Cumulative Exergy Research Articles

Energetic, exergetic, and exergoeconomic analyses of beer wort production processes

Energy efficiency strategies in industrial breweries examine the inefficiency of thermal systems from a thermodynamic perspective. However, understanding the costs of inefficiencies in systems, including non-thermodynamic costs, requires exergoeconomics. This study examined wort production in a standard Tier-1 brewery from the tripod of energy, exergy, and exergoeconomics analyses to assess the performance of brewing sections and to pinpoint components that contributed the most to exergy destruction and product cost rate. The energy analyses for the production system showed that the total specific energy for processing 10.05 tons of brew grains to 346.98 hL high-gravity wort was (86 ± 1) MJ/hL at an operational energy efficiency of 30.35%. The exergetic analyses showed that the cumulative exergetic destruction was 3.2737 MW, with the brewhouse section contributing 89.25% of the system’s inefficiencies. Also, the analyses showed that the wort kettle (42.7911%), mash tun (10.8086%), preheater (10.0683%), whirlpool (8.3522%), and adjunct kettle (6.2705%) are the top five components with the highest rates of cumulative exergy destruction. The exergoeconomic analyses revealed that the cost rate of processing chilled wort was estimated to be 0.0681 USD/s per overall exergetic efficiency of 6.61%. The five most significant components are the wort kettle (53.70%), whirlpool (16.42%), mash filter (10.44%), mash tun (6.875%), and adjunct kettle (3.31%) based on the relative total cost increases for the production processes. Additionally, wet steam throttling resulted in a 2.51% increase in exergetic efficiency, a 1.60% drop in exergetic destruction rate, and a decrease in cost rates to 0.0675 USD/s.

Environmental impacts of drug products: The effect of the selection of production sites in the supply chain

The environmental impact of drug products is largely determined by activities beyond the direct control of pharmaceutical companies, such as outsourced production of pharmaceutical building blocks. Therefore, this study evaluates the environmental impacts of a prostate cancer drug packaged in one blister (declared unit), thereby analysing the whole value chain to gain insight into 1) the main contributors to the impact of drug product production and 2) the effect of the geographical location of production of solvents and pharmaceuticals. The carbon and resource footprints of the entire life cycle of the drug product are determined, using the IPCC GWP 100 and the Cumulative Exergy Extraction from the Natural Environment methods, respectively. Unlike many other studies, the impacts of building blocks, called intermediate pharmaceutical ingredients (IPIs), are modelled based on primary data, literature and similar processes. The carbon footprint per declared unit equals 34 kg CO2-eq, of which IPIs and active pharmaceutical ingredient (API) production account for 96 %. The resource footprint is 647 MJex/declared unit, with IPI and API production accounting for 93 %. The main impact contributors of these processes are solvents and electricity consumption. Four alternative scenarios for IPI and API production are developed to evaluate the geographical influence of different production locations of solvents and pharmaceuticals between Europe and China. European production of solvents and pharmaceuticals appears to have the lowest carbon and resource footprint. In contrast, Chinese production of solvents and pharmaceuticals increases the carbon footprint by 49 %, while the resource footprint increases by only 4 %, although the natural resource consumption shifts from abiotic renewable resources and nuclear energy to fossil fuels. The high contribution of IPI production and the influence of geography of the supply chain highlight the need for accurate data from external suppliers to fairly estimate the environmental footprint of drug products.

Enhanced thermally integrated Carnot battery using low-GWP working fluid pair: Multi-aspect analysis and multi-scale optimization

