Search Results (177)

Horizontal well fracturing and thermal injection co-stimulation is widely regarded as a key technology for enhancing the development potential of gas hydrates in the Shenhu Area of the South China Sea, yet its economic feasibility has not been systematically evaluated. In this study, an improved net present value (NPV) economic evaluation model integrating the entire development process of drilling, fracturing, and injection-production was developed, and a techno-economic assessment was conducted based on field-scale numerical simulation data. The results show that neither fracturing nor thermal stimulation alone can achieve positive economic returns; although their combination significantly improves gas production performance, its economic viability is highly dependent on heat source cost and horizontal section length. When the heat source cost decreases from 0.8 to 0.2 RMB/kWh, and the horizontal section length increases from 300 to 1500 m, the NPV increases from –28.99 to 41.88 million RMB. Sensitivity analysis reveals that gas price is the most sensitive factor affecting NPV (variation range of 59.71 to 103.5 million RMB), followed by gas–liquid separation efficiency. It is recommended that prioritizing low-cost heat sources (e.g., geothermal or industrial waste heat), combined with long horizontal section design and downhole water control technologies, is the key strategy to ensure project profitability. Even for the direct warm seawater injection scheme, the horizontal section length should not be less than 1000 m. Full article

Ground source heat pump (GSHP) systems contribute to sustainable building decarbonization while confronting two intertwined challenges: long-term ground thermal imbalance in shallow borefields and the requirement for coordinated operation between thermal systems and electrical grid dynamics. Hybrid shallow–deep borefield configurations have been proposed to mitigate thermal imbalance for sustainable geothermal resource exploitation, yet their grid-interactive demand–response potential remains unexplored. Here, we develop a coupled thermal–electrical model for a shallow–deep mixed GSHP (SDBHE) system equipped with water-tank thermal storage, validated against scaled sand-tank experiments (3.5–8.3% error), and assess its year-round performance under time-of-use electricity tariffs for a 200,000 m² residential district in cold-climate conditions. The SDBHE system reduces the required shallow borehole count by 28% and total drilling length by 22% compared with a shallow-only baseline, saving 11% on operational electricity costs over 10 years. Integrating water-tank thermal storage with a 50% load-shifting strategy yields an additional 10.9–11% cost reduction without degrading the system’s coefficient of performance. Under higher load-shifting ratios, the combined capital and operational savings reach 19–29%, with the optimal allocation assigning the incremental high-price-period load preferentially to deep boreholes (COP 6.29 versus 5.25 for shallow). These results demonstrate that integrating shallow and deep geothermal tiers with thermal storage enables both capital-efficient borefield design and economically viable demand-side grid participation. The findings are bound by the cold-climate residential context and the rule-based control scheme; field-scale validation and lifecycle cost analysis are needed to generalize the conclusions. Full article

Data centers are large and rapidly growing electricity consumers, and cooling systems account for a substantial share of their energy demand. A key contribution of this study is a climate-sensitive, hourly techno-economic comparison of three data-center cooling configurations under consistent operating assumptions: a conventional water-cooled centrifugal chiller baseline, a magnetic bearing chiller (MBC) system, and an MBC system integrated with aquifer thermal energy storage (ATES). The comparison is performed for Phoenix, Arizona, and Fairbanks, Alaska, which represent substantially different cooling climates in the U.S. Hourly simulations use identical information technology (IT) load profiles, identical aggregate installed chiller capacity represented by two 4058 kW chiller units, common water-side economizer controls, and site-specific weather and electricity tariffs. Results show that the MBC system reduces annual cooling-system electricity consumption from 1169.4 to 957.4 MWh in Phoenix (18.1%) and from 361.6 to 319.4 MWh in Fairbanks (11.7%). Peak cooling-system electrical demand decreases by 119.4 kW in Phoenix and 71.6 kW in Fairbanks. Relative to the centrifugal baseline, the MBC case gives a 5.8-year simple payback in Phoenix but is not economically attractive in Fairbanks under the assumed tariff. The MBC-only case gives the lowest annual cooling electricity use in both climates. The MBC + ATES case is treated only as a screening-level, discharge-assisted cold-storage scenario rather than a full techno-economic assessment of seasonal ATES, and no site-specific hydrogeological feasibility assessment is performed. Under the assumed O&M cost structure, MBC + ATES gives a higher discounted value of savings than MBC-only, but this economic result is not caused by additional cooling-electricity savings relative to MBC-only. The MBC + ATES case also has a longer payback period because of its higher capital cost. These results show that the value of advanced cooling configurations depends on climate, free-cooling availability, electricity pricing, storage assumptions, and economic assumptions within the modeling framework considered in this study. Full article

