Net Present Value Research Articles

Rice husk reuse as a sustainable energy alternative in Tolima, Colombia

Colombia has great potential to produce clean energy through the use of residual biomass from the agricultural sector, such as residues obtained from the life cycle of rice production. This document presents a mixed approach methodology study to examine the combustion of rice husks as a possible energy alternative in the Tolima department of Colombia. First, the physicochemical characteristics of the rice husk were analyzed to characterize the raw material. Next, System Advisor Model (SAM) software was used to model a bioenergy plant to obtain biochar, bio-oil, and biogas from the combustion of rice husks and generate performance matrices, such as thermal efficiency, heat rate, and capacity factor. Then, the project was evaluated for financial feasibility using a mathematical model of net present value (NPV) with a planning horizon of 5 years. Finally, a subset of the local population was surveyed to assess perspectives on the project in the region. The results of the rice husk physicochemical analysis were the following: nitrogen content (0.74%), organic carbon (38.04%), silica (18.39%), humidity determination (7.68%), ash (19.4%), presence of carbonates (< 0.01%), and pH (6.41). These properties are adequate for the combustion process. The SAM simulation showed that the heat transferred in the boiler was 3180 kW, maintaining an efficiency between 50 and 52% throughout the 12 months of the year, meaning that the rice husk can generate electricity and thermal energy. The financial analysis showed that the internal rate of return (IRR) was 6% higher than the opportunity interest rate (OIR), demonstrating economic feasibility of the project. The design and creation of a rice husk processing plant is socially and environmentally viable and has the potential to contribute to the economic development of the Tolima community and reduce greenhouse gases. Likewise, this activity has the potential to promote energy security for consumers and environmental sustainability while at the same time being economically competitive.

Sensitivity Analysis of the Cost Coefficients in Multiobjective Integer Linear Optimization

This paper considers sensitivity analysis of the cost coefficients in multiobjective integer linear programming problems. We define the sensitivity region as the set of simultaneous changes to the coefficients for which the efficient set and its structure remain the same. In particular, we require that the component-wise relation between efficient solutions is preserved and that inefficient solutions remain inefficient, and we show that this is sufficient for the efficient set to be the same upon changes. For a single coefficient, we show that a subset of the inefficient solutions can be excluded from consideration. More specifically, we prove that it suffices to inspect the inefficient solutions of a q-objective problem that are efficient in one of two related q + 1-objective problems. Finally, we show that the sensitivity region is a convex set (an interval). Our approach generalizes to simultaneous changes in multiple coefficients. For illustration, we consider mean-variance capital budgeting and determine the region for which the set of efficient portfolios remains the same, despite a misspecification or a change in the net present values of the projects. Further computational experience with multiobjective binary and integer knapsack problems demonstrates the general applicability of our technique. For instance, we obtain all sensitivity intervals for changes to single coefficients of biobjective problems with 500 binary variables in less than half an hour of CPU time by excluding a large number of inefficient solutions. In fact, the number of excluded solutions is above 100 orders of magnitude larger than the number of remaining solutions. This paper was accepted by Chung Piaw Teo, optimization. Supplemental Material: The online appendix and data files are available at https://doi.org/10.1287/mnsc.2021.01406 .

Transesterification of Persea americana seed oil to methyl ester using bio-based heterogeneous catalyst: Optimization and techno-economic analysis

The techno-economic analysis of producing biodiesel from agrarian wastes at optimal condition was carried out. The acid activated empty palm fruit bunch ash (AAEPFBA) catalyzed the methyl ester production. The AAEPFBA catalyst was synthesized from waste palm fruit bunch, and modified with phosphoric acid. The activation was best achieved by adding H3PO4 acid in a ratio of 1:2 (g/ml). The modification of the catalyst increased the alkaline properties and surface area and decreased the particle size and adsorption energy. The process variables of temperature 61.9 °C, reaction time of 3.09 h, methanol/oil molar ratio of 10.2:1, catalyst concentration of 3.14wt%, and agitation speed of 321.54 rpm at a desirability of one gave an experimental optimal yield of biodiesel as 90.3%. Based on the experimental study, 3062 liters (2728kg) of biodiesel was evaluated annually. The annual operating cost, payback period, and internal rate of return are ₦2201288, 1.5years, and 7.6%, respectively. The sensitivity analysis of oil purchase cost, biodiesel selling price, and labour cost on Return on investment, PBP, IRR, and Net present value were investigated. In this study, the relative biodiesel selling price is a determinant of the profitability of producing avocado pear seed oil methyl ester. The overall results show that investors can embark on biodiesel production using avocado pear seed oil, and AAEPFBA as feedstocks.