Thermally integrated Carnot battery (TICB) emerges as a promising technology for long-duration energy storage. This study aims to improve its multi-dimensional performance from the optimization design level, thereby promoting its competitiveness. Firstly, a refined system architecture is developed, integrating subsystem layout modification and advanced thermal integration mode. Sixteen potential working fluid pairs are formed by screening low-GWP refrigerants as drop-in substitutes for R245fa. Then, a comprehensive evaluation framework is established to characterize this technology from energy, exergy, and economic perspectives, and a collaborative optimization method is introduced to facilitate integrated optimization. Finally, a whole cycle cumulative exergy analysis is conducted to explore directions for further improvement. Results indicate that, compared to the basic architecture, the round-trip efficiency (RTE) of the proposed system is elevated by over 30%. The use of different alternative refrigerants in the charging and discharging cycles makes the TICB not only sustainable but also more efficient. The thermodynamic dilemma of determining the heat pump evaporation temperature disappears with a closed-type heat source. To maximize overall thermo-economics, sufficient heat pump subcooling and evaporator internal superheat are necessary, and the ideal storage temperature span and pinch point temperature difference of heat exchangers must be identified. The collaborative optimization displays that the first-rank working fluid pair is R1234ze(Z)-R1224yd(Z), with an RTE of 85.2%, a volumetric energy density of 3.10 kWh/m3, and a levelized cost of storage of 0.303 $/kWh, respectively. Furthermore, the RTE is highly sensitive to the insulation quality of storage tanks. A mere 2.5% performance degradation can lead to a 10% points decline in RTE. Internal exergy destruction is primarily caused by poor heat transfer matching, while external exergy loss mainly results from underutilized heat sources during non-charging periods. Therefore, we recommend the district heating network as the target heat source for the dual-period TICB. These achievements offer a valuable reference for the research and development of efficient, affordable, and sustainable TICB.

Analyzing sustainability in bread production: a life cycle assessment approach to energy, exergy and environmental footprint.

Bread production is a pivotal component of global nutrition. However, its extensive production imposes significant strain on resources and energy, resulting in substantial environmental consequences. This study focuses on a multidimensional assessment of the environmental sustainability of the bread life cycle as a case study in Iran. By integrating four life cycle assessment (LCA) methods, this research demonstrates a comprehensive analysis of environmental effects, energy consumption, and exergy demand in bread production. It also identifies the hotspot stages and inputs within the bread production chain. Eventually, it proposes strategies for mitigating the environmental impacts in line with sustainable development goals. Data collection involved questionnaires by face-to-face interviews. The LCA evaluation was conducted using SimaPro software. Sustainability analysis was assessed using four different methods: CML, ReCiPe, cumulative energy demand (CED), and cumulative exergy demand (CExD) method, from cradle to bakery gate. The CML method results indicate that the highest environmental impacts are associated with marine aquatic ecotoxicity (157.04 to 193.36 kg 1,4-DB eq), fossil fuel depletion (11.05 to 12.73 MJ), eutrophication (4.20 × 10-3 to 4.70 × 10-3 kg PO4-3eq), acidification (8.09 × 10-3 to 9.16 × 10-3 kg SO2 eq), and global warming (0.61 to 0.69 kg CO2 eq). The ReCiPe method highlights wheat production stages and gas consumption as the most significant contributors to damage in terms of human health, ecosystems, and resource consumption indicators. The CED method reveals that fossil energy accounts for over 97% of the energy consumed during the bread life cycle. Energy consumption per kilogram of bread ranges from 12.07 to 13.93 MJ. The CExD method for producing 1 kg of traditional bread falls between 32.25 and 35.88 MJ. More than 60% of this value is attributed to renewable resources of water used in irrigation during the wheat farming stage, while over 35% is linked to non-renewable fossil resources, primarily due to the consumption of natural gas in bakery operations. To assess the potential decrease in environmental emissions, a sensitivity analysis was performed, considering the effects of substituting natural gas with biogas and grid electricity with photovoltaic electricity in the bakery. Then, three improved scenarios were developed, each demonstrating effective reductions in environmental impacts, with the most remarkable decreases observed in marine aquatic ecotoxicity (55%) and fossil fuel depletion (44%). Overall, the findings demonstrate that Sangak bread production exhibits a more environmentally friendly profile than other types of bread. These results can guide decision-makers in the bread production industry towards implementing sustainable practices that prioritize resource efficiency and environmental conservation. Also, stakeholders can develop strategies to reduce the environmental impacts and work towards a more sustainable future.

