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Abstract The photovoltaic (PV) power generation has randomicity and intermittence due to the influence by meteorological factors and it is of significance to establish a reasonable prediction model for PV power. Since it is tough to get a completely optimal prediction of PV power by a single model due to the existence of uncertainty, the paper considered proposing an ensemble method by integrating various individual models to achieve better accuracy. In this paper, a weight-varying ensemble (WVE) forecasting model is established to improve the precision of the short-term prediction of PV power. First, the extraction of feature vectors was implemented to find out the most important variables which also helps to improve the accuracy through data pre-processing. Second, the weather pattern was recognized and clustered based on a self-organizing feature map (SOM) method. Third, the five min-ahead prediction output was obtained using the WVE model that utilizes an integrated framework of Generalized Regression Neural Network (GRNN), Extreme Learning Machine Neural Network (ELMNN) and Elman Neural Network (ElmanNN), which were assembled by Genetic Algorithms optimized Back Propagation Neural Network (GA-BPNN). Results show that the WVE model achieved a higher accuracy with mean absolute percentage error (MAPE) of 5.17%, 5.26%, 5.49% and 5.82% for four types of data. The GA can be applied to optimization of other weight-varying ensemble problems. [ABSTRACT FROM AUTHOR]

Abstract The paper presents results developing an innovative power supply system on the basis of a modular, flexibly customizable and cost-effective lithium-ion battery and power converter unit for peak-shaving and load levelling applications in the industrial sector including advanced self-consumption optimization strategies for renewable energies. First, the paper describes a monitoring campaign with high resolution measurements on machine, plant and factory level. Second, technical and economic simulation models for the components (battery, power conversion system and energy management) and the integrated system (including total investment costs, conversion losses, state of charge estimation) are presented. The innovative features of the system are described, including a multi-criteria optimizing energy management based on an adaptive dynamic programming algorithm, battery condition monitoring and a hybrid battery storage approach. Third, results of the optimizing design process are presented. The optimal type and power rating of converters and switches and the optimal system topology are determined and discussed for an application example. Simulation results for three DC-DC and five DC-AC converter topologies and two different energy management concepts are discussed and compared. [ABSTRACT FROM AUTHOR]

Over the past decade, building energy modelling research has increasingly focused on urban-scale models. The shortcomings of analyzing urban buildings in isolation are well known and far from negligible (mainly, the inability to account for urban heat island and shading from neighboring obstructions). The aim of this paper is to assess the impact of the urban context via urban-scale modelling and inverse parameter estimation (calibration) using metered energy consumption of each building. We describe an automated calibration method for 58 buildings in a representative downtown district of Abu Dhabi. This district has undergone a detailed energy audit and a large amount of data about the building envelopes, cooling loads and electricity consumption has been collected from 2008 to 2010. In our models, buildings are subdivided in up to three use types documented in the audit (Residential, Office and Retail). Since it is well known that, due to the urban heat island effect, the urban ambient air temperature can differ significantly from the reference rural air temperature used in most building simulations, the calibration procedure will also estimate this differential together with unknown building parameters. The main contribution of the paper is to demonstrate that the proposed district-scale calibration is, in average, more accurate than individual building calibration and informs not only on buildings but also on the outdoor environment. The calibration was performed using Genetic Algorithm, reaching an average building MAPE of 25.24%. For the district as a whole, a MAPE of 12.01% was achieved. The estimation of Urban Heat Island intensity revealed a daily maximum of 5.6°C and an average daily differential of 3°C for a typical day, showing the relevance to consider it for any building energy simulation. [ABSTRACT FROM AUTHOR]

This paper focuses on the selection of number and size of boilers required for the heating units of the residential complexes. In this case study we proposed the selection of number and dimension of boilers for a heating unit of a residential complex located in Tirgu-Mures, Romania. The conclusion of this study is that the operational safety of the heating unit increases once the number of boilers increases, together with the decrease of thermal energy consumption and the increase of investment costs respectively. Based on our calculations, we recommend that the heating unit should be equipped with seven boilers, and should be provided with a controller for managing them in cascade. The method proposed in this paper can be used within the feasibility studies related to heating units of the residential complexes. [ABSTRACT FROM AUTHOR]