The merit-order effect (MOE), the suppression of wholesale prices by zero-marginal-cost variable renewable energy (VRE), is typically estimated as a single average coefficient per market. In a hydro-dominated system, the price-setting technology alternates between hydro and thermal plants, so the MOE should depend on the operating state. Using New Zealand nodal data, a baseline panel model first reproduces a published 2011–12 seasonal benchmark to within NZ$0.22/megawatt-hour (MWh). A model conditioning the VRE coefficient on reservoir storage (2015–24, 245 nodes, 28,827 node-month observations from approximately 42 million half-hourly records) passes every in-sample diagnostic (within R² = 0.81) yet fails out-of-sample and stability testing. The interaction adds no significant predictive value beyond a storage main effect (p = 0.15–0.22) and reverses sign across sub-periods (+58 to −51), an instability not attributable to collinearity. Replacing the storage level with the monthly thermal generation share, a dispatch-based proxy for the hydro-thermal regime, yields a stable, significant, out-of-sample-validated interaction (clustered t = 5.0, leave-one-month-out cross-validation gain +14.2%) that survives direct hydrological and demand controls, including a head-to-head test against a storage interaction. Identification rests on 120 monthly observations, since these regressors are system-wide. Price suppression is strongest in hydro-abundant months, at approximately NZ$5.8/MWh per 10% relative VRE increase, and attenuates toward zero as the thermal share rises, consistent with water-value pricing. A forward test on Jan 2025 to May 2026 data, which postdate model development, confirms the interaction’s predictive value (forward RMSE improvement +33%, wild cluster bootstrap p = 0.047). Re-estimation on the 2011–12 panel returns a weakly identified, directionally opposite interaction (bootstrap two-sided p = 0.053). The validated state dependence therefore characterises the 2015–24 market regime rather than a structurally invariant relationship. Full article