Exergy-water nexus of a multi-energy complementary trigeneration system with different fuel mixture ratios

Complex coupling relationships of energy, exergy and water streams in multi-energy complementary systems due to different characteristics of energy flows are necessarily revealed to determine the intensities of downstream products. This paper proposes a multi-energy complementary trigeneration system driven by biomass, solar energy, and natural gas to generate cooling, heating, and power products. An exergy-water analysis approach, considering energy levels of streams, is adopted to determine the exergy and water footprint intensities per unit energy products. A life cycle assessment method is used to calculate the water footprint of biomass and natural gas as the primary energy sources. The relationship between the exergy and water footprint intensity of the system equipment and output products is presented and discussed with the mixture ratios of natural gas and biomass product gas. Furthermore, the cumulative exergy and water footprint intensity of products are analyzed under different system working conditions, such as mixture ratio of biomass and natural gas and the solar irradiance. When the same mixture volume gas fuels drive the trigeneration system, the overall exergy efficiency is 25.38 % while the efficiency including the upstream cumulative exergy destruction is only 21.93 %. The unit water footprint intensities of power and cooling products based on exergy measurement are 7.12 kg/kWh and 36.32 kg/kWh, respectively. The exergy-water footprint sensitivity of biomass and natural gas on system product intensities are implemented to consider the uncertain variables. When the mixture ratio increases from 0 to 1, the cumulative exergy destruction of system power is declined by 35.62 % under the uncertain ranges of ±50 %. Also, its water footprint is declined by 91.62 %. The proposed model provides an effective tool to reveal the exergy-water nexus and determine the intensities of multi-energy products.

Exergetic life cycle assessment for green hydrogen production

Life cycle assessment (LCA) is a method for assessing the environmental impacts of products and processes. The life cycle inventory provides a measure of the quantitative throughput of a process, but it cannot measure the intrinsic quality of that throughput. Exergy is a measure of the quantity and quality of energy. When combining LCA and exergy analysis in an exergy-based life cycle assessment (ExLCA) a powerful tool for the quantification of resource efficiency can be established. This study performs a detailed bottom-up cradle-to-grave ExLCA based on cumulative exergy consumption and exergy analysis of the use phase for a state-of-the-art (SoA) and a future plant 5 MW proton exchange membrane (PEM) electrolyzer plant. Three scenarios are implemented, i.e. SoA plant operated in the German grid mix of 2018, SoA plant operated in a defossilized grid, and a future plant operated in a defossilized grid. In every scenario, more than 98 % of the resource demand originates from electricity generation alone and decreases significantly with renewable electricity operation. In plant construction, the anode catalyst material iridium causes approximately half of the resource demand and bears the largest lever for the resource reduction potential of the plant construction of 65 %.

Comparative exergy and economic analysis of deep in-situ gasification based coal-to-hydrogen with carbon capture and alternative routes

The deep in-situ gasification based coal-to-hydrogen (deep IGCtH) is attracting attention for its unique advantage in utilizing unrecoverable coal seam. In this paper, its improvement scope in energy conversion and utilization is analyzed using advanced exergy analysis, and the efficiency from cumulative exergy consumption (CExC) perspective and economic competitiveness with Lurgi surface gasification based coal-to-hydrogen (Lurgi SGCtH), coke-oven gas-to-hydrogen (COGtH) and natural gas-to-hydrogen (NGtH) are compared. Results indicate 39.9 % and 25.1 % of the exergy destruction of deep IGCtH and Lurgi SGCtH are unavoidable, while steam methane reforming and coal gasification possess the largest improvable potential, with avoidable endogenous/exogenous destruction of 96.63 MW/81.58 MW and 162.52 MW/151.19 MW, suggesting thermodynamic improvement can also be achieved by improving other components or optimizing process structure in addition to increasing its own efficiency. The CExC of deep IGCtH outputting 1 kg hydrogen is only 83.6 % that of Lurgi SGCtH, indicating it is more efficient route with significantly energy consumption reduction and can better demonstrate its efficiency advantage under large production capacity condition. The deep IGCtH shows only 68.7 % that of Lurgi SGCtH in investment and also presents significant advantage in cost. However, its profitability advantage over NGtH loses with hydrogen price increasing and there exists lower limit on capacity of 0.46 billion Nm3 to maintain cost and profitability competitiveness over COGtH. Furthermore, deep IGCtH shows emission reduction cost advantage over Lurgi SGCtH when capture rate exceeds 80 %, and profitability will not be limited by carbon tax and coal seam thickness within the considered range.

