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Coelastrella microalgae have gained attention due to their robustness, high lipid content, effective bioremediation agent, and ability to thrive in diverse environmental conditions. The objective of this study was to evaluate the economic feasibility of an integrated biorefinery of the unique original Coelastrella striolata var. multistriata strain 047 applied in agro-industrial wastewater, flue gases, and excess energy on a 1.2 ha open raceway pond (ORP). This study consists of three scenarios: (1) biocrude only (BO); (2) biocrude and biogas (BB); and (3) biocrude, biogas, and fertilizer (BBF). The findings indicated that the BB and BBF scenarios enhanced the financial feasibility and potential profitability of investment. This is reflected in the economic feasibility indicators for the BB scenario over a project lifetime of 20 years, which include a net present value (NPV) of $4,757,082, an internal rate of return (IRR) of 25.6%, a profitability index (PI) of 2.77, and a payback period of 3.75 years. Similarly, in the BBF scenario, financial viability is demonstrated with an NPV of $4,714,418, an IRR of 25.2%, a PI of 2.73, and a payback period of 3.79 years. Operational expenditures were identified as the most sensitive aspect of this study, particularly in the hydrothermal liquefaction (HTL) process for biocrude production. The utilization of effluent and excess energy from palm oil mill (POM) reduced the operational costs for energy and nutrients by up to 69% compared to the baseline, where palm oil mill effluent (POME) and excess energy were not utilized. Additionally, to achieve optimal results in the BO scenario, increasing the concentration of Coelastrella striolata var. multistriata strain 047 in POME proved to be the most effective approach for increasing biocrude oil production, reducing costs, and increasing economic sustainability. [ABSTRACT FROM AUTHOR]

Micro gas turbines ranging from 3 to 200 kW are vital for decentralized power generation due to their reliability, rapid load response, and adaptability to 100% hydrogen and hydrogen fuel blends. This paper conducts a techno-economic assessment of MGTs powered by hydrogen, focusing on their environmental, economic, and technical viability. Key factors include the transition from natural gas to hydrogen to achieve net-zero emissions and enhance grid stability. Despite hydrogen's higher initial costs, its declining production costs and cleaner combustion make it a promising alternative. The study utilizes five micro gas turbine models (3, 30, 65, 100, and 200 kW) to evaluate a techno-economic analysis using 100% hydrogen, a 30% hydrogen and 70% natural gas blend, and 100% natural gas as fuels. Technical results are supported by experimental data from the world's first 100% hydrogen-fired micro gas turbine unit in Stavanger, Norway. Standard cost estimations for capital, operation and maintenance, and fuel costs are provided. The study introduces a novel technique for cost estimation and assesses econometric indicators such as net present value, internal rate of return, return on investment, payback period, and cost-benefit analysis. It compares economic scenarios for 2024, 2030, and 2040, highlighting the impact of fuel price volatility and regulatory changes on micro gas turbine techno-economics. Micro gas turbines are ranked using the Technique for Order Preference by Similarity to Ideal Solution-Multi-Criteria Decision Making (TOPSIS-MCDM) method based on their techno-economic performance. The ranking of microturbines based on techno-economic analysis performance is a novel contribution of this paper. Finally, a sensitivity analysis on the five micro gas turbines is carried out by changing the hydrogen fuel price. This research provides a comprehensive framework for stakeholders to make informed investment decisions, ensuring a smooth transition to 100% hydrogen-based power generation. The findings support the adoption of hydrogen and natural gas blends as an interim solution towards achieving a hydrogen economy. • Comprehensive thermodynamic and economical modelling of MGTs utilizing H 2 and H 2 blends as fuel. • Novel, structured techno-economic analysis methodology proposed for 100% H 2 and H 2 fuel blend based MGTs. • Fleet of MGTs ranked (1st, 2nd .... nth) according to techno-economic performance utilizing MCDM-TOPSIS technique. • H 2 powered MGT techno-economy for year 2030 and year 2040 scenario assessment and comparison with year 2024. • Sensitivity analysis of MGTs with H 2 economy and their prominent effects. [ABSTRACT FROM AUTHOR]

The design and construction of a self-sustained solar photo-voltaic active thermal heating floating dome biogas plant (35 m3) offers an alternative solution for round year biogas production, managing food and agricultural waste, reducing greenhouse gas emissions and minimize pollution. Moreover, this proposed model addresses the challenge of achieving the desired operating temperature (35 ± 2 °C) specially during the cold climatic conditions, which often leads to low gas production and high hydraulic retention time in anaerobic digestion. The integration of solar modules with the biogas digester enables the utilization of thermal energy for slurry heating and electricity for force mode of operation, ultimately enhancing overall energy efficiency. However, to assess the performance of the system, proximate and ultimate analyses as well as a cost-benefit analysis were carried out, considering revenue, and costs associated with construction, operation, and maintenance. The plant produces a significant amount of gas (9–12 m3) and hot water (∼2000 L) replacing approximately one LPG cylinder/2 day as well as organic fertilizer. The economic analysis shows a positive net present value (19.5 lakhs), an internal rate of return (20%), and short discounted payback period (5.7 years). This highlights the economic feasibility of the proposed model and emphasizes the importance of considering economic factors in the design and implementation of sustainable energy solutions. Furthermore, this approach demonstrates the potential for sustainable development and the transition to cleaner and more efficient energy systems by integrating renewable energy generation, waste management, and cost reductions. [Display omitted] • Developed a self-sustained floating dome biogas plant integrated with solar panels. • Integrated system yields round year biogas production, thermal energy, and manure. • Significant (P < 0.05) biogas production was observed during fourth week (19.25%). • Payback period (4.8 yrs), NPV (1.9 million) and IRR (20%) have been recorded. • Due to high retention time, this hybrid system is suitable for colder climates. [ABSTRACT FROM AUTHOR]

Dairy manure (DM) contributes significantly to greenhouse gas emissions and ecosystem degradation, yet its resistance to biodegradation hinders widespread bioprocessing applications. Lignocellulosic materials in DM pose a particular challenge because of their recalcitrance. Bioprocessing under hyperthermophilic (≥70 °C) conditions potentially offers an advantage over traditional fermentation temperatures due to enhanced activity of enzymes and the kinetics of enzymatic reactions. This can lead to a higher conversion rate and a greater extent of biomass hydrolysis and acidification. To test the validity of this hypothesis, the current study evaluated the efficacy of anaerobic hydrolysis and acidogenic fermentation of DM under mesophilic, thermophilic, and hyperthermophilic conditions. All inocula were adapted to corresponding temperatures but were derived from the same mesophilic source. Hyperthermophilic conditions resulted in superior DM hydrolysis efficiency (53%) compared to mesophilic (34%) and thermophilic (42%) conditions. The hyperthermophilic environment was particularly favorable to the decomposition of crude proteins and hemicellulose, which were reduced by 64% and 54%, respectively. Furthermore, hyperthermophilic fermentation also yielded the highest volatile fatty acid (VFA) production rate of 460 mg/L/day during the first four days, representing improvements of 50% and 90% over mesophilic and thermophilic conditions. In part, this was attributed to the enhanced production of branched-chain VFAs, including an increase of 6–10% in isobutyric acid and 12–13% in isovaleric acid. At hyperthermophilic conditions, however, there was no accumulation of VFAs during the days 5–8 of fermentation, which could be due to acetate conversion by the syntrophic acetate-oxidizing bacteria. A considerable gain in hydrolysis efficiency and VFA production rate were accompanied by a reduction in microbial diversity, which suggests that hyperthermophilic temperature is a favorable environment for the selection of organisms with enhanced DM hydrolysis and fermentation capabilities. A significantly increased relative abundance of xylanolytic Caldicoprobacter (23% of population) and proteolytic Thermovirga (9% of population) could be the major contributors to improved decomposition of hemicellulose and protein. As revealed by the techno-economic analysis, acidogenic fermentation of DM at 70 °C and a retention period of 4 days provides the greatest positive net present value, highest internal rate of return of 9.2%, and shortest investment payback period of 9 years. This study demonstrates that hyperthermophilic conditions enable superior deconstruction and bioconversion of lignocellulose-containing biomass into VFAs under reduced retention times, offering a promising approach for improving DM management and generating bioproducts. [Display omitted] • Hyperthermophilic community had superior capability for proteins, cellulose and hemicellulose hydrolysis. • Hyperthermophilic community improved VFAs production rate during the first 4 days. • Considerable amount of branched-chain fatty acids was generated under HT temperatures. • Proteolytic Thermovirga and xylanolytic Caldicoprobacter dominated under hyperthermophilic temperature. [ABSTRACT FROM AUTHOR]

