Search Results (135)

Climate change is intensifying hydroclimatic extremes and agricultural water scarcity, sharpening trade-offs among yield stability, water saving, and farm incomes in major grain regions. Existing studies often optimise cropping patterns or irrigation schedules separately, seldom embedding yield robustness and policy instruments in one decision framework. We propose an integrated Machine-learning–System-dynamics–Non-dominated-sorting-genetic-algorithm-II (ML–SD–NSGA-II) framework linking long-horizon meteorological scenario generation, crop–water–economy feedback and multi-objective optimisation of crop areas and irrigation depths. ML models generate daily climate sequences to drive an SD model of soil moisture, yield formation, basin-scale allocable water, and farm returns; NSGA-II searches Pareto-optimal strategies that maximise profit and irrigation water productivity while minimising yield deviation. Applied to a rice–wheat irrigation system in the middle Yangtze River Basin, knee-point solutions lift irrigation water productivity by about 14%, maintain near-baseline profits, and reduce yield deviation. Scenario tests with block tariffs, quota-based subsidies, and extreme drought show pricing mainly curbs low-value water use in normal years, while under drought, physical scarcity dominates and economic tools offer limited buffering. This reveals the existence of a scarcity-regime threshold beyond which economic instruments become second-order relative to binding biophysical constraints. The framework supports transparent ex ante testing of tariff–subsidy packages for irrigation governance and adaptation. Full article

The decarbonization of the residential sector is a critical component of the European Green Deal, particularly in transition economies like Poland. This study proposes a comprehensive techno-economic optimization of a deeply retrofitted single-family house aiming for net-zero energy building (NZEB) status. The research specifically focuses on the Polish coastal climate zone, characterized by distinct humidity, wind, and temperature profiles compared to inland regions, which significantly influence the efficiency of air-to-water heat pumps (ASHP). Based on a real-world energy audit, the study simulates the synergy between a deep thermal envelope upgrade and a hybrid system comprising an ASHP, photovoltaics (PV), and battery energy storage (BES). This paper presents a detailed economic analysis of such hybrid systems under the new Polish ‘net-billing’ prosumer mechanism. The study evaluates the impact of electricity tariff structures (flat-rate G11 vs. time-of-use G12w) on the investment’s profitability. By calculating key performance indicators—including the levelized cost of energy (LCOE), net present value (NPV), and self-sufficiency ratio (SSR)—the research assesses various system configurations. The initial evaluation indicates that while deep retrofitting significantly reduces heating demand, integrating battery storage plays a critical role in enhancing economic returns under the net-billing framework. The analysis demonstrates that the optimized hybrid system (9.0 kWp PV + 10 kWh BESS) achieves an average annual self-sufficiency ratio (SSR) of 49.8% and reduces the non-renewable primary energy (EP) indicator to 0.0 kWh/(m²·year). Economically, the investment yields a positive NPV of €3194, an IRR of 5.25%, and a LCOE of €0.184/kWh, which is 34% lower than projected grid prices. Furthermore, switching to a time-of-use tariff (G12w) generates an additional 11% (€139) in annual savings. These quantitative findings provide actionable guidelines for policymakers and investors, confirming the financial viability and environmental benefit (annual reduction of 6.12 MgCO₂) of NZEB standards in coastal areas. Full article

Policy instability and regulatory barriers remain key obstacles to the long-term viability of agriphotovoltaics (APV) deployment. The Penthéréaz case in Switzerland provides empirical evidence of how cooperative governance and collective self-consumption can restore project feasibility after subsidy withdrawal. Using a single-case study and process-tracing approach based on cooperative documentation and regulatory records, the analysis explains how Penthéréaz Énergie Photovoltaïque S.A. cooperative (PEP)., initially structured as a subsidy-dependent venture, transitioned into a resilient collective self-consumption network supported by a private micro-grid. Following the withdrawal of federal feed-in tariffs, the project faced major economic risk and responded through decentralized financial restructuring, including community-funded debt at a 2% interest rate. The installation comprises 1180 photovoltaic panels with an installed capacity of 283 kWp, producing approximately 290,000 kWh per year while providing water-tightness and light permeability for agricultural infrastructure. The findings further indicate that operational success contributed to Swiss regulatory adjustments, enabling private distribution networks to cross public roads and secure geographic continuity for local energy sharing. With a reported self-consumption rate of 40% across a diversified user base including agri-food and residential consumers, the case demonstrates the operational value of local load-matching. The findings propose six context-dependent lessons derived from a single case, emphasizing governance capacity, tariff risk management, regulatory adaptability, and demand-oriented system design. Full article

