Search Results (613)

Although Sustainable Urban Drainage Systems (SUDS) are widely recognised as essential components of resilient urban water management, the large-scale planning and evaluation of such systems remain challenging. This study assesses the hydrological and economic performance of SUDS in Madrid (Spain) under the SSP1-2.6 and SSP5-8.5 climate scenarios, applying a dual-scale methodology based on the Curve Number (CN) model. At the catchment scale, SUDS show substantial potential for irrigation reuse, with runoff-rich catchments reaching hydrological saturation earlier (plateau at r ≈ 0.4) and runoff-limited catchments stabilising at higher implementation levels (plateau at r ≈ 0.6). At the parcel scale, partial-coverage configurations (50% irrigation coverage) outperform full-coverage solutions (100% irrigation coverage), achieving maximum retention levels of 70% in SSP1-2.6 and 50% in SSP5-8.5 while requiring less surface area (10–15%). From an economic perspective, positive net present values (NPVs), acceptable internal rates of return (IRRs), and feasible payback periods occur only at very low retention levels (r < 0.05), with financial performance declining rapidly as storage capacity increases. Full article

The evaluation of intervention strategies for the existing building stock, within the context of energy transition and increasing attention being given to sustainability, requires approaches capable of systematically integrating economic and environmental dimensions over the entire building life cycle. From this perspective, the present study develops and applies an integrated Life Cycle Costing (LCC) and Life Cycle Assessment (LCA) model aimed at comparing two alternative intervention strategies for traditional residential buildings: conservative retrofit of the existing structure and demolition with reconstruction according to Nearly Zero Energy Building (NZEB) criteria. The methodological framework, compliant with ISO 15686-5 and based on a simplified LCA-oriented approach inspired by EN 15978 principles, is applied to a representative case study of Swedish vernacular wooden architecture (röd stuga) located in the municipality of Falun. The assessments are carried out over 50- and 100-year time horizons, adopting Net Present Value (NPV) as the primary economic indicator and Global Warming Potential over 100 years (GWP100) and Cumulative Energy Demand (CED) as environmental indicators. The results show that the NZEB scenario, despite higher initial investment costs, achieves a significant reduction in life-cycle environmental impacts, with a decrease of approximately 20–25% in terms of GWP100 and about 45–50% in terms of CED compared to the retrofit scenario. The analysis also highlights a differentiated behavior of environmental indicators—while operational energy use remains dominant in cumulative energy demand, embodied impacts become increasingly significant in the GWP balance, particularly in high-performance scenarios. From an economic perspective, conservative retrofit results in lower global costs over the considered time horizons, although the economic gap tends to narrow in the long term. The integrated LCC–environmental assessment approach highlights the economic–environmental trade-offs and provides a replicable decision-support framework for sustainable regeneration policies targeting the existing residential building stock. Full article

Decarbonizing HVAC in hot–arid regions is challenging for natatoriums because year-round cooling must be delivered alongside stringent dehumidification and occasional heating under high ambient temperatures. In this paper, a fully renewable system has been developed and evaluated for an indoor swimming pool located in Abu Dhabi with a 679 m² swimming pool hall designed to accommodate 200 pool users. The hybrid system includes a high-temperature linear Fresnel reflector (LFR) solar field, stratified thermal energy storage (TES), a single-effect LiBr–H₂O absorption chiller for cooling, a water-to-water heat pump as a backup system for the stability of cooling and heating rates, and a photovoltaic (PV) system to offset the ancillary equipment power input of the hybrid system. The system performance was simulated and validated by using hourly data from Abu Dhabi. Optimization of design/operation parameters was carried out by a multi-objective genetic algorithm to achieve the maximum coefficient of performance (COP) and the minimum levelized cost of cooling (LCOE). The initial COP and LCOE were 0.701 and 0.037 $/kWh, respectively. They were optimized to 0.825 and 0.0254 $/kWh, respectively. The annual energy balance revealed a synergistic operation of the solar field, TES, and heat pump. The lifecycle assessment was utilized to compare the proposed hybrid system with the conventional vapor-compression systems in terms of energy, cost, and CO₂ emissions, in which the proposed system proved superior over conventional systems with a positive net present value (NPV) and net zero carbon emissions. Full article