This study introduces a new regional feed-in tariff (FIT) pricing mechanism for solar photovoltaic (PV) energy in China, informed by real option (RO) theory and incorporating the increasing significance of tradable green certificate (TGC) policy revenues. The mechanism aims to balance government and consumer burdens with investor benefits. By factoring in additional income from green certificate sales, the study calculates the internal rate of return (IRR) to fall between 8 and 16% and uses a Monte Carlo simulation to determine optimal FITs for 30 Chinese provinces. These optimal FITs are then compared with current FITs, which are categorized by three types of solar resource regions, revealing that many current FITs are set within an inappropriate range and require adjustment. Additionally, the study observes minor differences in provincial FITs within six regional power grids, suggesting that setting FIT guide prices at the regional grid level is more practical than by solar resource regions. A sensitivity analysis examines the impact of green certificate prices, carbon prices, and technological advancements on the FIT for solar PV, comparing scenarios in a realistic environment versus a more favorable one. The results indicate that in a better environment—with higher TGC and carbon prices and encouraged corporate innovation—the FIT for solar PV is closer to the cost of coal-fired electricity, thus promoting grid parity. The study advocates for adjustments to the FIT mechanism, higher TGC and carbon prices, and the encouragement of innovation to enhance the competitiveness of solar PV energy in China's energy market. [ABSTRACT FROM AUTHOR]

A large-scale offshore wind power integration has a reverse peak regulation effect on the electric load and requires newly built transmission corridors. This work adopts a wind-thermal (WT) bundled system for offshore wind power integration and transmission line capacity factor improvement. The Qingzhou I-VII offshore wind farms (5000 MW) and the Yangxi coal-fired power plant units #5, #6 (2 × 1240 MW) are taken as a case study. The offshore wind farms (OWF) act as the must-take generator to increase the renewable fraction while the thermal power plants (TPP) provide peak regulation service to trace the changing net load. The OWF and TPP share the transmission line and point of interconnection. The OWF integration level is determined by the 8760-h production simulation and the wind-thermal (W-T) capacity ratio is 1.4516:1 (3600 MW OWF) in the studied site. The curtailment rate, electricity shortage rate, transmission line capacity factor (CF), load following precision, renewable fraction, CO 2 emission of WT-W3600 condition are 9.02%, 5.41%, 61.36%, 91.43%, 50.46%, 6.97 million ton/year. There is a trade-off relationship between renewable fraction and curtailment rate in the WT system which restricts higher OWF integration. The demand-side response technologies such as power-to-X and energy storage are required to break the trade-off relation and reduce the electricity shortage rate. The WT system is economically viable and the net present value (NPV), levelized cost of electricity (LCOE), internal rate of return (IRR) of WT-W3600 are 3.55 billion¥, 0.4859¥/kWh, 4.82%. Co-locating the OWF and the floating solar photovoltaic (PV) is the future direction that benefits the intensive exploitation of sea area and offshore renewable energy development. Fig. Schematic of offshore wind-thermal (WT) power system at the same point of interconnection (for illustrative purpose to show the connection). [Display omitted] • WT system combines offshore wind power and thermal power plants. • The recommended wind-thermal (W-T) capacity ratio in Yangxi is 1.4516:1. • WT system improves transmission line capacity factor to 61.36%. • WT system improves renewable fraction and reduces CO 2 emission. • The NPV, LCOE, IRR of WT-W3600 are 3.55 billion¥, 0.4859¥/kWh, 4.82%. [ABSTRACT FROM AUTHOR]

The present study reports on the quantification of the economic feasibility and environmental sustainability potential of a biogas-based pressurized grid on a rural livestock farm in Cuba. Three different grids (Grid 1: Niña Bonita, Grid 2: Sabanilla, and Grid 3: Dos Ríos) were evaluated, with the main differences between them being the number of anaerobic digesters and the substrates to be managed. For this purpose, the economic evaluation was carried out based on the cost of the equipment. In addition, the Life Cycle Assessment (LCA) method was used to obtain the environmental profile of the whole system and each grid. The cost analysis included the monetization of cost savings derived from the monetization of fertilizer and energy sources. The selected functional unit was the 10 kg chemical oxygen demand (COD) in livestock manure and slaughterhouse wastewater. The results show the need for grid interconnection to balance biogas production and consumption. The proposed model demonstrates the economic feasibility of the biogas-based pressurized grid, with a payback period, internal rate of return (IRR), and net present value (NPV) of 4.6 years, 38%, and $2 188 993.08, respectively. Studies confirm that the price of digestate is critical to the economics of the process, with a high sensitivity to project profitability. From an environmental point of view, Grid 2 performed the worst, mainly due to CO 2 and N 2 O emissions (mainly in the lagooning process). However, the current grid supports the diversion of lagooning effluent for the irrigation of nearby fodder crops. In addition, the sensitivity analysis showed that the increase in the number of cattle (doubling) is crucial for the improvement of the environmental profile. Its variation proved that the substitution of fossil-based electricity can be considered a solution to reduce the environmental burden with bioenergy. • The economic and environmental impact of the biogas-pressurized grid was studied. • Digestate price is primary for system economic feasibility. • Electricity substitution is determining the beneficial environmental impact. • Wastewater for irrigation from a local perspective provides environmental benefits. • Experience in biogas-based pressurized grids is provided for similar regions. [ABSTRACT FROM AUTHOR]

Interest in large-scale compressed biogas (CBG) and biogas for electricity generation is increasing due to these technologies' potential for addressing dual energy and waste management challenges. However, sustainable operation of large-scale commercial biogas plants requires attention to numerous factors, including technical aspects (feedstock types, plant size, operational parameters, and biogas and fertilizer utilization strategies), costs (capital investment and operational), and affordability, as affected also by subsidies. This study conducts a case study of the sustainability of an existing operational large-scale biogas plant in Nepal, considering its operational condition, financial status, and environmental benefits under designed capacity and actual operating conditions. Design parameters related to biogas and digestate production, financial viability, and greenhouse gas (GHG) emission reduction potential were compared with the realized outcomes of the plant. Operational and financial data for the plant were obtained through visits to the plant supplemented by interviews of the plant manager. The analysis reveals that both the feedstock and digester efficiencies are much lower than the design expectations, by 55% and 62%, respectively. This has led to reductions in the production of biogas and biofertilizers by 72% and 90%, respectively. Moreover, while the internal rate of return (IRR) of the plant at design capacity was 23%, it is indeterminate for the actual operating condition, as the net present value is negative for all discount rates. The biogas plant does generate environmental benefits; the GHG emissions avoided are estimated to be around 274 tons of CO 2 equivalent per year under the actual operating conditions. Given these results, it is clear that improving the operational performance of large-scale biogas plants in contexts such as this one should be a priority. Moreover, the findings can help policymakers, investors, and other stakeholders make better plans for future development of biogas facilities, insisting on more realistic and careful assessments of technical and financial viability. • First study on the sustainability of an existing operational large-scale biogas plant in Nepal. • Design parameters were compared with the realized outcomes of the plant. • Biogas plant offer environmental benefits but is not achieving optimal performance levels. • Significant operational and financial challenges limits financial viability. • This study help policymakers, investors, and other stakeholders make improved decisions. [ABSTRACT FROM AUTHOR]