An assessment of agroforestry as a climate‐smart practice: Evidences from farmers of northwestern region of Bangladesh

AbstractAgroforestry systems have grown significantly in popularity in Bangladesh during recent years due to their favorable effects on the environment and human health. These systems are essential for supporting sustainable agriculture because they increase diversity, improve food security, and provide revenue. This study's main objective is to show how agroforestry is a widely used ecological and climate‐resilient practice in Bangladesh. The research explores investment analysis, adoption‐influencing factors, and a strength, weakness, opportunities, and threats (SWOT) analysis of agroforestry practices. A total of 340 respondents were chosen for this extensive study using a multistage random selection technique. The results showed a discrepancy in practice, with farmers exhibiting a high degree of awareness but limited application. Financial analysis employing metrics such as benefit‐cost ratio, net present value, and internal rate of return favored agroforestry, indicating its economic viability and potential benefits for adopters. Additionally, the adoption of agroforestry was found to be significantly influenced by a binary logistic regression model that highlighted several important features, including larger farm sizes, younger age groups, greater education levels, training experiences, frequent extension visits, and enhanced market access. The study also identified barriers to adoption, such as a lack of trained labor, poor technical assistance, and education. This thorough analysis clarifies the opportunities and constraints for agroforestry implementation in Bangladesh. It suggests broad adoption by means of focused training initiatives that empower farmers, provide observable advantages, and promote nationwide acceptance.

Design and multi-criteria optimization and financial assessment of an innovative combined power plant and desalination process

Geothermal power generation programs are crucial due to their long-term sustainability and environmentally friendly characteristics, particularly for potential energy-based applications in the future. Innovative designs can yield improve efficien by mitigating irreversibility, resulting in enhanced power production. Hence, this study investigates an innovative cascade thermal design model that employs geothermal resources to enhance the efficiency and output of low-temperature power generation systems, specifically through the integration of organic flash and organic Rankine cycles. Additionally, this model introduces a novel cogeneration approach by incorporating a desalination unit based on humidification-dehumidification processes, aiming to concurrently produce electricity and fresh water. Employing a combination of thermodynamic analysis and financial assessment, the system's performance was simulated and optimized in MATLAB, using the Multi-Objective Particle Swarm Optimization (MOPSO) method. A sensitivity analysis preceded the optimization, leading to the development of three distinct optimization scenarios focused on balancing power and freshwater production, maximizing exergetic efficiency and net present value, and optimizing fixed capital investment for maximum financial viability. The results highlight the second scenario as particularly effective, achieving a power generation of 254.3 kW, an exergetic efficiency of 44.84%, and a net present value of $405,099. Conversely, the third scenario offers the best balance between freshwater production capacity (0.504 kg/s), fixed capital investment ($820,822), and a payback period of 7.12 years. This research demonstrates the potential of integrating advanced thermal models with geothermal resources for sustainable and efficient energy and freshwater production, marking a significant step forward in the development of eco-friendly cogeneration systems.

Investigating the sustainability of biogas recovery systems in wastewater treatment plants- A circular bioeconomy approach

Advanced wastewater treatment options offer a unique opportunity to recover valuable resources such as energy (biogas), nutrients, and minerals embedded in the wastewater streams. However, considerable challenges remain when designing and planning sustainable wastewater treatment systems. This study aims to evaluate the sustainability of waste-to-energy (WtE) recovery in the form of biogas in a wastewater treatment plant (WWTP). The study investigates the performance of a biogas recovery system in different scenarios and applications from 2018 to 2040, considering the city of Tbilisi in Georgia. The study results reveal a significant biogas production potential, with an average annual energy (heat and power) generation of 137 GWh when biogas is recovered from the wastewater (WW) and sewage sludge (SS). The WWTP-based WtE systems can avoid up to 38,500 tCO2eq emissions every year. The combined recovery (from WW and SS) scenario is financially feasible with a net present value of 14.88 million EUR and a levelized cost of biogas of 0.08 EUR/m³. Recovered biogas can help avoid the usage of 172.34 million m³ of natural gas worth 42.4 million EUR. Sensitivity analysis shows that the quality of wastewater, price of energy, and capital cost of the anaerobic digestion plant are the key factors in determining the economics of WtE recovery systems. This research also demonstrates the interlinkages between sustainable development goals and various benefits of resource recovery systems. This study could be helpful for decision-makers involved in planning and deploying resource recovery systems in a circular bioeconomy approach in WWTPs globally.