Brazil possesses globally competitive offshore wind resources; however, financial viability is constrained by high capital expenditure (CAPEX) and industry risk. This study evaluates the investment feasibility of a 1 GW offshore wind project in northeast Brazil using a discounted cash flow (DCF) model. For the key parameter of CAPEX, a Baseline Case was established, assuming a 1.53% commodity price escalation from 2021 until the Financial Investment Decision (FID) date of 2027, and was sensitivity tested against an Optimistic Case, assuming 0% cost escalation and a Stress Case based on twice the commodity price escalation of 3.06% up to 2027. Each CAPEX Case was evaluated against 12 financing scenarios involving varying levels of public support through a blend of concessional debt and grants. Financial performance was measured using net present value (NPV) and Equity Internal Rate of Return (EIRR). Results indicate that project financial viability is achieved under the Baseline Case only with levels of grant funding and concessional debt that exceed realistic thresholds, unless PPA tariffs are raised by about 50% relative to current market benchmarks. The Optimistic Case is viable at current tariffs under more realistic financing structures but represents an unattainable degree of capital cost containment. The Stress Case is not viable at all without a doubling of current PPA tariffs. Sensitivity analysis further demonstrates that even the most promising financial scenarios are vulnerable to any shortening of the 20-year PPA contracting period, leading to greater merchant risk exposure. The paper concludes that catalysing Brazil’s nascent offshore wind market will therefore call for a combination of policy measures that: permit (and recoup) a transitional premium over current PPA prices; adopt structural measures to reduce associated CAPEX through local supply chain development; combine public and private sources of capital to soften financial terms; and incorporate price risk mitigation measures. Full article

This study evaluates the techno-economic feasibility of producing a functional baked snack formulated with sweet potato flour, cereals, and upcycled brewer’s spent grain (BSG). The analysis, developed in SuperPro Designer^®, integrates experimentally derived parameters from literature, justifying the transition from laboratory-scale data to an industrial production model. The analysis identified refrigerated storage (48 h) and tray drying as the primary bottlenecks limiting throughput. By synchronizing equipment cycles and increasing the number of units, the production capacity was adjusted from 154.32 to 1077.21 metric tons per year, capturing approximately 0.8% of the estimated annual demand for sweet potato snacks in Mexico. Economic evaluation for this scale demonstrated a capital investment of USD 24.6 million and annual operating costs of USD 8.49 million. The inclusion of a sedimentation-based water treatment, while increasing costs, enables a significant reduction in freshwater intake. The project yielded a payback period of 3.62 years and a Net Present Value (NPV) of USD 23.908 million. Sensitivity analysis revealed that profitability is strongly influenced by production volume and sweet potato costs. These findings provide a realistic framework for assessing the commercial viability of functional food formulations when scaled for industrial production. Full article

Rapid load growth and increasing operational uncertainty pose significant challenges to conventional distribution network planning. To address these challenges, this paper proposes a robust dynamic co-planning framework for distribution feeders and virtual distribution feeders (VDFs). Firstly, a dynamic co-planning model is developed to jointly optimize feeder reinforcement and battery energy storage system (BESS)-based non-wire alternatives over a multi-year horizon. Then, a robustness index (RI) is proposed to quantitatively evaluate the robustness of planning solutions under operational uncertainties without relying on assumed probability distributions. Four objectives are optimized simultaneously: (1) net present value cost (NPV), (2) cumulative overload quantity (COQ), (3) incremental capacity idle rate (ICIR), and (4) robustness index (RI). In addition, feeder emergency rating and battery degradation are incorporated to capture feeder-side thermal flexibility and storage aging characteristics in the planning process. Finally, the proposed method is tested on a modified IEEE 33-bus system. The results show that the proposed framework achieves a superior trade-off between cost, utilization, and robustness than conventional approaches, while reducing unnecessary BESS deployment and improving the physical consistency of the planning results. Full article