To promote the realization of the "dual carbon target", the implementation of rooftop distributed photovoltaic (RDPV) projects in the whole county will usher in large-scale development in China. However, comprehensive investigations into the economic benefits of RDPV projects in the whole county are still rare. This paper thus aims to evaluate the economic benefits of RDPV projects when considering multiple factors. The net present value (NPV), internal rate of return (IRR) and payback period (PBP) were used to analyze the financial feasibility of RDPV projects. The particle swarm optimization (PSO) algorithm was adopted to optimize the economic benefits of RDPV projects by calculating the different installation ratios of different building types, including industrial and commercial buildings, government buildings, public buildings, and residential buildings. A case study verified the feasibility of the optimization model of the economic benefits of RDPV projects in the whole county in China. The results revealed that the self-use ratio of power generation greatly impacted the economic benefits of RDPV projects and a single RDPV project became economically feasible when the self-use ratio of power generation was greater than 87.753%. When considering the limitations of the self-use ratio of power generation, installed capacity, and grid connection mode of different building types, compared to the single RDPV project, the economic benefits of RDPV projects on a county scale were not financially feasible based on the optimization model, which had an NPV of about −10.35 million yuan. Industrial and commercial buildings had the highest proportion of RDPV systems installed among the four building types, while residential buildings had the lowest proportion. The current results demonstrate the economic benefits of RDPV projects in the whole county, which will promote the development of RDPV projects and reduce carbon emissions in China. Therefore, this study is expected to provide investors of RDPV with recommendations for both decision-making and making scientific plans for the government. • This paper aims to evaluate economic benefits of RDPV projects in a whole county when considering multiple factors. • Self-use ratio of power generation greatly effects RDPV projects' economic benefits. • Maximizing the use of roofs can improve RDPV projects' large-scale effects. • Installing RDPV on industrial and commercial building has good economic benefits. • Investing in RDPV systems on residential buildings needs for caution. [ABSTRACT FROM AUTHOR]

Hydrogen is a prominent clean fuel option for combatting global warming and producing low-emission, ecologically friendly electricity. Consequently, the proton exchange membrane water electrolysis (PEMWE) hydrogen refueling station has undergone thorough economic and environmental analysis. This work intends to fill the gap by presenting the influence of various operating circumstances and design parameters on the economic and environmental aspects of PEMWE based on various behaviors and features (I–V curve) under various scenarios. Profitability analysis (PA) is performed in terms of the net present value (NPV), discounted payback period (DPBP), benefit-cost ratio (BCR), and internal rate of return (IRR) from cumulative discounted cash flow diagrams (CFD). Also, sensitivity analysis (SA) is conducted to assess the impact of different economic factors, while simultaneously establishing CO 2 footprint guidelines for optimal operating and design conditions. The findings highlight that enhancing economic feasibility and reducing environmental concerns are simultaneously achievable by increasing cathode pressure, operating temperature, and decreasing membrane thickness. At membrane thicknesses over 100 μm, the project becomes unprofitable and inefficient at 1.85 V. PEMWE becomes more valuable and sustainable with a current density of 12,000 A/m2 or higher, but it releases more CO 2 emissions. Hence, utilizing excess renewable electricity in PEMWE addresses environmental concerns and enhances the overall ecological sustainability of hydrogen production. [ABSTRACT FROM AUTHOR]

The objective of this article is to statistically analyze and apply process control on water consumption in toilet flush devices in a public university building using Shewhart, EWMA and combined Shewhart-EWMA control charts. Data such as water volume, number of activations and flush-time duration were collected utilizing Smart-Meter sensors. A script was developed in R language to perform the appropriate statistical analysis, such as finding control charts control limits and transforming the obtained raw data into key variables: total volume per day, average flush volume, flush duration, and number of flushes per day. During the data gathering period, the regular single-flush equipment was replaced by a dual-flush model. The control charts Phase 1 is based on the collected data before the installation of the dual-flush devices, while Phase 2 is based on after replacement. After installing the new dual-flush devices, all control charts displayed visible changes based on the key variables. The replacement of the flush valves brought about a considerable reduction in water consumption in both male and female restrooms. There was a 21.72% reduction in average water consumption and a 12.09% average reduction in flushing time duration. The equipment replacement resulted in an evaluated Internal Rate of Return of 0.73%. Periodic monitoring of Shewhart Control Charts proved useful for observing large shifts of data, while EWMA control charts were more useful in locating small but constant data shifts. All chart models proved useful in identifying water consumption reduction and events such as leakages and water supply cutoffs occurring during the data gathering period. • The article goal is to analyze water consumption in toilet flush devices. • Shewhart, EWMA, and Combined Shewhart-EWMA control charts have been applied. • Dual-flush devices presented a reduction of 21% of water per flush. • Dual-flush devices reduced the flush duration by 12%. • All control charts proved useful for monitoring water consumption in toilets. [ABSTRACT FROM AUTHOR]

As industrial air compressors are the most energy intensive, a comprehensive energy and exergy analysis, reducing energy usage by various energy savings measures are highly important to reduce their energy consumption and emission for the sustainable future growth. A comprehensive analysis on energy performance, exergy efficiency, CO 2 emission, sustainability, and the associated economic implications were studied in a typical industrial air compressor system of a TiO 2 manufacturing industry, located in Bahia, Brazil. Necessary input data were taken from this industry to analyze energy, exergy, emission, economic, and sustainability performance of the air compressor. The predicted overall exergy efficiency of the compressors varies from to 5.27%–21.94%. Sustainability indicators like Sustainability Index (SI), Depletion Number (DN), Waste Exergy Ratio (WER), & Environmental Effect Factor (EEF) were analyzed and the evaluated sustainability index found to vary from 1.05 to 1.28. Waste exergy ratio is estimated to be 0.95 and environmental effect factor is found to be 17.95 for compressor A. Discharge pressure reduction, power factor improvement, waste heat recoveries are the main areas where improvement have been identified. Reducing discharge pressure can save annually 3515.180 MWh of electricity leading to a reduction of 347.7 ton of CO 2 emission per year. It is also noted that the reduced discharge pressure lead to an increased exergetic efficiency. Among various options, reducing discharge pressure came out to be the most cost effective measure with lesser internal rate of return. The industry could save a total of 5634.2 MWh of electricity and reduce CO 2 emission by 557 ton per annum with an investment of US$ 570,000. The return on investment for the investment is estimated to be 9 months. • Overall exergy efficiency of the compressors varies from 21.94% to 5.27%. • Sustainability indexes found to vary from 1.05 to 1.28. • Waste exergy ratio is 0.95 and environmental effect factor is 17.95 for Compressor A. • Reducing discharge pressure can save annually 3515.180 MWh of electricity. • Investment of US$ 570000 can save 5634.2 MWh of electricity & reduce 557 ton CO 2. [ABSTRACT FROM AUTHOR]

Energy from biomass is essential for sustainable agricultural development. The generation of biogas and bio-fertilizer from the anaerobic co-digestion is fundamental in mitigating environmental problems and in the local generation of electricity. In this context, this study examines the technical and economic feasibility of the effects of co-digestion of sweet potato with dairy cattle manure on energy and nutrient recovery using semi-continuous digesters. The use of sweet potato in co-digestion is characterized as an innovation in the technological process of anaerobic digestion, the application of which on small and medium-sized farms is still a challenge in emerging economies. The assay was conducted using different proportions of sweet potato mixed with dairy cattle manure, which produced a linear increase in methane yield with concentrations of 63–65.5% and biogas capable of generating 2376.44 kWh d−1. In addition to the generation of cleaner electrical energy, the co-digestion process produces a bio-fertilizer with a potential production of 26.53 tons/year of N, 20.45 ton/year of P and 23.6 tons/year of K. These results are superior to the mono-digestion process. Regarding the necessity of using sweet potato, this new system of production was evaluated for a model medium-size farm dedicated to dairy production in the countryside of the state of São Paulo in Brazil. The results demonstrate the economic feasibility of the investment in the five analysed scenarios, as the internal rate of return varied between 46.8% and 57% and the payback was achieved in 2–3 years. This research demonstrates that the innovation of using sweet potato as an additional input to the digestion process can increase the sustainability of small and medium-sized dairy farms in a manner consistent with a circular economy. Image 1 • The sweet potato increases the production of biogas in digesters. • Co-digestion from sweet potato produces bio-fertilizer with quality nutrient. • Digesters are economically viable for clean energy generation from biomass. • Using a sweet potato to anaerobic co-digestion increases sustainability of farms. [ABSTRACT FROM AUTHOR]

