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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]

Buildings have significantly contributed to high energy demand (30.3%) and GHG emissions (26.1%) worldwide. Consequently, many developed countries have set carbon-neutral targets for 2050, mandating that all new constructions thereafter be designed as net-zero emission buildings (NZEBs). To achieve this goal, one of the most practical sources of renewable energy, solar power, is employed in this study to estimate the economic feasibility of implementing NZEBs in the non-residential sector of the United States. While past studies have typically estimated the economic payback period of solar power technology by assuming fixed values for "PV energy conversion rates (%)" and "investment costs ($USD)", this paper carefully investigated the economic feasibility of "solar-based NZEBs" by precisely tracking these dynamic future changes in PV panels. These techno-economic variables were carefully predicted using a statistical technique known as the five-parameter logistic (5 PL) function. The results show that Site 4 is the only solar region suitable for implementing "PV-integrated NZEBs", reaching a payback period of 8.44 years in 2040 (Scenario 1). Furthermore, with small technological improvements in PV energy efficiency (%), buildings located in Site 3 and Site 4 can meet the net-zero emission target with payback periods of less than 10 years in 2034 (Scenario 2). Finally, starting in 2044, the "PV-integrated system" will have a payback period of approximately 7 years in most study locations, even without federal support for the solar investment tax credit (SITC). Accordingly, federal support for solar power generation will be more effective if the SITC rate is gradually reduced by 2.5% annually starting in 2033. In conclusion, this paper suggests the economic feasibility of implementing solar-based NZEBs in the United States non-residential sector by considering the synergetic effect of technological improvement and cost reduction in PV-integrated systems. • This study predicted the cost and efficiency of PV panels to estimate the economic feasibility of solar-based NZEBs. • The cost reduction and technical advancement in PV panels can remarkably improve the economics of solar power. • The 5 PL function is systematically modeled to predict the total investment cost and efficiency of PV panels. • In most study locations, solar-based NZEBs are projected to achieve a 7-year payback period beginning in 2044. • The federal support for the SITC rate (%) is recommended to be gradually lowered starting in 2033. [ABSTRACT FROM AUTHOR]

In this study, the LNG cold energy recovery combined with a freezing-centrifugal desalination system is proposed. The thermodynamic and economic analysis is also carried out of the proposed system. To verify the results of sea ice centrifugation process, experimental analysis of sea ice centrifugal desalination is presented based on different types of sea ice: slurry and solid, which are prepared by the method of suspension crystallization method and progressive freezing method, respectively. The experimental outcomes demonstrated that higher rotation speeds and longer centrifugal times enhanced the desalination rate but resulted in decreased freshwater yield in both slurry and solid ice. For the slurry sea ice, achieving a rotation speed of 5000 rpm and a centrifugal time exceeding 3.0 min resulted in melted water with a salinity level below 0.05%, satisfying the standards of drinking water. Moreover, the unit product cost, payback period, and unit cost of CO 2 emission reduction for the proposed system are 0.49 $/t, 3.25 years and 18.92 kg/$, respectively. While the unit product cost, payback period, and unit cost of CO 2 emission reduction for the conventional system are about 0.84 $/t, 4.80 years, and 15.66 kg/$, respectively. Hence, the proposed system shows higher economic and environmental performance. • The proposed system has the function of desalination, LNG cold energy recovery and ice storage. • Salt in slurry sea ice can be removed more efficiently than in solid sea ice. • The desalination costis 0.49 $/t of the proposed system. • The payback period of the proposed system is 3.25 years. [ABSTRACT FROM AUTHOR]

An experimental investigation was conducted on a novel design of a stepped basin tubular solar still (SBTSS) and a tubular solar still (TSS) under different water depths/equivalent water depths in the weather conditions of Egypt. The proposed SBTSS design utilized stepped basins inside the TSS, which allowed for reducing the water depth for the same amount of salt water and volume of air, along with the benefits of a double slope solar still inside the SBTSS. Based on the experimental results, the thermal and exergy efficiencies were obtained for both TSS and SBTSS. The results showed that the novel SBTSS design had higher hourly and accumulated productivity, as well as thermal and exergy efficiencies, compared to TSS at different water depths. The maximum daily productivity recorded was 3826 mL/m2/day and 2572 mL/m2/day for SBTSS and TSS, respectively, at a depth/equivalent water depth of 1 cm. Moreover, the results indicated that the enhancement in accumulated productivity for SBTSS was 42.28% and 38.85% compared to TSS at water depths of 1.5 cm and 2 cm, respectively. The thermal efficiency for SBTSS and TSS was found to be 36.71% and 24.59%, respectively, at a water depth/equivalent water depth of 1 cm/10L, with an increment of 49.29% for SBTSS. Additionally, the cost per liter (CPL) of potable water and payback period for SBTSS were about 0.0159 US$/L and 124 days, respectively, at an equivalent water depth of 1 cm with a 10-year still life considered. On the other hand, the CPL of potable water and payback period for TSS at the same water depth were about 0.0185 US$/L and 146 days, respectively. [ABSTRACT FROM AUTHOR]

The concept of NZEB (Nearly Zero Energy Building) has a promising share to fulfill the future of sustainable development goals. However, exploiting renewable-based THESs (Trigeneration Hybrid Energy Systems) for providing the energetic demands of the building sector needs further attention. In this regard, the present paper proposes a sustainable THES driven by a biogas-fueled gas engine. The bottoming systems comprise absorption/electrical chillers (AC and EC), organic Rankine cycle (ORC), solar collector (PTC), and an auxiliary boiler. A detailed sustainability evaluation framework (technical and eco-environment) is derived to approve the performance of the THES. Within this procedure, the best working fluid of the ORC is firstly selected and then the sensitivity of the system performance to the design variables is assessed by a comprehensive parametric study. To make the derived framework more applicable, a case study building is considered and the proposed THES is sized to meet its electricity, heating, and cooling energies. The analyses proved that R123 shows the best techno-economic performance among six investigated ORC working fluids. The parametric study illustrated that the highest and lowest sensitivity of the THES's performance is related to the outlet temperatures of EC condenser and AC evaporator. Furthermore, the energy, exergy, and economic efficiencies of the THES for the case study building are 61.78%, 25.24%, and 44.77%. In this condition, discounted payback period is 7 years, demonstrating the feasibility of this proposal. The maximum CO 2 emission is released in November, with a total electricity generation of 320 MWh. [Display omitted] • Renewable-based hybrid system is introduced to produce cold, heat, and power. • Comprehensive sensitivity analysis is done to assess impact of some decision variables. • A case study building is considered to boost NZEB concept based on the proposed system. • Energy efficiency and payback period is 61.78% and 7 years for the case study building. • Using renewables in energy systems to reduce fossil fuel share has great significance. [ABSTRACT FROM AUTHOR]

The development of cold storage systems with solar-integrated thermal energy storage (TES) could be an exciting alternative energy solution to fossil fuel-based cold storage. For this novel technology to be commercially applicable, significant scientific research is required. Although few attempts have been made in this area, the limitations of existing studies encourage further investigation to advance the field. This research aims to develop a solar-based hybrid cold storage (SHCS) system and perform the techno-economic analysis (TEA) of the system to address the existing research challenges and enhance the understanding of commercial applications. An SHCS of L 4.88 m × W 2.44 m × H 2.44 m has been developed by integrating 500 kg phase change materials (PCM) of ethylene glycol aquas solution, as latent thermal energy storage (LTES), to store energy and provide backup during off-solar time. Three different modes of the power system, Latent Thermal Energy Storage (LTES)-based, Electrochemical Energy Storage (EES)-based (Battery), and no storage; and three types of construction materials, sandwich polyurethane (PUR) panels, sandwich expanded polystyrene (EPS) panels, and concrete were considered in the TEA of the SHCS. The power mode with LTES showed a nearly 1.5 years shorter payback period and 130 % higher net present value (NPV) than the EES mode. The solidification and melting characteristics of the LTES system are uniform at different levels during charging and discharging, which may enhance the heat transfer rate. The PCM system is remarkable in that it maintains a storage temperature of 3 °C in the fresh food chamber for approximately 13 h without an external source of energy. Regarding the construction material of SHCS, sandwich PUR panels outperformed concrete owing to their lower density (40 kg/m3), improved thermal insulation, and modular nature, though the rate of return of PUR panels is slightly lower (0.26 % and 0.81 %) than its counterparts due to its higher initial cost. Overall, it was found that PUR panel-made SHCS integrated with an LTES system provides better techno-economic performance when energy storage is necessary and could be considered to scale up the system in the future for commercial application. • A novel PCM integrated solar hybrid cold storage (SHCS) system was developed. • A techno-economic analysis was performed to observe the economic feasibility. • Charging PCM for 6 h gives 20 h backup, keeping cabin temperature at 5–8 °C. • LTES-based mode showed a shorter payback period than EES-based option. • Sandwich PUR panels offer lower density, better thermal resistance, and mobility. [ABSTRACT FROM AUTHOR]

