Cumulative Demand Research Articles

Bid-Aggregation Based Clearing of Day-Ahead Electricity Markets

In this work we propose a heuristic clearing method for a simplified model of European day-ahead electricity auction markets, considering divisible standard bids and block orders. In the first part of the process, a computationally less demanding problem is solved using an approximation of the cumulative demand and supply curves, which are derived via the aggregation of simple bids. Based on the outcome of this problem, estimated ranges for the clearing prices of individual periods are determined. In the final step, the clearing for the original bid set is solved, taking into account the price ranges determined previously as constraints, reducing the feasibility region of the clearing problem. By removing bids whose acceptance or rejection is already determined by the assumed price range constraints, the size of the problem is also significantly reduced. Via simple examples, we show that due to the possible paradox rejection of block orders the proposed bid-aggregation based approach may result in a suboptimal solution or in an infeasible problem, but we also point out that these pitfalls of the algorithm may be avoided by using different aggregation patterns. We propose to run multiple threads of the algorithm, using different aggregation patterns. We evaluate the performance of the algorithm via numerical tests.

Spare parts provisioning strategy of warranty repair demands for capital-intensive products

The inventory cost of stocking spare parts is a nonnegligible expenditure of providing after-sales service for the manufacturers making capital-intensive products, such as electric vehicles. Especially, for warranty repair service, it is important to manage the spare stock appropriately to satisfy the warranty claims of customers as well as reduce the associated inventory costs. In this paper, we investigate the spare parts inventory issue related to a critical component for under-warranty units of a product. In particular, under the free-replacement warranty policy, failed component will be replaced by a new one by consuming the spare stock. According to the field claim data, we find that the general trend of warranty claims is nonstationary, which will be affected by the product sales and under-warranty failures. Thus, we first propose a model to forecast the time-varying warranty repair demand by explicitly considering the randomness from two major sources, that is, product sales and under-warranty failures. Under the assumptions of Poisson sales process and exponential failure distribution, the closed-form expressions of mean and variance of cumulative warranty repair demand over time are obtained. Because the number of warranty claims in each period is a one-time data, the associated distribution information is unavailable. Then, based on the properties of the demand statistics, we derived a worst-case upper bound for the associated inventory cost and formulate a three-phase finite-horizon spare parts inventory model, which can be used to appropriately address the time-varying warranty claims. Finally, numerical experiments are conducted to investigate the key parameters affecting the optimal decisions where a case study based on real data is presented.

Analyzing sustainability in bread production: a life cycle assessment approach to energy, exergy and environmental footprint.

Bread production is a pivotal component of global nutrition. However, its extensive production imposes significant strain on resources and energy, resulting in substantial environmental consequences. This study focuses on a multidimensional assessment of the environmental sustainability of the bread life cycle as a case study in Iran. By integrating four life cycle assessment (LCA) methods, this research demonstrates a comprehensive analysis of environmental effects, energy consumption, and exergy demand in bread production. It also identifies the hotspot stages and inputs within the bread production chain. Eventually, it proposes strategies for mitigating the environmental impacts in line with sustainable development goals. Data collection involved questionnaires by face-to-face interviews. The LCA evaluation was conducted using SimaPro software. Sustainability analysis was assessed using four different methods: CML, ReCiPe, cumulative energy demand (CED), and cumulative exergy demand (CExD) method, from cradle to bakery gate. The CML method results indicate that the highest environmental impacts are associated with marine aquatic ecotoxicity (157.04 to 193.36 kg 1,4-DB eq), fossil fuel depletion (11.05 to 12.73 MJ), eutrophication (4.20 × 10-3 to 4.70 × 10-3 kg PO4-3eq), acidification (8.09 × 10-3 to 9.16 × 10-3 kg SO2 eq), and global warming (0.61 to 0.69 kg CO2 eq). The ReCiPe method highlights wheat production stages and gas consumption as the most significant contributors to damage in terms of human health, ecosystems, and resource consumption indicators. The CED method reveals that fossil energy accounts for over 97% of the energy consumed during the bread life cycle. Energy consumption per kilogram of bread ranges from 12.07 to 13.93 MJ. The CExD method for producing 1 kg of traditional bread falls between 32.25 and 35.88 MJ. More than 60% of this value is attributed to renewable resources of water used in irrigation during the wheat farming stage, while over 35% is linked to non-renewable fossil resources, primarily due to the consumption of natural gas in bakery operations. To assess the potential decrease in environmental emissions, a sensitivity analysis was performed, considering the effects of substituting natural gas with biogas and grid electricity with photovoltaic electricity in the bakery. Then, three improved scenarios were developed, each demonstrating effective reductions in environmental impacts, with the most remarkable decreases observed in marine aquatic ecotoxicity (55%) and fossil fuel depletion (44%). Overall, the findings demonstrate that Sangak bread production exhibits a more environmentally friendly profile than other types of bread. These results can guide decision-makers in the bread production industry towards implementing sustainable practices that prioritize resource efficiency and environmental conservation. Also, stakeholders can develop strategies to reduce the environmental impacts and work towards a more sustainable future.