This study presents a screening-level conceptual, stoichiometric, and scenario assessment of a pathway linking sulfur dioxide (SO₂) capture from coal-fired flue gas to sulfuric acid production and the downstream reaction of sulfuric acid with pretreated scrap aluminum. A regenerable sodium sulfite (Wellman–Lord) capture route, followed by gas polishing and drying, catalytic SO₂ oxidation, controlled SO₃ absorption, acid conditioning, and an Al–H₂SO₄ reactor, is used as the reference configuration. The sulfur balance distinguishes sulfur in coal, ash retention, gaseous SO_x, SO₃/acid mist, absorber inlet and stack slip, captured sulfur, regenerated sulfur, and sulfate purge. Under the central assumptions, 1 t of sulfur in coal yields 0.849 t of recovered sulfur equivalent, 2.599 t of H₂SO₄, 0.477 t of aluminum feed, 2.419 t of anhydrous-equivalent Al₂(SO₄)₃, 4.240 t of commercial aluminum sulfate on a 17 wt% Al₂O₃ basis, and 42.4 kg of H₂ at 80% aluminum conversion. The upstream base-energy screen is 3.3–7.2 GJth and 0.18–0.45 MWhe per tonne of sulfur in coal. Diluting the acid to the selected 0.5–1.0 M aluminum-reaction window and subsequently producing a 17 wt% Al₂O₃ product creates a minimum water-removal load of 21.6–47.6 t and a latent-heat floor of approximately 49–108 GJth/t S. Retail prices are replaced by 2024 customs unit values, and internal-acid-production and sulfuric-acid-opportunity-cost boundaries are evaluated separately. In the central opportunity-cost case, the H₂ value must reach approximately 6.9 USD/kg merely to balance material values before CAPEX, OPEX, energy, purification, transport, and environmental-compliance costs. The Afşin–Elbistan A case is treated as a full-design-throughput illustration based on an historical 18 Mt/y coal requirement, not as a measured current operating average; coal sulfur is tested over 1.0–2.5 wt%. The aluminum step is restricted to cooled and diluted 0.5–1.0 M H₂SO₄ at 40–60 °C, and direct H₂ production from 96 to 98 wt% acid is not assumed. Plant-specific capacity factor, time-matched coal assays, flue-gas flow, oxygen-corrected stack data, reaction kinetics, gas purity, and product quality remain to be verified. The integrated sustainability screening indicates conditional circular-economy potential rather than a demonstrated sustainability advantage: sulfur recovery must be weighed against energy and water demand, sulfate purge and wastewater, diversion of recyclable aluminum from remelting, hydrogen purification, and market-scale product offtake. The pathway therefore remains a research hypothesis requiring experimental validation, process simulation, techno-economic assessment, comparative life-cycle assessment, safety analysis, and market verification. Full article

The evolution of wireless networks toward 6G and Open Radio Access Network (O-RAN) architectures brings unprecedented demands for flexible and energy-efficient resource allocation mechanisms. A key challenge is to allocate radio resources effectively among heterogeneous units while satisfying diverse quality-of-service (QoS) requirements. Traditional allocation methods often fail to capture energy efficiency considerations or lack adaptability in highly dynamic and decentralized environments. To address this, we formulate the resource allocation problem as a non-cooperative game among SDN-enabled Central Units (CUs) and Distributed Units (DUs), where each player’s utility captures a trade-off between throughput gains and resource costs under threshold-based SINR QoS constraints. We show that the game admits an exact generalized potential function, guaranteeing the existence of a pure-strategy Nash equilibrium and convergence under sequential best response dynamics. The SDN controller supervises the network by adjusting system-level parameters, such as the resource price, to guide the network toward efficient and fair allocations. This formulation provides a rigorous and tractable framework for distributed spectrum sharing in 6G O-RAN systems, with the potential to support intelligent and adaptive control in future wireless networks. The proposed framework is evaluated against both classical resource allocation strategies (equal and greedy allocation) and advanced optimization-based and game-theoretic baselines, including convex optimization, proportional fairness, water-filling, and Stackelberg formulations, and shows competitive performance. Full article

Multipurpose reservoirs provide both irrigation water and flood protection, yet flood risk reduction is rarely valued alongside market-priced water supply benefits. As a result, reservoir evaluations and storage allocation decisions may underestimate the economic contribution of flood mitigation. This study estimates the economic value of flood protection provided by Navajo Dam on the San Juan River, New Mexico, where irrigation and municipal water supply are the reservoir’s primary authorized purposes. Historical hydrologic records were used to compare regulated and unregulated flow conditions and quantify the reduction in expected agricultural flood damages attributable to reservoir operations. Results indicate that dam regulation reduces expected annual agricultural flood damages by approximately $366,000, equivalent to a marginal flood protection value of $1.34 per acre-foot of flood-control storage. Expressing flood protection in the same units as irrigation water values enables a direct comparison of competing reservoir services and highlights the extent to which conventional appraisal methods may undervalue risk-reduction benefits. The proposed framework provides a practical approach for incorporating flood mitigation into economic assessments of multipurpose reservoirs and supports more comprehensive and balanced water resources planning. Full article