This paper analyses the selection of priorities in case of the rehabilitation of water distribution networks. The ranking of the technical solutions was performed using the Leader method. This paper also presents a case study regarding the rehabilitation of water distribution network in Cluj-Napoca, Romania. The result of this study shows that the rehabilitation of water distribution network in Cluj-Napoca, Romania has to begin with the substitution of asbestos cement pipes. [ABSTRACT FROM AUTHOR]

This paper focuses on the selection of number and size of boilers required for the heating units of the residential complexes. In this case study we proposed the selection of number and dimension of boilers for a heating unit of a residential complex located in Tirgu-Mures, Romania. The conclusion of this study is that the operational safety of the heating unit increases once the number of boilers increases, together with the decrease of thermal energy consumption and the increase of investment costs respectively. Based on our calculations, we recommend that the heating unit should be equipped with seven boilers, and should be provided with a controller for managing them in cascade. The method proposed in this paper can be used within the feasibility studies related to heating units of the residential complexes. [ABSTRACT FROM AUTHOR]

This paper analyses the selection of priorities in case of the rehabilitation of water distribution networks. The ranking of the technical solutions was performed using the Leader method. This paper also presents a case study regarding the rehabilitation of water distribution network in Cluj-Napoca, Romania. The result of this study shows that the rehabilitation of water distribution network in Cluj-Napoca, Romania has to begin with the substitution of asbestos cement pipes. [ABSTRACT FROM AUTHOR]

In this paper, the optimization of transmission system of electric drive tracked vehicles is studied. The purpose of optimization is to obtain maximum transmission efficiency. The research content in this paper includes two parts: theoretical analysis and computer simulation. The theoretical analysis is to determine the factors that affect the efficiency of the transmission system. The computer simulation is to optimize the actual transmission mechanism to obtain maximum transmission efficiency. The research methods in this paper can help the designer to determine the parameters and the optimal control strategy of the transmission system. The result of this paper has applied value to the design of transmission mechanism of electric drive tracked vehicles. [ABSTRACT FROM AUTHOR]

This paper investigates the possibility to enhance the thermal characteristics of a building fabric taking into account the economic feasibility in order to avoid useless expensive interventions. The problem consists in realizing an internal insulation system for a single apartment located in Trieste. A genetic optimization has been implemented in order to search a large number of solutions with multiple objects and constraints. EnergyPlus has been used for dynamic building and plant simulation and modeFRONTIER for optimization loop setup. The objectives are the used heating energy consumption and the life cycle refurbishment cost, using a net present value approach. An additional objective has been added in order to guarantee the maximization of the interior useful floor area, which is directly influenced by the internal insulation thickness. Different approaches have been compared, considering actions dealing with opaque surfaces only or considering the replacement of existing windows. The paper demonstrates that an automatic optimization approach can help designers to identify the best suited intervention for building refurbishment. [ABSTRACT FROM AUTHOR]

In this paper, we examine the ability of a hydropower cascade to balance variability from wind power. We consider a coordinated hydro-wind system that satisfies a single power balance, and we use a real-time control scheme to optimize system operations such that wind and load curtailment is minimized. The control scheme considers system hydraulics (including dynamic tailrace elevations and water travel times) and system constraints. Generation from an individual hydropower plant is modeled using a convex piecewise planar approximation. We give results from a case study involving hydro and wind power in the Pacific Northwest region of the United States. The objective of this paper is to present a framework for evaluating how the regulation of wind generation affects hydropower operations. Our intention is to use this framework in future work to perform a systematic study of balancing capability across different hydraulic conditions, system constraints, and wind generation scenarios. [ABSTRACT FROM AUTHOR]

