•The dual identity of ammonia as energy storage medium and fuel is achieved.•Power-to-ammonia-to-power and biomass-to-ammonia-to-power are conceptualized.•Eight scenarios in two pathways are ...technically and economically evaluated.•The biomass-to-ammonia-to-power pathway has higher efficiencies and ammonia yield.•The optimal scenario has six years discounted payback period and 415.5 MUSD net present value.
In the energy system transition, energy storage technology is vital for increasing the penetration of renewables, where chemical energy storage is most suitable for long-term grid-scale energy storage. Green ammonia is selected to replace hydrogen for the sake of storage efficiency, safety, and cost. Most time, ammonia is seen as either an energy storage medium or a fuel. However, the dual identity of ammonia as an energy carrier is discussed less. So, this study conceptualizes power-to-ammonia-to-power (P2A2P) and biomass-to-ammonia-to-power (B2A2P) pathways where ammonia is served as an energy carrier for both energy storage and fuel. Eight scenarios involving recent ammonia production and utilization technologies are technically and economically evaluated based on hourly weather and demand data. The results show that the B2A2P pathway presents a better performance because the average energy and exergy efficiencies are hardly influenced by the supply and demand balance of electricity. They can reach 40–50% in contrast to 27–47% in the P2A2P pathway. Besides, the B2A2P pathway provides a considerable amount of ammonia (around 10,000 t/month), which takes the major part of revenues. Although the CAPEX (603.3–675.1 MUSD) and OPEX (30–40 MUSD) in the B2A2P pathway are much higher than that of P2A2P (159.2–181.1 and 6–9 MUSD, respectively), the optimal scenario of the B2A2P pathway has a shorter discounted payback time (six years), and higher net present value (415.5 MUSD).
•Evaluation of solar resources in the absence of measured data.•Optimization of 2 PTSTPPs integrated with TES and FBS and using oil and salt as HTFs.•4E comparative study of the two optimized plants ...alongside the Andasol 1 plant.•The salt plant resulting as the best one and has been chosen for the viability study.•Tamanrasset is the best location for construction of PTSTPPs.
In the present study, optimization of two parabolic trough solar thermal power plants integrated with thermal energy storage (TES), and fuel backup system (FBS) has been performed. The first plant uses Therminol VP-1 as heat transfer fluid in the solar field and the second plant uses molten salt. The optimization is carried out with solar multiple (SM) and full load hours of TES as the parameters, with an objective of minimizing the levelized cost of electricity (LCOE) and maximizing the annual energy yield. A 4E (energy–exergy–environment–economic) comparison of the optimized plants alongside the Andasol 1 as reference plant is studied. The molten salt plant resulting as the best technology, from the optimization and 4E comparative study has been chosen for the viability analysis of ten locations in Algeria with semi-arid and arid climatic conditions. The results indicate that Andasol 1 reference plant has the highest mean annual energy efficiency (17.25%) and exergy efficiency (23.30%). Whereas, the highest capacity factor (54.60%) and power generation (236.90GWh) are exhibited by the molten salt plant. The molten salt plant has least annual water usage of about 800,482m3, but demands more land for the operation. Nevertheless the oil plant emits the lowest amount of CO2 gas (less than 40.3kilo tonnes). From the economic viewpoint, molten salt seems to be the best technology compared to other plants due to its lowest investment cost (less than 360 million dollars) and lower levelized cost of electricity (LCOE) (8.48¢/kWh). The viability study proposes Tamanrasset, as the best location for erection of a parabolic trough solar thermal power plant with a low LCOE of 7.55¢/kWh, and a high annual power generation (more than 266GWh). According to the feasibility analysis, the semi-arid and arid Algerian sites are suitable for realization of PTSTPP with integrated TES and FBS; especially the southern locations (19°N–32°N, 8°W–12°E).
New technologies in hip and knee arthroplasty are commonly evaluated using cost-effectiveness analyses and similar economic assessments. There is a wide variation in the methodology of these studies, ...introducing the potential for bias. The purpose of this study was to evaluate associations between potential financial conflicts of interest (COI) and the outcomes of economic analyses. We hypothesized that authors’ COI and industry funding would be associated with conclusions favorable to a new technology.
Economic analyses making cost-effectiveness or economic implementation claims on patient-specific instrumentation, robotics, and implants used in hip and knee arthroplasty published from 2010 to 2022 were identified. Papers were evaluated to determine if conclusions were favorable to the new technology being studied. Fisher’s exact test was utilized to determine the relationship between the presence of COI and an article’s conclusions.
