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Research Article
Adaptive Infrastructure Management of the Angat Dam: Evaluating Water Supply Reliability Amidst Urbanization and Climate Extremes in Metropolitan Manila
Ma. Teresa Villena Villacorta*
,
Joseph Raniel Bianes
Issue:
Volume 11, Issue 5, October 2026
Pages:
155-163
Received:
21 July 2026
Accepted:
5 August 2026
Published:
11 September 2026
Abstract: Metropolitan Manila depends heavily on the Angat Dam system, while urban demand and hydroclimatic variability place increasing pressure on reservoir operations. This study evaluates monthly reservoir elevation and billed water-demand records from January 2019 to December 2025 using descriptive and inferential trend analysis, an operationally grounded analytical stress threshold of 180 m, threshold sensitivity testing, and reliability-resilience-vulnerability (RRV) indicators. Institutional and project documents were also reviewed to interpret adaptive infrastructure-management responses. Mean billed demand increased from 2,826.58 million liters per day (MLD) in 2019 to 2,946.37 MLD in 2025, peaking at 3,069.50 MLD in May 2024. The estimated annual demand slope was 23.72 MLD per year, but it narrowly missed statistical significance at the 5% level (p = 0.054). At 180 m, ten of 84 monthly observations were failures; the minimum was 160.97 m in July 2019. The system achieved 88.10% reliability, 40.00% resilience, and mean vulnerability of 5.86 m. Sensitivity testing at 175, 180, and 185 m produced reliability values of 96.43%, 88.10%, and 84.52%, respectively, while resilience remained between 33.33% and 40.00%. Results show that high overall reliability can coexist with slow recovery and concentrated seasonal risk. The evidence supports anticipatory reservoir operation, climate-informed monitoring, demand management and non-revenue-water reduction, transmission redundancy, source diversification, and institutionalized RRV monitoring. The study demonstrates a transparent, replicable screening approach for climate-sensitive urban water infrastructure where detailed hydraulic models are unavailable.
Abstract: Metropolitan Manila depends heavily on the Angat Dam system, while urban demand and hydroclimatic variability place increasing pressure on reservoir operations. This study evaluates monthly reservoir elevation and billed water-demand records from January 2019 to December 2025 using descriptive and inferential trend analysis, an operationally ground...
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Research Article
Effect of CIGS Absorber Thickness on the Performance of In2S3-Buffered Thin-Film Solar Cells: Role of the MgF2 Antireflection Coating
Issue:
Volume 11, Issue 5, October 2026
Pages:
164-178
Received:
3 September 2026
Accepted:
11 September 2026
Published:
27 September 2026
Abstract: This work numerically investigates, using the Silvaco ATLAS simulator, a thin-film solar cell based on a Cu(In,Ga)Se₂ (CIGS) absorber combined with a non-toxic In2S3 buffer layer replacing conventional CdS, building on an earlier doping-optimization study that identified NA = 3×1016 cm-3 as optimal for both configurations investigated (with and without a MgF2 antireflection coating). At this doping level, two otherwise identical structures, one with MgF2 and one without, are compared to isolate the effect of CIGS absorber thickness (0.5 to 4 µm) on Jsc, Voc, FF and η. Efficiency increases monotonically with thickness, reaching 24.7% with MgF2 and 21.93% without at 4 µm, a nearly constant relative gain of about 12.6% attributable almost entirely to the increase in short-circuit current. The analysis also tracks the effective series (Rs) and shunt (Rsh) resistances extracted from the simulated J–V curves to clarify the mechanism behind the improvement of the fill factor with thickness. The decrease in Rs and increase in Rsh are consistent with reduced electrical losses in thicker absorbers, though these values are read as effective electrical descriptors rather than direct proof of a microstructural change, since no grain-boundary or defect-density model was varied with thickness. A marginal-gain analysis of the full thickness interval, combined with a relative active-material-use analysis, identifies 2–3 µm with MgF2 as the best trade-off between performance and material use. A particularly compact illustration is that a 1 µm CIGS cell with MgF2 (η = 22.17%) already outperforms a 4 µm cell without MgF2 (η = 21.93%), using only a quarter of the absorber volume, showing that improved front-surface optical management can compensate for a substantial reduction in absorber thickness.
Abstract: This work numerically investigates, using the Silvaco ATLAS simulator, a thin-film solar cell based on a Cu(In,Ga)Se₂ (CIGS) absorber combined with a non-toxic In2S3 buffer layer replacing conventional CdS, building on an earlier doping-optimization study that identified NA = 3×1016 cm-3 as optimal for both configurations investigated (with and wit...
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Research Article
Techno-economic Optimization of PV-battery-diesel Systems for Reducing Diesel Use at Eleven Off-grid Telecom Sites in Niger
Mahamadou Hamidine*,
Chafiani Halidou Goumey,
Arifa Warouma
Issue:
Volume 11, Issue 5, October 2026
Pages:
179-193
Received:
6 September 2026
Accepted:
16 September 2026
Published:
29 September 2026
Abstract: Remote off-grid telecommunication sites in Niger depend heavily on diesel generation, leading to high fuel use, operating costs, and direct emissions. This study evaluates site-specific photovoltaic (PV)-battery-diesel retrofit configurations for eleven operational sites using measured baseline data, analytical component sizing, and hourly hybrid optimization of multiple energy resources (HOMER) Pro simulations over one year. Technical performance, generator dispatch, diesel use, lifecycle economics, sensitivity to diesel price and total capital expenditure (CAPEX), and avoided direct CO2 emissions are assessed jointly. Rather than representing the network with one typical site, the analysis retains the measured differences in electrical demand, solar resource, storage requirement, generator operation, and investment cost across all eleven sites. Across the portfolio, annual diesel consumption decreases from 161,749.75 to 34,757 L, a 78.5% reduction, while cumulative generator runtime falls by 82.4%. Aggregate annual operating expenditure (OPEX) decreases from approximately USD 302,159 to USD 88,259, yielding savings of about USD 213,899/year. Site-level payback periods range from 1.83 to 8.12 years; all configurations have positive net present value (NPV), and their internal rates of return (IRR) range from 10.7% to 54.8%, exceeding the 8% discount rate. Positive aggregate NPV is retained under ±20% variations in diesel price and total CAPEX. Avoided diesel use corresponds to approximately 340.3 tCO2/year. Overall, the results show that site-specific hybridization can substantially reduce diesel dependence while retaining generator backup and favorable investment performance.
Abstract: Remote off-grid telecommunication sites in Niger depend heavily on diesel generation, leading to high fuel use, operating costs, and direct emissions. This study evaluates site-specific photovoltaic (PV)-battery-diesel retrofit configurations for eleven operational sites using measured baseline data, analytical component sizing, and hourly hybrid o...
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