Intrajejunal levodopa in Parkinson's disease: Optimization of PEG application

The various forms of Percutaneous Endoscopic Gastrostomy (PEG) are highly relevant in neurology, as pump-administered intrajejunal levodopa application is one of the indispensable forms of therapy in advanced Parkinson's disease. Optimal PEG placement and follow-up are therefore significant for the success of the therapy. However, the standard intrajejunal administration of levodopa gel via a JET-PEG, i. e. a PEG with an internal catheter inserted into the jejunum, is not without problems for various reasons. In particular, the considerable cumulative complication rates demand a reconsideration of the situation. The very limited absorption area of the drug in the region of the flexura duodenojejunalis must also be taken into account. Causes of complications are predominantly a non-optimal application technique of PEG and internal catheter as well as the frequent lack of an adequate follow-up. In this paper, the details of a modified and optimized application technique compared to the conventional techniques are presented. These new methods have proved their usefulness in clinical applications for years, and additionally a new application form, the Hybrid-PEG, is presented. However, many of the details derived from anatomical/physiological, surgical and endoscopic aspects must be strictly observed during the application in order to reduce or avoid minor and major complications. In particular, problems are caused by local infections in the area of the insertion point of the PEG including peritonitis, leaks and buried bumper syndrome (BBS). The relatively frequent dislocations of the internal catheter also prove to be particularly troublesome. These can ultimately be avoided by clip fixation of the catheter tip down in the jejunum. In particular, the use of the newly developed Hybrid-PEG, a combination of endoscopically controlled gastropexy with three sutures and subsequent central thread-pull-through of the PEG tube, can significantly reduce the complication rate and thus achieve a decisive improvement for patients. The aspects discussed here are highly relevant for all those involved in the therapy of advanced Parkinson's disease. Trustful interdisciplinary collaboration between neurology and endoscopy/surgery/gastroenterology is a prerequisite for good clinical outcomes.

Valorization of fruit and vegetable waste in a novel three-stage hybrid anaerobic digester for enhanced biogas production: Performance study and microbial community analysis

The study proposes the performance of a three-stage hybrid mesophilic anaerobic digester comprising a suspended-growth hydrolytic reactor, a hybrid (suspended-growth + attached-growth) acidogenic down-flow reactor, and a hybrid methanogenic up-flow reactor, for enhanced biogas production. Commingled fruit and vegetable waste (FVW) – shredded to sizes 1 – 4 mm – plus 2.5 L of tap water served as the feedstock in 8 different batch combinations, where the weight of the waste was increased from 3.5 to 7 kg. Decoupling the three major anaerobic steps ensured desirable working pH ranges for the hydrolytic (4.02 – 6.79), the acidogenic (5.69 – 6.62), and the methanogenic stages (6.94 – 7.7). Triplicate studies of each batch type vis-à-vis all three stages were performed. The highest cumulative soluble chemical oxygen demand percentage removal of 96.3 % was noticed in the case of batch run 5. The maximum biogas yield of 781.8 ml/g CODremoved was corresponding to batch 7, with 6.5 kg FVW, whereas the lowest biogas yield, 735.8 ml/g CODremoved, was corresponding to batch 1. The produced biogas from the methanogenic digester was of high quality (≤ 0.01 % H2S) and constituted 58–62 % CH4 and 6–7 % H2. Microbial community analysis confirmed the presence of pertinent bacterial and archaeal groups, such as Firmicutes, Proteobacteria, Spirochaetes, and Methanothrix, including key homoacetogenic genera, such as Acetobacterium Woodii, Desulfotomaculum, and Desulfitobacterium.