Environmental sustainability assessment of biodegradable bio-based poly(3-hydroxybutyrate-co-3-hydroxyvalerate) from agro-residues: Production and end-of-life scenarios

In the context of a circular bio-based economy, more public attention has been paid to the environmental sustainability of biodegradable bio-based plastics, particularly plastics produced using emerging biotechnologies, e.g. poly(3-hydroxybutyrate-co-3-hydroxyvalerate) or PHBV. However, this has not been thoroughly investigated in the literature. Therefore, this study aimed to address three aspects regarding the environmental impact of PHBV-based plastic: (i) the potential environmental benefits of scaling up pellet production from pilot to industrial scale and the environmental hotspots at each scale, (ii) the most favourable end-of-life (EOL) scenario for PHBV, and (iii) the environmental performance of PHBV compared to benchmark materials considering both the pellet production and EOL stages. Life cycle assessment (LCA) was implemented using Cumulative Exergy Extraction from the Natural Environment (CEENE) and Environmental Footprint (EF) methods. The results show that, firstly, when upscaling the PHBV pellet production from pilot to industrial scale, a significant environmental benefit can be achieved by reducing electricity and nutrient usage, together with the implementation of better practices such as recycling effluent for diluting feedstock. Moreover, from the circularity perspective, mechanical recycling might be the most favourable EOL scenario for short-life PHBV-based products, using the carbon neutrality approach, as the material remains recycled and hence environmental credits are achieved by substituting recyclates for virgin raw materials. Lastly, PHBV can be environmentally beneficial equal to or even to some extent greater than common bio- and fossil-based plastics produced with well-established technologies. Besides methodological choices, feedstock source and technology specifications (e.g. pure or mixed microbial cultures) were also identified as significant factors contributing to the variations in LCA of (bio)plastics; therefore, transparency in reporting these factors, along with consistency in implementing the methodologies, is crucial for conducting a meaningful comparative LCA.

EN Optimization strategy for system management of cold thermal energy storage (CTES) in conditions of dynamic changes in energy carrier value

In world of contemporary challenges involving the continual increase in demand for energy resources and corresponding environmental pollution, the necessity has arisen to develop and implement advanced technologies to reduce energy consumption. This calls for enhancing energy utilization efficiency and optimizing energy generation systems, taking into account the utilization of alternative and renewable energy sources. Specifically, thermal energy storage becomes crucial as an effective economic option. Thermal energy storage systems enable meeting heating or cooling needs during optimal periods when it is more energy-efficient. Traditional management methods rarely prove optimal due to fluctuating electricity tariffs, cooling loads, and ambient temperature. This leads to suboptimal achievement of maximum savings in the utilization of thermal energy storage systems. In this work, the advantages of Cold Thermal Energy Storage (CTES) systems based on Ice Thermal Energy Storage (ITES) were analysed alongside existing management strategies implemented in most enterprises and buildings utilizing ITES. A simplified engineering methodology for analysing the thermodynamic efficiency of CTES was proposed. It was determined that cold losses during exergy analysis during storage are caused by both losses through surfaces and internal exergy losses (i.e., exergy consumption due to irreversibility within the reservoir). For modern systems, exergy losses encompass both external and internal components. As an example, if the heat transfer at the external surface temperature of the storage reservoir equals the ambient temperature, external exergy losses would be zero, while total exergy losses would be entirely due to internal consumption. Conversely, if heat transfer occurs at the liquid's temperature for storage, a greater portion of exergy losses will be due to external losses. In all cases, the cumulative exergy losses, comprising internal and external exergy losses, remain constant. The implementation of CTES allows for shifting the use of electrical energy from peak to off-peak hours. During off-peak hours, electrical energy is used to charge the storage to fulfil (fully or partially) the peak demand for refrigeration equipment. Ice-based ITES has the potential to reduce maximum energy consumption, peak demand, and most importantly, the average cost of energy consumed