This paper aims to investigate the performance of an Earth Air Heat Exchanger (EAHE) to improve the indoor conditions of an industrial poultry building after its installation, considering the optimal position and installation configuration (separate or collected inlets), which have not been addressed previously. In this regard, an industrial broiler house containing 20,000 chickens equipped with four cooling pads operated by a mechanical ventilation system located in Biskra, Algeria, was simulated with six scenarios, including the original. The model developed is verified with the field test measurements and experimental and numerical data in the literature. The results showed that optimizing the cooling pad position increases average indoor air temperature and velocity distribution by 0.1% and 8%, respectively. Moreover, the position and configuration of installing the EAHE inlets play an important role in uniforming indoor air distribution. Scenario 3, with 80 EAHE inlets versus exhaust fans, has the best indoor air uniformity, with a maximum velocity and temperature difference between its sections of 1.15 m s−1 and 1.4 K, respectively. Overall, EAHE showed a good ability to cool and maintain appropriate indoor air temperatures, achieving a difference of 15 °C between inside and outside, in addition to providing annual energy savings of 921,600 kWh/year and reducing 30,643 tons of CO 2 emissions during its lifespan, in contrast, its simple payback time estimated 4 years. • The contribution of an earth air heat exchanger in improving the indoor conditions of a poultry house. • Simulate the potential design, position, and installation configuration scenarios. • Installing the earth air heat exchanger improved the indoor temperature and velocity. • The third scenario is the optimal design for indoor air uniformity. • The simple payback period of the earth air heat exchanger is four years. [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]

To solve the problems of existing buildings with high energy consumption, the government has organized for private sectors to implement green retrofits for the Public-Private-Partnership reconstruction of buildings (PPP-BR). However, most private sectors are reluctant to implement green retrofits because of high costs, low benefits and long payback periods. The existing literature analyzed PPP-BR projects, barriers and incentives of green retrofits. However, it does not provide any quantitative method to illustrate the effectiveness of incentives and the strategy changes of investment groups. To fill this gap, this paper reveals the game strategy change of encouraging green retrofits and implementing green retrofits in government groups and investment groups through an evolutionary game analysis. On this basis, the case simulation method is used to change the parameters to analyze the incentive effectiveness and the strategy change of green retrofitting by investment groups. It can be found that the final evolutionary game results will take on two forms: first, the government groups encourage green retrofits, and the investment groups implement green retrofits; second, the government groups do not encourage green retrofits, and the investment groups do not implement green retrofits, respectively. When the government groups highly encourage green retrofits, the investment groups will also increase its willingness to implement green retrofits. The simulation results show that reducing costs and increasing benefits will promote green retrofits; however, this incentive measure will be limited by objective conditions. Comparatively speaking, the policy incentive measures are less affected by an objective environment, but positive policy incentive measures will get negative effects. In contrast, negative policy incentive measures that may cause problems will be most effective. Therefore, the combination of positive and negative policy incentive measures will be the better and more moderate way to promote green retrofits for PPP-BR. Image 1053 • Evolutionary game model could analyze green retrofit evolution strategies of two groups. • Case simulation method could analyze incentive effectiveness quantitatively. • Reducing costs and increasing benefits promote green retrofits but limiting by environment. • Single positive policy incentive measures will get negative effects. • Combination of positive and negative policy incentive measures is the better measure. [ABSTRACT FROM AUTHOR]

Crude Distillation Unit (CDU) represents significant challenge for retrofitting and energy optimisation as the most energy intensive consumer in a conventional crude oil refinery. Pinch Technology and its based-methodologies are found primary keys for decades to energy savings in refining industries for a range of common economic-based and environmental objectives or applications. Typical benefits in energy savings are reported within 20–40% of original designs. However, such savings are limited and questioned when modern refiners are dealt with. The current paper addresses the revamping of a modern refinery exhibiting an existing high energy efficiency (≈93%). This implies the maximum potential energy savings would only be 7% at current process conditions. The present research proposes an algorithm that tackles energy recovery of modern refiners, enabling additional savings beyond the energy targets set by the existing process. The algorithm starts by process simulation and validation against real plant data, followed by a network optimisation, e.g. stream splitting, to reach the energy targets set by Pinch Analysis. The energy targets are then moved to another lower level by performing potential process modifications to reduce the energy consumption further. Results showed that the current modern refinery unit could reach its energy targets by stream splitting modifications with hot energy savings of 2.69 MW. Process modifications resulted in additional energy savings of 31.3% beyond the current level of the existing plant alongside less than a year of payback period for estimated capital investment. An environmental assessment is performed, and comparable reductions were obtained with respect to greenhouse gas, with reduction in CO 2 emissions by 45.1%. The proposed retrofit methodology is applicable to minimising energy consumptions of refiners including modern units to achieve energy levels beyond energy targets by new process modifications. Image 1048 • A systematic approach for revamping an existing energy efficient refinery (≈93%). • A rigorous simulation model for a modern CDU with a maximum error 3%. • Additional energy savings beyond the Pinch limitation. • The novel applied process modifications led to 45% reduction in CO 2. [ABSTRACT FROM AUTHOR]

The Philippines is an emerging solar photovoltaic (PV) market, installing ∼1 GW in the span of last 2 years. This growth was enabled by the enactment of supporting policies: feed-in-tariff (FIT) and net-metering (NM), despite increasing criticism on the latter. This study addresses the terms, conditions and effectiveness of these policies reflected as the interannual growth in PV power production with respect to the potential realizable capacity in the country. Additionally, a life cycle cost and greenhouse gas (GHG) emission reduction analysis is presented to demonstrate the economic viability and environmental impact of implementing an on-grid residential PV installation in the country – in the context of these policies. Financial results showed that theoretical 100 kW-FIT/1.89 kW-NM PV projects were attractive and would lead to a GHG emission reduction of 102.9 tC0 2 e and 1.9 tC0 2 e, respectively. The FIT case had a Net Present Value (NPV) of PHP 4.7M (∼EUR 84k), a benefit-cost ratio of 4.17, and a simple payback period of 4.1 years. Net-metering had a positive NPV of PHP 27k (∼EUR 482), a benefit-cost ratio of 1.50, and a simple payback period of 7.8 years. The main profitability drivers were found to be the initial capital cost for FIT and the avoided retail electricity costs for NM. Project development can be further promoted by providing financial grants on top of FIT/NM and by modifying high-risk conditions such as FIT's "first-come-first-served" basis. The theoretical minimum viable FIT Phase 3 rate was also calculated to be 4.20 PHP/kWh (∼0.07 EUR/kWh). [ABSTRACT FROM AUTHOR]

A flexible retrofitting method for thermal-energy-storage-coupled thermal power units is proposed. The exergy flow Sankey diagram and efficiency of the three charging methods was analyzed in detail, and comparative data were provided. The new thermal energy storage mode coupled with steam ejectors was the optimal solution, with a significantly higher round-trip efficiency than the published results. Further study of the mode revealed slight temperature variations in the molten salt did not affect system efficiency. As the extraction of reheated steam decreases and the extraction of main steam increases, the minimum generation capacity of the unit decreases continuously, reaching a minimum of 40 MW (6.67%). In contrast, the maximum output of the unit at 100% THA release can reach 682 MW, which caused the unit load to change from 26-100% to 6.67–113.67% before and after the retrofit. As the ejection coefficient increased, the round-trip efficiency increased significantly, corresponding to 73%, 77%, and 80% at the study points. The mathematical model based on principal component analysis can effectively characterize the relationship between the ejection coefficients, extraction of main steam, extraction of reheat steam, low valley peaking rate, peak modulation rate, and round-trip efficiency, providing a signal conversion basis for automatically controlling peaking commands during unit operation. Finally, the benefits before and after retrofitting were analyzed in terms of thermal plant operation, proving that the payback period of the system was 4.09 years. Peak tariff and auxiliary service revenue are the most critical parameters affecting the payback period, and a 10% reduction in the peak tariff corresponds to an increase in the payback period of one ∼ two years. The results of this study provide substantial theoretical and practical guidance for the flexible retrofitting of thermal power units. [Display omitted] • Thermal power unit coupled with ejector and TES proved to be both technically and economically. • The minimum and maximum loads of the retrofitted units are 6.67–113.67% compared to 26–100%. • Round-trip efficiencies of 73%, 77% and 80% correspond to ejection coefficients of 1, 1.5 and 2. • Exergy losses and efficiencies of different integration modes were detailed analyzed. • The system payback period is 4.09 years and the peak tariff is the most critical factor. [ABSTRACT FROM AUTHOR]

Nitrogen oxide emissions, also referred to as NOx including NO and NO 2 are hazardous to human life and have negative effects on the environment. Wet and dry treatments have both been explored as methods to significantly minimize these emissions. The wet process offers several benefits, the most notable of which are the flue gas adaptability, low operating temperatures, and the lack of poisoning and catalyst inactivation. In the research work, a NO X filter is being developed, with composite material for better transparency and non-reactive nature. Mechanical and electronic components have been employed to develop a stable and rigid experimental setup that effectively handles environmental challenges. Different tests are performed during performance analysis with known quantities of NO X through cylinders and varied the flow rate of ambient air. The concentration of NO X , H 2 O 2 , nitric acid, and other parameters were captured to get the optimum configuration that will provide maximum efficiency. The envisaged cost of implementing a solar tree-based air pollution monitoring and control system is estimated at $2796. This cost projection serves to exemplify the techno-economic analysis of the system, showcasing its potential to contribute to a cleaner environment and facilitate renewable energy utilization. The different financial model payback periods of the system are from 3.12 to 5.21 years. The developed system benefits people with respiratory health issues, elderly people, children, and infants, sports enthusiasts, traffic police persons, street hawkers or vendors, and people living in areas where the pollution level is high. • Development of solar tree based air pollution monitoring and control system. • Real time monitoring and control of different air pollutants (PM, NO 2 , CO etc.) • Techno economic analysis with different financial model of the system. • Payback periods of the system are 3.12–5.21 years under different schemes. [ABSTRACT FROM AUTHOR]