The cumulative plastic deformation demand for buckling restrained braces imposed by the strong motions in the 2023 Türkiye earthquake sequence

The Türkiye earthquake sequence on February 6, 2023, was featured by the closely located earthquake doublet of Mw 7.8 and Mw 7.5. The consequent strong ground motions are supposed to be able to impose high demands on the ultra-low-cycle fatigue performance of metallic dampers in buildings, including the widely used buckling restrained braces. This study evaluates the cumulative plastic deformation (CPD) demands on buckling-restrained braces (BRBs) in multi-story buildings imposed by the strong ground motions in the 2023 Türkiye earthquake doublet. Thirty-two records of the highest peak ground accelerations were selected from the strong motion database. Among them, eight captured the ground motions during both events, and the rest only captured the shaking of either of the events. The CPD demands on the BRBs in reinforced concrete frames with various fundamental periods, brace-to-frame stiffness ratios, and BRB ductility ratio are calculated by nonlinear time history analyses and are summarized in the form of enveloped spectra of CPD ratios at constant ductility. The results show that the CPD demands on BRBs increase with smaller brace-to-frame stiffness ratios and larger BRB ductility ratios. The enveloped CPD demands are several hundreds of times the nominal yield deformation of the BRB, which are much higher than the CPD demands for the calibration tests of BRBs stipulated by AISC 341 in the US.

Incorporating platinum circular economy into China's hydrogen pathways toward carbon neutrality.

Hydrogen is gaining tremendous traction in China as the fuel of the future to support the country's carbon neutrality ambition. Despite that hydrogen as fuel largely hinges on the supply of platinum (Pt), the dynamic interlinkage between Pt supply challenges, hydrogen development pathways, and climate targets in China has yet to be deeply analyzed. Here, we adopt an integrated assessment model to address this important concern and corresponding strategies for China. The results indicate that the booming hydrogen development would drive China's cumulative demand for Pt metal to reach 4,200-5,000 tons. Much of this demand, met through a limited supply pattern, is vulnerable to price volatility and heightened geopolitical risks, which can be mitigated through circular economy strategies. Consequently, a coordinated approach to leverage both global sustainable Pt sourcing and a robust domestic Pt circular economy is imperative for ensuring cost-effective hydrogen production, aligned with a climate-safe future.

Metals for energy & digital transition in Spain: Demand, recycling and sufficiency alternatives

This study employs Material Flow Analysis (MFA) to comprehensively forecast metal demand in alignment with energy and digital transition policies at the country level, focusing on Spain. Our analysis spans eight technologies and ten metal groups, projecting metal demand and end-of-life recycling by 2050. We apply ambitious collection and recycling rate objectives, providing estimates of primary extraction requirements. We define and evaluate six scenarios targeting circular economy and sufficiency alternatives aimed at reducing primary extraction. Our results highlight electric mobility as the predominant driver of future metal demand, accounting for 54–92 % of cumulative demand for aluminum, copper, manganese, cobalt, nickel, lithium, dysprosium, and neodymium. From a global justice perspective, the 'equitable fraction of global reserves' for lithium and cobalt is surpassed. Ambitious recycling efforts could potentially cover 23–68 % of the cumulative metal demand between 2020 and 2050, while implementing circular economy and sufficiency alternatives might reduce primary extraction requirements by 11–61 %.