The global shipping industry is surging ahead, and with it, a quiet revolution is taking place on the water: marine lithium-ion batteries have emerged as a crucial clean energy carrier, powering everything from ferries to container ships. When these vessels dock, they increasingly rely on shore power charging systems to refuel—essentially, plugging in instead of idling on diesel. But predicting how much power they will need is not straightforward. Think about it: different ships, varying battery sizes, mixed charging technologies, and unpredictable port stays all come into play, creating a load profile that is random, uneven, and often concentrated—a real headache for grid planners. So how do you forecast something so inherently variable? This study turned to the Monte Carlo method, a probabilistic technique that thrives on uncertainty. Instead of seeking a single fixed answer, the model embraces randomness, feeding in real-world data on supply modes, vessel types, battery capacity, and operational hours. Through repeated random sampling and load simulation, it builds up a realistic picture of potential charging demand. We ran the numbers for a simulated fleet of 400 vessels, and the results speak for themselves: load factors landed at 0.35 for conventional AC shore power, 0.39 for high-voltage DC, 0.33 for renewable-based systems, 0.64 for smart microgrids, and 0.76 when energy storage joined the mix. Notice how storage and microgrids really smooth things out? What does this mean in practice? Well, it turns out that Monte Carlo is not just academically elegant, it is practically useful. By quantifying uncertainty and delivering load factors within confidence intervals, the method offers port operators something precious: a data-backed foundation for decision-making. Whether it is sizing infrastructure, designing tariff incentives, or weighing the grid impact of different shore power setups, this approach adds clarity. In the bigger picture, that kind of insight matters. As ports worldwide strive to support cleaner shipping and align with climate goals—China’s “dual carbon” ambition being a case in point—achieving a reliable handle on charging demand is not just technical; it is strategic. Here, probabilistic modeling shifts from a simulation exercise to a tangible tool for greener, more resilient port energy management. Full article

Greywater reuse presents a promising strategy for reducing potable water demand and supporting the irrigation of urban green infrastructure, yet its implementation in early planning phases remains limited by fragmented regulations, data gaps, and the absence of practical decision support tools. This study develops a comprehensive evaluation matrix based on Multi-Criteria Decision Analysis (MCDA) to assess the feasibility of greywater reuse in residential district development. The framework integrates eight domains (legal, technical, infrastructural, ecological, economic, and social factors) and is complemented by automated supporting worksheets for water balance, ecological indicators, and economic parameters. Application of the matrix to two contrasting residential case studies demonstrated its diagnostic value: the new-build district in Dortmund showed a high reuse potential, strongly influenced by favourable infrastructure conditions and ecological indicators, whereas the existing building in Weimar yielded a moderate potential due to infrastructural constraints and lower greywater availability. Sensitivity analyses further revealed that local water tariffs, intended-use scenarios, and stakeholder weightings substantially affect outcomes. Overall, the results show that the matrix supports transparent early-stage decision-making, identifies critical bottlenecks, and strengthens governance-oriented integration of greywater reuse in sustainable urban development. Full article

This study investigates the complex interactions between operational and financial variables that influence infrastructure investment in Romania’s wastewater sector, a serious area for environmental sustainability and compliance with European environmental standards. Using a comprehensive dataset covering all regional water service operators, accounting for over 90% of the country’s population, across the period 2012–2022, the analysis employs dynamic panel data methods to examine how treated wastewater volumes, operating expenditures, revenues, tariffs and the number of connected users shape investment decisions and the modernization of wastewater infrastructure. The results reveal strong links between operational performance and investment behavior, indicating that revenues from wastewater services and efficiency in organic pollutant removal (CBO5) are key determinants of capital investment. The findings further show that an expanding user base generates substantial investment needs, supporting the extension and upgrading of wastewater treatment networks. By combining a dynamic econometric framework with a comprehensive national sample, the study makes an original contribution to the literature by providing robust empirical evidence on the interaction between financial performance, operational efficiency and sustainability objectives in the wastewater sector. The results underscore the importance of good financial planning, strategic management and sustainable investment policies, and offer relevant insights for policymakers, utility operators and researchers concerned with improving wastewater infrastructure performance under current economic and environmental challenges. Full article