Pyro-hydrolysis of CaCl 2 waste for HCl regeneration, which entails high temperatures and substantial energy consumption, remains challenging due to concerns regarding cost and CO 2 emissions. This study presents a low-emission process integrating CO 2 capture with SiO 2 -assisted CaCl 2 pyro-hydrolysis technology for HCl regeneration, with a comparative techno-economic feasibility evaluation using Aspen Plus. When employing the same process components as for FeCl 2 pyro-hydrolysis, it is demonstrated that 18 wt % HCl acid, a similar concentration to that generated from FeCl 2 pyro-hydrolysis, can be produced from SiO 2 -assisted CaCl 2 pyro-hydrolysis with a higher energy consumption. The CaCl 2 pyro-hydrolysis were further optimized with the integration of water recycling and exhaust heat recovery, reducing the water and energy consumption down to −1.1 kg/kg-HCl gas and 21,601 kJ/kg-HCl gas, respectively. The water consumption is lower than that of the FeCl 2 process (+ 5.4 kg/kg-HCl gas) and the energy consumption is at a comparable level with the FeCl 2 process (20,989 kJ/kg-HCl gas). Furthermore, with the integration of a two-stage CO 2 capture unit, the CO 2 emission was reduced down to 0.07 kg/kg-HCl gas with a CO 2 capture efficiency of 91%. Economic analysis results reveal that the capital and annual operating cost for the CO 2 capture coupled CaCl 2 pyro-hydrolysis is 12.5 million A$, and 4.1 million A$, respectively. The NPV, IRR, and payback duration of 13 million A$, 12.04%, and 8.6 years, respectively, could be achieved for the optimized CaCl 2 pyro-hydrolysis scenario. The sensitive analysis results suggest that the HCl market price and annual operating cost are the most influential parameters and should be especially considered in a future deployment. • Techno-economic analysis of SiO 2 -assisted pyro-hydrolysis of CaCl 2 was conducted. • SiO 2 -assisted pyro-hydrolysis of CaCl 2 is comparable with the FeCl 2 process. • CO 2 emission can be reduced to 0.07 kg/kg-HCl with a capture efficiency of 91%. • NPV, IRR, and payback period were estimated to be A$ 13 M, 12.04%, and 8.6 years. • Pyro-hydrolysis of CaCl 2 waste for HCl regeneration is techno-economically feasible. [ABSTRACT FROM AUTHOR]

The exploitation of low-grade heat sources that are available from existing thermal systems processes consists a promising concept for the production of energy. In this research, the integration of an Organic Rankine Cycle (ORC) unit on a supermarket transcritical CO 2 refrigeration system with ejectors is investigated, which is supplied with low-grade heat by the common discharge of the compressors. The optimization analysis proves that for different combinations of CO 2 temperature and pressure in the ORC evaporator, as well as for different ORC condensation temperatures, there is a different optimum ORC evaporation temperature that leads to the highest energy production. Concerning the annual performance analysis conducted for the city of Athens, Greece, operation with isopentane is found to provide the greatest energy production with 10.36 MWh annually, which corresponds to a 3.69% reduction in the refrigeration system's energy consumption. For operation under the ambient temperature of 40 °C, the corresponding reduction of the refrigeration system consumption due to the presence of ORC is 7.54%. Finally, the financial analysis reveals that toluene is the most advantageous solution, leading to a payback period of 3.9 years, with a net present value by the end of the project's lifetime equal to 34.32 k€. • Integration of an Organic Rankine Cycle to a transcritical CO 2 refrigeration system. • Optimization analysis of the system for operation with different working fluids. • Energetic and financial investigation for the case of Athens, Greece. • Isopentane leads to annual production of 10.36 MWh with 3.69% energy savings. • The lowest payback period is 3.9 years and it is achieved for operation with Toluene. [ABSTRACT FROM AUTHOR]

Buildings are one of the major sectors responsible for high energy demand and GHG emissions worldwide, which is driving expectations for implementing net-zero emission buildings (NZEBs) in many countries. Specifically, most developed countries have a carbon-neutral target set up for 2050, mandating all new buildings from then to be constructed as net-zero emission. Therefore, this paper investigated the economic feasibility of implementing NZEBs in the United States residential sector by combining a heat pump system with two renewable energy sources that are heavily supported by the federal government: solar and geothermal technologies. First, this study clearly demonstrates that "net-zero emission" is the most challenging task among neutralizing the energetic, economic, and environmental by-products from building operations. Moreover, this study analyzed the payback periods of multiple NZEB scenarios by considering the potential future changes in technology and policy necessarily required to meet the net-zero emission target by 2050. For reference, the technological and institutional factors were represented by "PV energy conversion rate" and "CO 2 equivalent price of emission trading scheme (ETS)", respectively. The results show that improving the PV energy conversion rate is much more effective in reducing the payback period of NZEBs compared to raising the CO 2 equivalent price of ETS. However, the growing public awareness for this CO 2 regulation policy will soon bring synergistic effect with the advancement of PV technology. In conclusion, this research framework clarifies the rather vague technological and institutional challenges that should be addressed to allow NZEBs to become economically feasible in the United States residential sector. Therefore, many building engineers, PV technicians, and policymakers should actively contribute to improving the techno-economic drivers for implementing NZEBs by 2050. • Most developed countries are mandating all new buildings from 2050 to be constructed as net-zero emission. • Net-zero emission target is hardly achievable without the simultaneous energy supply from solar and geothermal. • PV energy conversion rate should reach 43.50% to meet the net-zero critical point. • Improving the PV energy conversion rate is highly essential for reducing the payback period of NZEBs. • The growing public awareness of ETS will bring synergistic effect with the advancement of PV technology. [ABSTRACT FROM AUTHOR]

Significant energy subsidies are believed to be the main factor that has resulted in high energy intensities of Iranian industries. The Subsidy Reform Act of 2010 was directed at modifying energy consumption pattern and fostering energy efficiency enhancement. This study aims at analyzing the effect of energy subsidy reform on promoting energy efficiency in six energy intensive industries of Iran. In order to do so, the energy efficiency practices that have not been adopted after the implementation of the first phase of energy subsidy reform are investigated. Data analysis reveals that if financially interesting investments are determined as those with payback periods less than three years, there exist more than 80 PJ energy saving potential that have not been realized yet. The large amount of missed energy savings demonstrates that before complete energy subsidy removal, barriers that discourage investors from moving forward with energy efficiency projects should be removed. These barriers can be classified as informational barriers, financial barriers and administrative and regulatory barriers. Inspired from product life cycle, a sequential strategy is proposed to strengthen the positive impacts of increasing energy prices and to weaken the negative effects of barriers. The strategy is composed of an introductory stage in which deployment of energy efficiency solutions starts to grow without further increasing energy prices; a growth stage when viable and interesting energy efficiency solutions are adopted and then the efficiency market becomes mature. Next phases of energy subsidy reform can be implemented at this stage. [ABSTRACT FROM AUTHOR]

Poultry litter can be converted into thermal or chemical energy which can assist in meeting the energy needs. The current study focuses on a critical review of the cause-and-effect analysis of hydrothermal gasification (HTG) process yield, safety, and economic analysis. HTG batch and continuous technologies have been investigated, each with its own set of constraints. For example, resident time in a continuous reactor ranges from a few seconds to minutes, whereas it ranges from several min to hours in a batch reactor. Process parameters temperature, pressure, resident time, and solid content also contribute to the syngas quality, but temperature has the most significant effect among all. Syngas quality can be improved by managing process parameters such as 500–550 °C, 25–28 MPa, 120–150 min resident time, and 10–20% of the solid biomass content. Catalyst application in HTG promotes more hydrogen production. HTG is environmentally sustainable as compared to direct land disposal of biomass. H 2 production costs range from $ 1.94 to 7.0 per kg and an investment payback period of 3.3–5.16 years. Process safety approaches that are appropriate to conduct HTG safety analysis have been investigated, and some control measures have been proposed which can be applied to make the HTG process safer. Finally, HTG future perspective and recommendations have been given based on current work. • Strengths and weaknesses of hydrothermal gasification process are summarized. • HTG optimum operating conditions are 500–550 °C, 25–28 MPa, 120–150 min, and 10–20% solid content. • Future perspective and recommendations are proposed for hydrothermal gasification process. • The safety and control measures of hydrothermal gasification process are analyzed. • Economic and environmental performances of hydrothermal gasification process are reviewed. [ABSTRACT FROM AUTHOR]