Abstract Research studies concerning heating and cooling systems have increased in recent years, pledging great potential for energy saving, efficient thermal energy distribution and renewable energy source integration. Currently, heating systems are managed on the basis of operator experience or by using adaptive controllers, however these solutions are not suitable when there are remarkable variations in boundary conditions (e.g. weather changes). In this context, Model Predictive Control is a promising strategy as it optimizes the control action based on the prediction of the future behavior of both system dynamics and disturbances by means of simplified models. This paper presents the control of a building heating system through a Model-in-the-Loop Model Predictive Control approach. A detailed model that replicates the behavior of the real system is controlled with a predictive controller based on a novel Dynamic Programming optimization algorithm implemented in Matlab®. The performance of the innovative controller is compared to the results obtained with a PID controller. Overall, the Model Predictive Control strategy is able to fulfill comfort requirements properly while minimizing energy consumption. [ABSTRACT FROM AUTHOR]

Abstract In this paper, the electricity consumption model and pressure drop model of humidification-dehumidification (HDH) system is developed. An experimental study is carried out to investigate the effects of operating parameters on the pressure drop of HDH system. The pressure drops in humidifier, dehumidifier and the total pressure drop increase with the increase of air and solution mass flow rate. The values of undetermined coefficient in the pressure drop model are obtained based on the experimental data. Meanwhile, the validation of the pressure drop model is varied though experiment. On this basis, the optimization model for minimum specific total energy consumption (STEC) is proposed. The optimization results show that the value of optimized STEC increase with the increase of evaporation rate requirements. The value of air mass flow rate (m g) should be as small as possible. The adjustment of solution mass flow rate (m l) and solution inlet temperature in humidifier (T lhi) is a priority. The minimum value of optimized STEC is 822.676 kJ/kg. [ABSTRACT FROM AUTHOR]

Abstract Increasing electricity demand is exerting growing pressure on scarce freshwater resources. Especially in China, the spatial mismatch of energy and water caused water-shortage regions shoulder heavy electricity generation tasks. This spatial layout could further aggravate national water scarcity. In this paper, to provide insights for a more rational electricity generation-trade pattern, we built an electricity generation tasks redistribution model to optimize national electricity generation pattern. In this model, the objective function is minimizing the water use related to electricity generation for drier regions through transferring electricity generation tasks to adjacent wetter regions. The equality constraint condition is that the total amount of national electricity generation must sufficiently supply the total electricity demand. The inequality constraint is that the adjustment range of electricity generation of each province is limited by local installed capacity. The results show that, in the optimal scenario, the water consumption related to electricity generation of regions in water "shortage grade 1" and "shortage grade 2" (drier regions) can be decreased by 46% and 44%, respectively. [ABSTRACT FROM AUTHOR]

Abstract Among many kinds of batteries, lithium-ion batteries have become the focus of research interest for electric vehicles (EVs), thanks to their numerous benefits. However, there are many limitations of these technologies. This paper reviews recent research and developments of lithium-ion battery used in EVs. Widely used methods of battery sorting are presented. The characteristics and challenges of estimating battery's remaining useful life (RUL) and state-of-charge (SOC) are critically reviewed, along with a discussion of the strategies to solve these issues. A new method of sorting retired lithium-ion batteries and estimating the RUL and SOC of the retired lithium-ion batteries is proposed. [ABSTRACT FROM AUTHOR]

Abstract The main characteristic of an indirect evaporative cooler (IEC) is the high dependency on ambient air conditions. To ensure stable indoor temperature and provide better thermal comfort, proper control strategy is essential. However, very limited studies report the controller used in IEC. In this paper, a novel control scheme named high-low (H-L) is proposed for regenerative indirect evaporative cooler (RIEC). Under H-L control scheme, the fans would be switched between high speed and low speed rather than completely turned off. The H-L control adopts the multi-speed technology, providing energy saving potential compared with conventional on-off control and overcome the complexity and costly of variable speed technology. The annual performance of RIEC was simulated under H-L control based on the RIEC model and dynamic indoor heat and mass balance model. The influence of low speed to high speed ratio (L/H) is discussed in order to propose an optimal L/H by considering both the thermal comfort and annual energy consumption. The results show that the H-L control can provide stable indoor temperature and satisfactory thermal comfort with Predicted Mean Vote (PMV) in the range of -0.5 to 0.5 for 76.2% of time. The optimal L/H is found to be 0.25 to 0.33 because of high thermal comfort provided and lowest energy consumption. [ABSTRACT FROM AUTHOR]