Metaheuristic algorithms can fail to balance global exploration and local exploitation, occasionally becoming trapped in suboptimal regions on highly multimodal problems. The Groupers and Moray Eels (GME) algorithm, inspired by the associative hunting strategies of marine predators, provides a cooperative optimization framework. However, the sequential interaction phases of GME can fail to maintain diverse topological coverage across heavily constrained landscapes. To address these limitations, we propose an enhanced variant, GPS-CC-GME. The approach improves the initial agent distribution by deploying a number-theoretic Good Point Set (GPS) generation protocol to establish a uniformly dispersed starting space. In addition, algorithmic stagnation is addressed through a dual-crossover search architecture. A horizontal crossover stage enforces information sharing among randomized agents to sustain global diversity, and a vertical crossover phase isolates specific dimensional vectors within individual agents for localized fine-tuning. We evaluated the proposed model on the CEC2017 benchmark suite, where it secured the highest overall ranking compared to the baseline GME and several standard metaheuristics. GPS-CC-GME was then applied to a high-dimensional optimization scenario for petroleum reservoir production. The algorithm yielded higher Net Present Value (NPV) metrics than the canonical framework. The results indicate that embedding deterministic initialization and bidirectional mutation operators into multipredator models can improve search outcomes in non-linear engineering tasks. Full article

The Build–Operate–Transfer (BOT) model is one of the most widely used Public–Private Partnership (PPP) methods for financing large-scale infrastructure projects. In this model, the concession period, which is the most critical parameter of the contract between the government and the private-sector investor, is a decision variable that directly affects the interests of both parties and varies depending on many uncertainty factors. The vast majority of models in the existing literature have been tested on hypothetical projects, and it is observed that parameters such as country-specific legal regulations, traffic volume guarantees, and financing conditions affecting discounting over time are not sufficiently incorporated into existing models. This study develops an integrated stochastic financial model, building on the established NPV–Monte Carlo–bargaining framework in the literature, that determines the optimum concession period for highway projects to be tendered via the BOT model in Türkiye. In the proposed model, uncertain parameters (construction cost, inflation, loan interest rate, traffic volume, toll increase rate, operation and maintenance costs) are defined with probability distributions; the Net Present Value (NPV) based financial model is solved via Monte Carlo simulation; and the obtained concession range is narrowed using a Rubinstein-type alternating-offers bargaining-game framework. The model simultaneously integrates parameters that prior studies addressed only in isolation: the equity–debt structure, loan repayment conditions, the government’s traffic volume guarantee, expropriation costs, and legal limits specific to Türkiye. The proposed model was validated by applying it to the Ankara–Niğde Highway Project, which was tendered in 2017. The results indicate that the concession range calculated by the model (11 years, 9 months, 2 days–24 years, 4 months) is consistent with the actual bids in the tender process. Following the application of bargaining-game theory, the range was narrowed to between 13 years, 4 months, and 16 days and 13 years and 5 months; this interval represents the concession range that best balances the profitability of both parties. This study provides a multidimensional evaluation framework for decision-makers by presenting comprehensive profitability analyses under different scenarios (including/excluding guaranteed traffic volumes and the project being fully constructed by the state). Full article

Wind curtailment in Great Britain (GB) is increasing, leading to underutilisation of low-carbon energy and higher system costs. This paper develops a data-driven techno-economic framework for a hydrogen generation and storage system that converts curtailed wind energy into hydrogen. By modelling curtailment time series and electricity prices, and considering a proton exchange membrane (PEM) electrolyser-based power-to-gas system, The framework explicitly represents the operation and interaction of the PEM electrolyser, hydrogen compression, and high-pressure storage under time-varying curtailment and electricity price conditions using reconstructed GB curtailment time series. The levelised cost of hydrogen (LCOH), net present value (NPV), and delivered hydrogen volumes are evaluated. A new sizing metric, curtailment utilisation, is introduced to link curtailment availability with electrolyser and storage productivity. Using a GB curtailment dataset, two key relationships are identified. First, increasing access to low-cost curtailed energy reduces the LCOH until electrolyser utilisation saturates, beyond which additional energy purchases provide diminishing benefits. Second, hydrogen storage exhibits an economic optimum: Undersized tanks increase costs due to ramping and venting losses, whereas oversized tanks raise capital investment requirements and increase the LCOH. For the best-performing configuration, corresponding to 70.2 MWh of curtailed energy, a 2.3 MW electrolyser, and a 94 m³ high-pressure tank, the system achieves an LCOH of £3.51/kg H₂ (excluding downstream delivery) and an NPV of £2.17 M and meets 98.01% of the hydrogen demand. These results indicate that optimal system design requires not only appropriate component sizing but also explicit consideration of curtailment profiles and pricing structures. The proposed framework provides decision-grade guidance for developers and policymakers evaluating hydrogen production from wind curtailment. Future work will extend the model to hybridise with other energy storage system technologies, enable revenue stacking across multiple markets, address real-gas storage modelling, examine the sensitivity of stack degradation, and incorporate transport and delivery costs. These findings show that viable hydrogen production from curtailed wind depends on both low-cost electricity and coordinated electrolyser storage sizing under realistic curtailment conditions. The framework provides practical guidance for developers and policymakers. Full article