Evaluating ecological sustainability of mechanized and traditional systems of damaskrose production using extended exergy analysis

Environmental resource efficiency is a major challenge in the management of agroecosystems and their sustainability. The Extended Exergy Analysis (EEA) is a novel approach that assesses the total amount of resources extracted from the environment to produce agroecosystem products. This study applied the EEA to compare the sustainable development of Damask rose flower production in two mechanized and traditional systems in Nehbandan County, South Khorasan province, using the data of 2021–2022. The EEA calculated the flows of labor, capital, and environmental costs in the systems based on the first and second thermodynamic laws. The results showed that the traditional system had lower cumulative exergy consumption (CExC) and environmental modification cost than the mechanized system, indicating higher ecological sustainability. The extended exergy indices, such as the special capital conversion of energy and material input (kcap), the special capital conversion of product sale (KCAPEEA), extended exergy cost (eec) and the cumulative degree of perfection (CDP), also revealed that the traditional system was more cost-effective, economical, technologically efficient, and closer to the optimal conditions than the mechanized system. To achieve a sustainable agricultural crop production system, new patterns and models for selecting inputs and reducing environmental costs are recommended.

Comparison of the cumulative exergy demand of phase change and reverse osmosis desalination plants with environmental impacts approach

In the scope of the current study, an investigation into the cumulative exergy demand index was conducted for freshwater production across multiple distillation technologies. These technologies encompassed Waterfall Cascading Distillation with Linear Parabolic Solar Concentrator (WCDLPC), Distillation with Linear Parabolic Concentrator and Vacuum Pump (DLPCVP), Distillation with Stand-Alone Point-Focus Parabolic Solar Concentrator (DSPPC), Reverse Osmosis with Non-renewable Energy (RONRE), and Reverse Osmosis with Solar Renewable Energy (ROSRE).The functional unit was established as the production of one ton of freshwater using various desalination technologies. The Outcomes of the analysis pertaining to the cumulative exergy demand in diverse saline water desalination technologies revealed notable findings. Specifically, in the Reverse Osmosis Desalination System with the Conventional System as well as in other desalination technologies (ROSR, WCDLP, DLPCVP and DSPPC), the electricity factor and the photovoltaic panel factor respectively exhibited the most substantial contributions to the cumulative exergy demand. Remarkably, it was observed that the RONRE technology exhibited the highest cumulative exergy demand, reaching 107.04 MJ, while the ROSRE technology demonstrated the lowest demand at 5.98 MJ. Furthermore, the integration of renewable solar energy in lieu of non-renewable electricity within the reverse osmosis technology exhibited a remarkable reduction in cumulative exergy demand, achieving a reduction of 17.90 times. Similarly, the substitution of the waterfall cascade system with a vacuum system in the WCDLPC technology resulted in a 2.69 times reduction in cumulative exergy demand.

An innovative renewable energy–based tri-generation system for electricity, LNG regasification and hydrogen production

Waste incineration is a potent technique, that deals with the waste generated in a sustainable way to properly manage and reduce the generated waste and produce useful energy simultaneously. However, the waste-to-electrical efficiency of incineration plants is less (20–22) % because of the high moisture content of waste and flue gas heat losses. In the present study, a tri-generation system consisting of a solar parabolic trough collector integrated with a waste-to-energy plant, a liquefied natural gas (LNG), and a hydrogen production system is proposed and thermodynamically investigated. Parabolic trough collectors serve as a secondary heating source to the steam coming out of the incineration boiler. The useful heat collected by the parabolic trough solar field is provided to the fluid exiting the incineration boiler and entering into the steam turbine to improve the steam condition, while LNG is vaporized by the energy of exhaust flue gas and produces power for the PEM electrolyzer. Waste-to-energy incineration facility is capable of operating with a feed rate of 350 tons/day, producing 6.3 MW of power at an inlet temperature of 400 °C of the turbine. However, the net power produced is increased to 7.72 MW with increase in turbine inlet temperature to 515 °C. Results of the study conclude that the energetic and the exergetic efficiencies of the incineration plant are found to be 27.93 % and 26.51 %, respectively. In addition, both the first and second law efficiencies are observed as 21.51 % and 25.74 %, respectively, while the rate of hydrogen production is 7.72 kg/h. The cumulative exergy destruction rate of the system is 29.3 MW and the WtE boiler shares the maximum portion (58.14 %) of the exergy destruction.