Abstract For remote agriculture-based rural areas, utilizing the local renewable resources such as biomass, wind, and solar energy could be potentially more efficient than long-distance transmission of electricity. In this paper, a multi-objective optimization model for the design of standalone hybrid renewable energy systems (HRES) in remote rural areas is proposed. The objective is to maximize the profits and the carbon abatement capability of the system by optimal process selection and sizing of HRES components including solar, wind, and biomass generation systems. A case study for the design of an HRES on the Carabao Island in the Philippines is conducted. The result shows a 122 kW solar power plant, a 67 kW onshore wind farm and a 223 kW biomass pyrolysis system constitute the optimal configuration of the hybrid energy system, generating a daily profit of US$ 940. The greenhouse gas emission of the optimal system is -3,339 kg CO 2 eq/day, indicating good carbon sequestration performance. [ABSTRACT FROM AUTHOR]

Abstract The simulation of thermal dynamic characteristics of district heating system is of great significance for heat source optimization and scheduling. However, there are two problems in the real-time simulation of temperature distribution in urban district heating systems. First, the structure of the system is complex and it is difficult to obtain all detailed information to establish an accurate model, and the actual varying operating conditions are also hard to be reflected in the model. Second, the accurate and elaborate model could not meet requirements of real-time calculation and optimization. Therefore, the model must be simplified to reflect the dynamic changes of key parameters and be updated simultaneously by using actual operation data. In this paper, the key parameters of the dynamic temperature model are identified and optimized based on the function method and operation data, and a case is studied to verify the feasibility of the method, which demonstrates that it can calculate the outlet temperature distribution of the district heating system accurately and quickly. Thus, this work lays a model foundation for actual heat source optimal scheduling. [ABSTRACT FROM AUTHOR]

Abstract: Underwater robotic vehicles(URV) are employed to inspect subsea facilities. In order to deftly operate underwater robotic vehicles, firmly attached structure is required. The choice of docking point is very important. Multiple redockings caused by an inappropriate choice increases the duration and cost of the mission. This paper proposes a method to assist the URV operator identifying appropriate docking position in the context of a desired facile workspace. The method is consistent with classical procedures developed for industrial robotics. We propose a positioning strategy based on the task of intuitively determining docking positions. We take facility of operator as the optimization criterion. In this paper, the condition number of the operator is adopted as a measure of operator facility. This paper calculates joint limits and presents Theoretical analysis and simulation results. [Copyright &y& Elsevier]

Abstract: The employment of Heating, Ventilation and Air-conditioner (HVAC) technology is viable option for the dynamic thermal comfort in the transitional spaces where connect the interior and exterior space. In this paper, the optimization to thermal environment parameters in the hot summer and warm winter zone is benefit to human comfort, health and energy saving is discussed. According to the dynamic comfort equations and the advantage of artificial immune algorithm in solving combinatorial optimization to engineering problems, the artificial immune algorithm has been applied to the optimization of thermal parameters for the HVAC design within a transitional space. Furthermore, it is pointed out that the proposed method in this paper might be employed in the control of the HVAC conditioning system. [Copyright &y& Elsevier]

Abstract: A significant number of efforts are underway to develop and assess technologies that will lead to technically and economically viable routes to reduce the CO2 emissions of fossil energy systems, particularly coal-fired power plants. Developing technologies to reduce emissions from these sources is essential for controlling atmospheric levels of CO2 because of the widespread reliance on coal as an inexpensive and abundant energy source. Two major systems-level design challenges exist. The first is how to design new plants that incorporate CCS technology. The second is how to retrofit existing plants to capture CO2. Both design challenges can benefit from an optimization approach, which considers the application of multiple potential technologies and analyzes ways in which the whole plant-wide system can be integrated to increase overall efficiency. This paper will present a modular framework for the analysis and optimization of power generation systems with CCS that helps to meet these design challenges. In order to more completely understand the economic and operational tradeoffs associated with the various potential carbon capture technologies, and how they can be applied to new and existing plants, a unified, systemic framework has been developed to provide a common basis for evaluation. Given the complexity of the design problem and the fact that new technologies are continually being developed, this framework is modular in nature and incorporates algorithms for the selection, integration and optimization of carbon capture technologies for both new and existing plants. In addition to the framework itself, this paper discusses simulation modules representing various capture technologies and power plant components. The framework provides the means to link the various modules together in order to provide a holistic, systems perspective of plant wide operations. Results of analyses and optimization scenarios performed with the framework are also presented. [Copyright &y& Elsevier]