Off-grid groundwater cotton irrigators using traditional technologies have had few options to reduce water extraction costs. New options of blending of Alternating Current and Direct Current through an all-in-one soft start converter/controller offer opportunities to lower costs, diversify fuel sources and continuous off-grid power in remote locations. Diesel energy can be replaced by renewable fuel sources through installing an electric submersible pump powered by solar photovoltaic in combination with a diesel generator. An investment analysis using a discounted cashflow over 25 years showed a 23% internal rate of return and payback over 5 years. Benefits of installing a renewable fuel source included lower greenhouse gas emissions per bale of cotton produced and less labour to monitor and service traditional diesel irrigation plant. Emissions calculations reveal a reduction of 26%, or 35 kg CO 2 e per cotton lint bale, and an abatement of 2665 t/CO 2 e for the life of the project. The cost of emissions abatement under the Renewable Energy Target to displace almost one million litres of diesel was found to be $31 t CO 2 e. • A microgrid solution reducing energy costs and emissions is analysed for an irrigation pump in NSW, Australia. • The microgrid includes photovoltaic panels and a diesel generator used to power a submersible pump 24 h a day. • The analysis indicates a 5-year payback and 23 per cent internal rate of return for the investment. • Emissions are reduced by 26 per cent (per 227 kg cotton lint bale) equating to 2665 t/CO 2 e abatement over the project life. [ABSTRACT FROM AUTHOR]

Abstract Studying the economic performance is of great significance to the policy improvement and investment decisions making of concentrated solar power (CSP) industry. This study developed a cost-benefit model to analyze the economic benefits of CSP industry, under the current technological level and policy system of China. The results showed that: Firstly, the huge initial costs resulted in that the investment of CSP industry had to bear a long capital recovery period, which might add the investment risks; meanwhile it was still economically feasible because of better expected benefits. Secondly, for CSP industry, the internal rate of return mainly varied from 8% to 12%, and the average levelized cost of energy was $0.148/kWh; the economic performance of CSP industry was attractive from the multiple dimensions analysis, and the benchmark feed-in-tariffs could provide effective support for the CSP industry development of China. Thirdly, adopting solar tower CSP technology was better choice to improve the economic benefits of CSP industry, compared with parabolic trough and linear Fresnel CSP technologies. Lastly, the direct normal irradiation, initial costs, annual electricity production and loans ratio had important impacts on the economic benefits of CSP industry, and should be paid more attention in investment decisions. Graphical abstract The policy system determines the costs and benefits of CSP industry by the economic parameters, and then affects the economic performance of CSP industry. The analysis on the economic benefits can provide scientific basis references for the industrial policy improvement and investment decisions. Image Highlights • Develop a cost-benefit model to analyze the economic performance of CSP industry. • Capital recovery period, usually more than 11 years, adds investment risks of CSP. • In spite of high initial costs, investment in CSP industry is economically feasible. • IRR of CSP industry mainly varied from 8% to 12%, with average LCOE of $0.148/kWh. [ABSTRACT FROM AUTHOR]

Waste ship-oil sludge (WSOS) is considered as a hazardous waste as it affects the aquatic and dependent ecosystems. However, energy-rich fuels can be obtained upon treating this waste instead of discharging into the sea. Pyrolysis of oily wastes yields a higher proportion of energy-rich fuel when compared to solid wastes. This study provides an insight into the production of different products at various stages of thermal decomposition of completely mixed WSOS and compares its fuel properties such as calorific value, acid content, flash point, distillation, etc. with commercial diesel and aviation fuels. Non-combustible phenol-rich liquids were obtained at a temperature of 220 °C–300 °C (stage – 1) and 300 °C–400 °C (stage – 2). The stage – 2 product contained octa atomic sulphur and the concentration of sulphur in the subsequent stages increased consequently. Stage 3 (475 °C–550 °C) and stage 4 (550 °C–650 °C) products were analysed for commercial fuel properties and compared to conventional diesel and aviation fuels as they contained 45.79% and 56.29% of diesel-equivalent (C 13 – C 18) hydrocarbons respectively. Stage 3 corresponded well with Grade No.1 diesel fuel according to the ASTM D-975-19 standards and exhibited better properties in comparison with the stage 4 product. An inductive method of techno-economic analysis was carried out. The analysis returned a positive net present value (69,142.49), a high internal return rate (53.78%), and a payback period of 13.52 months, indicating that the sale of pyrolyzed WSOS as commercial fuel will be profitable. [Display omitted] • Four-stage thermal degradation of hazardous waste ship-oil sludge was carried out. • A fixed-bed pyrolysis reactor was designed to produce diesel-equivalent fuels. • Octa atomic sulphur and phenolic compounds were separated from the fuel. • Pyrolyzed WSOS exhibited superior properties to that of commercial diesel. • Payback period of 13.52 months was deduced on commercial sale of pyrolyzed product. [ABSTRACT FROM AUTHOR]

Biorefining to produce chemical materials is a viable path to a renewable and sustainable future. The energy crop Miscanthus is grown with high yield and low cost. In this study, platform chemicals (acetic acid, glycolaldehyde, and acetol) and novolac resins were produced using Miscanthus at a baseline plant capacity of 15 t/h. The profitability of different biochar applications (soil amendment, heat supply, and activated carbon) was investigated by mass balance and energy consumption analysis and economic assessment. The heat supply scenario had the best profitability with an internal rate of return (IRR), payback period, levelized cost, and minimum selling price of 24.5%, 4.32 years, CNY 8,480/t, and CNY 10,840/t. Sensitivity analysis showed that IRR was most sensitive to resin price, plant capacity, and capital costs. The minimum plant capacity with an IRR over 25% was 25 t/h. Monte-Carlo simulation results showed a low investment risk for soil amendment and heat supply scenarios. • Performance of a 15 t/h Miscanthus refinery plant was evaluated. • Compared the benefits of biochar for heating, soil amendment, and activated carbon. • Resin products yield considerable benefits, but platform chemicals return is poor. • Economic analysis showed good profitability with an optimal IRR of 24.5%. • Monte-Carlo simulations show low investment risk for 25 t/h plant capacity. [ABSTRACT FROM AUTHOR]

Utilizing the high-pressure exergy of a pipeline gas is a route to overcome the challenge of high power consumption in liquefying natural gas. Through the expansion in city gate stations (CGSs), a notable cold duty is achieved that can liquefy a part of a natural gas feed. Based on this concept, the present research proposes a novel system for natural gas liquefaction utilizing pipeline exergy integrated with helium recovery and innovative carbon dioxide capturing and liquefaction. The process was evaluated by energy, exergy, economic, and exergoeconomic analyses. Results showed that the proposed system can co-produce LNG, liquid helium, and liquid CO 2 products with low energy consumption, simplicity, and high profitability. The specific power consumption (SPC) and the exergy efficiency of the natural gas liquefaction system are 0.227 kWh/kg LNG and 64.24%, respectively, which shows a desirable performance as well as a notable potential for improvement. The process equipment of the helium liquefaction system also offers a higher total cost rate, mostly constituting an exergy destruction cost rate. The integrated system exhibits appropriate profitability by the internal rate of return of 47% and the payback period of 3.25 years. A conceptual illustration of the integrated LNG/LHe/LCO 2 process. [Display omitted] • A novel process is proposed to co-produce LNG, liquid He, and Liquid CO 2. • Energy, exergy, and exergoeconomic analyses are applied to evaluate the process. • The process shows low power consumption, high simplicity, and high profitability. • The exergy efficiency of the liquefaction system is calculated as 64.2%. • The IRR and the payback period of the process are calculated by 47% and 3.25 years. [ABSTRACT FROM AUTHOR]