Due to the global energy crisis worsening, numerous businesses have prioritized energy conservation and consumption reduction. However, in mines with multiple main fans, the main fans' operation efficiency is low to meet the ventilation on-demand, and the ventilation system's energy consumption is very high. This paper proposes an energy-saving control strategy for ventilation on demand with multiple fans network, which can save much energy in mines. We use the circuit method to calculate the operating condition parameters required for the joint control of multiple main fans by analyzing the influence features of multiple fans' mutual disturbance. We study the advantages and shortcomings of the traditional fan control method and create control strategy expressions for multiple fans. The two-step fan control strategy uses the adjusting wheel blades' angle method to determine the high-efficiency operating angle and the modulating fan speed method for accurate air quantity control. Furthermore, the effectiveness of the control strategy in ventilation on demand and fan energy-saving are verified on the three-dimensional complex ventilation pipe network experimental platform. The research results show that, compared to the two typical fan control strategies, our control strategy can save energy by 27.74% and 26.92%, respectively. If this strategy is applied to a mine with two main fans rated power of 500 kW, it can save energy 2,429,806 kW per year, saving USD 442.69 per day or USD 161,582.1 per year. The payback period for this strategy is approximately 14.1 months. Therefore, this research can provide a promising step towards intelligent control of air quantity on-demand while indicating enormous potential for energy savings in mine ventilation systems. • Propose a novel control strategy for multiple fans to improve main fan operating efficiency. • Analyzed the mutual disturbance characteristics between multiple main fans in a complex ventilation network. • Created control strategy expression for multiple main fans. • Verified the ventilation on-demand and energy-saving effects of multiple fans control strategy on a complex pipeline network platform. [ABSTRACT FROM AUTHOR]

The study aimed to investigate the feasibility of utilizing atmospheric water generation systems (AWG) in the agricultural sector by implementing a liquid desiccant-based moisture harvesting system. The system was modeled using an adiabatic simulation approach to evaluate the performance of the system in terms of moisture removal rate during the dehumidification process. Additionally, an economic analysis was conducted to compare the costs and payback period of three different water extraction scenarios for the agricultural sector in Jordan. The scenarios considered the Levelized Cost of Water (LCOW) and payback period over a 20-year life cycle. The results of the study showed that the average annual water extracted during the tomato cultivation period was 2,198 m3 and 1,451 m3 for the strawberry cultivation period. The payback period for non-subsidized water selling prices was between 6 and 12 years and between 3 and 4 years if water was purchased from artesian wells. The LCOW for the different scenarios ranged from 1.92 USD/m3 to 2.91 USD/m3, depending on the type of crop and the desiccant solution used. Overall, the study demonstrated that the implementation of an AWG system in the agricultural sector can be a viable option with a reasonable payback period and cost-competitive LCOW. • Feasibility of using AWG in agriculture via liquid desiccant moisture harvesting. • Economic analysis of water extraction scenarios in Jordan. • AWG showed average annual water extraction of 2,198 m3 for tomato cultivation. • Payback period for non-subsidized water selling prices was 6–12 years. • AWG implementation can be a viable option with a cost-competitive LCOW. [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]

To take into account the crop growth of greenhouse and reduce energy consumption, this study investigated to optimize and retrofit a typical solar greenhouse in the severe cold climate of China into a net-zero energy solar greenhouse (NZESG). The envelope passive insulation measure and roof flexible photovoltaic (PV) technique are innovatively combined and some optimization cases were proposed based on simulation and analytical studies. The foamed cement insulation boards with different thicknesses and envelope positions were added as 11 passive insulation retrofit cases. The flexible PV panels in checkerboard (PV1), horizontal (PV2) and longitudinal (PV3) arrangements were positioned on the greenhouse roof and their electrical energy was estimated through PVsyst software. The optimal case was obtained based on the local technical standard for nearly zero energy consumption buildings and energy-saving, carbon reduction, payback period and cost multi-objective entropy weight method. The key finding is that passive energy-saving retrofit Case (a) & PV1 has the highest comprehensive score and is the optimal NZESG case. Its investment cost and payback period of Case (a) & PV1 are 45526.40 CNY and 5.23 years respectively. Case (a) adopts 50 mm foamed cement board with external insulation. Although the effect of energy-saving and CO 2 reduction is poor, Case (a) has the shortest payback period and the lowest cost. PV1 has the lowest investment and higher power generation. It also shows that the investment payback period and cost weight are high, which are the key parameters for comprehensive evaluation of the retrofit cases; The entropy weight method is objective and scientific. The retrofit measures and optimization method can facilitate the promotion and application of NZESGs. [ABSTRACT FROM AUTHOR]

With the widespread development of renewable energy sources, collective self-consumption (CSC) has been increasingly considered over recent years to sell the surplus of generated power to nearby consumers. However, appropriate energy allocation rules must be designed to efficiently share the energy among consumers. This paper aims to study two kinds of repartition keys for a CSC operation with multiple producers in the framework of an industrial multi-energy microgrid located in France. The default key considered in French regulations is compared to an optimized key based on the maximization of the income for the producers, in such a way as to maximize profitability by allocating the energy according to the consumers' electricity purchase price. The simulation results show that a CSC with an optimized key decreases the total electricity bill by 11.7%. For some producers, a reduction in the payback period between 6 months and 5 years is observed, compared to the case without CSC. A sensitivity analysis on economic assumptions is also proposed. The results show that the grid use tariff exemption is a key lever and makes it possible to find a more profitable selling price for producers and consumers, and to significantly reduce the payback period for investors. • A collective self-consumption (CSC) operation for an industrial microgrid is studied. • Two kinds of energy allocation rules are proposed and compared. • An optimization problem allocates the energy to increase the producers' income. • The CSC allows electricity bill savings and improves the profitability. • The results are sensitive to the CSC tariff and a grid use tariff exemption. [ABSTRACT FROM AUTHOR]

Community shared solar (CSS) program has great potentials in contributing to the complete decarbonization of the power sectors worldwide. Few research have focused on its potential diffusion from the user perspective. This paper fills the gap by conducting a survey-based unlabeled choice experiment in the Guangdong Province, China to investigate the determinants of potential users' willingness to participate in CSS programs. We analyzed the survey data using a random parameter logit model. Our results show that users are more likely to participate in CSS programs with lower upfront payment, trialability, shorter payback period, a public utility as provider and larger impact on climate change mitigation. However, they are likely to accept longer payback period in CSS programs with higher participation rate because of the potential benefit from interpersonal communication. Users' previous knowledge of CSS programs and income will also increase their willingness to participate in CSS programs with higher upfront payment. Our results provide important implications for designing policies and business models to promote the distributive renewable energy in China. • Community shared solar is widely accepted among surveyed individuals in our choice experiment. • The business model, and the ownership structure of community shared solar affect its potential adoption. • The interpersonal communication and public promotion of community shared solar program can increase its popularity. [ABSTRACT FROM AUTHOR]

Bio-dimethyl ether (bio-DME) is a promising advanced biofuel for the disposal of conventional diesel fuel, which is one of the most relevant sources of particulate matter and nitrogen oxides in urban centres and is completely banned from some European cities. DME is produced in two ways: dehydration of methanol produced from syngas (indirect or two-step process) and direct synthesis from syngas (direct or one-step process). This work aims at studying, optimizing and economically and environmentally assessing a novel conceptual design to convert biogas into bio-DME. Contrarily to traditional DME processes, the synthesis from biogas strongly benefits from milder conditions due to the smaller plant size, rural context, and biological feedstock fluctuations, motivating an ex-novo techno-economic feasibility study and sensitivity analysis performed in Aspen HYSYS V11 suite. The proposed process layout allows converting 1045 kg/h of silomais-based biogas (67%v/v CH 4 content) into 516 kg/h of bio-DME at ASTM D7901-14 standard specification for fuel purposes. Sensitivity analysis identifies reactor temperatures as important process variables and defines three key performance indicators as: (i) global yield of the process; (ii) DME versus methanol selectivity; (iii) and the thermal load for the downstream section. The last one is computed as the sum of reboiler and condenser duties normalized with respect to the DME massive flowrate, and the study provides 1.05 kWh/kg DME as downstream section global specific duty. The process provides an innovative way to face the EU RED II challenge due to a 49.4 wt.% bio-DME yield and also thanks to a competitive 9.5 yr of payback period. [Display omitted] • A conceptual design for bio-dimethyl ether (DME) synthesis from biogas is broached. • Sensitivity analysis on the main operational parameters is performed. • Greenhouse gas emissions are simultaneously evaluated for the purification section. • CAPEX/OPEX are detailed estimated providing an appealing payback period (PBP). [ABSTRACT FROM AUTHOR]