The increasing integration of distributed photovoltaic (PV) systems in urban environments requires planning frameworks that simultaneously address economic viability, environmental sustainability, and power system performance. This study develops a simulation-based techno-economic and environmental assessment framework for evaluating hybrid rooftop photovoltaic (PV) and building-integrated photovoltaic (BIPV) deployment under harsh climatic conditions. Detailed system modelling using PVsyst and ETAP is conducted to analyse energy production, economic performance, environmental impact, and grid interaction characteristics, including voltage deviation and harmonic distortion. To support deployment planning and operational decision-making, the simulation outputs are incorporated into a multi-objective optimisation framework that evaluates trade-offs among levelized cost of energy (LCOE), net present value (NPV), carbon emission reduction, and power quality indicators. Three deployment configurations including rooftop PV only, BIPV only, and a hybrid PV–BIPV system are assessed using structured trade-off analysis and Pareto optimality principles. Results indicate that the hybrid configuration provides the most balanced performance across technical, economic, and environmental objectives. The system achieves an average performance ratio of 77.36% and generates approximately 2075 MWh of annual energy while maintaining grid voltages within acceptable limits and harmonic distortion well below IEEE 519 thresholds. Economic analysis shows strong financial feasibility with an LCOE of approximately 0.05 USD/kWh, a payback period of 8.1 years, a net present value of about 2.88 million USD, and a return on investment exceeding 145%. Loss analysis further identifies temperature effects and dust accumulation as the dominant performance constraints under harsh environmental conditions. Moreover, Pareto-based evaluation confirms the hybrid PV–BIPV configuration as the preferred deployment strategy among the evaluated alternatives. The proposed framework demonstrates how integrated simulation and multi-objective optimization can serve as a practical decision-support tool for planners and policymakers seeking to optimise distributed renewable energy deployment under climatic and operational uncertainties. Full article

Economic evaluation plays a pivotal role in investment decision-making for mining projects, especially under volatile market conditions. In this study, a risk-based decision-support framework is developed to assess the economic sustainability of an open-pit gold mining operation by integrating sensitivity analysis with Monte Carlo simulation, where Net Present Value (NPV) is used as the primary performance indicator. The proposed approach provides a flexible and practical computational framework for evaluating investment risk under uncertainty. A case study from an open-pit gold mine in Kyrgyzstan is used to compare two scenarios: continuation of the current operation and an alternative option involving a $30 million investment to improve mill processing performance. The sensitivity analysis shows that gold price, mining cost, and recovery rate are the most influential parameters affecting project outcomes, while Monte Carlo simulation is used to capture uncertainty in these variables and to generate a distribution of possible NPV results. The results indicate that gold price and recovery rate have a dominant influence on project value, and that improving mill performance leads to higher recovery and increased economic returns. The simulation results show a median NPV of approximately 220 million USD with a probability of negative NPV (17.52%), while the enhanced scenario achieves an IRR of approximately 13%, indicating improved financial performance. In addition, the findings suggest that accounting for uncertainty provides more reliable support for investment decisions and contributes to a more efficient use of mineral resources. In this context, the proposed framework contributes to sustainability assessment tools by supporting economically sustainable resource utilization through risk-based evaluation of recovery improvement under uncertainty. While the present study focuses on the economic pillar of sustainability, the framework can provide a basis for future integration of environmental and social indicators. Full article

This study develops a lifecycle economic comparison framework for shared energy storage, in which multiple users share a common storage asset through capacity leasing. A multi-service revenue structure, including capacity leasing, spot-market arbitrage, auxiliary frequency regulation, peak shaving, and capacity compensation, is established for comparative evaluation. Case studies are conducted for lithium iron phosphate (LFP) and vanadium redox flow (VRF) batteries across six representative Chinese electricity markets and six standardized revenue-combination scenarios. The results show that, among the scenarios that more closely reflect current operating practices, P3 (capacity compensation + spot market + auxiliary frequency regulation) delivers the highest net present value (NPV). P6 combines all five revenue streams without explicitly modeling service-coupling dispatch constraints, and is therefore treated as a theoretical benchmark rather than an immediately deployable operating mode. Under this benchmark assumption, its calculated NPV is 21.1% and 41.7% higher than that of P3 for the two battery types, respectively. The study also shows that power-related services are more sensitive to rated power, while spot-market and peak-shaving revenues are more dependent on rated capacity. Full article