Electric vehicle-based distant energy sharing between zero-emission coastal office and hotel buildings

With the rapid growth of distributed renewable energy systems, energy sharing brings a practical solution to mitigate mismatching between intermittent electricity generation and building demand. In past research, energy sharing was designed mostly for onshore energy integrated systems and is commonly realised with the assistance of microgrids, distributed battery storage, or peer-to-peer energy trading. This research innovatively proposed a distant energy sharing between the ocean energy-supported coastal office building and hotel building by ten electric vehicles, enabling the circulation of ocean renewable energy between two buildings. This project aims to accomplish maximum technical, environmental and economic benefits for the stakeholder. Using bidirectional vehicle-building interaction, advanced control algorithms, including shifting vehicle batches, sizing renewable capacity, and involving stationary batteries, are implemented successively in the TRNSYS simulation as analysis groups to enhance the current system's performance. According to the results, the vehicle-based bidirectional energy sharing between these two buildings can attain a relative net present value of 49.18 million HKD and a weighted matching index of 0.63. After implementing advanced controls with stationary batteries, the system achieved a relative net present value of 62.15 million HKD with an improved matching index of 0.70. Both batteries contributed to increase the matching performance of the system, but the increase in battery capacity reduces the benefit due to their replacement cost. This research developed an energy management system for effectively utilising electric vehicles and coastal renewable energy for distant energy sharing. It elucidated the technological, environmental, and economic benefits to the stakeholders for effective decision-making.

The potential of agricultural and livestock wastes as a source of biogas in Vietnam: Energetic, economic and environmental evaluation

Many economies, including Vietnam, have substantial potential for producing energy from agricultural waste. However, the analysis of using agricultural waste as a renewable energy source and its associated economic and environmental benefits remain unclear. This study aims to a) estimate trends in greenhouse gas (GHG) emissions from livestock and crop residue burning; b) evaluate the environmental benefits of using biogas in substitution for coal, wood, and liquefied petroleum gas (LPG) under various scenarios; c) assess the economic viability of a household-scale biodigester, and d) propose recommendations for the effective exploitation and utilization of biogas. GHG emissions were calculated for livestock and crop residue burning (CRB) using activity data and emission factors. The environmental analysis was conducted to understand the role of biogas in reducing GHG by assuming 100 % exportation of biogas in substitution for fuels for electricity and heat generation. The economic benefits were assessed through internal rate of return (IRR), net present value (NPV), payback period, levelized cost of electricity (LCOE), and levelized cost of heat (LCOH). Results indicate that, between 2000 and 2050, CO2-eq emissions will rise from 38.5 to 95.2 Mt. Environmental analysis shows that replacing coal or wood with biogas can bring more benefits than LPG, in reducing GHG emissions by 68.2 and 67.9 Mt CO2-eq in 2020 and by 148.4 and 147.9 Mt CO2-eq by 2050. Economic analysis shows that investment in biodigesters is most viable when replacing LPG with biogas, with NPV = $4878, IRR = 57.2 %, PBP (simple) = 1.7 years, and LCOH = $0.029/kWh.