Abstract Indonesia has a lot of civilization without electricity in remote areas. In order to fulfill the high demand of electricity, low cost and environmentally friendly power plants are required to reach remote areas. Micro-hydro power plants are proposed as a solution that could penetrate the limited accessibility for transport, technology, and cost. This paper covers a case study of optimization potential analysis of micro-hydro power plant (MHPP) in Subang. This study analyze the current technical specification of the MHPP in Subang in order to optimize the operation to reach the attached generator capacity with the condition of low head and low discharge of the river. Analysis of the existing MHPP proposes a redesign focused on the penstock pipe and turbine. According to the calculations, penstock pipe design has the minimum required diameter of 0.7 m in order to withstand the debit of 1.1 m3/s. Besides, in order to optimize the cross flow turbine performance with the debit of 1.1 m3/s, the existing turbine's radius should be redesigned to 0.71 m, with the existing turbine's blade length should be redesigned to 0.248 m. All of the redesigns proposed could increase the potential power generation up to 200% from the current condition. [ABSTRACT FROM AUTHOR]

Abstract The link between water, energy, and food has gotten more attention over the last years. The increased needs for water, energy and land resources, as well as the environmental degradation and, in some cases, scarce resources, have driven the search for strategies for sustainable development within the Water-Energy-Food (WEF) nexus concept. This paper presents an approach to assess water and power distribution grids for food production, based on WEF nexus approach, in order to support decision-making and guide the sustainable development, sensitive to the nexus policies. The proposed optimization model seeks to identify the optimal solution including economic, environmental and social aspects that satisfy the stakeholders. The model is applied to a case study in the Sonora desert, Mexico. The results show that the proposed methodology is a suitable tool to evaluate multiple scenarios for the decision-making process. [ABSTRACT FROM AUTHOR]

Abstract Indonesia has a lot of civilization without electricity in remote areas. In order to fulfill the high demand of electricity, low cost and environmentally friendly power plants are required to reach remote areas. Micro-hydro power plants are proposed as a solution that could penetrate the limited accessibility for transport, technology, and cost. This paper covers a case study of optimization potential analysis of micro-hydro power plant (MHPP) in Subang. This study analyze the current technical specification of the MHPP in Subang in order to optimize the operation to reach the attached generator capacity with the condition of low head and low discharge of the river. Analysis of the existing MHPP proposes a redesign focused on the penstock pipe and turbine. According to the calculations, penstock pipe design has the minimum required diameter of 0.7 m in order to withstand the debit of 1.1 m3/s. Besides, in order to optimize the cross flow turbine performance with the debit of 1.1 m3/s, the existing turbine's radius should be redesigned to 0.71 m, with the existing turbine's blade length should be redesigned to 0.248 m. All of the redesigns proposed could increase the potential power generation up to 200% from the current condition. [ABSTRACT FROM AUTHOR]

Abstract The link between water, energy, and food has gotten more attention over the last years. The increased needs for water, energy and land resources, as well as the environmental degradation and, in some cases, scarce resources, have driven the search for strategies for sustainable development within the Water-Energy-Food (WEF) nexus concept. This paper presents an approach to assess water and power distribution grids for food production, based on WEF nexus approach, in order to support decision-making and guide the sustainable development, sensitive to the nexus policies. The proposed optimization model seeks to identify the optimal solution including economic, environmental and social aspects that satisfy the stakeholders. The model is applied to a case study in the Sonora desert, Mexico. The results show that the proposed methodology is a suitable tool to evaluate multiple scenarios for the decision-making process. [ABSTRACT FROM AUTHOR]

