2 emissions of 270 kg/MT steel with a LCOS of $365/MT steel. Combining renewable energy sources and carbon capture, BF-BOF CTG CO 2 emissions can be reduced to 16 kg/MT steel, and EAF configurations can achieve similar deep reductions to reach 25 kg/MT steel. The corresponding LCOS with these decarbonization levels is estimated to increase to $542/MT steel and $348/MT steel, respectively. The estimated CO 2 avoidance costs vary from -$90/MT CO 2 to $646/MT CO 2 , depending on the various decarbonization technologies and energy prices. [Display omitted] [ABSTRACT FROM AUTHOR]

Background: The need for liquid fuels in the transportation sector is increasing, and it is essential to develop industrially sustainable processes that simultaneously address the tri-fold sustainability metrics of technological feasibility, economic viability, and environmental impacts. Biorefineries based on lignocellulosic feedstocks could yield high-value products such as ethyl acetate, dodecane, ethylene, and hexane. This work focuses on assessing biochemical and biomass to electricity platforms for conversion of Banagrass and Energycane into valuable fuels and chemicals using the tri-fold sustainability metrics. Results: The production cost of various products produced from Banagrass was $1.19/kg ethanol, $1.00/kg ethyl acetate, $3.01/kg dodecane (jet fuel equivalent), $2.34/kg ethylene and $0.32/kW-h electricity. The production cost of different products using Energycane as a feedstock was $1.31/kg ethanol, $1.11/kg ethyl acetate, $3.35/kg dodecane, and $2.62/kg ethylene. The sensitivity analysis revealed that the price of the main product, feedstock cost and cost of ethanol affected the profitability the overall process. Banagrass yielded 11% higher ethanol compared to Energycane, which could be attributed to the differences in the composition of these lignocellulosic biomass sources. Acidification potential was highest when ethylene was produced at the rate of 2.56 x 10-2 and 1.71 x 10-2 kg SO2 eq. for Banagrass and Energycane, respectively. Ethanol production from Banagrass and Energycane resulted in a global warming potential of - 12.3 and - 40.0 g CO2 eq./kg ethanol. Conclusions: Utilizing hexoses and pentoses from Banagrass to produce ethyl acetate was the most economical scenario with a payback period of 11.2 years and an ROI of 8.93%, respectively. Electricity production was the most unprofitable scenario with an ROI of - 29.6% using Banagrass/Energycane as a feedstock that could be attributed to high feedstock moisture content. Producing ethylene or dodecane from either of the feedstocks was not economical. The moisture content and composition of biomasses affected overall economics of the various pathways studied. Producing ethanol and ethyl acetate from Energycane had a global warming potential of - 3.01 kg CO2 eq./kg ethyl acetate. [ABSTRACT FROM AUTHOR]

The United States produced more than 66.2 billion Liters of biofuel, primarily in the form of corn ethanol (61 billion Liters) and soybean biodiesel (6 billion Liters), for the transportation industry in 2017. No work currently exists that evaluates both the economic and environmental outcomes of this industry with adequate geospatial resolution and national scope. In this study, a model framework is constructed to perform Techno-Economic Analysis and Life Cycle Assessment using high-resolution input datasets to provide a granular estimation of corn ethanol and soybean biodiesel sustainability performance in most counties in the United States in 2017 (the most recent year for which data is available). Results show a total life cycle, greenhouse gas emission volume of 99.5 million Mg CO 2-eq produced in 2017 by these two biofuels (94.8 million Mg from corn ethanol, and 4.7 million Mg from soybean biodiesel), excluding indirect land use change emissions. This volume corresponds to a combined carbon intensity of 65.3 gCO 2-eq /MJ, which is a greenhouse gas improvement compared to petroleum-based gasoline (the carbon intensity of conventional gasoline is 93.0 gCO 2-eq /MJ). However, these biofuels are produced at an additional economic cost ($6.2 billion over the displaced gas/diesel). Additionally, these biofuels generate unfavorable impacts in other environmental categories when compared to petroleum-based fuels, particularly in areas of water, land, and nitrogen intensity. This work enables stakeholders to assess the specific value of biofuels as a means of emission reduction and determine if the attained improvements are worth the associated opportunity costs. [Display omitted] • Corn Ethanol and Soybean Biodiesel evaluated with multiple LCA metrics. • Country wide and county level results are provided for the 2017 biofuel industry. • Total life cycle, greenhouse gas emission volume of 99.5 million Mg CO2-eq produced in 2017. • Combined carbon intensity of 65.3 gCO 2-eq /MJ for corn and soy based biofuels in 2017. • Techno-economic results show biofuels result in $1.8 billion over the displaced gas/diesel cost. [ABSTRACT FROM AUTHOR]