Profitability and cost-effectiveness analysis of brucellosis control in Armenia: A One Health approach

Abstract Brucellosis is endemic in the Republic of Armenia and constitutes a financial and public health burden on the nation. Control of the disease is currently using the test-and-slaughter strategy, reportedly at a coverage level deemed insufficient to interrupt transmission by the authorities responsible for disease control. A key aspect of this control strategy is the shared costs between the agricultural and public health sectors. An earlier study conducted by the Advanced One Health Class at the Swiss Tropical and Public Health Institute developed a mathematical-compartmental transmission model to represent the transmission of Brucella between cattle, sheep, and humans. The study simulated the performance of the existing control strategy and three other upgraded scenarios over a decade, giving the cumulative incidence of human and livestock prevalence (2022–2031). Based on the cumulative incidence of human and livestock prevalence from 10-year simulations, this study evaluates Armenia’s current brucellosis control program’s profitability, cost-effectiveness, and cost distribution for the existing test-and-slaughter level and three proposed upgraded scenarios in cattle and sheep. In these scenarios, the percentages represent the proportion of animals that were culled when they tested positive for brucellosis: Scenario 1 – 86% of cattle and 65% of sheep; Scenario 2 – 88% of cattle and 70% of sheep; Scenario 3 – 90% of cattle and 75% of sheep. Further estimations were made on public and private health costs, and income loss of human brucellosis patients averted through the different livestock-level interventions. The incremental livestock production and the averted human health cost were summed up as societal benefits of brucellosis interventions. From a societal perspective, the most profitable scenario is estimated to have a net present value of US$ 41.82 million, from an overall cost of US$ 48.27 million and a benefit of US$ 6.45 million, resulting in a benefit-cost ratio of 0.133 at 80% compensation for farmers’ losses and discounted at 5%. From a public health perspective, the cost-effectiveness ratio for the same intervention scenario is US$ 1587 per DALY averted (95% CI: US$ 1268–US$ 2009). When private costs, which are the private income loss and out-of-pocket costs of patients, are added to the public health costs, the cost-effectiveness decreases to US$ 6727 per DALY averted at a 5% discount rate (95% CI: US$ 5371–US$ 8504). These cost-effectiveness and benefit-cost ratios highlight the remarkable disparity in the cost of the test-and-slaughter strategy across the agriculture and public health sectors. Our study highlights the need to reassess the cost-effectiveness of the test-and-slaughter strategy for brucellosis control in Armenia and consider an equitable distribution of the cost of the test-and-slaughter strategy among the sectors as this could facilitate better disease control and cost-effectiveness of the strategy. Armenia should view brucellosis elimination as a public good, justifying public spending for compensation. As seen in other countries, its elimination could boost the economy by lowering trade barriers, making brucellosis-free status a societal benefit. One Health impact statement Our study focuses on controlling brucellosis in Armenia using an integrated approach called One Health, which seeks to demonstrate the incremental benefit of closer cooperation between human and animal health and other sectors. We evaluate how profitable and cost-effective test-and-slaughter interventions are in improving the health of both humans and animals while also considering the costs for farmers and the state. Using a One Health approach, we can better understand the cross-sector expenses related to the disease and develop more efficient strategies to interrupt transmission and eventually eliminate the disease. The result is improved animal and human health outcomes, enhanced livelihoods, and a positive contribution to the economy’s overall growth (Narrod et al ., 2012 ). To carry out this study, we collaborated closely with non-academic partners from the Food Safety and Inspectorate Body (FSIB) and the National Centre for Disease Control in Armenia (NCDC). This collaboration resulted in the creation of valuable knowledge and practical solutions, underscoring the importance of working together across different sectors, including indigenous communities, academia, and non-academic organizations.

Techno-Economic Analysis of Biogas Production from Cow Manure

Biogas has been considered as a renewable alternative energy produced by anaerobic digestion of cow manure. A process of anaerobic digestion of cow manure was simulated by Aspen Plus software to analyze the cost of production. The simulated project used cow manure wastes as a feedstock. From the study, economic analysis includes Net Present Value (NPV), Internal Rate of Return (IRR), Payback period (PBP), and B/C Ratio. The resulting BEP value is 539.20, the NPV is 6,414,566,421.98, the IRR is 249.84%, and the B/C ratio is 1.66. These values can be said that the business of cow dung which is processed into biogas is feasible to run.