The objective of this study was to assess the effects of tire pyrolytic oil (TPO) blends on diesel engine performance, evaluate the techno-economic viability, and optimize the process variables using the response surface methodology (RSM) in order to increase the maximum product yield. To test engine performance and exhaust emission characteristics, the derived pyrolytic oil was employed in a four-stroke diesel engine with different diesel fuel blend ratios. It has been found that engine performance using a pyrolytic oil blend is much closer to the diesel fuel engine performance. This paper has briefly explored the economics of TPO production and the reliability improvements of the pyrolysis processes to make them viable for commercial applications. The techno-economic feasibility analysis has been conducted on a 10 tons'/day capacity pyrolytic plant. It has been found that the total cost and net revenue generation from one ton of scrap tires are $225.25 and $410.2, respectively. Additionally, the 8-year project's payback period is only 2.96 years, while the internal rate of return (IRR) was found to be 27.81%. The reduction in greenhouse gas (GHG) emissions was estimated at 1,658.62 tons per year. The RSM was used to optimize the process parameters for maximizing product yield. At the ideal conditions of 464.11 °C operating temperature, 59.53 min of running time, and 1.63 cm particle size, the projected maximum pyrolytic oil yield of 87.31 wt% and char yield of 7.63 wt % was reached. The reliability and applicability of the process were ensured through the developed regression model for pyrolytic oil and char with a high F-value and low P-value. The predicted results were validated, and it was found that the experimental data varied only by 1.21% from the predicted values. Therefore, this study provides investors with scientific guidance for pyrolysis-based energy generation projects in Bangladesh that are financially viable. [ABSTRACT FROM AUTHOR]

Sustainable aviation fuel (SAF) production is one of the strategies to guarantee an environmental-friendly development of the aviation sector. This work evaluates the technical, economic and environmental feasibility of obtaining SAFs by hydrogenation of vegetable oils thanks to in-situ hydrogen production via aqueous phase reforming (APR) of glycerol by-product. The novel implementation of APR would avoid the environmental burden of conventional fossil-derived hydrogen production, as well as intermittency and storage issues related to the use of RES-based (renewable energy sources) electrolysers. The conceptual design of a conventional and advanced (APR-aided) biorefinery was performed, considering a standard plant capacity equal to 180 ktonne/y of palm oil. For the advanced scenario, the feed underwent hydrolysis into glycerol and fatty acids; hence, the former was subjected to APR to provide hydrogen, which was further used in the hydrotreatment reactor where the fatty acids were deoxygenated. The techno-economic results showed that APR implementation led to a slight increase of the fixed capital investment by 6.6% compared to the conventional one, while direct manufacturing costs decreased by 22%. In order to get a 10% internal rate of return, the minimum fuel selling price was found equal to 1.84 $/kg, which is 17% lower than the one derived from conventional configurations (2.20 $/kg). The life-cycle GHG emission assessment showed that the carbon footprint of the advanced scenario was equal to ca. 12 g CO 2 /MJ SAF , i.e., 54% lower than the conventional one (considering an energy-based allocation). The sensitivity analysis pointed out that the cost of the feedstock, SAF yield and the chosen plant size are keys parameters for the marketability of this biorefinery, while the energy price has a negligible impact; moreover, the source of hydrogen has significant consequences on the environmental footprint of the plant. Finally, possible uncertainties for both scenarios were undertaken via Monte Carlo simulations. [ABSTRACT FROM AUTHOR]

A tri-generation-based sustainable poultry litter (PL) valorization process has been developed in this study. To make the proposed process economically viable and energy efficient, the primary gasification process of PL is further enhanced to convert syngas into dimethyl ether (DME). According to our energy analysis, the current tri-generation process exhibits 57% energy efficiency, which is 12% higher than that of PL gasification (45%). A particle swarm optimization (PSO)-based algorithm was applied to optimize the gasification and DME production process. According to PSO results, the optimum operating conditions are 667 °C, 2 bar, and 1.78 air ratio in the gasification process, while using reaction temperatures of 400 and 100 °C in the DME reactors leads to 242.6 kg/ton DME with 4414.6 kJ/s net heat. On the contrary, only 190.8 kg/ton DME with 4642.2 kJ/s net heat can be generated in the base process. The optimized process is economically viable to achieve an 80% plant operational efficiency with an internal rate of return (IRR) of 16.3% when compared with the base process, which becomes infeasible when the plant efficiency is <90%. A sustainability index (SI) was developed, and the results show that the optimized process was more sustainable (0.290) than the base process (0.279). Therefore, our optimized DME process is more economically viable and eco-friendly. • An innovative process for poultry litter valorization is proposed. • The energy efficiency of the poultry litter tri-generation process is 57%. • Biomass gasification process is optimized by particles swarm optimization (PSO). • Life cycle assessment of dimethyl ether production from poultry litter. [ABSTRACT FROM AUTHOR]

Due to the late introduction of Feed-in Tariff (FiT) Scheme to Hong Kong's context, its effectiveness, efficiency, and optimization have merely been investigated yet. Therefore, this study proposes two FiT mechanisms according to the policy characteristics and structure elucidated from existing literatures (i.e., payoff, tariff, and contract structures) (i) Mechanism 1 (i.e., M1): follows the current policy characteristics with a short-term contract structure, which terminates in 2033; and (ii) Mechanism 2 (i.e., M2) introduced a widely adopted policy characteristic with a long-term contract structure, which allows to sell all electricity generated to the power grid. The proposed FiT rate under M1 and M2 guarantees the profitability of the solar photovoltaic (PV) installers with different scales. For residential PV installers (i.e., small-scale PV systems with installed capacity less than10 kW), 6–10 years of discounted payback period (DPB) is considered as the optimization objective. As for industrial PV installers (i.e., large-scale PV systems with installed capacity of 200–1000 kW), 8–12% of internal rate of return (IRR) is considered as the optimization objective. Results indicate that the current FiT rate is slightly high for residential PV installers, and it is recommended to be lowered after 2024 to fit the proposed FiT range, and then levered up in 2028 to ensure the profitability of late participation under M1. Meanwhile, the current FiT rate is found significantly low for industrial PV installers, and it is suggested to be levered up to the proposed FiT range. Furthermore, policy reform is highly recommended altering from M1 to M2 when current policy expires (i.e., 2033). In terms of the techno-economic analysis based on the calculation of levelized profit of electricity (LPOE) where self-consumption of PV system-generated electricity is considered as energy bill savings under M1, the long-term profitability for industrial PV installers under M1 is found to be higher than M2, whereas the opposite is observed for residential PV installers. The contribution of this study is attributed to the flexibility and applicability of the optimized results, the context-specific investigation of the market-independent renewable energy development, and the comprehensive parameters considered in the model development. The results of this study are believed to shed light on policy implications, grid parity, and investment recommendations for the government, utility companies, and PV installers in the long run. [Display omitted] • Payoff, tariff, and contract structures regarding FiT Scheme are reviewed. • FiT rates were optimized under current (M1) and improved (M2) FiT mechanisms. • DPB and IRR are considered for residential and industrial PV installers. • Results have shed light on policy implications regarding current FiT rates. • Policy reform is suggested according to economic analysis in a long run. [ABSTRACT FROM AUTHOR]

A significant commercial chemical namely succinic acid can be produced using glycerol from the biodiesel industry. Previously, key attributes of the upstream and the downstream processing in the synthesis of bio-based succinic acid were identified, which substantially influence the technological competitiveness compared to petroleum-based production. Accordingly, this study aims to simulate succinic acid production from glycerol with the most promising technology. The techniques of reactive extraction and direct crystallization, as well as the use of dimethyl sulfoxide (DMSO) as an electron acceptor, are investigated. Selected scenarios are evaluated based on techno-economic, energy, exergy, and greenhouse gas (GHG) emissions performances to acquire a broader perspective on the sustainability of the technology. The obtained results indicate that the addition of DMSO in the fermentation is key for the bio-based succinic acid production – the best profit of 190 million USD of the net present value, 33.3% of the internal rate of return, and 4.48 years of the payout period are estimated. Additionally, bio-based succinic acid production could compete with the petrochemical route, particularly the reduction of GHG by 26%. Therefore, the production of succinic acid from glycerol is feasible given the positive net present value and lower GHG emissions compared to the petrochemical route. [Display omitted] • Techno-economic analysis was employed for the development of bio-based SA production. • The addition of DMSO significantly improved profitability and sustainability. • Direct crystallization was a beneficial approach for SA purification. • Glycerol is a suitable substrate for SA production when compared with other substrates. • SA production via the glycerol-based process can compete with the petroleum-based process. [ABSTRACT FROM AUTHOR]