Environmental damages, cumulative exergy demand, and economic assessment of Panus giganteus farming with the application of solar technology

The use of photovoltaic (PV) technology in agricultural production can mitigate the environmental impacts of mushroom farming. However, changes in the environmental impacts and economic benefits of the application of PV technology are still unclear. Thus, we evaluated the environmental impacts, energy flow, and economic aspects of mushroom (Panus giganteus) farming systems without solar PV (WS) technology and with PV technology from the generation of substrate materials through harvesting. In addition to a 27 % increase in terrestrial ecotoxicity, P. giganteus farming with PV technology reduced all impact categories by 4–60 %, with a 60 % reduction in CO2 emissions and a 25 % reduction in land resources. These findings highlight the importance of combining PV technology with mushroom farming in agricultural carbon reduction and the efficient use of land resources. In terms of the climate change impact, the PV system reduced CO2 emissions by 2.94 kg CO2 eq./kg of mushrooms compared with the WS system, wherein the aspects of substrate transformation, spawn running, and cultivation were reduced by 78.27–89.91 %. The cumulative exergy demand (CExD) analysis showed that P. giganteus farming combined with PV technology reduced the total CExD by 48 %. With the application of PV technology, the top contributor to the total CExD of mushroom farming shifted from electricity to transportation throughout the supply chain. The PV system reduced costs by 22.09 % and increased the total revenue by 22 % and the cost-benefit ratio by 50 %. Halving the transportation distances of substrate materials and performing localized substitution of wood chips resulted in a 3–34 % reduction in the environmental impacts category and a 23–30 % reduction in nonrenewable fossil energy consumption. These results showed that improvements helped optimize the environmental performance in terms of carbon reduction and energy mixing. Thus, combining PV technology with greenhouse mushroom farming can improve trends in energy and environmental damage.

Measuring the symbiotic performance of single entities within networks using an LCA approach

This paper introduces the Symbiotic Performance Indicator, a novel indicator aiming to quantify the environmental benefits generated by by-product exchanges in an industrial symbiosis network. Despite the significant advancements in assessing industrial symbiosis, the lack of indicators for individual entities involved in by-product exchanges hinders a comprehensive understanding of its environmental benefits. This indicator accounts for resource use and greenhouse gas emissions using a life cycle perspective. The resource use is measured using the Cumulative Exergy Extraction from the Natural Environment method, while greenhouse gas emissions are evaluated using the IPCC 2013 Global Warming Potential (100a) method. The use of this indicator is illustrated in a real case study where plastic waste is exchanged among three entities in Mendoza (Argentina). The overall results show that resource use and greenhouse gas emissions can be reduced by 19% and 15%, respectively. Full and partial allocation methods are proposed within the formulation of the Symbiotic Performance Indicator. The indicator results show that the exchange of materials may seem less attractive when using full allocation methods, as one entity gets 100% of the benefits from the by-product exchange compared to the other. Partial allocations make the by-product exchange convenient for both entities which may encourage collaboration. In conclusion, the proposed indicator helps account more precisely for individual environmental benefits behind by-product exchanges, and thus enables better decision-making to set up an industrial symbiosis network.