Generally, Montazer Ghaem Combined Cycle Power Plant (MGCCPP) is equipped with natural draft dry cooling towers (NDDCT) and its performance strongly depends on environmental conditions such as wind speed. Thus, the present study aims to evaluate the effects of wind blowing on the cooling towers (CTs) efficiency and propose methods to improve their performance. It can help increase plant efficiency and decrease energy loss, which leads to cleaner production. For this purpose, the cycle of MGCCPP is modeled simultaneously using CFD and energy-exergy analyses for the first time. Moreover, the effect of windbreak walls (WBWs) on CT performance and CCPP are addressed. The results of CFD analyses are used to recognize the behavior of the towers in different wind speeds and deriving heat rejection. Based on obtained results, using the WBW in the prevailing wind leads to about 6.5 MW excess power in each unit. According to the economic analysis, the payback period of the three proposed plans is 14, 15.5, and 16 months, which is fully justified. • Three NDDCTs s are modeled using CFD analyses. • All the cycle equipment are modeled using EES. • Wind break walls are used to reduce the wind effects. • 3E (Energy, Exergy and Economical) analyze is done for the plant. • The payback period of the three proposed plans is 14, 15.5, and 16 months. [ABSTRACT FROM AUTHOR]

The objective of this study is to analyze four different poultry litter conversion technologies including fast pyrolysis (FP), slow pyrolysis (SP), anaerobic digestion (AND), and aerobic digestion (AD) in Pakistan, India, and Bangladesh. Strengths, Weaknesses, Opportunities and Threats analysis has been used to analyze these technologies comprehensively. The environmental performances of these technologies have been reviewed based on the previously published works. The economic analysis of these technologies has done by calculating plant-based payback period and gross profit. The results show that FP, SP, and AND technologies outperformed the land disposal method in both economic and environmental aspects. FP involved the highest investment but shortest payback period while AND process was feasible in technical, political, and environmental aspects with a longer payback period. The current policies in these countries have been analyzed, and it could be concluded that they do not use the poultry waste effectively. As these countries mainly focused on biological conversions and neglected the thermal technologies. The findings of this study can provide effective insights for policymakers to draft poultry waste-related policies for achieving sustainable and carbon-neutral valorization of poultry litter. [ABSTRACT FROM AUTHOR]

Low global warming potential hydrofluorocarbon (HFC)-ionic liquid (IL) mixtures are a promising type of environmentally friendly binary working pair that can overcome the drawbacks of traditional mixtures. To compensate for the high-grade power consumption of its applicable compression-assisted absorption refrigeration systems, a novel combined absorption system with a compression booster for the cogeneration of power and refrigeration (CAPRC) is proposed via this study. The system operates efficiently by utilizing low-grade heat sources in a cascaded manner. It was studied using energy, exergy, and economic analyses with verified models. 1,1-difluoroethane/1-hexyl-3-methylimidazolium bis(triflfluoromethylsulfonyl)imide was first pre-selected from potential working pairs due to its superior thermodynamic properties and highest performances in absorption systems. The performances of the CAPRC under typical space-cooling conditions were then analyzed theoretically for various operating modes and control parameters. Noted in cold mode, CAPRC could produce a constant cooling load by enhancing the utilization of heat sources through the adjustment of compression ratio and expansion ratio, indicating its outstanding adaptability to time-variable low-grade heat sources. The CAPRC could also generate 80.91% more net power than the reference system and offered 12.87% and 10.68% higher effective energy and exergy efficiencies, respectively, under optimized base-case control parameters in dual-output mode. A subsequent sensitivity analysis was conducted to assess its power and cooling production and effective efficiencies under various external conditions. The shortest payback period was finally estimated to be 6.43 years, which is 19.28% less than the reference system, further demonstrating the cost-effectiveness of the proposed system. • One absorption system with green mixtures for cleaner cooling and power production. • High adaptability to time-variable low-grade heat sources for the proposed system. • 1,1-difluoroethane/1-hexyl-3-methylimidazolium bis(triflfluoromethylsulfonyl)imide was pre-selected. • Higher energy and exergy performances compared to the combined system with Kalina. • Verified shorter payback period of the proposed system and its dual-output mode. [ABSTRACT FROM AUTHOR]

Abstract: This paper performs a cost-effectiveness analysis of some of the best available technologies (BAT) that can contribute to decreasing the energy consumption and CO2 emissions in the European Union’s (EU27) cement industry. Several capital budgeting decision criteria have been used (the payback period, the net present value and the internal rate of return) to study whether or not an investment should be considered worthwhile. The results show that, independent of the capital budgeting decision criteria used, the number of cost-effective retrofitting possibilities available is large compared to the rate of improvements that the industry undertakes annually. This shows the insensitivity of the industry to financial criteria when it comes to making their investment decisions. The possible thermal energy improvement in the clinker production, if all these BATs were implemented, has been quantified to be around 10%. This achievement would place the cement industry in the upper bound of the benchmark range for clinker manufacture. However considering the delays observed nowadays in terms of diffusion of BATs in the cement industry, it requires a conducive policy environment that combines support for both technology development and to their deployment. [Copyright &y& Elsevier]

Abstract: The paper shows implementation of in-plant control measures in two pasta plants and conducts economic analysis for revenues from these modifications. In order to reuse wastewater, 12 end-of-pipe samples for each plant were tested for physico-chemical characteristics using standard methods. The results showed that the adopted in-plant modifications such as installation of water flow meters, spring valves on water hoses, and design of a steam condensate recovery system contributed efficiently in saving water and energy consumption throughout the pasta plants. An estimated annual benefit of $228,245 can be achieved. Cost benefit analysis for the implemented environmental improvements proved to be very economic with a short payback period and resulted in great savings. [ABSTRACT FROM AUTHOR]

The present study developed a cleaner production bio-cementitious mortars (BCM) using immobilised Bacillus sphaericus activity. In order to achieve a sustainable enhancement of BCM, the effect of curing in distilled water (DW as normal water), deposition medium (DM as controlled nutrient), and runoff water (RW as uncontrolled nutrient) was investigated compared to control cementitious mortars (CCM). The BCM production was optimised based on curing days (3–90 days) and setting time (225–340 min). The results revealed that the optimal conditions to generate BCM in different curing media were recorded after 84 days with 240 min of the setting time. The compressive strength ranged from 40 to 54 MPa in BCM, compared to 40.5–41.5 MPa in CCM, ISA was 0.1–0.08 mL/m2/s in BCM and 0.11–0.12 mL/m2/s in CCM, water absorption was 3.23%–2.54% in BCM and 8.08%–7.42% in CCM, porosity was 7.98%–5.99% in BCM and 13.70%–13.37% in CCM, weight was 3.35–85.88 g in BCM and 1.90–81.70 g in CCM, and water permeability was 1.87–1.1 m/s in BCM and 3.04–2.99 × 10–12 m/s in CCM. The consolidation of pore inside the BCM was due to sufficient nutrient for bacterial activity. This enabled continuous production of more CaCO 3 to fill the pore. The microstructural test results proved the formation of the CaCO 3 precipitation inside the cement matrix. This is parallel with the improvement of BCM performances by the modification of porosity and pore, especially for the sample cured in the runoff water which showed that the precipitation of CaCO 3 were denser and strong. The techno-economic analysis revealed that the specific cost of bio-cementitious material production is estimated to be USD 46.12 per m3 with 45% of the IRR (the investment) efficiency and the payback period (PBP) of 10 years of the lifetime which indicate that the production of bio-cementitious material and is economically feasible. [Display omitted] • A bio-cementitious materials (BCM) by immobilized B. sphaericus was developed. • The consolidation of pore inside bio-cementitious was due to the nutrient. • The formation of the CaCO 3 precipitation improved the cement properties. • The techno-economic analysis conformed potential of bacteria for generating BCM. [ABSTRACT FROM AUTHOR]

The current work discusses the implementation of grid-connected, residential rooftop photovoltaic (PV) systems under the scenario of low (300 kWh/month), medium (600 kWh/month), and high (2100 kWh/month) electric loads. The analysis shows that, under all load scenarios, using rooftop PV systems with increasing PV ratings increased renewable fraction (by at least 5% for 1 kW PV under high electric load to as much as 89% for 12 kW PV under low electric load) and reduced carbon emission (by at least 5% for 1 kW PV under high electric load to negative carbon emission for 12 kW PV under low electric load). Furthermore, the highest PV rating (12 kW PV) was preferred under low, medium, and high electric loads, with net present cost (NPC) 29%, 72%, and 29% lowered than the respective grid reference systems. Nevertheless, a long discounted payback period was required, especially under low electric load (above 20 yr). A few scenarios with regard to PV module price, PV sellback rate, tariff rate, and carbon tax were therefore analyzed, which led to NPC reductions of 20%, 40%, 40%, and 12%, respectively, for 6 kW PV under low electric load, in addition to shortened discounted payback periods. Although Malaysian data were used for analysis purposes, the current work has worldwide implications, where it serves as a techno-economic model that provides a sustainable development framework for understanding technically and economically the installation of rooftop PV systems for residential households and driving the implementation of rooftop PV installations especially across Southeast Asia. • Grid-connected, residential rooftop PV systems with different loads were analyzed. • PV with higher ratings increased renewable fraction and reduced carbon emission. • The highest PV rating was preferred under low, medium, and high loads, NPC-wise. • Changes in PV module price, sellback rate, tariff rate, and carbon tax lowered NPCs. • The findings serve as a model that provides a sustainable development framework. [ABSTRACT FROM AUTHOR]