Abstract Solar thermal heaters (STs), photovoltaics (PVs) and ground source heat pumps (GSHPs) are widely used nowadays due to their advantages of environmental protection and energy saving. The combination of solar thermal, photovoltaic and GSHP can achieve an even better performance and such a system is referred to as PV/ST-GSHP in this study. The overall efficiency of the PV/ST-GSHP system is highly dependent on the capacity size which is large or small would affect the overall efficiency and the power of PVs and STs affects the efficiency as well. This paper established an optimization model for a PV/ST-GSHP system based on the environment, energy and economy criteria. The model focused on the optimal planning of PV and ST under the restriction of a limited size of area and of the practical loads of heat and cooling, for which the rated capacity of GSHP is included. Genetic algorithm is employed to solve the optimization problem. After optimization, the multi-objective value is 26.88%. [ABSTRACT FROM AUTHOR]

Abstract The simultaneous production of different energy vectors from hybrid polygeneration plants is a promising way to increase energy efficiency and facilitate the development of distributed energy systems. The inherent complexity of polygeneration energy systems makes their economic, environmental and energy performance highly dependent on system synthesis, equipment selection and capacity, and operational strategy. Mixed Integer Linear Programming (MILP) is the state of the art approach to tackle the optimization problem of polygeneration systems. The guarantee of finding global optimality in linear problems and the effectiveness of available commercial solvers make MILP very attractive and widely used in optimization problems of polygeneration systems. Nevertheless, several drawbacks affect the MILP formulation, such as: the impossibility of taking into account nonlinear effects; the necessity of considering all the time periods at once; the risk of high-dimensionality of the problem. To tackle these limitations, several techniques have been developed, such as: piecewise linearization methods; rolling horizon approaches; dimensionality reduction by means of energy demands clustering algorithms. In this paper, limits and potentials of MILP methods for the optimization problem of polygeneration energy systems are reviewed and discussed. [ABSTRACT FROM AUTHOR]

Combined Cooling, Heating and Power (CCHP) systems have been widely utilized in the buildings to achieve high efficiency cascade utilization of energy. Heat pump is another widely utilized technology to improve the building energy efficiency. The paper presents a hybrid system which integrates the CCHP with river water source heat pump to combine the advantages of these two technologies. A physical model with energy storage module was firstly developed for the combined system. A case study was further carried out to investigate the optimized configuration and operation performance of the combined system. [ABSTRACT FROM AUTHOR]

Passive design strategies are preferable for constructing low-energy buildings given their significant influences on the building energy consumption. The building layout, envelop thermophysics, building geometry and infiltration & air-tightness are major considerations of the passive design to achieve building sustainability. In this paper, modelling experiments on a generic residential building in hot and humid climates are conducted to integrate a robust variance-based sensitivity analyses with an early-stage design optimization process. Daylight, ventilation and thermal conditions are simulated with EnergyPlus to obtain the total lighting and cooling energy consumption under the hybrid ventilation and daylight dimming control algorithm. The non-dominated sorting genetic algorithm (NSGA-II) is then coupled with the modelling experiment to obtain the Pareto frontier as well as the final optimum solution. Furthermore, different settings of NSGA-II are investigated to improve the computational efficiency of the optimization process. Findings from this study will guide decision-makers through a holistic optimization process for energy-saving targets in a passively designed green building. [ABSTRACT FROM AUTHOR]

Heat networks (HNs) and heat pumps (HPs) are potential low-carbon heating technologies that can deliver the 2050 carbon target reduction in the UK. The optimal design of the heating system on a national scale to maximize the economic benefits while satisfying carbon target remains an open question. By applying the HN investment model and the integrated heat and electricity system model, this paper compares the decomposed system cost of HNs, hybrid HP-Bs (HPs and gas boilers) and air source HPs (ASHP), analyzes the impact of different heating strategies on the operation and investment of the electricity system, and presents the optimized strategy for heat sector decarbonization. According to the cost assumption, hybrid HP-Bs based approach may have significant economic advantage over the other two heating technologies when each of these is applied individually, while HNs in urban areas play an important role in the optimized heat technology portfolio. [ABSTRACT FROM AUTHOR]