Wind power renewable energy (RE) integration is receiving due attention from the majority of power utilities because of the increasing need for energy and the global environmental concerns of fossil fuel sources. However, wind energy (WE) generation is ultimately limited by its size due to the stochastic intermittency and uncertainty as a sustained source of power. Prevalent wind at any location is site-specific and strongly depends on the terrain and topographic features. This paper focuses on the study of economic viability of wind farm in Ras Sedr, in the Egyptian Sinai Peninsula. A detailed wind resource assessment using collected wind data and statistical analysis are discussed for harnessing adequate wind power and energy. The annual wind speed of the selected site, of dominant north and northwest direction, varies from 6.52 to 7.21 m/s at 10 and 25 m (a.g.l.) heights respectively. The selection procedures of the best wind turbine (WT) of (class II) for the site, according to IEC 61400, are fully investigated. The preliminary wind survey of the optimal micro-sitting of WTs are also explicitly analyzed. The possibility of implementing a wind power plant project of 200 MW farm capacity is studied. Hundred Vestas V90 WT units of 2 MW capacity each are considered for Ras Sedr wind farm. Using WAsP and WindPRO softwares, the wind farm expected net annual energy output is 840.62 GWh which can be economically feasible with the proposed National Electricity Tariff. In addition, the profitable net present value (NPV) and internal rate of return (IRR) values of 67.27 M€ and 12% respectively are estimated. The feasibility of the proposed wind farm is economically verified. [ABSTRACT FROM AUTHOR]

The acid-hydrolyzed residues of lignocellulosic biomass are the primary organic solid wastes during xylose production, while their management and/or valorization have often been overlooked. Here, based on the xylose production platform, four scenarios were established for techno-economic and life cycle assessments (TEA-LCA) of sugarcane bagasse-derived hydrolysis residue obtained from H 2 SO 4 pretreatment, including landfill (baseline), incineration with cogeneration system, bioethanol production, and biomethane production. According to the TEA results, the landfill scenario exhibited the lowest economic benefits, with an internal rate of return (IRR) of 18.8% and a net present value (NPV) of 23,270,090 $. In contrast, the incineration scenario showed the best economic results, with IRR and NPV improving by 4.7% and 68.8%, respectively. The bioethanol and biomethane scenarios exhibited an IRR of 0.2% and 2.2% higher than the IRR of the landfill, respectively. Furthermore, the economics of all four scenarios were sensitive to plant capacity, hemicellulose to xylose conversion rate, and xylose price. The LCA showed that landfill was the worst option, followed by bioethanol and incineration, while the biomethane scenario reduced 39.3% of the adverse impacts using the ReCiPe single score, as it avoided a higher amount of production of synthetic fertilizer and natural gas. The environmental performance was sensitive to the conversion rate of hemicellulose to xylose as per the sensitivity analysis. This study indicated that the valorization of acid-hydrolyzed residues into bioenergy was attractive for the xylose plant, and give the decision-makers a clear perspective for developing a sustainable disposal policy for acid-hydrolyzed residues. [Display omitted] • Disposal of hemicellulose hydrolysis residue is a key issue in xylose production. • TEA-LCA of four scenarios for treating hydrolysis residue were compared. • Incineration scenario showed the economic advantage with a 3.34-years payback time. • Landfill and methane production had the worst and best environmental impacts, respectively. [ABSTRACT FROM AUTHOR]

The requirement for ethylene glycol (EG) continues to surge owing to the booming demand for indispensable platform materials. Unfortunately, there is limited insight into engineering modeling, process enhancement, and process optimization to achieve carbon neutrality in ethylene glycol production. Herein, four biomass-to-ethylene glycol (BtEG) processes that integrate renewable energy for hydrogen production and CO 2 utilization are proposed to find the best strategy for the carbon-neutral and cost-effective development of the ethylene glycol industry. Rigorous steady-state modeling and simulation of the proposed BtEG processes with various gasification agents are conducted to investigate the effect of different gasification agents on the performance of the BtEG processes. The technoeconomic and environmental performance of the proposed processes is assessed and compared with the conventional process. Results show that the proposed BtEG processes can significantly boost the system performance of the conventional process. The carbon utilization efficiency, exergy efficiency, and internal rate of return of four proposed BtEG processes are improved by 38.96%–43.2%, 0.98%–7.13%, and 1.94%–11.28%, respectively. The environmental performance of the proposed BtEG processes is greatly superior to that of the conventional process since the life cycle GHG emissions of the proposed processes are negative, which are lower than −1.47 t/t. Therefore, this study provides a sustainable and cost-efficient improvement direction for the carbon-intensive ethylene glycol industries. [Display omitted] • Four BtEG processes with various gasification agents were designed and simulated. • Effect of various gasification agents on the technoeconomic performance of BtEG process are optimized. • Proposed BtEG process can increase carbon efficiency from 39.3% to 82.5%. • Proposed BtEG process can improve internal rate of return from 17.56% to 28.84%. • Life cycle GHG emissions of the proposed BtEG processes is negative. [ABSTRACT FROM AUTHOR]

This study explored which envelope solutions in retail buildings led to cost-optimal levels considering the Energy Performance of Building Directive and Portuguese regulation. For such, energy simulations were run in BIM software based on the analysis of a case study in Portugal. Typical alternative solutions were tested against the original case study, and solutions with considerably lower U-value considering the code for commercial buildings (0,7 W/m2°K for walls and 0,5 W/m2.°K for roofs). To assess the cost-effectiveness of alternative envelope solutions, the Payback Period, the Net Present Value and the Internal Rate of Return at 15 years and 50 years were assessed. Results indicate that solutions with lower U-values are related to 2–5% savings in energy consumption and can be cost-effective at 15 and 50 years, namely vacuum insulation panels of 2.5 cm and sandwich panels of 8–12 cm. This leads to the conclusion that lowering present code U-values can be cost-effective, but it will result in additional initial costs. [Display omitted] • Legal Portuguese U-values for retail buildings could be revised under a 50 y lifecycle perspective. • U-values for walls at 0,29–0,42 W/m2°K and at 0,29–0,35 W/m2°K for roofs can be cost-effective. • 2,5 cm VIP and 8–12 cm sandwich panels are possible solutions to lower U-values of retail buildings. [ABSTRACT FROM AUTHOR]

Biodiesel and bioethanol play an important role as renewable liquid fuels. Bagasse, a by-product from the bioethanol industry, can generate a "sugarcane bagasse hemicellulose hydrolysate" (SCBH) that contains fermentable sugars, mainly xylose. Oleaginous yeasts (eg., Rhodotorula toruloides) can grow in SCBH, producing microbial oil (MO), a source of triacylglycerol for biodiesel production. The integration of bioethanol and biodiesel (from MO) production may be a promising approach in order to exploit synergies between bioethanol and biodiesel processes within a biorefinery. This integration may improve the economic and environmental performance of both processes. This work presents the techno-economic-environmental analysis of the integrated production of first-generation bioethanol, bioelectricity, and biodiesel in a Brazilian sugarcane biorefinery, where MO from the yeast R. toruloides feeds the biodiesel unit. The biorefinery, processing 4.0 million t of sugarcane per harvest, produces 71.7 m3/h of bioethanol, 2.55 m3/h of biodiesel (that can replace 75.6% of the diesel demand in the field), and 86.3 MW of surplus bioelectricity. A life cycle assessment shows that the integrated biorefinery had a lower environmental impact than the first-generation bioethanol plant. The integrated process exhibits a positive economic performance (net present value of approx. 110 million of dollars and internal rate of return of about 14.5% per year, higher than the minimum acceptable rate of return, assumed as 11% per year), indicating that this is a feasible industrial option. Sensitivity analysis shows that R&D should mainly focus on the MO bioreactor operation. [Display omitted] • The biorefinery produces bioethanol, bioelectricity and biodiesel. • The biodiesel raw material is microbial oil produced on-site. • The biodiesel produced in situ could replace 75.6% of the diesel consumption. • The biorefinery had positive economic and environmental performance. • The most influential process variables are related to the bioreactor operation. [ABSTRACT FROM AUTHOR]