• Economics & carbon footprint of a piloted US flexible plastic packaging recycling. • Roof coverboard, pallets, pellets, and film are downstream market pathways. • Cleaning and pelletizing steps contributed the most to recycled product footprints. • Recycled products are environmentally & economically better than competitors. As demand for plastic increases, there is an urgent need to ramp up its collection and recycling rate. This study reports results of a pilot study in the United States to recycle flexible plastic packaging (FPP) from single stream curbside collection focusing on both the economic feasibility and carbon footprint. To explore the marketability of recycled FPP, four downstream market pathways were studied, including roof coverboard, plastic pellets, pallets, and film. Results indicated that (1) the cleaning and pelletizing process at reclaimers contributed the most to the total greenhouse gas (GHG) emissions of recycled FPP products, and (2) the GHG emissions of recycled FPP products in all four pathways are lower than the comparator products. Therefore, using a higher percentage of recycled FPP substituted in a product can result in greater GHG emission reductions. All the recycled FPP products also showed favorable economics compared to their direct competitors. [ABSTRACT FROM AUTHOR]

Material Recovery Facilities (MRFs) are crucial players in achieving a circular economy. MRFs receive complex waste streams and separate valuable recyclables from these mixtures. This study conducts techno-economic analysis (TEA) to estimate the net present value (NPV) and life cycle assessment (LCA) to estimate different environmental impacts of a commercial scale standalone, single-stream MRF to assess the economic feasibility and environmental impacts of recovering valuable recyclables from an MRF processing 120,000 tonnes per year (t/y). The TEA employs a discounted cash flow rate of return (DCFROR) analysis over a 20-year facility lifetime, along with a sensitivity analysis on the impact of different operating and economic parameters. Results show that the total fixed cost of building the MRF facility is $23 MM, and the operating cost is $45.48/tonne. The NPV of the MRF can vary from $3.57 MM to $60 MM, while 100-year global warming potential can range from 5.98 to 8.53 kg carbon dioxide equivalents (CO2-eq) per tonne of MSW. We have also found that MSW composition (arising from regional effects) significantly impacts costs, 100-year global warming potential, and other impact categories such as acidification potential, eutrophication potential, ecotoxicity, ozone depletion, photochemical oxidation, carcinogenic effects, and non-carcinogenic effects. Sensitivity and uncertainty analysis indicate that waste composition and market prices significantly impact the profitability of the MRF, and the waste composition mostly impacts global warming potential. Our analysis also indicates that facility capacity, fixed capital cost, and waste tipping fees are vital parameters that affect the economic viability of MRF operations., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Plastic usage has quickly grown in recent years as plastics have become an essential material in everyday life. Unfortunately, recycling rates have not matched the increased growth, with the majority of waste plastic currently landfilled in the United States. New chemical recycling technologies, i.e. pyrolysis, are needed to increase the recycling rates of waste plastics. However, pyrolysis is challenged with bridging of feed into the hot reactor and in the high cost of waste plastic feedstock. In this work a novel liquid-fed pyrolysis process, designed to eliminate bridging, was modeled through process simulation and assessed over a range of processing conditions. A secondary sortation of inexpensive mixed plastic waste from material recovery facilities provided a low-cost feedstock (PE, PP) for pyrolysis. A techno-economic analysis and life cycle assessment found favorable economic and environmental results for pyrolysis oil when compared to fossil naphtha ($561/t, 0.52 kg CO 2 eq./kg). A sensitivity analysis found the economic results most responsive to waste plastics feedstock costs, pyrolysis gas sales, operating capacity, and waste disposal costs. Furthermore, it is recommended to recover and sell sorted PET from the mixed plastic bale and implement heat integration in pyrolysis, which in our study achieved lower minimum selling price and greenhouse gas emissions for pyrolysis oil then for fossil naphtha. [Display omitted] • Novel liquid-fed plastics pyrolysis applied to produce synthetic naphtha. • Secondary sortation of mixed plastic waste enables chemical recycling. • Identified sustainable processing conditions through robust scenario analyses. • Most favorable parameters achieve a 10x reduction in minimum selling price. • 5x reduction in greenhouse gas emissions achieved compared to fossil naphtha. [ABSTRACT FROM AUTHOR]