Industrial process systems must reduce energy use and carbon emissions while maintaining productivity under binding constraints. Energy-use rights trading (EURT), also referred to as energy-consuming rights trading, energy quota trading, or energy-consumption permit trading, converts administrative energy-consumption control into tradable entitlements. This narrative and integrative review uses a transparent search-and-screening audit and reframes EURT primarily through the Chinese pilot experience, while using international energy-efficiency certificate and obligation schemes as comparative context. The review examines how quota scarcity, quota prices, monitoring, reporting and verification, trading liquidity and policy coordination may influence process-level energy management, production scheduling, heat integration, waste-heat recovery, equipment renewal, fuel substitution, electrification, digital monitoring and low-carbon retrofit decisions. It compares EURT with carbon-emissions trading, pollution-permit trading, white-certificate or energy-efficiency-obligation schemes, water-rights trading and renewable-energy certificates. Evidence suggests that EURT can support pollution reduction, carbon mitigation, and green productivity improvement when quota scarcity is binding, markets are liquid, monitoring is reliable, and policy coordination is credible, but findings remain heterogeneous and vulnerable to contamination from overlapping policies. A stylized process-system illustration shows how quota prices can alter the ranking of retrofit investments. Future research should integrate transaction records, equipment-level energy data, process simulation and multi-policy identification strategies. Full article

Preferential flow paths and ineffective water circulation are difficult to quantify in ultra-high water-cut reservoirs because long-term waterflooding intensifies dynamic heterogeneity and oil–water flow interactions. This study develops a displacement unit (DU)-scale method that integrates dynamic liquid-volume splitting, saturation tracking, and techno-economic water-cut evaluation while considering time-varying reservoir properties. The method was applied to a typical ultra-high water-cut block in the Daqing Oilfield to characterize the temporal evolution of preferential flow paths. A total of 902 DUs were delineated from streamline envelopes, and validation with production profile data from representative wells showed an accuracy exceeding 82%. Under an oil price of 60 USD/bbl, the proposed economic water-cut criterion identified 368 economically strong preferential-flow DUs, accounting for 40.79% of all DUs. Two indicators, the water-cut profit–loss margin (Δf_w) and oil displacement efficiency (E_d), were then used to establish a Δf_w-E_d classification matrix. The DUs were divided into four types: economically ineffective strong-channeling units, channeling units with remaining potential, mature stable production units, and homogeneous units. The results support differentiated control measures, such as channel plugging, profile control, cyclic waterflooding, and fluid-rate optimization, for improving waterflood management in mature reservoirs. Full article

With the increasing adoption of the Engineering, Procurement, and Construction (EPC) contracts in government-funded and large-scale infrastructure projects, bill-of-quantities bidding based on preliminary design has emerged as a new procurement approach. Although this approach improves early-stage investment control, it also imposes higher requirements on contractors’ cost-management capabilities. Based on whole-process cost-control theory, this study develops a design-driven full-process cost-control framework for EPC projects using a reclaimed water plant project in northwest China as a case study. The model comprises three layers: a design-driven decision-making layer, a whole-process cost-control layer, and a collaborative management support layer. It covers the key stages of bidding, design, procurement, construction, and final settlement, and integrates design, cost, and procurement management with Building Information Modeling (BIM) and dynamic monitoring based on Earned Value Management (EVM). The case results show that the model can effectively identify and control cost risks, promote the integration of design optimization and cost control, and improve cost management performance. The final settlement price was 0.93% below the contractual settlement ceiling and about 6.6% below the initial investment estimate. This study provides both theoretical support and practical guidance for enhancing full-process cost control in EPC projects under preliminary-design bill-of-quantities bidding. Full article