ECONOMIC FEASIBILITY OF ON-GRID PHOTOVOLTAIC SYSTEMS IN A SINGLE-FAMILY HOUSE IN RIO DE JANEIRO CITY

Brazil is a tropical country with favorable conditions for the generation and utilization of solar energy. This energy source becomes even more attractive when considering the dry periods that impact hydroelectric power generation in the country, resulting in an increase in energy costs reflected monthly in consumers' bills through tariff flags. In order to enhance residential architectural designs and promote energy efficiency, a feasibility study of photovoltaic systems was conducted, considering key economic indicators and the current tariff flags. To accomplish this, research was conducted in collaboration with Mounting Companies for a case study located in the city of Rio de Janeiro, adopting technical assumptions commonly used for residential photovoltaic system sizing. For the graphical sizing of the case study, factors such as the environment and summer and winter solstices were taken into account, and a shadow study was conducted to assess the potential loss of power generation by the photovoltaic system throughout the year. The shadow study revealed that, during both solstices, the optimal time for power generation by photovoltaic systems is between 9 a.m. and 6 p.m. Essentially, the calculated values of NPV (Net Present Value) and IRR (Internal Rate of Return) indicate that the project is economically viable and particularly advantageous during the yellow and red tariff flags, situations in which energy costs tend to be higher for consumers.

Design and Economic Analysis of a Solar Thermal Pre-Cooling System for Agro-Cold Chain in Lesotho

The agricultural sector in Lesotho grapples with significant challenges regarding post-harvest losses. Given that 40% of all agricultural products require cold storage, food quality is compromised due to lack of cold storage to extract the heat from exposure to high field temperatures after harvest. This research proposes a solar thermal cooling system tailored to the specific needs of preserving fresh agricultural produce, leveraging Lesotho’s abundant solar energy resources. Through TRNSYS simulation and MATLAB economic analysis, optimal system parameters are determined, ensuring both technical efficiency and financial viability. The outcomes indicate that the proposed absorption solar thermal cooling system, incorporating evacuated tube collectors and an auxiliary boiler, effectively manages a cooling load of 7.318 kW, preserving fresh vegetables at 6.1°C. The optimized design features a chiller with a Coefficient of Performance of 0.8, a collector area of 12 m², and a hot storage volume of 0.2 m³, maximizing solar energy utilization. Importantly, economic metrics such as Levelized Cost of Energy ($0.085/kWh), Net Present Value ($9,200), Discounted Payback Period (12 years), and Savings to Investment Ratio (achieving 1 in year 13) demonstrate the financial feasibility and profitability of the system. These findings underscore the potential of solar thermal cooling as a promising investment option for addressing refrigeration needs in Lesotho, offering a sustainable solution to mitigate post-harvest losses and enhance economic performance in the agricultural sector.

Feasibility Assessment of a Small-Scale Agrivoltaics-Based Desalination Plant with Flywheel Energy Storage—Case Study: Namibia

As climate change and population growth threaten rural communities, especially in regions like Sub-Saharan Africa, rural electrification becomes crucial to addressing water and food security within the energy-water-food nexus. This study explores social innovation in microgrid projects, focusing on integrating micro-agrovoltaics (APV) with flywheel energy storage systems (FSSs) and small-scale water desalination and purification plants. Employing a mixed-methods approach to assess the economic viability of FSS and APV-powered desalination, we believe that social innovation could serve as a significant tool for rural development, requiring collaboration between governments, the private sector, and nonprofit organizations. While FSS technology for microgrids has not been entirely developed, it holds promise as an alternative energy storage solution. Our capital budgeting analysis, presented within the context of social innovation, reveals positive Net Present Values (NPV) and a short payback period over the project’s 20-year lifespan.

Maximizing Net Present Value for Resource Constraint Project Scheduling Problems with Payments at Event Occurrences Using Approximate Dynamic Programming

Resource Constraint Project Scheduling Problems with Discounted Cash Flows (RCPSPDC) focuses on maximizing the net present value by summing the discounted cash flows of project activities. An extension of this problem is the Payment at Event Occurrences (PEO) scheme, where the client makes multiple payments to the contractor upon completion of predefined activities, with additional final settlement at project completion. Numerous approximation methods such as metaheuristics have been proposed to solve this NP-hard problem. However, these methods suffer from parameter control and/or the computational cost of correcting infeasible solutions. Alternatively, approximate dynamic programming (ADP) sequentially generates a schedule based on strategies computed via Monte Carlo (MC) simulations. This saves the computations required for solution corrections, but its performance is highly dependent on its strategy. In this study, we propose the hybridization of ADP with three different metaheuristics to take advantage of their combined strengths, resulting in six different models. The Estimation of Distribution Algorithm (EDA) and Ant Colony Optimization (ACO) were used to recommend policies for ADP. A Discrete cCuckoo Search (DCS) further improved the schedules generated by ADP. Our experimental analysis performed on the j30, j60, and j90 datasets of PSPLIB has shown that ADP–DCS is better than ADP alone. Implementing the EDA and ACO as prioritization strategies for Monte Carlo simulations greatly improved the solutions with high statistical significance. In addition, models with the EDA showed better performance than those with ACO and random priority, especially when the number of events increased.