Of 43 eligible articles, 76.7% were cost-effectiveness analyses, 23.2% were cost analyses, and 67.4% of articles had conclusions favorable to a technology. Of the 29 articles with favorable conclusions, 26 had an author with a financial COI (89.7%), and 14 had industry funding (48.3%). Of the 33 articles with a financial COI, 26 (78.8%) had favorable conclusions, and of the 16 articles with industry funding, 14 (87.5%) had favorable conclusions. Fisher’s exact test revealed a statistically significant association between an article having favorable conclusions and the presence of an author’s COI or industry funding (odds ratio, 13.5; 95% CI confidence interval, 2.3 to 79.9; P = .003).
Financial COIs were present in 79.1% of lower extremity arthroplasty economic analyses on technologies and were associated with an article having conclusions favorable to the new technology. Surgeons and decision-makers should be aware of the variability and assumptions in these studies and the potential bias of the conclusions.
This study provides comprehensive energy, exergy, and economic evaluations and optimizations of a novel integrated fuel cell/geothermal-based energy system simultaneously generating cooling and ...electricity. The system is empowered by geothermal energy and the electricity is mainly produced by a dual organic cycle. A proton exchange membrane electrolyzer is employed to generate the oxygen and hydrogen consumed by a proton exchange membrane fuel cell utilized to support the network during consumption peak periods. This fuel cell can be also used for supplying the electricity demanded by the network to satisfy the loads at different times. All the simulations are conducted using Engineering Equation Solver software. To optimize the system, a multi-objective optimization method based on genetic algorithm is applied in MATLAB software. The objective functions are minimized cost rate and maximized exergy efficiency. The optimum values of exergy efficiency and cost rate are found to be 62.19% and 18.55$/h, respectively. Additionally, the results reveal that combining a fuel cell and an electrolyzer can be an effective solution when it comes to electricity consumption management during peak load and low load periods.
•Proposed an innovative geothermal-PEMFC system.•Use PEM fuel cell as energy storage.•The multi-objective optimization method was performed using evolutionary algorithm.
Overcoming the existing environmental issues and the gradual depletion of energy sources is a priority at global level, biohydrogen can provide a sustainable and reliable energy reserve. However, the ...process instability and low biohydrogen yields are still hindering the adoption of biohydrogen production plants at industrial scale. In this context, membrane-based biohydrogen production technologies, and in particular fermentative membrane bioreactors (MBRs) and microbial electrolysis cells (MECs), as well as downstream membrane-based technologies such as electrodialysis (ED), are suitable options to achieve high-rate biohydrogen production. We have shed the light on the research efforts towards the development of membrane-based technologies for biohydrogen production from organic waste, with special emphasis to the reactor design and materials. Besides, techno-economic analyses have been traced to ensure the suitability of such technologies in bio-H2 production. Operation parameters such as pH, temperature and organic loading rate affect the performance of MBRs. MEC and ED technologies also are highly affected by the chemistry of the membrane used and anode material as well as the operation parameters. The limitations and future directions for application of membrane-based biohydrogen production technologies have been individuated. At the end, this review helps in the critical understanding of deploying membrane-based technologies for biohydrogen production, thereby encouraging future outcomes for a sustainable biohydrogen economy.
•Significance and impacts of deploying bio-hydrogen.•Different membrane-based technologies for bio-hydrogen production have been discussed in detail.•Membrane fouling is the main hurdle for membrane-based technologies.•Techno-economic analyses give a propensity for further development in bio-hydrogen production.
•Six combined cooling and power systems with multi-mode operation are proposed.•The proposed systems can realize diversified power and cooling supply.•Evaluated by parametric study and ...multi-objective optimization.•The ORC/ARC is considered as the optimal system in any of the operation mode.•The energy efficiency at the optima is 58.13% and unit cost of product is 4.25 $/GJ.