Industrial waste heat recovery shows significant potential for increasing energy efficiency in industry. However, to design strategies that exploit this potential, it is necessary to have data about the quantity and characteristics of industrial waste heat flows. This information is not always readily available and many companies do not even have a systematic record of these energy flows. Hence, bottom-up methodologies to estimate that recovery potential by means of key transfer figures are useful tools within this field. In the present article, four different methods are applied to determine the industrial waste heat recovery potential in the Autonomous Community of the Basque Country (northern Spain), an energy-intensive industrial region with large energy dependency from the outside. Besides, the analysis of the economic viability of the industrial waste heat recovery is essential, because it determines the final adoption of energy efficiency measures. For that aim, the authors develop an easy-to-apply bottom-up methodology to carry out an assessment for the economic potential of the estimated industrial waste heat at different temperature levels. This method is applied to 129 companies, whose potentials are characterized and discussed. The obtained results show that, for waste heat streams above 400 °C, more than 90% of the studied companies present payback periods below five years. For those industries with waste heat temperatures below 200 °C, the ratio decreases to around 40%, still a noticeable value. The estimations show a significant opportunity to implement solutions to recover this wasted energy, especially in the iron and steel sector and the petrochemical industry. The development of public policies that encourage these measurements would be also beneficial. • Evaluates the techno-economic potential of industrial waste heat recovery. • Lack of assessments of IWH recovery potential at local, regional or national scales. • 13%–16% of the primary energy consumption might be recovered. • For streams above 500 °C, almost all the companies present viable recovery potentials. • Iron and steel and petrochemical sectors present positive economic perspectives. [ABSTRACT FROM AUTHOR]

The upfront energy, material requirements, manufacturing country, and installation location of photovoltaic (PV) panels results in different payback periods for discrete environmental indicators. While individual PV systems may find the pollutants emitted during their manufacturing and installation paid back in a few years, the rapid growth of the PV industry may have resulted in the formation of a temporary pollutant sink. The goal of this study was to determine the moment in which the PV industry could have become a net pollutant avoider, with detailed analysis for 8 impact categories considered. We performed life cycle assessments (LCAs) of the main types of PV panels manufactured and installed from 2000 to 2018, with projections up to 2025, incorporating technology improvements regarding efficiency, energy and material use, and changes in manufacturing and installation locations. Results for the baseline scenario show the PV industry achieved greenhouse gas (GHG) emissions payback between 2012 and 2016 depending on the energy sources displaced (coal and natural gas, respectively). Sensitivity analysis revealed that the effects of varying irradiation, performance ratio, rebound effect and GHG emissions from manufacturing within certain ranges did not dramatically impact the payback time with results minimally changed by only one year. However, all the conservative estimates added into the worst-case scenario delayed the GHG payback time to 2020, showing that combined effects have a large impact. The analysis of other impact categories revealed that the PV industry is not as effective in preventing other damages to the environment as it is in avoiding GHG emissions with payback times for human toxicity, and ionizing radiation not expected to occur in the study period. Hence, more technology improvements are necessary to lower the impact in other environmental categories beyond climate change and make solar PV more sustainable. [Display omitted] • The net greenhouse gas emissions of the photovoltaic industry have been determined. • Sensitivity analysis delimits the greenhouse gas emissions payback years of the PV industry. • Cumulative emissions and payback years of 8 environmental indicators are shown. • Contribution analysis shows the main impacting inputs and processes on each category. [ABSTRACT FROM AUTHOR]

Small-scale solar energy production on rooftops can contribute to renewable energy targets and reduce domestic energy costs. However, installation rates are low in some cities despite abundant sunshine and generous financial incentives. In this study a drop-off survey was carried out to investigate the intentions and barriers to adopting rooftop solar panels in the remote tropical city of Darwin, in the Northern Territory (NT), and to quantify the minimum feed-in-tariff (FiT) needed to install residential solar panels. More than half of the 652 respondents intended to install solar panels. Age and renting were negatively, and high energy needs and an estimated short payback period positively, associated with installation intentions. Each additional year that potential adopters expect to take paying off panels reduces their likelihood to install them by 10%. Results of a contingent valuation assessing the minimum FiT needed for people to newly adopt solar panels showed that the median amount needed was 14.40 c/kWh (95% confidence interval: 10.74–25.83 cents). This was almost half that offered at the time of the survey (a premium FiT of around 26 c/kWh, GST inclusive) but more than the new FiT that has been introduced since (9 c/kWh, GST inclusive). There is the option that the new FiT could be augmented by a subsidised part to provide enough incentives for potential adopters. Under the new FiT, the likelihood of installing solar panels is highly dependent on the self-consumption rate of the solar energy and affordability of batteries for storage. An ex-ante evaluation showed that, if everything else remains the same, the adoption rate can be expected to decline by about 40% or 17% for people consuming 30% or 60%, respectively, of the solar energy themselves. [ABSTRACT FROM AUTHOR]

In this paper, municipal solid waste (MSW) based electricity production and district heating (DH) potential of Turkey are considered. Three MSW based waste-to-energy (WtE) scenarios is developed: (i) Scenario-I , a DH system integrated into a gas turbine power plant (GTPP), (ii) Scenario-II , a DH system integrated into an organic Rankine cycle (ORC), and (iii) Scenario-III , which is based solely on a DH system. As a result of the thermodynamic and thermoeconomic analyzes of these developed scenarios using an existing MSW-based cogeneration facility's actual operating data, the system with the most extended payback period (about 5 years) is found as the GTPP-DH system developed in Scenario-I, which also has the highest investment cost. On the other hand, the system with the shortest payback period (about 2 years) is found as the DH system developed in Scenario-III, which also has the lowest investment cost. Overall exergy efficiencies of the GTTP-DH, ORC-DH, and DH systems are found to be 41.86%, 16.15%, and 31.87%, respectively. When the developed WtE scenarios adapted to the pilot provinces selected from each geographical region of Turkey, it is found that the GTPP system developed in Scenario-I can increase the power generation capacity of MSW plants for each province by about 20%. • DH and electricity production potentials of the MSWPs are considered. • Three MSWP based WtE scenarios are developed: GTPP-DH, ORC-DH, DH network. • Heat demand of 4344 dwellings can be met with DH system developed in Scenario I. • Heat demand of 946 dwellings can be met with DH system developed in Scenario II. • Heat demand of 7069 dwellings can be met with DH system developed in Scenario-III. [ABSTRACT FROM AUTHOR]

Life cycle assessment (LCA) and life cycle costing (LCC) are innovative tools based on an innovative approach allowing to investigate the environmental and economic burdens of a product or service throughout its lifecycle. Although usually carried out individually, their integration in a comprehensive analysis could provide a substantial asset in every kind of decision-making procedures. In this study, the sustainability of a newly developed component for refrigeration units is investigated by applying these two tools in a cradle to grave approach in different scenarios. Results from the LCA show the huge impact associated with the manufacturing process of the kit compared to the transport. However, the use phase environmental analysis showed an environmental payback period always lower than 10 years. Results from the LCC show that the initial investment cost represents the highest share for the final user. Furthermore, favourable discounted payback periods are generally found, leading to net savings above 270,000 € in the case best-case scenario. [Display omitted] • LCA and LCC of an optimisation kit for industrial refrigeration units were studied. • The highest impact of the overall process is during the manufacturing stage. • The environmental payback period of the kit is lower than 10 years. • LCC showed the initial investment is up to 88% of the total cost. • The initial investment is recovered after 4 years and 10 months at the latest. [ABSTRACT FROM AUTHOR]

The photovoltaic poverty alleviation project (PPAP), as an integration of solar photovoltaics and poverty alleviation, has gained great attention since it was proposed in China. So far, four different modes of PPAP have been formed - household level, village level, jointly-village level, and centralized PPAP. A comprehensive understanding of the effectiveness of different PPAP modes is essential to achieve the aim of getting rid of poverty in Chinese rural areas and to provide references for other developing countries. Therefore, this paper, for the first time, evaluates the economic performance of PPAP under the four modes. By employing cost-benefit analysis, this research elaborates on the effectiveness of PPAP from three aspects – cashflow, net present value, and payback period. The results show that the village level and the jointly-village level PPAP are the most effective modes. However, due to the overplus of installed capacity per household, the centralized PPAP, which is in line with the local governments' income, becomes the most popular mode. Besides, bank loans can significantly increase the number of benefited households, and the beneficiary ratio is critical to the effectiveness of corporations' participation. [ABSTRACT FROM AUTHOR]

Residential solar photovoltaic (PV) installations have boomed in China over recent years. However, knowledge about the economic performance of residential PV investments is still limited. Therefore, this study attempts to make a complete economic assessment of residential PV systems at the county-level. After a brief description of China's incentive policies, a model is constructed with economic measures of internal rate of return and payback period based on discounted cash flow. Then, a reference PV system of 5 kW p is investigated in 2181 geographical areas using scenario analysis and sensitivity analysis. There is breakeven for residential PV investments all over China even without incentives. The areas with good performance of residential PV investments are located mostly in Northern China (Shandong and Hebei), Southern China (Guangdong and Hainan), northeast China (Liaoning, Jilin, and Heilongjiang), and southwest China (Sichuan and Tibet). The boom of residential PV installations is likely to recede in 2021 as the population with acceptable profitability declines since the central and local subsidies expire. But some excellent residential PV suppliers have the potential to compensate for the performance decrease in many ways such as increasing annual generation and reducing initial cost. This paper contributes by providing some insights into the economic performance and market of residential PV installations in China. [ABSTRACT FROM AUTHOR]