A New Approach to the Economic Evaluation of Thermomodernization: Annual Assessment Based on the Example of Production Space

Energy and economic assessments are of great relevance in the context of decision processes for the most optimal solutions for building renovations. Following the method recommended by UNIDO, economic analyses of thermal modernization options are carried out based on the Simple Payback Time (SPBT), Net Present Value Ratio (NPVR) and Internal Rate of Return (IRR) indices. Incorporating these indicators and a new approach that involves aggregating thermomodernization activities not only in the cold and warm seasons separately, but throughout the whole year, an economic evaluation of the thermomodernization of a production space was carried out. In this case study, the renovation options included wall insulation, window replacement, the installation of infrared heater, a two-flow air diffuser (TFAD) and variable air volume. The economic effect indicated by the highest NPVR over a normative period of 15 years was obtained for the installation of an infrared heater and a TFAD with a variable mode ventilation system. The SPBT for this case was also the lowest.

Optimization of a Hybrid Solar–Wind Microgrid for Sustainable Development: A Case Study in Antofagasta, Chile

This paper introduces a genetic algorithm designed to optimize the sizing of a hybrid solar–wind microgrid connected to the main electric grid in Chile, serving a simulated town of 2000 houses. The goal is to promote sustainable development by using renewable energy sources (RES) to supply a small village. The model, considering local meteorological conditions, aggregated load, and Chilean electrical regulations, establishes the optimal number of photovoltaic modules and wind turbine generators and allows for the monitoring of the microgrid’s operation, whose operating strategy is proposed herein. Adhering to Chilean regulations, a maximum exporting power of 9 MW is analyzed, with no restrictions on importing power, which is needed when the renewable resources are not enough to meet the demand. The optimization algorithm, aimed at sizing the RES supply, identified an optimal solution composed of 5 photovoltaic modules of 500 Wp each (2.5 kWp in total) and 123 wind turbines of 100 kW each (total of 12,300 kW), meeting around 85% of the demand through renewable generation. Due to time mismatches between generation and load patterns, the remaining energy was imported. The project’s net present value is approximately EUR 25 M, with a levelized cost of energy at 37 EUR/MWh. A comparison with HOMER grid simulations validates the efficacy of the developed model.

Sustainable energy transition in Bangladeshi academic buildings: A techno-economic analysis of photovoltaic-based net zero energy systems

Bangladesh faces challenges with global carbon emissions and energy security due to its heavy reliance on imported fossil fuels. This paper investigates the techno-economic viability of photovoltaic (PV) systems for achieving net-zero energy in academic buildings as a sustainable alternative. The study evaluates the performance of PV systems based on factors including annual energy production, capacity factor, net-zero energy potential, self-consumption/sufficiency ratio, renewable fraction, levelized cost of energy (LCOE), net present value (NPV), payback period, profitability index (PI), and carbon emission reduction. The results indicate that optimally sized PV systems can generate net positive energy: 6.18 MWh for universities, 4.04 MWh for high schools, and 3.62 MWh for primary schools. Economic viability was assessed under two billing methods (net metering and all energy buy/sell), and all cases showed positive NPV and PI values greater than 1. Decarbonization analysis revealed significant reductions in CO2 emissions: 2026.5 tons for universities, 18.9 tons for high schools, and 9.7 tons for primary schools. Finally, a sensitivity analysis assessed the optimal PV system size for seven other regions in Bangladesh. These findings suggest that the widespread adoption of PV systems in academic buildings can play a crucial role in achieving net-zero energy, contributing significantly to the government and policymakers' pursuit of sustainable development goals.