This study assessed six tomato (Solanum lycopersicum L.) cultivars within an integrated solar-powered closed hydroponic system in Al Dhaid, UAE (25°16′11.2″ N, 55°55′52.2″ E). The system combined an insect-proof net house, closed hydroponics, root-zone cooling, ultra-low-energy drip irrigation, and a cost-effective solar-powered reverse osmosis (RO) desalination unit to address salinity constraints. The cultivars, selected for their adaptability to controlled environments in the UAE, were evaluated for yield, water-use efficiency (WUE), and fertilizer-use efficiency (FUE). Among them, Torcida recorded the highest mean yield (0.619 kg/m²/harvest), WUE (27.1 kg/m³), FUE (26.5 kg fruit/kg fertilizer), and marketable fruit ratio (66.3%), followed by Roenza, Eviva, and SV 4129 TH; Lamina was intermediate, while Saley, a bushy type, produced the lowest yield. The top cultivars achieved cumulative yields exceeding 7 kg/m²—surpassing regional open-field benchmarks (4–5 kg/m²; 3–6 kg/m³). Compared with conventional cooled hydroponic greenhouses (3.5 kg/plant; 8 kg/m³), the system demonstrated similar productivity using three times less water. The RO unit produced water at baseline 1.05 USD/m³—58–68% below regional tariffs—while minimizing reliance on grid electricity and mechanical cooling. Overall, the integrated solar-powered hydroponic–RO model proved technically reliable, resource-efficient, and economically viable, offering a scalable solution for sustainable vegetable production in hyper-arid regions. Full article

The United Nations Sustainable Development Goals (SDGs) set the criteria for sustainable economic development. These goals encompass four dimensions, including social, human, economic, and environment, of which the last two goals (i.e., economic and environment) were contemplated in this study. A case study for Corner Brook, a middle-sized city, located in the western region of the province of Newfoundland and Labrador, Canada, revealed that the current urban water use pricing mechanism is not matched with the SDGs, which reflects impediments to the city’s achievements to become a sustainable economic development community. Residents are billed a fixed rate for water use rather than a tiered or usage-based rate. This is not a resilient policy, as it fails to conserve water resources, ultimately leading to wasting freshwater produce, inhibiting economic growth, creating social exclusion, and degrading natural resources. We recommend changing the current flat-rate based water billing mechanism to either increasing block tariffs or two-part tariffs, adjusted by seasonal rates; issuing governmental policies, such as rebates, subsidies, and lower property taxes to entice residents’ willingness-to-install water meters on their premises; encouraging provisions such as using rain barrels to help cut down water consumption; and raising public knowledge through social media on how high per capita water use is in the region, including how much it costs to install water meters. These recommendations will also help provincial and municipal policymakers pursue the SDGs. Full article

This paper presents a comprehensive economic comparison between renewable and fossil-fuel-based heating systems for a newly constructed residential building in Kraków, Poland, over the period 2022–2030. The analysis introduces the concept of Corrected Final Energy Consumption (CFEC) as a harmonized measure for comparing various energy sources and applies the Present Value of Total Lifecycle Cost (PVTLC) as an appropriate financial metric for non-commercial residential investments. Four heating options were examined: district heating system (DHS), gas boiler, air-to-water heat pump, and heat pump combined with photovoltaic (PV) panels. Based on real tariffs and standardized data from the Energy Performance Certificate (EPC), the DHS option demonstrated the lowest lifecycle cost, while the air-to-water heat pump—despite environmental advantages—proved the most expensive without substantial subsidies. Sensitivity analyses confirmed the strong influence of investment subsidies and fuel price fluctuations on the competitiveness of alternative systems. The findings highlight the methodological shortcomings of conventional annual-cost approaches and propose PVTLC as a more reliable decision-making tool for residential energy planning. The study also discusses regulatory, climatic, and behavioral factors affecting investment outcomes and emphasizes the need to integrate financial, environmental, and social criteria when evaluating household-level energy solutions. Full article