The study aims to conduct a comprehensive cost-benefit analysis (CBA) for incremental energy star ratings in Melbourne and Perth by upgrading the thermal performance of the building façade. CBA is performed over 20, 40, and 60 years by considering the refurbishment of an existing building façade or a newly constructed house to ensure the highest energy efficiency at the lowest reasonable cost. The hybrid approach of using a dynamic energy simulation tool ( FirstRate5 ) and @RISK optimizer provides a feasible solution for obtaining a specific star rating. This study shows energy saving costs can offset the additional investment of insulation levels and energy-efficient glazings. However, life cycle energy savings are minimized after a certain point of supplementary yield insulations, such as ceilings R (6) and walls R (3). Hence the results are evaluated in terms of financial appraisals, such as net present value (NPV), benefit-cost ratio (BCR), internal rate of return (IRR), and other indicators for incremental star-rated designs. The results of the financial appraisals recommend upgrading the obligatory star rating from 6-star to 8-star is a cost-effective solution irrespective of climate and time horizon. Sensitivity indices of design variables exhibit the significance of functionality and cost implications in the established energy rating scheme. Possible economic recession (at > 7%) due to COVID and the Ukraine war, the investment coefficient (r ≤ −0.56) with NPV increases significantly against energy savings cost (r ≥ 0.8). Given the present energy rating scheme, these findings provide an exhaustive perception of policy implications. [Display omitted] • A hybrid approach integrates energy simulation ( FirstRate5 ) and @RISK for optimization. • CBA is evaluated in terms of NPV, BCR, IRR, and PB over the variable service life. • Ceiling R(6) and walls R(3) are feasible solutions for optimal trade-offs. • CBA suggests upgrading thermal efficiency from 6 to 8-star rating as per indicators. • Monte Carlo simulations perform a confidence interval for the energy rating schemes. [ABSTRACT FROM AUTHOR]

Passive houses optimize energy gains and losses to attain higher energy efficiencies, comfort levels, and affordability. This article allows attaining a broader understanding of the risks and opportunities of passive technologies and their impacts through a social cost-benefit analysis framework. Time value of money was incorporated to evaluate the net present values (NPV), cost-benefit ratios, and internal rates of return. Five alternative houses consisting of passive and net-zero technologies were compared against a conventional design (traditional model). The base model with renewable energy integrations indicated higher impacts on the cumulative cost-benefits in economic, social, and environmental perspectives. Furthermore, a sensitivity analysis evaluated the effects of independent variables such as the interest rate and energy consumption on the performance metrics. This paper allows users to attain a holistic idea of implementing passive dwellings in a selected region through a social cost-benefit point of view. • A framework to evaluate passive house application for a region was developed. • Economic, social, environmental costs and benefits were considered in the framework. • Socio-environmental factors have a significant impact on the study's performance. • Incorporation of renewable energy provides higher benefits for the alternatives. • Passive houses increase overall benefits and decrease environmental impacts. [ABSTRACT FROM AUTHOR]

As the environmental impact from ship operations is being reduced, the fraction which the shipbuilding industry contributes to is expected to increase. It is therefore important to reduce the negative impacts resulting from energy consumption during shipbuilding, and to replace existing energy sources with renewable energy. In this study, the potential use of solar photovoltaic power, wind turbines and generators in stand-alone and grid-connected hybrid systems were assessed for a large Italian shipyard, using a microgrid design optimisation software. As a standalone system, a solar photovoltaic (PV) power system offered a Levelised Cost of Electricity (LCOE) of 0.053 ($/kWh), an Internal Rate of Return (IRR) of 11% and a discounted payback period of 6.2 years. As a hybrid system with grid connection, a configuration using solar PV, a wind turbine and a diesel generator offered an LCOE of 0.109 ($/kWh), an IRR of 28.9% and a discounted payback period of 3.53 years. The sensitivity analysis showed that cases with one configuration of generators were more sensitive to the diesel price than to the cost of renewable energy technologies. • The use of renewable energy sources accelerates clean production in shipyards. • Micro grid systems can accelerate the digitalisation of shipbuilding processes. • Solar energy was found to be the most economical solution for the shipyard. [ABSTRACT FROM AUTHOR]

The concept of sustainably reusing food waste to produce value-added byproducts, such as biodiesel, was studied. Food waste is an organic-rich source of lipids. An optimization study of the extraction of oil from food waste using a solvent for biodiesel production was undertaken. A biochar catalyst derived from citron (Citrus medica) peel containing a rich carbon source. A biodiesel yield of 96.3% was obtained under the optimized reaction conditions of a 1:10 oil to methanol molar ratio, 4 w% catalyst loading, reaction temperature of 55 °C, and a reaction time of 52 min. The conditions were optimized by response surface methodology with a central composite design. The biochar catalyst maintained a significant biodiesel yield for four cycles. This techno-economic analysis found that the annual plant revenue was $24,140,000 for a project lifetime of 20 years, the payback time was 3.16 years, the internal rate of return after tax was 39.92%, and the net present value at 10.0% interest was $55,017,000. A minimum biodiesel selling price of 0.46 $/kg was used, and the environmental sustainability of the produced biodiesel was assessed by a life cycle assessment. The impact of global warming potential on the FW-based biodiesel scenario was −3.967 kg CO 2 equivalent. [Display omitted] • Oil extraction and biodiesel production process parameters were optimized. • Biochar catalyst from waste Citrus medica peel was used for biodiesel production. • 10 MT/h biodiesel production plant payback period is 3.16 years with NPV 55.02 M$. • Process global warming was −3.967 kg CO 2 equiv (Well to Wheel). [ABSTRACT FROM AUTHOR]

Integration of agriculture and renewable energy resources (RER) is currently a hot topic discussed worldwide based on the need for green energy and sustainable economy. The decreasing trend of global market value for the traditional agricultural commodity such as Rubber and Palm Oil really affected the Gross National Income (GNI) and thus, the government of Malaysia outlined a number of strategic thrusts to boost economic growth. Herbal products have been given sufficient rooms for extension as the first approved Entry Point Projects (EPP1) driver of sustainability. Orthosiphon Stamineus also known as Java Tea is among the five commercialize High-Value Herbal crops (HVHc) and chosen to be deployed under PV arrays based on its sustainability and potential market value. The financial analysis is based on 3-months harvesting cycle with reference to the harvesting coefficience p c and realistic cash flow. The Internal Rate of Return (IRR) is valued at 15.74% that benchmarks positive net return for herbal producers. The cash functions based on Return-on-Investment (ROI) can be achieved after 10 months cycle of production with Net Present Value (NPV) of RM8,863.59. This initiative flows in line with the Cleaner Production (CP) concept of efficient usage of natural resources to minimize waste and pollution. The concept of agro-technology integration is presented with strong financial return for the unused space under PV arrays configured for large scale PV farms. [ABSTRACT FROM AUTHOR]