Monolithic design of self-adaptive CMOS converter and robust event-triggered consensus control for integration of multi-renewable energy sources with battery storage system

Recently, integrating renewable energy sources (RESs) has been one of the most effective ways to overcome the power shortage problems due to the cumulative load demand, which cannot be covered using conventional power production. DC-DC converters with a wide voltage conversion range are highly important when integrating RESs to achieve voltage matching. In recent years, many large-scale improvements have been made to the DC-DC converters to improve reliability, effectiveness, flexibility, modularity, and cost-effectiveness. This study investigates the feasibility of integrating RESs and designing the most effective structure using complementary metal-oxide semiconductors (CMOS) for DC-DC converters. A novel monolithic CMOS buck converter with an adaptive sensing feedback system (ASFS) circuit is proposed for renewable integrated systems. The proposed converter based on ASFS provides a wide range of conversion voltages, low cost, and reliability. It depends on the pulse-width modulation (PWM) technique with a voltage-control duty-cycle (VCDC) circuit. The proposed multi-input DC-DC converter is tested to integrate three RESs to form an integrated hybrid system. The proposed converter is built to integrate the PV, wind turbine (WT), wave energy source, and battery energy storage system (BESS). The proposed DC-DC converter is tested to adjust the output voltage of the RESs at 12 V with a load current of 2.4 A to facilitate the integration process. The results show the success of the proposed converter in maintaining the output voltage at 12 V, with maximum efficiency of the CMOS buck DC-DC converter reaching 96.25 % over a wide input voltage range from 15 V to 35 V. Moreover, the maximum peak-peak ripple over the output voltage reaches 600 mV at the maximum input voltage of 35 V. A control method-based event-triggered consensus algorithm has been proposed to regulate the system voltage and ensure active power sharing in the microgrid system. The controller's settling time and rise time have been measured, and a robustness analysis has been performed based on the connections and disconnections of DGs and the impact of faults.

Optimal production management when there is regime switching and production constraints

AbstractWe study a production problem in which the cumulative consumer demand for an item follows a Brownian motion with drift, with both the drift and the variance parameters modulated by a continuous-time Markov chain that represents the regime. The company wants to maintain the inventory level as close as possible to a target inventory level, but there is a linear cost of production. We assume that the production rate is nonnegative. The company is penalized for deviations from the inventory target level and the cost of production, and the objective is to minimize the total discounted penalty costs. We consider two models. In the first model, there is no upper bound for the production rate, and in the second model there is an upper bound for the production rate. We solve both problems analytically and obtain the optimal production policy and the minimal total expected discounted cost. Our solutions allow us to obtain interesting managerial insights.

Multi-time scale dynamic operation optimization method for industrial park electricity-heat-gas integrated energy system considering demand elasticity

This study proposes a multi-time scale dynamic optimization (MSDO) method for ultra-short-term scheduling in industrial electricity-heat-gas integrated energy systems. The aim is to enhance the feasibility of scheduling schemes and to utilize flexibility potential. The MSDO method considers equipment response differences and demand fulfillment time disparities. The dynamic aspect is reflected in the supply-demand matching within the scheduling time window. A single-layer model with unified temporal granularity is constructed based on lag parameter identification. The study proposes various forms of energy demand elasticity, including steam networks and cumulative demand, and investigates the optimal minimum temporal granularity for scheduling. Case results demonstrate that the MSDO method effectively characterizes the multi-energy time lag of equipment. Compared with methods disregarding lag parameters, the MSDO method enhances total profit by ¥ 120711.42 and improves operation stability by 2.96%. The MSDO method outperforms baseline methods in cost and stability, accommodating a 160% increase in renewable energy growth. Under different elasticity spaces, the profit of the cumulative demand method exceeds that of the average method. The time lag of different equipment impacts scheduling profits. An optimal choice exists for the minimum temporal granularity to strike a balance between computational efficiency, economy, and feasibility.