Agrivoltaic (AV) systems are increasingly recognized as a strategy to enhance sustainable land management, yet their application in post-conflict settings remains underexplored. This study addresses this gap by evaluating AV deployment in two Colombian municipalities located in PDET/ZOMAC regions, using an integrated framework that expands the conventional Water–Energy–Food (WEF) nexus into the Water–Energy–Food–Soil–Climate–Communities (WEFSCC) nexus. The research combined GIS-based site characterization, crop yield and water balance modeling (contrasting traditional irrigation with hydroponics), and photovoltaic performance simulations for 30 kW systems, under conservative and moderate scenarios. Economic analyses included Net Present Value (NPV), Internal Rate of Return (IRR), and Free Cash Flow (FCL), with sensitivity tests for crop prices, yields, tariffs, and costs. Results indicate that AV can reduce crop irrigation demand by up to 40%, while generating 17 MWh/month of electricity per site. Cabrera exhibited higher profitability than Pisba, explained by yield differences and site-specific energy outputs. Comparative analysis confirmed consistency with experiences in Africa and Europe, while emphasizing local socio-environmental benefits. Conclusions highlight AV systems as resilient tools for sustainable land management in Colombia’s post-conflict regions, with actionable implications for land-use regulation, fiscal incentives, and international cooperation programs targeting rural development. Full article

The transformation of energy systems towards low emission is one of the key assumptions of the climate and energy policy of the European Union and many countries around the world. These changes include not only the power and transport sectors but also the heating of residential buildings, which consume significant amounts of energy and emit large amounts of greenhouse gases. This article presents a detailed comparative analysis of the costs of heating using an air-to-water heat pump and a condensing gas boiler. The study concerned a retrofitted single-family building from the 1990s, located in southern Poland. The calculations were made taking into account daily meteorological data for two full heating seasons: 2022/2023 and 2023/2024. This approach made it possible to more precisely reproduce real operating conditions. The study was conducted for various configurations of the central heating system: surface and radiator. The following parameters were also taken into account: (1) variable heat pump parameters, such as supply temperature LWT and coefficient of performance COP; (2) current tariffs for electricity and natural gas; and (3) forecasted tariffs for electricity and natural gas in the conditions of market liberalization and phasing out of protective mechanisms. A comparison of the two heating seasons revealed lower costs with a heat pump. In some cases, the cost of heat generated by a gas boiler was over 100% higher than with a heat pump. This applies to both heating seasons. Under the current tariffs, the calculated gas cost for the first season was PLN 6856 (EUR 1605) (1 EUR = 4.27 PLN) compared to heat pump heating costs ranging from PLN 3191 to PLN 4576 (EUR 747 to 1072). For future gas and electricity tariffs, the costs were PLN 8227 (EUR 1926) for gas and PLN 3841 to PLN 5304 (EUR 899 to 1242) for a heat pump. Similarly, for the second heating season, these values were PLN 6055 (EUR 1418) for gas heating and PLN 2741–3917 (EUR 642–917) for a heat pump under the current tariffs, and PLN 7267 (EUR 1702) and PLN 3307–4540 (EUR 774–1064) under future tariffs. This means percentage savings of between approximately 33% and 55%, depending on the heating type and tariff. Therefore, the obtained results indicate the higher profitability of using an air heat pump compared to a gas boiler. This advantage was maintained in all the discussed scenarios, and its scale depended on the type of installation, supply temperature, and the selected electricity tariff. The highest economic profitability was noted for low-temperature systems. These results can provide a basis for making rational investment and design decisions in the context of the energy transformation of single-family housing. Full article