In iron-making plants, the carbon emission problem is significant, and the existing reduction strategies focus on hydrogen utilization. Among the hydrogen production processes, a sulfur-iodine (SI) cycle is one of the most competitive candidates and there is a potential for the modification of the process design specifically targeted for the applications on blast furnaces (BF). We suggest a design for the SI process to produce H 2 gas for use as a reductant in the BF during iron smelting. We first validated the conventional SI process by using a commercial process simulator with plant data and simplified the process to increase energy efficiency, profitability, and CO 2 mitigation. We calculated the energy efficiency of the various process designs and derived the unit production cost of H 2. We discussed the economic feasibility of the SI process in BF applications and showed the potential to mitigate global warming. The energy efficiency of the conventional SI process was estimated to be 32% and was increased to 38% by excluding a sulfuric acid decomposer. The unit production cost was estimated to be 1.22US$ kg H2 −1 for the conventional SI process, and 0.80US$ kg H2 −1 for the modified SI process of sulfuric acid co-production. The economic feasibility of the SI/MSI cycles was confirmed with a calculation of an internal rate of return and net present value. Also, generated H 2 was utilized as an alternative fuel in BF, with an expected coke-replacement ratio of 0.168–0.232kg Coke m H2 −3, and for the environmental prospects, an annual reduction was expected to 1077ktCO 2 -eq in the hot metal production scale of 3.8 Mt y−1. • 4 cases of the Sulfur-Iodine cycle were compared to integrate with the blast furnace. • Energy, economics, and CO 2 reductions of the simplified process were discussed. • The overall energy efficiency increased up to 38% by eliminating the washing step. • The unit production cost of hydrogen was 0.8 US$/kgH 2 (Base case: 1.22 US$/kgH 2). • The CO 2 reduction potential was 1.07 MtCO2-eq/y. [ABSTRACT FROM AUTHOR]

With the development of China's economy and industry, demand for natural gas is growing, making coal to synthetic natural gas (CtSNG) a feasible alternative energy supply solution. However, in existing CtSNG projects have been found several issues, e.g., natural gas excess in the non-heating season, low economic performance, low carbon utilization ratio, as well as low energy efficiency. To tackle down the mentioned problems, two novel conceptional schemes are proposed and analyzed in this study in accordance with process modeling and simulation. A coal-based polygeneration process of synthetic natural gas, methanol and power (CtSMP) and a coal-based polygeneration process of synthetic natural gas, methanol and power for adjusted scenario (CtSMPa) are developed for different SNG and methanol outputs to adapt to the change of market demand. In addition, a comprehensive techno-economic analysis is conducted to exhibit the advantages of the proposed polygeneration processes. As compared to CtSNG, CtSMPa and CtSMP achieve an increase of 5.9% and 6.7% in carbon utilization index and in exergy efficiency of 5.5% and 3.9% respectively. Besides, the production costs decrease by 6.6% and 7.6%. Moreover, the internal rate of return increase substantially from 6.82% to 13.32% and 15.52%. In this study, an efficient method is developed to achieve peak shaving of CtSNG process, and guidelines can be supplied to further develop a coal-based polygeneration system with chemicals, energy, power and heat integrated. • Two polygeneration processes with different SNG and methanol outputs are proposed. • The new processes can achieve an increase of 5.9% and 3.9% in exergy efficiency. • The new processes can reduce CO 2 emissions by 14.2% and 14.6%, respectively. • The new processes improve internal rate of return from 6.82% to 13.32% and 15.52%. • The proposed system can integrate chemicals, energy, power and heat. [ABSTRACT FROM AUTHOR]

The "bridge framework" is a systematic decision-making support tool for process integration retrofit of industrial plants, which proposes the use of "bridge analysis" in a structured fashion. Its potential of rigorously analysing industrial processes has been discussed, but no applications on actually operating plants considering process constraints have been presented to date. The paper demonstrates the capabilities of the bridge framework in analysing an actually operating milk powder production plant. Its step-by-step application is thoroughly described and discussed, highlighting inherent strengths and weaknesses of the method. Moreover, a clarification of the "energy transfer diagram" is proposed, distinguishing avoidable and unavoidable heat degradation in the heat exchanger network by introducing the concept of "limit heat transfer interface". The results proved that the bridge framework is a rigorous tool, which provided valuable insight to the analyst aiding the open-ended decision-making activities related to the retrofit of both process operations and heat exchanger network. Seven design proposals were identified, out of which the best resulted in 54000 €/y of economic saving with an internal rate of return of 34% and a minimum risk level. The step-by-step application of the method demonstrated that good engineering judgement is critical for achieving beneficial solutions. Expertise on process operations as well as energy analytics is essential for completing the project. Finally, the concept of "limit heat transfer interface" allowed to completely link bridge analysis and pinch analysis and to clarify the meaning of the "grand composite curve". • The Bridge framework is applied to an existing milk powder production plant. • The method is proven valuable supporting decision-making activities in retrofit projects. • The energy transfer diagram is extended displaying avoidable heat degradation. • The terminology used in displaying the grand composite curve is clarified. • An algorithm for calculating the energy-saving potential of bridges is proposed. [ABSTRACT FROM AUTHOR]

The decline of bioethanol consumption can jeopardize the future of bioethanol producers. This research aims to design the conversion process of ethanol into a more versatile and valuable product, e.g., diethyl ether (DEE). To produce DEE, two types of ethanol can be utilized. Previously, the anhydrous ethanol was tested experimentally via catalytic dehydration on the Ru-HBZ catalyst. Satisfactory results were obtained, particularly acetaldehyde was not formed in the reaction. Herein, the catalytic experiment is extended using hydrous ethanol as feed resulting in an observable amount of acetaldehyde. These experimental results are implemented in the design of DEE production processes. Three production cases are investigated including the utilization of the anhydrous ethanol (Case I) and the utilization of the hydrous ethanol (Cases II and III). The most profitable process is obtained in Case I with the pay-out period of 4 years and % IRR (percentage of internal rate of return) of 55%. Acetaldehyde appears problematic in the DEE purification in Case II – the process is not profitable if distillation is selected for acetaldehyde removal. By implementing adsorption for the acetaldehyde removal, the process in Case III becomes profitable which is comparable to Case I. In addition, about a 5% reduction in the CO 2 emission and a 7% gain in the energy utilization efficiency are observed in Case III. Finally, the utilization of hydrous ethanol (Case III) can be more attractive when the difference in selling prices of the hydrous and the anhydrous ethanols is more than 50%. • Acetaldehyde was attained if hydrous ethanol was used in catalytic dehydration. • Diethyl ether production was simulated rigorously based on the laboratory results. • Useful techno-economic analysis was conducted for diethyl ether production. • Formation of acetaldehyde negatively influenced the process profitability. • Removal of acetaldehyde via adsorption could enhance the process profitability. [ABSTRACT FROM AUTHOR]

Methanol production from biomass in the light of direct chemical looping processes is a promising alternative for green and sustainable methanol production, given that traditional methanol synthesis uses fossil energy as the feedstock and consumes considerable energy. In this study, two methanol production routes from biomass through direct chemical looping processes are proposed: The first configuration (Configuration 1) is based on biomass chemical looping gasification (B-CLG); the second (Configuration 2) is based on biomass chemical looping hydrogen production (B-CLHP). The optimal operating parameters of the two chemical looping processes were determined by parameter analysis. Comparative thermodynamic and techno-economic analyses were then conducted to observe the thermodynamic and economic performances of the two routes. The thermodynamic results indicated that both configurations can achieve similar energy and exergy efficiencies (∼60%). Exergy analysis revealed that the exergy efficiency of B-CLG (75.61%) is higher than that of B-CLHP (71.59%), the syngas conditioning process in Configuration 1 has a greater exergy loss (2108 kW compared to 1001 kW), and the exergy efficiency of the methanol synthesis and purification process in Configuration 2 is higher (90.42% compared to 82.9%). Techno-economic results show that Configuration 2 is more economically feasible, with levelized cost of methanol, net present value, internal rate of return, and dynamic payback period of 383.59 USD/t, 4.13 million USD (MUSD), 9.45%, and 8.29 y, respectively, being superior to those of Configuration 1 (479.46 USD/t, 18.65 MUSD, 16.65%, and 18.52 y, respectively). [Display omitted] • Direct chemical looping based methanol production routes are proposed and compared. • The proposed routes have similar energy and exergy efficiencies of around 60%. • Direct chemical looping hydrogen production based route is economically competitive. [ABSTRACT FROM AUTHOR]