Assessing resource depletion of NCM lithium-ion battery production for electric vehicles: An exergy-based perspective

Electric vehicles (EVs) play an important role in the low-carbon transition of transportation, and lithium-ion battery (LIB) is a key component of EVs. Because of the high demand for energy and critical metals for LIB production, it is necessary to quantify the associated resource consumption intensity from multiple perspectives. In the present study, the exergy derived from the second law of thermodynamics was applied to assess the abiotic resource depletion associated with lithium nickel cobalt manganate (NCM) battery production, including NCM111, NCM523, NCM622, and NCM811. For comparability of results, the functional unit was defined as 1 kWh NCM power pack. The results showed that the cumulative exergy demand (CExD) value of the NCM523 pack production is 2857.56 MJ/kWh, with the cathode material manufacturing process accounting for 56.77% because of the significant contribution of CoSO4. The CExD of battery production can be effectively reduced by reducing cobalt use and adding a solvent recovery device. The supply stage of upstream raw and auxiliary materials is the key to CExD reduction. The comparison results indicated a significant reduction in the CExD of Ni-rich NCM batteries due to improvement in energy density and reduction in cobalt demand. In addition, the comparison of abiotic resource depletion characterization results and method characteristics among the CExD, ReCiPe, and CML-IA methods showed that using CExD has clear advantages with regard to objectivity and long-term stability in the evaluation of rapidly innovated battery products. Applying exergy-based accounting methods for resources contributes to a scientific understanding of abiotic depletion levels and improves resource efficiency in the relevant industries.

Production of chemicals and utilities in-house improves the environmental sustainability of phytoplankton-based biorefinery

Life cycle assessment was used to evaluate the environmental impacts of phytoplanktonic biofuels as possible sustainable alternatives to fossil fuels. Three scenarios were examined for converting planktonic biomass into higher-value commodities and energy streams using the alga Scenedesmus sp. and the cyanobacterium Arthrospira sp. as the species of interest. The first scenario (Sc-1) involved the production of biodiesel and glycerol from the planktonic biomass. In the second scenario (Sc-2), biodiesel and glycerol were generated from the planktonic biomass, and biogas was produced from the residual biomass. The process also involved using a catalyst derived from snail shells for biodiesel production. The third scenario (Sc-3) was similar to Sc-2 but converted CO2 from the biogas upgrading to methanol, which was then used in synthesizing biodiesel. The results indicated that Sc-2 and Sc-3 had a reduced potential (up to 60 % less) for damaging human health compared to Sc-1. Sc-2 and Sc-3 had up to 61 % less environmental impact than Sc-1. Sc-2 and Sc-3 reduced the total cumulative exergy demand by up to 44 % compared to Sc-1. In conclusion, producing chemicals and utilities within the biorefinery could significantly improve environmental sustainability, reduce waste, and diversify revenue streams.

Ecological accounting of the Chinese society 2012–2020 based on extended exergy

China's social system has undergone unprecedented economic transformation in the past decade. It is essential that the relationship between the country's socio-economic development and natural ecosystem be revealed, thereby revealing the evolutionary trajectory of its biophysical sustainability. The extended exergy accounting (EEA) method offers a thermodynamics-based tool to evaluate the structure and function of a social system and objectively estimate the impacts of human activities on sustainable development and broader ecosystems. This study aims to perform extended exergy analysis to trace the flows of resources, labor, capital, and environmental remediation exegetics in China's society from 2012 to 2020. During the accounting period, the average annual growth rate of total extended exergy (TEE) was just 1.2%. The TEE in the conversion and tertiary sectors ew noticeably faster than those in other sub-sectors, while the TEE in the extraction and agriculture sectors showed a declining trend. The TEE in 2020 reached 764.50 EJ, of which 179.13 EJ were attributed to Cumulative Exergy Consumption, 74.89 EJ were attributed to labor, 68.85 EJ to capital, and 441.63 EJ to environmental remediation costs. The indicator assessment reflects an enhancement in the sustainability of the Chinese social system, particularly the rapid improvement in labor and capital-related indicators. Comparing the results with other countries demonstrates that the gap between China and developed nations has narrowed, with China's indicators for balancing resource production and capital flows rivaling those of the U.S. and the U.K. The objective revelation of the developmental and transitional trajectory of Chinese society, based on the EEA approach, provides valuable insights for other developing countries in achieving sustainable development.