Businesses are employing distributed generation techniques, such as wind turbines, to decarbonise their electrical energy supply by reducing their dependence on fossil-fuel-generated energy. This study investigates the effectiveness of a company making a €3,500,000 investment in a 3-MW on-site wind turbine to supply some or all of their factory electrical loads. The results should benefit the investing company and other potential investors by evaluating the economic, environmental, and social outcomes of the investment. A case study methodology was used. The study found that the payback period was six and a half years, and the turbine installation benefited the environment by offsetting 3,195 tonnes of CO 2 per annum. As part of the power-quality analysis of the wind-turbine output, the short-term variability of the power output signal was calculated as the coefficient of variation values. The study found that the most stable power output is achieved when the turbine is generating at full output power (i.e., 3-MW). In addition to the existing range of traditional power quality parameters, the coefficient of variation parameter was found to be an essential aspect of electrical power quality and should be included in future practice. Image 1 • Short-term variations should be considered in current range of power quality analysis parameters. • Method to calculate short-term power variations is presented. • Coefficient of Variation values of between 0.005 and 0.026 were calculated at maximum power output i.e. 3-MW. • 3-MW wind turbine contributed positively to cleaner production philosophy. • A six-and-a-half-year Payback Period was established with 3195 tonnes of CO 2 emissions saved annually. [ABSTRACT FROM AUTHOR]

Microalgae is a potential candidate to produce renewable fuels. However, current gasification technologies are limited due to char- and tar-accumulation in the gasifier. We have reported a single step, tar-free catalytic reactive flash volatilisation (RFV) of microalgae to produce hydrogen or methane. In this work, the experimental results were used to develop a detailed ASPEN PLUS® flowsheet model to perform techno-economic assessment of hydrogen and methane production. A plant located in India, processing 12790 kg/h of microalgae to produce 1239 kg/h of H 2 or 3484.96 kg/h of CH 4 was considered. Process scale-up and heat integration principles were used to generate relevant data. Simultaneously, the experimental and simulation data are used to perform life cycle assessment (LCA). The results indicated that the payback period for hydrogen production was 3.78 years with 22% of IRR. Moreover, the life cycle climate change impact was 7.56 kg CO 2 eq./kg H 2 produced, which was 36.47% lower than the steam reforming of methane. Methane production was not economically feasible. However, it was environmentally preferred with the life cycle climate change impact of 1.18 kg CO 2 eq./kg CH 4 produced. Sensitivity analysis was performed to identify opportunities to achieve further reduction in costs and life cycle impacts. It was observed that the payback period was more sensitive to feedstock cost compared to other parameters. 25% increase in the feedstock cost resulted into 35.38% increase in the payback period. • The TEA and LCA of H 2 and CH 4 production from microalgae using RFV has been done. • With the prevailing cost of H 2 (₹650/kg), payback period of 3.78 years was estimated. • GHG impact of H 2 production via RFV of microalgae is 36.47% less compared to SRM. • For H 2 production, hydro-electricity reduces GHG impact by 87%. [ABSTRACT FROM AUTHOR]

The prime mover size for a Combined Cooling Heating and Power (CCHP) system is determined through the adoption of different strategies in load following, which are based on a fraction of demands. Multi-objective optimization is employed for finding the optimal design in each case by considering annual average efficiency (AEF), payback period (PBP), and annual carbon dioxide emission (ACE) as the objectives. Then, a comprehensive comparative study is conducted to compare the objective functions and monthly values of different performance criteria with each other. Comparisons are made among results of optimization for different scenarios, and the ones obtained from the base case condition (building without a CCHP system), as well as following electrical and thermal demands conditions. Along with these comparisons, the sensitivity analyses are done to determine the impact of variation of each demand on the optimum results individually. The results indicate that following an optimum fraction of electrical demand is the best strategy for all the investigated load ratios. In the reference load ratio, it has 14.3% and 4.6% better AEF and ACE than the base case. Moreover, for the reference load ratio, the initial purchase price and operating cost are 33.8% and 12.2% lower, leading to a PBP of 1.687 years. According to the sensitivity analyses, it is also found that the highest level of variation in the optimum fractions comes from changes in the cooling load. • Sizing engine based on a fraction of electrical demand is found as the best strategy. • Using the best found strategy improves efficiency by 14.3% during a year. • For the best sizing strategy, annual carbon dioxide emission decreases by 4.6%. • The best sizing strategy enjoy the payback period of 1.687 years. • Cooling load variation leads to the highest changes in results of optimization. [ABSTRACT FROM AUTHOR]

Lack of consideration of photovoltaic panel temperature in a concentrating photovoltaic (CPV) system causes a great misconception and leads to the financial risk of system installation since the increment in PV cell temperature significantly reduces the performance. In this study, an energy-efficient and cost-effective V-trough PV system with low-temperature configuration was proposed to achieve better performance by using easily accessible reflector material instead of the high reflective anodized aluminum reflector with high cost. The concentrating photovoltaic systems were designed, produced, and installed. Anodized aluminum reflector (AAR) protected with nanocomposite using a coil-coating, and polished stainless steel (PSSR) were used as reflector mirrors. The electrical performance parameters of CPVs were experimentally analyzed as a function of cell temperature and compared with a 1-Sun PV system. The net present value (NPV) method was used for the economical evaluation of the system. The results indicate that high reflectivity can cause the temperature elevation in the PV cell thereby decreasing the fill factor, voltage, and power output of the system. The power generation of the AAR-CPV system was about 17.4% lower than that of the 1-Sun PV system due to higher cell temperature. On the other hand, a low reflective PSSR-CPV system generates about 17.84% and 42.7% higher power compared to 1-Sun PV and AAR-CPV systems, respectively. The payback period of PSSR-CPV appears to be 6 years and is equal with that of the PV system on a yearly basis, however, PSSR-CPV yields a greater return. An easily accessible polished stainless steel having reasonable reflectivity may be a better attitude for increasing the incident solar irradiation with a slight increase in the PV cell temperature for a CPV system based upon the economical and experimental analysis for a cost-effective and energy-efficient design of CPV technology. Image 1 • Cost-effective, energy-efficient CPV with low-temperature configuration was proposed. • Experimental and economic analyses were made for CPVs with different reflectors. • PSSR-CPV system generates about 17.84% higher power than PV. • PSSR-CPV system generates about 42.7% higher power than AAR-CPV. • The payback period of PSSR-CPV appears to be 6 years (same as PV system). [ABSTRACT FROM AUTHOR]

In this paper, a plant consisting of a solid oxide fuel cell and solid oxide electrolysis cell is proposed for power provision based on solar energy. In this system, water enters the solid oxide electrolysis cell and is split into H 2 and O 2 through the utilization of the generated power by the photovoltaic panels. The produced hydrogen is stored and sent to the solid oxide fuel cell for clean and consistent power generation. The required hydrogen of the fuel cell is measured for 24 h and the electrolysis and photovoltaic units are designed in such a way to satisfy the demand of the fuel cell while the surplus hydrogen is considered for sale. A sensitivity analysis is also conducted on the system to assess the impact of vital parameters on output power, system efficiency, total product cost and total cost rate, total exergy destruction, and payback period. Furthermore, multi-criteria optimization is applied to the system utilizing various optimization algorithms. The outcomes demonstrate that the maximum amount of exergy destruction occurs in the photovoltaic system. The results of the parametric evaluation illustrate that the payback period of the plant can reduce to 7 years when surplus hydrogen is 4 times higher than the required H 2 of the fuel cell. Furthermore, higher current densities of the SOEC system can reduce the efficiencies while increasing the payback period, so lower current densities would be more suitable. Also, there would be a local optimum point in terms of total product cost and net power outlet with the current density of the SOFC system. The optimization findings indicate that PESA-II is the most suitable algorithm for this particular system as it results in more suitable optimum points that are closer to the ideal point. In addition, at the final optimum solution point concluded by the LINMAP method, the exergy efficiency of the system would be 62% and the total cost rate is 1.297 $/h. • A novel solar driven lumped SOFC/SOEC is proposed for power and H 2 production. • A parametric study is performed to assess the effect of input variables. • Energy, exergy, exergoeconomic analyses and multi-objective optimization are applied. • Different optimization algorithms are compared based on Taylor diagram. [ABSTRACT FROM AUTHOR]