Constructing bimetal, alloy, and compound-modified nitrogen-doped biomass-derived carbon from coconut shell as accelerants for boosting methane production in bioenergy system

Accelerants can enhance methane production in biomass energy systems. Single-component accelerants cannot satisfy the demands of anaerobic co-digestion (AcoD) to maximize overall performance. In this work, nitrogen-doped bio-based carbon derived from coconut shells, containing bimetallic Ni/Fe nanoparticles, FeNi3 alloys, and compounds (Fe2O3, FeN, and Fe3O4), was constructed as hybrid accelerants (Ni-N-C, Fe-N-C, and Fe/Ni-N-C) to boost CH4 production and CO2 reduction. The cumulative biogas yield (553.65, 509.65, and 587.76 mL/g volatile solids), methane content (63.58%, 57.90%, and 67.39%), and total chemical oxygen demand degradation rate (60.15%, 54.92%, and 65.38%) of AcoD with Ni-N-C (2.625 g/L), Fe-N-C (3.500 g/L), and Fe/Ni-N-C (2.625 g/L) were higher than control (346.32 mL/g volatile solids, 40.13%, and 32.03%), respectively. These digestates with Ni-N-C, Fe-N-C, and Fe/Ni-N-C showed excellent stability (mass loss: 22.97%-32.75%) and total nutrient content (4.43%-4.61%). Based on the synergistic effects of the different components of the hybrid accelerant, an understanding of the enhanced methanogenesis of AcoD was illustrated.

Early Mapping Method for Different Planting Types of Rice Based on Planet and Sentinel-2 Satellite Images

In Northeast China, transplanted rice cultivation has been adopted to extend the rice growing season and boost yields, responding to the limitations of the cumulative temperature zone and high food demand. However, direct-seeded rice offers advantages in water conservation and labour efficiency. The precise and timely monitoring of the distribution of different rice planting types is key to ensuring food security and promoting sustainable regional development. This study explores the feasibility of mapping various rice planting types using only early-stage satellite data from the rice growing season. We focused on Daxing Farm in Fujin City, Jiamusi City, Heilongjiang Province, for cropland plot extraction using Planet satellite imagery. Utilizing Sentinel-2 satellite imagery, we analysed the differences in rice’s modified normalized difference water index (MNDWI) during specific phenological periods. A multitemporal Gaussian mixture model (GMM) was developed, integrated with the maximum expectation algorithm, to produce binarized classification outcomes. These results were employed to detect surface changes and map the corresponding rice cultivation types. The probability of various rice cultivation types within arable plots was quantified, yielding a plot-level rice-cultivation-type mapping product. The mapping achieved an overall accuracy of 91.46% in classifying rice planting types, with a Kappa coefficient of 0.89. The area extraction based on arable land parcels showed a higher R2 by 0.1109 compared to pixel-based area extraction and a lower RMSE by 0.468, indicating more accurate results aligned with real statistics and surveys, thus validating our study’s method. This approach, not requiring labelled samples or many predefined parameters, offers a new method for rapid and feasible mapping, especially suitable for direct-seeded rice areas in Northeast China. It fills the gap in mapping rice distribution for different planting types, supporting water management in rice fields and policies for planting-method changes.

Prospects of Passenger Vehicles in China to Meet Dual Carbon Goals and Bottleneck of Critical Materials from a Fleet Evolution Perspective

China has pledged to peak its CO2 emissions by 2030 and achieve carbon neutrality by 2060. To meet these goals, China needs to accelerate the electrification of passenger vehicles. However, the rapid development of electric vehicles may impact the supply of critical raw materials, which may hinder the low-carbon transition. Therefore, the impact of vehicle electrification on CO2 emissions and the corresponding bottlenecks in the supply of critical raw materials should be systematically considered. In this study, we developed the China Automotive Fleet CO2 Model (CAFCM) to simulate a mixed-technology passenger vehicle fleet evolution. We further assessed the impact of energy and CO2 emissions and evaluated the demand for critical battery materials. We designed three scenarios with different powertrain type penetration rates to depict the potential uncertainty. The results showed that (1) the CO2 emissions of passenger vehicles in both the operation stage and the fuel cycle can peak before 2030; (2) achieving the dual carbon goals will lead to a rapid increase in the demand for critical raw materials for batteries and lead to potential supply risks, especially for cobalt, with the cumulative demand for cobalt for new energy passenger vehicles in China being 5.7 to 7.3 times larger than China’s total cobalt reserves; and (3) the potential amount of critical material recycled from retired power batteries will rapidly increase but will not be able to substantially alleviate the demand for critical materials before 2035. China’s new energy vehicle promotion policies and key resource supply risks must be systematically coordinated under the dual carbon goals.