Current solutions for waste heat recovery from data centers are mainly district heating and refrigeration. However, intermittent demand for space heating and cooling resulted from seasonal or spatial variations makes inefficient utilization of waste heat. To better harvest the low-grade thermal energy in data centers, combined cooling and power systems are proposed, with the capability of adjusting the energy output to meet diverse energy demands hourly and seasonally. In total, six cogeneration systems with different configurations are investigated, with the power cycles being either organic Rankine cycle or Kalina cycle, and the refrigeration cycles being vapor compression refrigeration cycle, ejector expansion refrigeration cycle or absorption refrigeration cycle. Depending on the energy demands of data centers, each system has three operation modes: combined cooling and power, power alone and cooling alone. The performance is evaluated in terms of both the thermodynamic and economic performance by parametric study and multi-objective optimization. Results show that the organic Rankine cycle/absorption refrigeration cycle hybrid system has the best thermal-economic performance in all three modes. According to the comprehensive evaluation of the TOPSIS method and the entropy weight method, the energy efficiency at the optima is 58.13%, and the unit cost of product is 4.25 $/GJ, with the net power output of 4.25 kW and the cooling capacity of 150 kW.
Nowadays, with increasing energy consumption, global warming, and many problems caused by weather conditions, the tendency to use novel methods of energy generation with high efficiency and low cost ...that reduce environmental pollution has increased. This study investigates the feasibility of using gas pressure energy recovery in natural gas pressure reduction stations by turboexpanders for cogeneration of power and refrigeration. Turboexpanders and compression refrigeration cycles are employed to recover the energy from natural gas pressure reduction stations. Then, natural gas along with the compressed air enters the Brayton power generation cycle and its waste heat is used in the carbon dioxide (CO
2
) power generation plant, multistage Rankine cycle, and multi-effect thermal desalination unit. This integrated structure generates 105.6 MW of power, 2.960 MW of refrigeration, and 34.73 kg s
−1
of freshwater. The electrical efficiencies of the Rankine power generation cycle, CO
2
power generation plant, and the whole integrated structure are 0.4101, 0.4120, and 0.4704, respectively. The exergy efficiency and irreversibility of the developed integrated structure are 60.59% and 68.17 MW, respectively. The exergy analysis of the integrated structure shows that the highest rates of exergy destruction are related to the combustion chamber (59.68%), heat exchangers (14.70%), and compressors (14.46%). The annualized cost of the system (ACS) is used to evaluate the developed hybrid system. The economic analysis of the integrated structure indicated the period of return, the prime cost of the product, and capital cost are 2.565 years, 0.0430 US$ kWh
−1
, and 372.3 MMUS$, respectively. The results reveal that the period of return is highly sensitive to the electricity price, such that the period of return in the developed integrated structure is less than 5 years for the electricity price of 0.092 US$ kWh
−1
and more. Also, the period of return is less than 5 years for the initial investment cost of 632.9 MMUS$ and less, which is economically viable.
•A novel waste heat recovery system with an S-CO2 cycle is proposed and optimized.•Standard coal consumption rate of the power plant decreases by up to 5.19 g·(kW·h)−1.•Exergy losses and destructions ...in the novel system decreases significantly.•Economic analysis reveals that capital investment can be recycled in 3.067 years.
Waste heat recovery from boiler exhaust flue-gas is an effective way to save energy in coal-fired power plants. The integration of a low-pressure economizer (LPE) is a conventional choice for waste heat recovery. In this study, thermodynamic analyses of a coal-fired power plant (CFPP) integrated with an LPE is conducted on a 600 MW CFPP as reference case. Standard coal consumption rate (SCCR) of the power plant could be decreased by 1.76 g·(kW h)−1 by the LPE. Exergetic analysis reveals that significant irreversibility is exhibited by the air pre-heater (APH) of the waste heat recovery system with an LPE. Guided by the exergetic analysis of the conventional waste heat recovery system, a new conceptual system for waste heat recovery integrated with an S-CO2 cycle for CFPPs is designed in this study. In this novel system, the boiler flue-gas is split into two flows: one to heat air in APH, and another to drive an S-CO2 power cycle as the heat source. Parameters of the S-CO2 power cycle are thermodynamically optimized with the help of Genetic Algorithm. Optimal initial pressure and pressure ratio are 9.136 MPa and 5.84, respectively. Maximum cycle efficiency of the S-CO2 power cycle is 17.39%. With the optimal parameters, SCCR of the CFPP integrated with the S-CO2 power cycle decreases by 3.80 g·(kW h)−1. If the LPE is further integrated, the reduction of SCCR can reach 5.19 g·(kW h)−1. The essential reason for the significant energy saving is revealed through exergetic analysis. Exergy losses and destructions also decrease significantly in the novel waste heat recovery system. Finally, the economic performance of the proposed system is evaluated. Results show that the novel waste heat recovery system is economically suitable, and that capital investment could be recycled in 3.067 years.