Filter wash water (FWW) from public swimming pools is a recoverable resource, yet full-scale evidence on safe on-site reuse with documented economics is scarce. We evaluated a full-scale integrated recovery unit (SOWA) installed at an indoor public pool. The SOWA system—sedimentation, granular filtration operated at a hydraulic loading rate (HLR) of 7.5–10 m³ m⁻² h⁻¹, ultrafiltration, and chlorine-dioxide (ClO₂) disinfection—was monitored for physicochemical and microbiological performance. Turbidity decreased from 23.1 nephelometric turbidity units (NTU) to 0.25 NTU; chemical oxygen demand, reported as the permanganate index (COD_Mn), fell from 10.4 to 1.6 mg O₂ L⁻¹; and total microbial count declined from 1.6 × 10⁴ to 30 colony-forming units per millilitre (CFU mL⁻¹). Indicator organisms (Escherichia coli, Intestinal enterococci and Pseudomonas aeruginosa) were not detected, and all quality criteria complied with national standards. At the Olender facility, monthly freshwater use dropped from 1700 to 1000 m³ after 24/7 SOWA operation, while combined chlorine was maintained at 0.12 mg Cl₂/L and no issues with chloroform were observed. The unit recovered 4.7 m³ h⁻¹ of FWW for non-potable uses. According to manufacturer catalogue data, the recovery process can reach up to 96%, enabling annual savings up to ~EUR 9000 and a payback of ~2 years under favourable tariffs and loads. Our outcomes are consistent with independent full-scale reuse trains (e.g., ultrafiltration/reverse osmosis) and with disinfection-by-product control strategies reported in the literature, and they align with international guidance for swimming-pool water reuse. This study provides a rare, end-to-end implementation at full scale, documenting continuous operation, verified microbial safety, regulatory compliance, quantified water and cost savings, and site-specific economics for a compact, multi-barrier FBW recovery system that can be directly transferred to similar facilities. Full article

Water and energy are strongly intertwined, especially in wastewater treatment plants (WWTPs) whose electrical loads can strain local grids. This work evaluates the technical, economic, and environmental feasibility of powering the WWTP attached to the smart building of Ibn Tofail University (Morocco) with building-integrated photovoltaics (PV) and a complementary wind turbine. Using the HOMER Pro optimizer, two configurations were compared: (i) stand-alone PV and (ii) a hybrid PV/wind system. The hybrid design raises the renewable energy fraction from 8.5% to 17.9%, cutting annual grid purchases by 8% and avoiding 47.9 t CO₂ yr⁻¹. The levelized cost of electricity decreases from 1.08 to 0.97 MAD kWh⁻¹ (≈0.11 to 0.10 USD kWh⁻¹), while the net present cost drops by 6%. Sensitivity analyses confirm robustness under grid electricity tariff and load-growth uncertainties. These results demonstrate that modest wind additions can double the renewable share and improve economics, offering a replicable pathway for WWTPs and smart buildings across the MENA region. Full article

Water scarcity and rising urban demand pose growing challenges for sustainable water management in Brazil, where over 73 million people may face shortages by 2035. Given this scenario, rainwater utilisation has emerged as a strategic alternative for preserving water resources, helping to reduce potable water consumption and relieving demand on public supply systems. This study aimed to evaluate the potential for potable water savings through the implementation of a rainwater harvesting system in a fitness centre without a swimming pool, located in southern Brazil—a building typology rarely addressed in the literature. Water end-uses were empirically characterised using water flow measurements and questionnaires conducted in an existing facility operated by the same franchise. A daily balance simulation was performed using the Netuno computer programme (Version 4), and an economic feasibility assessment was conducted based on local costs and tariff structures. The results showed that non-potable end-uses represented 24.4% of total water consumption. The rainwater harvesting simulation indicated an ideal tank capacity of 11,000 L, enabling potable water savings of 7.04%. The economic analysis showed an implementation cost of R$13,240.72 and a consequent return on investment of fifteen months. These findings confirm the technical and economic viability of rainwater harvesting systems for fitness centres and highlight the relevance of local conditions in shaping performance and investment returns. Full article

The sharp rise in electricity prices in South Africa has raised a growing concern over household electricity use, affordability, and the need for sustainable consumption patterns. This increasing cost of electricity has added financial pressure on South Africans already burdened by rising prices of water, food, and fuel. This study aims to determine the relationship between residential electricity consumption and electricity prices in South Africa, using annual time series secondary data spanning from 1975 to 2024. To determine the long-run relationship the study employed econometric techniques such as Fully Modified Ordinary Least Squares (FMOLS) and Dynamic Ordinary Least Squares (DOLS), then, for robustness, the Vector Error Correction Model (VECM) and diagnostics checks. The findings of the study revealed a negative relationship between electricity prices and residential electricity consumption. While disposable income showed a positive relationship with residential electricity consumption, the population growth revealed a negative relationship with residential electricity consumption. Based on the empirical findings of the study, South African policymakers should ensure the affordability of electricity and user-efficiency so that population growth does not worsen energy inequality. Hence, policymakers should ensure basic access for all households by supporting low-income groups and applying higher tariffs for higher consumption. These measures promote fairness, meet essential electricity needs, and encourage responsible use. Full article