Illustrating China's journey to balance, circular, and secure potassium cycles in the last three decades

Potassium (K), a critical mineral for the living system, is primarily used in the production of mineral K fertilizer to support national food security. However, the anthropogenic and natural cycle of K is less studied to reveal its corresponding nutrient availability and demand, soil balance and efficiency. This study, as one of the first attempts, aims to trace K flows and stocks along its cycle in China by applying substance flow analysis (SFA), K residues generation and circularity model during 1990–2020. It also seeks to explore the soil K balance at both national and provincial scales. The findings indicate that the cumulative demand for K was 628.8 million metric tons (Mt), of which 61.8 % was obtained from K residues. The soil K balance in China had shifted from deficit to excessive, with the soil being excessive by ∼12.5 % in 2020. However, the soil K balances in 31 provinces showed significant temporal and spatial variations, with ∼51.3 % of total cultivated area depleted in soil K in 2020. Our further analysis of China's strategies along such journey towards a balance, circular, and secure K cycles can help to inform other nations for reducing their dependence and competitions on K minerals.

Design of Clean Water Booster Pump for High-Rise Buildings

A sanitary system is a supporting component designed to meet the clean water requirements of a building, primarily for sanitation activities. The average sanitary equipment used typically requires a shower pressure of ±1 Bar. However, the shower pressure can be significantly affected by factors such as the distance from the top tank and the building's layout, considering only the pressure due to gravity. To address inadequate shower pressure, an auxiliary pump known as a booster pump is necessary. The need for a booster pump is determined by the cumulative demand from plumbing equipment, where the total capacity required is 6057 liters/hour. To address this demand, the system employs two pump units, each with a capacity of 3 m3/hour. The distribution pipes utilized in the system adhere to established standards and are made of random polypropylene with a diameter of 2 inches and a flow rate of 0.005889 m3/second. The overall head loss resulting from this installation amounts to 31.62 meters. To accommodate the booster system, a pressure tank with a capacity of 67 liters is employed. The minimum working pressure required for the pumps is 1.8 Bar.

Evaluating rare-earth constraints on wind power development under China's carbon-neutral target

China proposed a target to achieve carbon neutrality before 2060. Wind power is crucial for mitigating climate change and achieving carbon neutrality. However, its development depends on the potential constraints of rare-earth elements. Therefore, first projecting the rare-earth demand for wind power equipment in the context of achieving carbon neutrality and identifying potential obstacles are necessary. However, the carbon-neutral pathway for China's power sector is unclear, let alone the corresponding rare-earth demand. Consequently, this study explores a potential cost-effective carbon-neutral pathway for China's power sector and quantifies the demand for rare-earth elements used for producing wind power equipment under different pathways, by integrating dynamic material flow analysis and a national energy technology model. The results showed that the rare-earth supply may be inadequate for wind power development in terms of achieving carbon neutrality in China, especially for dysprosium and terbium. To neutralise the carbon emissions of China's power sector, the cumulative rare-earth demand during 2021–2060 would be 222–434 kt, of which at most 1/3 could potentially be obtained by circular usage from end-of-life wind turbines. However, the existing low secondary recovery rate of rare-earth elements makes the available circular amounts very small. Shifting to a wind power market dominated by direct-drive turbines may increase the cumulative rare-earth demand by up to 34 %. Without material intensity reduction for the wind power technologies, an additional 38 % demand for rare-earth elements will occur, exacerbating the risk of shortage.