Occupant behavior in residential buildings has a direct impact on the effectiveness of energy-saving measures. In order to realize a buildings' carbon mitigation targets, the impact of individual occupancy profiles needs to be integrated with building simulation models. This paper introduces a decision support framework as a potential solution to make energy performance upgrade choices based on different occupancy profiles. This framework has been demonstrated through a case study of two single-family detached homes in Canada, which were highly instrumented with sensors for monitoring energy input and output. The case studies represented two common occupancy profiles-(1) a family of four (consisting of 2 working adults and 2 teenagers); and (2) a retired couple. Firstly, calibrated energy models were developed by using one-year energy use data collected through an intrusive load monitoring technique. Secondly, energy upgrade combinations were considered for each profile and tested for additional investment, payback period and greenhouse gas (GHG) emissions. Lastly, the most suitable combination of energy upgrade for each profile was ranked using a multi-criteria decision-making method (e.g., TOPSIS). Results indicated that the retired couple used more energy than the family of four and required energy upgrades with usually higher payback periods to achieve the same level of GHG emission reduction. The results of this research are timely for energy policymaking and developing best management practices, which need to be implemented along with the deployment of more stringent building standards and codes. • A scenario-based framework was developed for residential homes energy upgrades. • It considers occupant behavior and preference in selecting energy upgrades. • Field data is used to represent energy use of a family of four and a stay-at-home retired couple. • Energy upgrades are same under pro-economic choices for two profiles. • Energy upgrades vary under pro-environmental scenarios for two profiles. [ABSTRACT FROM AUTHOR]

Climate change caused by excessive CO 2 emissions in the atmosphere has attracted widespread public concern in recent years. Current industrial methods generally utilize monoethanolamine for CO 2 capture; however, the CO 2 regeneration requires a high temperature and energy demand during every adsorption/desorption process, along with material losses. Many solid amines with high capture capacity and stability are developed as adsorbents to overcome the limitations. However, the environmental impacts caused by adsorbents themselves are not holistically considered and discussed; meanwhile, material syntheses and consumptions are also associated with CO 2 emission. To determine the environmental impacts and identify hotspots of novel CO 2 capture adsorbents, two carbon nanotube supported polyethyleneimine, physically adsorbed and covalently bonded, were compared with traditional monoethanolamine method using life cycle assessment. The carbon payback periods were also analyzed to gain understanding on whether the currently evaluated novel materials are suitable for industrial application. Results suggest that, material usage, especially carbon nanotubes, contributes the majority of the overall environmental impacts for both types of carbon nanotube supported polyethyleneimine. Meanwhile, their carbon payback periods are over 40 times longer than monoethanolamine during the synthesis phase. However, the energy consumption of physically adsorbed polyethyleneimine saves up to 60% compared to monoethanolamine in every adsorption/desorption cycle due to its lower heat capacity. In addition, the rate of cumulative CO 2 remission for carbon nanotube supported polyethyleneimine is twice higher than monoethanolamine, indicating the potential application for industrial CO 2 capture. Overall, our study indicates that current status of solid amine has a potential in CO 2 capture, but requires much improvements. Future research should pay attention on decreasing the initial material synthesis and increasing the product life time due to their high environmental tradeoffs. Meanwhile, our study highlights that unilateral emphasis of the CO 2 capture efficiency by novel materials may not be adequate, comprehensive considerations should be focused on the comparison throughout material life cycles including use and preparation phases. Image 1 • Life cycle environmental impacts of carbon capture techniques were assessed. • Carbon nanotube supported amine generates higher environmental burdens than MEA. • Carbon nanotube supported amine reduces CO 2 after 917 adsorption/desorption cycles. • Life cycle impacts should be analyzed when use novel materials to mitigate CO 2. [ABSTRACT FROM AUTHOR]

The current study is a preliminary approach to develop a structural framework of the Internet of Things (IoT) adoption barriers that exist in the waste management systems of smart cities in developing economies such as India. To attain this aim, the present study uses hybrid Multi-criteria decision-making methods (MCDM) and has identified 15 adoption IoT Barriers (IoTBs) from literature review obstructing the IoT implementation in smart cities of India. The IoTBs are further analyzed through the Total Interpretative structural modeling (TISM) approach, the Fuzzy Matriced'Impacts Croisés Multiplication Appliquéan Classement (MICMAC) model, and the Decision Making Trial and Evaluation Laboratory (DEMATEL) method. The TISM approach is used to develop a structural framework of IoTBs in smart cities' waste management (SCWM) projects. The literature shows that several bottlenecks exist. Such bottlenecks may include operational cost and payback; a lack of standardization, regulations, directions, and policy norms; incomplete technical knowledge among policymakers; internet connectivity, privacy, and security issues; or problems with mobility, transparency, and a lack of IT infrastructure; all of these issues influence IoT adoption in SCWM. The present work discloses that the lack of regulations, directions, and policy norms, and the lack of standardization and Internet connectivity are the most critical IoT barriers hindering the development of smart cities, particularly in their waste management practices. The Fuzzy-MICMAC approach is useful in calculating driving and dependence powers of the IoTBs, and the DEMATEL method helps reveal the influence/strength of IoTBs that affect SCWM. This study will help policymakers, stakeholders, and government to understand the significant IoTBs affecting waste management practices, and it will definitely assist them to undertake decisions for eradicating these barriers for a more efficient IoT implementation in SCWM projects. Image 1 • Operational cost and payback period has the maximum dependence on all the other IoT adoption barriers. • IoT implementation needs government support in developing regulatory norms, policies, and directions for effective SCWM. • Lack of standardization and internet connectivity issues are the among the key driving barriers in SCWM. [ABSTRACT FROM AUTHOR]

Combined heat and power (CHP) is an electricity generation strategy that benefits all sides with a vested interest in the nations' energy future. The technology allows for the efficient production of electricity and heat, which in turn reduces the carbon footprint and energy costs of a facility with significant heat and electricity loads. This paper investigates, through a detailed dynamic simulation, how a highly non-traditional CHP facility can leverage those forces to economically and environmentally benefit. Four system configurations of a composites manufacturing facility, one existing and three proposed systems, including two CHP configurations and one combined cooling, heating, and power (CCHP) configuration are evaluated from both economic and environmental views. The three proposed configurations are based on a 600 kW microturbine as the primary mover. The dynamic model showed great potential to capture the dynamics of the system configurations including the dynamics of temperature, oven exhaust fraction, electrical efficiency, and overall efficiency of the system configurations. All 3 CHP systems have a payback period between 8.03 and 8.33 years. The proposed system configurations reduce up to 22.7% of the CO 2 emission compared to the existing facility, supplying the demands in a cleaner manner. • 3 novel CHP and CCHP systems are proposed for an existing non-traditional facility. • A dynamic simulation is developed to simulate existing and proposed systems. • Economic and environmental analysis is performed to compare systems. • 7.95-year payback period for CHP system via $270,000/yr reduction in resource cost. • Up to 22.1% of CO 2 emissions can be avoided compared to the existing system. [ABSTRACT FROM AUTHOR]

Solar-driven technologies for electricity production are very promising technologies for developing sustainable and viable energy units. The objective of this work is the energy and financial investigation of a solar-driven thermoelectric generator system. This system operates without concentrator; it absorbs the incident solar irradiation and it converts it partially to electricity. In this paper, a small module is investigated in details and the analysis is extended for a solar field of 100 m2. A numerical model is developed in Engineering Equation Solver for simulating the solar thermoelectric generator behavior and it is validated using experimental data from the literature. The maximum instantaneous efficiency is found close to 4.5% in the reference operating conditions, while the mean yearly efficiency for the climate conditions of Athens (Greece) is found at 3.2%. The yearly electricity yield is found to be 5414 kWh for a solar potential per area of 1695 kWh/m2. The parametric financial analysis proved that generally, the investment is viable and for a reasonable specific capital system cost of 1000 €/kW the payback period is about 4.5 years and the levelized cost of electricity is around 0.044 €/kWh. • A solar-driven thermoelectric generator is studied in energy and financial terms. • The system is investigated on a yearly basis for the location of Athens in Greece. • The yearly electrical efficiency is found at 3.2% and the electricity production 5414 kWh. • In the main scenario, the levelized cost of electricity is found at 0.0617 €/kWh. • The payback period is found to be about 4.5 years which indicates a viable investment. [ABSTRACT FROM AUTHOR]

The membrane bioreactor-nanofiltration hybrid process has been proven to be promising for textile wastewater treatment. High water recovery could be achieved through the recirculation of nanofiltration concentrate to the membrane bioreactor. However, its influence on both the performance and economic feasibility of the membrane bioreactor-nanofiltration was not fully investigated, especially at larger scale. In this study, a pilot-scale membrane bioreactor-nanofiltration system was used for the on-site treatment of textile wastewater. The hydraulic retention time of membrane bioreactor was first optimized (Stage A), then the membrane bioreactor-nanofiltration system was operated at different water recovery rates (Stage B). The results showed that the sludge activity was relatively stable, but the nanofiltration concentrate recirculation significantly influenced the pollutants removal efficiencies of membrane bioreactor. The membrane bioreactor-nanofiltration effluent is suitable for reuse and the high water recovery could bring considerable benefits that enhance the economic feasibility of the process with a net income of 1.24 M USD/y and a payback period of 3.11 y. Image 1 • Textile wastewater treated by membrane bioreactor-nanofiltration was reused at high water recovery. • Membrane bioreactor could adapt to nanofiltration concentrate recirculation with relatively stable performance. • Full-scale membrane bioreactor-nanofiltration reduces 13.7% footprint compared to the existing process. • Full-scale membrane bioreactor-nanofiltration provides a net income of 1.24 M USD/y. • Estimated payback period of membrane bioreactor-nanofiltration system is 3.11 y. [ABSTRACT FROM AUTHOR]