This article investigates the possibility of providing electricity from solar/wind hybrid systems for a remote location with no electricity connection in the city of Edirne in the westernmost province of Turkey in order to decrease the high cost of utilizing only stand-alone diesel system and to achieve considerable fuel savings. In this study, National Renewable Energy Laboratory's (NREL) HOMER (Hybrid Optimization Model for Electric Renewables) software is used to perform the techno-economic feasibility of such hybrid systems considering both solar data and wind data. Additionally, the contribution of solar and wind on energy production, cost of energy, and total operating hours of diesel generator is examined for the optimal hybrid configurations. Furthermore, fuel savings and reduction in carbon emissions of different hybrid systems are investigated. Finally, suitability of utilizing hybrid solar–wind energy system over stand-alone diesel system is discussed mainly based on different solar global irradiances, wind speed, and diesel price. [ABSTRACT FROM PUBLISHER]

Guayule (Parthenium argentatum A. Gray) is a desert-dwelling crop that can produce hard rubber for tires and has the potential to help meet the water conservation needs of arid regions such as the Southwest U.S. Previous work has quantified the cost and environmental impact from guayule rubber production. However, establishing the economic viability of a domestic guayule industry requires identifying value-added products from the residual non-rubber guayule biomass, referred to as bagasse. Using guayule bagasse for bioenergy production is one potential solution, but the best pathway for thermochemical conversion of bagasse to fuels has yet to be defined. In this work, process models of pyrolysis and pelletization of bagasse are developed to inform a path to commercialization. A facility processing 200 tonnes of guayule bagasse per day is considered with a system boundary defined from biomass cultivation to fuel combustion. The materials and energy inventory results enabled the first comparative assessment of bagasse to fuels by concurrently performing techno-economic analysis and well-to-wheels life cycle assessment on both pathways. The minimum fuel selling price for the bagasse to fuels pathway was $0.076 per MJ ($9.26 per gallon of gasoline equivalent) and the minimum selling price of pellets from bagasse was $176 per tonne. This work compares the economic and life cycle results of both processes to make conclusions about the economic potential of bagasse and environmental impact of its conversion, areas to reduce production cost of biofuels, and potential for greenhouse gas emissions reduction compared with conventional fuels. In addition, the work identifies areas where future research may optimize production costs such that these fuels can be integrated alongside guayule rubber into a successful bioeconomy for the Southwest United States. [Display omitted] • Economic and life cycle assessment of guayule bagasse to products (fuel & pellets). • Guayule bagasse pellet production is more cost effective than pyrolysis. • Price of bagasse pyrolysis fuels could be lowered by reducing costs of bagasse and hydrogen. • Bagasse pyrolysis fuels have lower greenhouse gas emissions compared to fossil fuels. • Improved data from dual solvent extraction of bagasse would increase certainty of models. [ABSTRACT FROM AUTHOR]

Powerline carrier (PLC) communications have been heralded by the FCC as the "3rd wire" to every home, and have matured to the point of field trials and limited deployment. This paper examines the technology from a techno-economic perspective, factoring in regulatory issues and network design (focusing on the United States). Results indicate that PLC does not appear to represent a major disruptive technology, especially from a price-performance perspective. In addition, a baseline stochastic model created for the analysis shows that not only do competition and penetration matter, but locational distribution (i.e., how many consumers can share upstream equipment) is critical in determining PLC's competitiveness. [ABSTRACT FROM AUTHOR]

The widespread COVID-19 pandemic led to a shortage in the supply of N95 respirators in the United States until May 2021. In this study, we address the energy, environmental, and economic benefits of the decontamination-and-reuse of the N95 masks. Two popular decontamination methods, including dry heat and vapor hydrogen peroxide (VHP), are investigated in this study for their effective pathogen inactivation and favorable performance in preserving filtration efficiency and structural integrity of respirators. Two multiple reuse cases, under which the N95 masks are disinfected and used five times with the dry heat method and 20 times using the VHP method, are considered and compared with a single-use case. Compared to the single-use case, the dry heat-based multiple-use case reduces carbon footprint by 50% and cumulative energy demand (CED) by 17%, while the VHP-based case decreases carbon footprint by 67% and CED by 58%. The dry-heat-based and VHP-based multiple reuse cases also present environmental benefits in most of the other impact categories, primarily due to substituting new N95 respirators with decontaminated ones. Decontaminating and reusing respirators costs 77% and 89% less than the case of single-use and disposal. The sensitivity analysis results show that the geographical variation in the power grid and the times of respirator use are the most influential factors for carbon footprint and CED, respectively. The result also reaffirms the energy, environmental, and economic favorability of the decontamination and reuse of N95 respirators. [ABSTRACT FROM AUTHOR]