This study addresses the technical, environmental, economic, and systemic role of multi-apartment residential buildings as hydrogen consumption nodes within urban energy systems. A representative five-story building comprising 30 apartments and 2400–2800 m² of heated floor area, located in a cold European climate, was modelled with an annual heat demand of approximately 185,000 kWh. Four heating configurations were assessed: a conventional natural gas/biomethane boiler (baseline), a hydrogen boiler, a hydrogen-fuel-cell combined heat and power (CHP) system, and a hybrid heat-pump–hydrogen solution. Dynamic simulations indicate that all hydrogen-based systems can fully satisfy space heating and domestic hot water demand without modifications to the internal hydronic distribution network. The fuel cell CHP achieved an overall efficiency of 93%. It generated approximately 54,000 kWh/year of on-site electricity, while the hybrid configuration reached a seasonal efficiency of 108% and the highest primary energy reduction (46%). Operational CO₂ emissions decreased from 37,800 kg/year (gas baseline) to 1900 kg/year (green hydrogen boiler), 1200 kg/year (fuel cell CHP), and 900 kg/year (hybrid system), corresponding to reductions of up to 98%. Peak-load analysis demonstrated improved operational stability in CHP and hybrid systems, characterised by reduced cycling frequency and enhanced thermal resilience through hydrogen storage integration. Capital expenditure (CAPEX) ranged from 41,000 EUR (gas baseline) to 101,000 EUR (fuel cell CHP), reflecting additional storage, safety, and control requirements. Over a 20-year lifecycle (5% discount rate), the hybrid system achieved the lowest levelized cost of heat (0.076 EUR/kWh), followed by fuel cell CHP (0.081 EUR/kWh), compared to 0.087 EUR/kWh for gas. Payback periods ranged between 9 and 13 years, depending on configuration and hydrogen pricing assumptions. Sensitivity analysis identified a break-even hydrogen price of approximately 0.085 EUR/kWh, while carbon pricing above 100 EUR/t CO₂ significantly improves economic competitiveness. District-scale aggregation modelling suggests that hydrogen-equipped multi-apartment buildings can reduce grid electricity imports by 30–40% through on-site generation and seasonal storage. The findings confirm that multi-apartment buildings offer structural and economic advantages for early hydrogen deployment compared to dispersed housing typologies. By combining high demand density, centralised infrastructure, and compatibility with sector-coupling strategies, such buildings can function as distributed energy hubs within decarbonized urban systems. Full article

The escalating impacts of climate change, characterized by rising average temperatures and erratic precipitation patterns, pose a significant threat to Mediterranean-climate ecosystems and high-revenue agricultural products. Among these, the Italian white truffle (Tuber magnatum Picco) represents one of the most economically valuable yet vulnerable species, with market prices reaching €4600 kg⁻¹ in 2025. Due to the persistent challenges in large-scale domestication and its reliance on specific wild habitats, the sustainability of T. magnatum production is increasingly jeopardized by prolonged droughts. This study presents a field-based case study conducted in a natural truffière in central Italy, aimed at evaluating the effects of climatic stressors and exploring the potential role of irrigation as an adaptive management strategy. A small-scale irrigation experiment was implemented over a single growing season using a Before–After–Control–Impact framework, combined with soil moisture modelling and T. magnatum DNA amount monitoring. The results indicate that supplemental irrigation can mitigate summer soil water deficits and reduce the decline in T. magnatum DNA under drought conditions. However, given the limited spatial and temporal scale of the experiment and the limited number of ascocarps collected during the study period, these findings should be considered preliminary. Overall, this study provides initial evidence that targeted irrigation may represent a promising approach to support the resilience of natural truffières under climate variability while highlighting the need for long-term and larger-scale investigations to validate its effectiveness. Full article