Co-simulation-based conventional exergy evaluation of a hybrid energy generation-vanadium redox flow battery-air source heat pump system

A conventional exergy assessment approach permits determining the magnitudes of irreversibility that have happened within the investigated system components, which indicates the potential for improvement for these components. In this study, this approach was applied to a hybrid powered air source heat pump with vanadium redox flow battery system through co-simulated (solar photovoltaic and wind turbine) TRNSYS integrated with MATLAB Simulink) work. Due to the absence of a sophisticated VRFB model in the TRNSYS application, the battery model created in the Matlab Simulink environment was utilized and then summoned into the TRNSYS simulation studio by use of the TRNSYS utility model.Exergy destruction and exergy efficiency were used as performance criteria for evaluating the conventional exergy performance of the utilized components in the established co-simulation model. While yearly cumulative exergy destruction values ranged from 194.2 kWh for R to 23318.2 kWh for the PV field, annual average exergy efficiency amounts varied between 0.0494 for ASHP and 0.9345 for R. The PV field with the highest exergy destruction and relatively low exergy efficiency causing the highest improvement priority, but the opposite is true for power conditioning equipment, specifically IR and R.

Cradle to gate environmental impact assessment of the Iranian forestry operations

This study conducts the first cradle-to-gate life cycle assessment (LCA) study on forestry operations in Iran and provides comprehensive regionalized life cycle inventory (LCI) data on the Iranian forest sector. This LCA employs midpoint and endpoint impact categories based on the IMPACT 2002+ method in addition to the cumulative exergy demand (CExD) indicator. The results of this study show that fuel consumption in harvesting machinery and fertilizer application in reforestation are two sources of direct emissions that contribute to different environmental impact categories. Transportation is the main hotspot in most midpoint environmental impact categories, such as global warming, or endpoint categories, such as human health. The total exergy removed from nature to produce 1 t of wood as logs is about 978 MJ-eq, accounting for 7.7% of the energy content in 1 t of wood. The global warming impact category equals 58 kg CO2-eq or 5.4% of the total CO2-eq contained in 1 t of wood as logs. The environmental performance of the system could be improved by expanding local clients rather than clients from other regions and upgrading inefficient machinery. Gains are also possible by conducting a comparative LCA analysis of different adaptable forest management strategies and harvesting methods compared to the business-as-usual approach in the Iranian forestry sector.

Life cycle assessment, life cycle cost, and exergoeconomic analysis of different tillage systems in safflower production by micronutrients

In recent decades, one of the biggest challenges facing agriculture has been sustainability. To achieve sustainability goals, it is necessary to consider the compatibility of environmental, economic, and energy aspects. The main aim of this study is to conduct an environmental-economic-exergy assessment of safflower production under different tillage systems with Zn and Fe micronutrients using life cycle cost (LCC), life cycle assessment (LCA), and exergoeconomic analysis. For this purpose, three scenarios are evaluated: conventional tillage (Sc-CT), reduced tillage (Sc-RT), and no-tillage setup (Sc-NT). The LCA method ReCiPe2016 is used to assess environmental impacts based on one ton of safflower seeds as a functional unit. In addition, the emissions social cost (ESC) is considered as a hidden part of LCC in safflower production. Finally, a combination of cumulative exergy demand and net profit is used to compute an exergoeconomic index in agriculture as a novelty. Results indicate that On-Farm emissions derived from nitrogen and diesel fuel are the most significant contributor, accounting for over 50% of the impact on human health and ecosystems. Sc-RT with 62.62 Pt and Sc-NT with 71.66 Pt are the best and worst LCA scenarios of this study. Sc-CT has the highest ESC, with 51.14 $, and Sc-NT has the lowest LCC, with 380.39 $. Exergy results show that nitrogen fertilizer has the largest share of cumulative exergy demand, and Sc-RT, with 0.073 $ MJ−1, is the best scenario from an exergoeconomic perspective. In summary, Sc-RT, Sc-CT, and Sc-NT are ranked first, second, and third, respectively, from an environmental-economic-exergy-friendly point of view.