Performance analysis of a compressed air energy storage incorporated with a biomass power generation system

Compressed air energy storage technology is recognized as a promising method to consume renewable energy on a large scale and establish the safe and stable operation of the power grid. To improve the energy efficiency and economic performance of the compressed air energy storage system, this study proposes a design for integrating a compressed air energy storage system with a biomass power generation system. In the energy storage process, the feedwater from the biomass power generation system is used to cool the compressed air in the compressed air energy storage system. In the energy release process, the flue gas from the biomass power generation system is used to heat the compressed air. Besides, the compressed air from the compressed air energy storage system first works in the expander and then goes to the biomass power generation system for combustion. Based on the system simulation, the proposed system is assessed from the energy, exergy, economy, and environment perspectives. The results show that the round-trip efficiency and the energy storage density of the compressed air energy storage subsystem are 84.90 % and 15.91 MJ/m3, respectively. The exergy efficiency of the compressed air energy storage subsystem is 80.46 %, with the highest exergy loss in the throttle valves. The total investment of the compressed air energy storage subsystem is 256.45 k$, and the dynamic payback period and the net present value are 4.20 years and 340.48 k$. Besides, the proposed system’s CO2 emission is 258 kg/GWh. This study provides a new option for enhancing the performance of compressed air energy storage through the system integration.

Biological and economic feasibility of cultivating the mangrove cockle Anadara tuberculosa (Sowerby, 1833) in a shrimp farm reservoir with estuarine influence in Santa Elena, Ecuador

The extraction of Anadara tuberculosa, a commercially valuable species in the tropical Eastern Pacific mangroves, presents significant ecological risks. To mitigate these risks, captive production of A. tuberculosa is crucial. This study examines the somatic conditions of laboratory-produced A. tuberculosa spat and their cultivation on a pilot scale in a canal-reservoir of a shrimp farm. Spat measuring 6.2 ± 0.9 mm were placed in baskets and cultured in suspension at a density of 776.6 ± 26.0 cockles (0.54 cockle per square centimeter). Environmental variables at the culture site were monitored. After 24 months of culture, the cockles reached a size of 44.7 ± 0.6 mm with a survival rate of 65.0 ± 0.6%. These production results were extrapolated to evaluate the economic viability of production in a shrimp farm canal-reservoir with estuarine influence. The proposed economic model yielded 325,000 market-ready Anadara tuberculosa mangrove cockles (in five culture cycles) with an estimated net present value (NPV) of $22,914.00. The modified internal rate of return (MIRR) reached 15.20 percent, and the cost-benefit ratio was $1.96. Economic projections indicate that the initial capital investment could be recovered within five years and one month (payback). This research provides evidence of the biological feasibility, including somatic growth, survival rates, and the relationship with environmental variables at the site, as well as the economic feasibility of cultivating A. tuberculosa in a canal of a shrimp farm with estuarine influence. The findings offer valuable insights for scaling up aquaculture production and initiating restoration processes for this species.

Modeling and assessment of the techno-economic analysis of biogas and its potential for the generation of electricity from water hyacinth biomass

The study presents the economic feasibility assessment of converting the produced biogas from water hyacinth biomass into electricity. Approximately, 0.3793 m3CH4/kgVS was generated from the water hyacinth biomass. The research indicated that the available water hyacinth population on the Lower Volta River in the year 2020 could potentially generate a methane yield of 53.676 × 106m3. The volume of methane gas generated had the potential to produce an annual electricity output of 110.792 × 106 kWh, which could be integrated into the national grid. The economic analysis indicated positive results with an initial total investment cost of $67,273,700. The project showed a positive net present value (NPV) of $8,923,769 and a levelized cost of 0.172 $/kWh. The simple payback and equity payback periods were determined to be 5.5 and 11.3 years, respectively. Furthermore, a sensitivity analysis conducted showed that the project’s NPV remained positive when variations in input parameters such as initial cost, operations, and maintenance cost were less than 15% sensitive range. However, a 30% reduction in the feed-in tariff cost resulted in a negative NPV. In conclusion, biogas production from water hyacinth biomass in Ghana can make a significant contribution to the country’s energy mix and help alleviate the energy shortfall in rural areas.