As engineering systems grow in complexity, reliable metaheuristic optimizers are increasingly essential. While swarm intelligence algorithms are widely applied, recent approaches like the Cuckoo Catfish Optimizer (CCO) can experience premature convergence due to limited local exploitation and simplistic boundary handling. To address these limitations, this paper proposes the Dung Beetle with Reflection CCO (DBRCCO), integrating two principal mechanisms. First, an adaptive local search strategy inspired by dung beetle foraging is incorporated to intensify exploitation within dynamically contracting regions. Second, a momentum-preserving reflecting boundary mechanism replaces traditional clamping, maintaining population diversity near constraint edges. DBRCCO is evaluated against eight contemporary metaheuristic algorithms using the 29 CEC2017 benchmark functions and a reservoir production optimization problem. Statistical analyses indicate that DBRCCO achieves competitive performance, securing a Friedman ranking of 1.5172 ($p<0.05$). In the reservoir application, DBRCCO improves the mean Net Present Value (NPV) by 12.54% while reducing variance by over 72% relative to the standard CCO. These findings suggest that DBRCCO offers a stable and effective alternative for complex optimization tasks. Full article

To address the issue of performance degradation resulting from continuous thermal accumulation in the soil for conventional ground source heat pump (GSHP) systems in cooling-dominated regions, a hybrid ground source heat pump–domestic hot water system (HGSHP-DHW) is proposed, along with a corresponding mode-switching control strategy. The heat pumps for cooling, heating, and domestic hot water in the HGSHP-DHW share the same ground heat exchanger (GHE) group. To accommodate varying energy demands in different seasons, the configuration of the ground source/side loop is switched according to signals from the control strategy. The average soil temperature rise, the coefficient of performance (COP) of the heat pump units, the system performance factor (SPF), the life cycle climate performance (LCCP), and the net present value (NPV) are selected as comprehensive evaluation indicators for fifteen years of operation. A comparative analysis with traditional systems, including chiller–boiler (CB), cooling tower coupled hybrid ground source heat pump (CT-HGSHP) and GSHP, which are all equipped with an air source heat pump (ASHP) for DHW, is also conducted. By the 15th year, the average soil temperature rise in the HGSHP-DHWs is 4.94 °C, a reduction of 55.5%, effectively alleviating soil thermal accumulation. In terms of energy efficiency, the SPF is 3.79, an increase of 70.8% with 43% reduction in the accumulation of energy consumption (P_ac), achieving high-efficiency and energy-saving operation. For environmental performance, the LCCP is 2,435,587 kgCO₂, a reduction 38.8% in carbon emissions, showing a remarkable emission reduction effect. In respect of economic returns, the NPV is 644,867 CNY, which is positive and indicates favorable investment viability. Full article

This study presents a techno-economic analysis of deploying distributed energy resources (DERs), specifically photovoltaic (PV), battery energy storage systems (BESSs) and electric vehicles (EVs), in apartment buildings configured as Virtual Power Plants (VPPs). Utilizing cooperative game theory, the research models strategic collaboration between apartment residents (demand side) and utility operators (plant side) to maximize energy efficiency and economic returns. The VPP structure is analyzed over a 15-year life cycle, incorporating net present value (NPV), payback period (PBP), and government subsidy impacts. A cooperative game framework is applied using the Shapley value to ensure fair profit allocation based on each party’s contribution. Results indicate improved self-sufficiency, peak load reduction, and mutual financial benefits. Scenario analyses show that government subsidies to the plant side significantly increase the likelihood of successful cooperation, while declining DER costs enhance the VPP’s economic viability. The findings demonstrate that apartments configured as VPPs achieve strong economic viability (39% ROI, 10.5-year payback) and operational performance (70% self-sufficiency, 40% peak reduction) when grid arbitrage is enabled and moderate government subsidies (35% PV, 45% BESS) are provided. This research provides a replicable model for urban energy planning and policy development, promoting sustainable energy transitions through shared DER infrastructure and cooperative stakeholder engagement. Full article