Community microgrids are developed within existing power systems by integrating local distributed energy resources (DERs). So power distribution systems can be seamlessly partitioned into community microgrids and end-users could be largely supported when an extreme event happens. However, because of the low inertia characteristics of DERs, their power capacity should be well designed to cover unexpected events and guarantee system reliability. This paper presents a quantitative and qualitative combined methodology for DERs selection, and an economic approach to meet the system reliability requirements. Discrete time Fourier transform (DTFT) and particle swarm optimization (PSO) are employed to obtain the optimal solution, with consideration of load demand and renewable generation uncertainties. In addition, a sensitivity analysis is conducted to show how DERs’ capacity design is impacted by counted portion of the forecasted renewable generation. [ABSTRACT FROM AUTHOR]

Combined cooling, heating and power (CCHP) system fuelled by natural gas is expected to play an important role in the sustainable energy strategy. The aim of this paper is to describe a natural-gas CCHP system for a hotel located in Dalian (China). In this study, by minimizing the annual total costs (ATC), the capacity and numbers of power generation unit (PGU) is determined. Meanwhile, the application of CCHP system is given to ascertain the relationship between the optimum installed capacities, operation strategy and performance evaluation. The results show that with a single PGU, the trend of ATCS increases firstly with the increasing of the capacity, reaches the maximum value, and then mostly decreases. Furthermore, with two units in parallel, when the major unit capacity is higher than the optimum value, its impact plays a dominant role on the ATCS. However, when the major unit is lower than the optimum value, the impact can be determined by the minor unit. Sensitivity analysis of energy prices is executed, which will affect the capacity of the system and cooling ratio correspondingly. The rise of nature gas price makes the optimal capacity of the system decreased and the cooling ratio increased. [ABSTRACT FROM AUTHOR]

The Malaysian Government has been introducing fuel diversification policies over the past decade by considering other sources of fuel such as alternative and renewables into the electricity mix as a measure to lengthen the oil and gas reserves against premature depletion. Since electricity consumption forms about a fifth of the total energy consumption, and directly impacts the country’s economy and people’s well-being, it is necessary to pay emphasis on Malaysia’s long-term power sector planning by identifying sustainable options which will enhance Malaysia’s energy security and mitigate climate change. This paper presents an analysis of the long-term power generation options for Malaysia by deploying the integrated MARKAL-EFOM system (TIMES) model. The examined scenarios are business as usual (BAU) and optimized least cost scenarios which include: existing technology, plus renewable, plus nuclear as well as, plus photovoltaic (PV) and storage. The results indicated that Malaysia has sufficient renewable energy resources to meet the projected electricity demand by 2050 and fossil fuels can be fully replaced with electricity sourced from large hydropower and combination of other indigenous sustainable energy sources. The variability issue of renewables can be stabilized with the integration of storage systems into the grid. This analysis also demonstrated that installation of 8.57 GW solar PV panels on existing rooftops combined with 3.6 GW large-scale pumped heat energy storage (PHES) system can generate electricity comparable to a 2.0 GW nuclear plant at a lower system cost of $102.4 billion. Hence, if Malaysia were to adopt a sustainable policy, then nuclear power would not be an ideal option as uranium fuel relies on continuous imports. [ABSTRACT FROM AUTHOR]

Coal is the dominating fuel for heating, resulting in serious air pollution in China especially in winter. To mitigate the problem, Chinese government has issued policies to motivate consumers to use natural gas to replace coal. Considering the high price of natural gas, in order to further promote the utilization of natural gas, this paper has proposed a new method that considers the external cost of fuel when optimizing the energy structure for space heating. The external cost is commonly used to reflect the impacts of pollutant emissions to measure social benefit. The proposed method has been applied to a case study for the regions of Beijing and Tianjin. Results show that optimizing the fuel consumption in Beijing and Tianjin as a whole can reduce the external cost by 36 million dollars. [ABSTRACT FROM AUTHOR]