Comparison of the cumulative exergy demand of phase change and reverse osmosis desalination plants with environmental impacts approach

In the scope of the current study, an investigation into the cumulative exergy demand index was conducted for freshwater production across multiple distillation technologies. These technologies encompassed Waterfall Cascading Distillation with Linear Parabolic Solar Concentrator (WCDLPC), Distillation with Linear Parabolic Concentrator and Vacuum Pump (DLPCVP), Distillation with Stand-Alone Point-Focus Parabolic Solar Concentrator (DSPPC), Reverse Osmosis with Non-renewable Energy (RONRE), and Reverse Osmosis with Solar Renewable Energy (ROSRE).The functional unit was established as the production of one ton of freshwater using various desalination technologies. The Outcomes of the analysis pertaining to the cumulative exergy demand in diverse saline water desalination technologies revealed notable findings. Specifically, in the Reverse Osmosis Desalination System with the Conventional System as well as in other desalination technologies (ROSR, WCDLP, DLPCVP and DSPPC), the electricity factor and the photovoltaic panel factor respectively exhibited the most substantial contributions to the cumulative exergy demand. Remarkably, it was observed that the RONRE technology exhibited the highest cumulative exergy demand, reaching 107.04 MJ, while the ROSRE technology demonstrated the lowest demand at 5.98 MJ. Furthermore, the integration of renewable solar energy in lieu of non-renewable electricity within the reverse osmosis technology exhibited a remarkable reduction in cumulative exergy demand, achieving a reduction of 17.90 times. Similarly, the substitution of the waterfall cascade system with a vacuum system in the WCDLPC technology resulted in a 2.69 times reduction in cumulative exergy demand.

Random Furrowing for a Stochastic Unit Commitment Solution

The Unit Commitment Problem involves the inherent difficulty of obtaining optimal combinatorial power generation schedules over a future short term period. The formulation of the generalized Unit Commitment Schedule formulation involves the specific combination of generation units at several de-rated capacities during each hour of the planning horizon, the load demand profile, load indeterminateness and several other operating constraints. This largely deterministic schedule continues to find favor with several plant operators, keeping in mind the close operating time-periods involved. However, the deterministic nature of the load profile is sought to be phased out by a stochastic pattern that is realistic and mirrors real-life situations, owing to modern trends in Demand side management. This shift is in tune with the ongoing power restructuring activities of electricity power reforms. The stochastic profile is obtained by a suitably tuned 2-parameter Weibull distribution that uses appropriate shape and scale parameters. The resulting band of generated load profiles are used to evaluate net power and penal costs associated with a set of pervasive randomized probability indices. The exact UCS comprises of a specific unit absolute state corresponding to a certain time period within the planning horizon. Subsequently, regression analysis is applied to establish the correlation between the absolute states and the cumulative randomized load demand against the intervals within the planning horizon. This method is analogous to random furrowing of probabilistic demand profile.

Environmental damages, cumulative exergy demand, and economic assessment of Panus giganteus farming with the application of solar technology

The use of photovoltaic (PV) technology in agricultural production can mitigate the environmental impacts of mushroom farming. However, changes in the environmental impacts and economic benefits of the application of PV technology are still unclear. Thus, we evaluated the environmental impacts, energy flow, and economic aspects of mushroom (Panus giganteus) farming systems without solar PV (WS) technology and with PV technology from the generation of substrate materials through harvesting. In addition to a 27 % increase in terrestrial ecotoxicity, P. giganteus farming with PV technology reduced all impact categories by 4–60 %, with a 60 % reduction in CO2 emissions and a 25 % reduction in land resources. These findings highlight the importance of combining PV technology with mushroom farming in agricultural carbon reduction and the efficient use of land resources. In terms of the climate change impact, the PV system reduced CO2 emissions by 2.94 kg CO2 eq./kg of mushrooms compared with the WS system, wherein the aspects of substrate transformation, spawn running, and cultivation were reduced by 78.27–89.91 %. The cumulative exergy demand (CExD) analysis showed that P. giganteus farming combined with PV technology reduced the total CExD by 48 %. With the application of PV technology, the top contributor to the total CExD of mushroom farming shifted from electricity to transportation throughout the supply chain. The PV system reduced costs by 22.09 % and increased the total revenue by 22 % and the cost-benefit ratio by 50 %. Halving the transportation distances of substrate materials and performing localized substitution of wood chips resulted in a 3–34 % reduction in the environmental impacts category and a 23–30 % reduction in nonrenewable fossil energy consumption. These results showed that improvements helped optimize the environmental performance in terms of carbon reduction and energy mixing. Thus, combining PV technology with greenhouse mushroom farming can improve trends in energy and environmental damage.