This study explores a photovoltaic/thermal (PV/T)-based electrolysis system designed for dual production of hydrogen fuel and domestic hot water (DHW), providing a sustainable energy solution amid rising global emissions. A dynamic rule-based control mechanism with hysteresis thresholds on hydrogen-storage state of charge (SoC) is implemented to balance electrolyzer operation with intermittent solar availability, maintaining PV/T power outputs while preventing storage overfilling and minimizing start–stop cycling. The system is assessed across 27 geographically diverse cities spanning a wide range of solar irradiation and energy price structures. Annual hydrogen yields range from 20 kg/yr in high-latitude locations (Helsinki, Stockholm) to 33.5 kg/yr in high-irradiation regions (Riyadh, Abu Dhabi), while the levelized cost of hydrogen (LCOH) spans from 6.47 USD/kg (Riyadh) to 22.86 USD/kg (Helsinki). Economically, the system achieves its strongest performance in solar-rich, high-energy-cost environments: Rome records the highest net annual cash flow (858.9 USD/yr) and shortest payback period (2.47 years), followed by Davos, Madrid, Brasília, and Canberra. In contrast, locations with subsidized energy tariffs—such as Algiers, Kyiv, and Tehran—yield low or negative net cash flows, rendering the system economically unviable without policy support. Environmental analysis reveals annual CO₂ avoidance ranging from 0.33 ton/yr (Stockholm) to 2.97 ton/yr (Riyadh), with a global mean of 1.095 ton/yr and a combined total of approximately 29.6 tons/yr across all examined sites. A machine learning model is developed to generalize performance predictions across unseen locations, achieving leave-one-out (LOO) R² values of 0.953 (net cash flow), 0.935 (LCOH), and 0.947 (LCO-DHW), with mean absolute errors below ±1 USD/kg and ±0.03 USD/kWh. The findings confirm that, under fixed capital cost assumptions, local electricity price and solar irradiation are the dominant drivers of economic viability, while grid carbon intensity and solar resource jointly govern environmental performance, with markets offering irradiation above 1500 kWh/m²·yr and electricity prices exceeding 0.2 USD/kWh representing the most promising deployment targets. Full article

At the Second Water Intake Pump Station of the Chenhang Reservoir in Shanghai, suboptimal pump scheduling resulted in electricity consumption cost attributable to pump-motor equipment accounting for an exceptionally large proportion of the total power expenditure. In response to the economical operation issues, a mathematical model of power consumption cost for the pump station was established by introducing time-of-use electricity pricing and constraint suppression terms. Taking the minimum cost as the research objective, the differential evolution (DE) algorithm was employed to establish a fitness function for electricity cost, aiming to find the most economical and reliable scheduling strategy. However, owing to its low computational speed and high complexity, machine learning was introduced to establish neural network surrogate models of the DE algorithm. By comparing three surrogate models, the Multilayer Perceptron (MLP) neural network model was adopted as the most appropriate surrogate model. It was optimized for robustness improvement and verified on site. The results demonstrate that implementing the surrogate model achieves over 25% savings in electricity cost per thousand cubic meters of water, while slashing the solution time by 88.53% compared to the standard DE algorithm. Furthermore, the overall power consumption is reduced by 2.20% under a cost-priority strategy and by 15.89% under a power-priority strategy, thereby directly mitigating the carbon footprint of the pump station. The proposed hybrid computational framework in this study bridges the gap between the computationally expensive heuristic optimization and the strict real-time control requirements in engineering, highlighting its significant contribution to the sustainable and low-carbon operation of water infrastructure. Full article

This study investigates the tariff-oriented operation of residential air-to-water heat pump systems integrated with thermal energy storage under long-term real climatic conditions. In contrast to studies based on short-term simulations or advanced predictive control, this work evaluates a simple rule-based control strategy with a focus on practical applicability. The analysis is based on hourly simulations using measured meteorological data over an eight-year period for multiple locations characterized by continental climatic conditions. Two system configurations were considered: a reference system without thermal energy storage and a storage-integrated system operating under a dual-tariff electricity pricing scheme. The results show that thermal energy storage enables effective load shifting toward lower tariff periods, resulting in consistent electricity cost reductions of 19–23% across all analyzed years and locations. These savings are achieved without significant changes in seasonal performance. However, the economic analysis indicates that the payback period remains relatively long (20 years), exceeding typical thresholds for residential investments under current conditions. Overall, the findings highlight the importance of operational flexibility and demonstrate that simple control strategies can improve the economic performance of residential heat pump systems. Full article