• Detailed cost estimation of advanced nuclear plants methodology extended to HTGRs. • Large HTGRs shown to have 32% overnight capital costs than recent LWRs. • The HC-HTGR reduced overnight capital costs 20% from large HTGR costs. • Discussion of required engineering of new systems for the HC-HTGR. • Low-carbon high temperature process heat in the range of $6.13–12.48/GJ. In 2018, nuclear energy generated 55% of United States' and one third of the world's carbon free electricity, making nuclear energy a key tool in efforts to mitigate climate change before 2050. However, the current nuclear technology, light water reactors (LWRs), is limited to 300°C, so it cannot be used to decarbonize industrial process heat which accounts for 12% of US greenhouse gas emissions. High temperature gas reactors (HTGRs) can meet the high temperature demand with carbon free nuclear heat. The estimated cost of HTGRs, such as the Next Generation Nuclear Plant (NGNP), are even higher than state-of-the-art LWRs. In this paper, we expanded our nuclear cost estimating tool to include HTGRs and find that the NGNP overnight capital costs were 32% higher than an advanced LWR per unit capacity. The higher cost will naturally result in larger risk to cost overrun as recently experienced by larger LWRs in western nations. With a design-to-build mindset to minimize cost and construction risk, we introduce the horizontal, compact HTGR (HC-HTGR). The reactor core and steam generator are mounted horizontally on rails and in-line with one another, decreasing the size of the reactor building relative to the power capacity four times when compared to traditional HTGRs. The HC-HTGR reduced overnight civil structure costs by 42%, indirect costs by 38%, and total capital costs by 20% from NGNP. We discussed the required engineering of new systems for the HC-HTGR including vessel supports, the reactor cavity cooling system, and steam generator design. Finally, we estimated the fuel and operations costs of the HC-HTGR, and a survey of low-carbon industrial process heat technology showed the HC-HTGR can deliver a highly competitive levelized cost of heat in the range of $6.13–12.48/GJ. [ABSTRACT FROM AUTHOR]

• A rate-based model for aqueous ammonia system is calibrated with experimental data. • Absorption columns for the ammonia-based carbon capture are designed. • A post-combustion capture plant is integrated with a coal-fired power plant. • Ammonia (amines)-based primary energy for carbon capture is lower (higher). • Cost of electricity is lower for ammonia-based than amine-based technology. Ammonia is a promising solvent for the chemical absorption of carbon dioxide owing to its characteristics of low toxicity, low degradation, low cost, and low heat of desorption. The present work evaluates the energy and economic performances of the aqueous ammonia technology applied to a coal-fired power plant. First, the kinetics of absorption are characterized in the Aspen Plus software and are calibrated against the experimental data from the Munmorah pilot plant. Then, the validated model is used for sizing the full-scale plant columns and for simulating the overall capture plant. After determining the sizes of the plant components and their energy consumptions, the capture plant is integrated with the coal-fired power plant, and the economic analysis is assessed with both retrofitted and green-field approaches as described in reports from the European Benchmarking Task Force and the United States National Energy Technology Laboratory, respectively. The novelties presented here are the new approach in the absorption reactions implemented in the rate-based model, which changes the dependency of the ammonia concentration in the absorption process, as well as the full economic analysis with both retrofitted and green-field assumptions, which enable a sound comparison of the outcomes. The results with the retrofitted approach compared with the monoethanolamine case of the European Benchmarking Task Force report returned higher electric efficiency (36.3% versus 33.50%), lower levelized cost of electricity (87.66 €/MWh el versus 92.27 €/MWh el), and lower cost of carbon dioxide avoided (47.03 €/ton CO2 versus 51.62 €/ton CO2). The results using the green-field approach compared against the Cansolv case of the National Energy Technology Laboratory report returned higher electric efficiency (33.06% versus 32.50%), lower cost of electricity (124.3 $/MWh el versus 133.2 $/MWh el) and lower cost of carbon dioxide avoided (66.5 $/ton CO2 versus 75.25 $/ton CO2). In both comparisons, aqueous ammonia had appreciably better performance than the ammine reference cases. [ABSTRACT FROM AUTHOR]