In the past decade, aircraft fuel burn has been continually decreased, mainly by improving thermal and propulsion efficiencies with consequent decrement in specific fuel consumption. In view of future emission specifications, the requirements for SFC in the forthcoming years are expected to become more stringent. In this paper, a preliminary design of a turbofan engine for entry in service in 2025 was performed. The design of a baseline 2010 EIS engine was improved according to 2025 specifications. A thermodynamic analysis was carried out to select optimal jet velocity ratio, pressure ratio, and temperatures with the goal of minimizing specific fuel consumption. A gas path layout was generated and an aerodynamic analysis was performed to optimize the engine stage by stage design. The optimization resulted in a 3-shaft turbofan jet engine with a 21% increase in fan diameter, a 2.2% increment in engine length, and a fuel burn improvement of 11% compared to the baseline engine, mainly due to an increment in propulsive efficiency. A sensitivity analysis was also conducted to highlight what the focus of technology development should be. [ABSTRACT FROM AUTHOR]

Water and energy are essential for human life and inextricably linked to each other. Water is used in the processes of energy generation and transportation and energy is also used in the processes of water exploitation and transportation. In a utility plant, water is used as working fluid for power generation and heat carrier. Large amount of fresh water is required in the utility system to compensate for the water loss due to boiler blowdown, cooling tower blowdown, cooling tower water evaporation, and process hot utility utilization. Since the requirement of boiler feed water is strict, the water treatment in the industrial utility plant is quite energy intensive. Thus, the simultaneous design and optimization of water desalination process and energy generation process is significant. In this paper, a novel superstructure of water desalination and energy generation system is proposed. Thermal membrane distillation unit is applied for water desalination together with reverse osmosis unit. A mathematical model is formulated for the thermodynamic analysis and optimization of the novel system. Two objective functions are used to evaluate the design scheme. A case study is elaborated to test the proposed system and developed model. [ABSTRACT FROM AUTHOR]

Accurate cloud image forecasting is very necessary for sky image based solar power forecasting. To provide a means that can track the cloud deformation process and then forecast the cloud shape and position in a future sky image, a cloud image forecasting approach is proposed in this paper. Firstly, the cloud pixels in sky images are identified using Otsu’s method. Secondly, a mathematical description method of cloud location, shape, and deformation is suggested, so that the key information of cloud and its deformation process can be extracted from original images and then digitized. Thirdly, genetic algorithm (GA) is applied to optimize the cloud deformation process according to digitized historical cloud information. In the end, the cloud shape and position in a future image is forecasted using linear extrapolation. The feasibility and effectiveness of the proposed method are validated by simulation. [ABSTRACT FROM AUTHOR]

Gas-phase polymerization is a method that is widely used in the polymer production process. The heterogeneous reaction between monomer gas and solid catalyst takes place in the fluidized bed reactor to produce the polymer product. The design and production planning of this process is a difficult task due to the complicated fluid behavior and polymerization reaction inside the fluidized bed reactor. In this paper, a model of the fluidized bed polymerization reactor for linear low density polyethylene (LLDPE) production is developed using the Aspen Custom Modeler (ACM) to predict the polymer characteristics and flow behavior. The developed model is then integrated to the main process flow simulation in order to optimize the energy consumption in the polymer production process. The results show that the total energy requirement is reduced while maintaining the same polymer characteristics. [ABSTRACT FROM AUTHOR]

Remote terminal units (RTUs) can trip the circuit in case of a fault in a power system when work with the central control room. RTUs are used to monitor faults at different parts of the power system. This paper presents optimal placement of RTUs by using Particle Swarm Optimization (PSO) technique to minimize customer outage, travel costs and improve System Average Interruption Duration Index (SAIDI). The method is applied to IEEE 13 Node Test Feeder. The Results show as the number of RTUs installed in nodes with many customers is increased, SAIDI improves. [ABSTRACT FROM AUTHOR]

The goal of this paper is to present a new optimization framework for design and analysis of a stand-alone energy supply system to rural communities using 100% renewable energy sources (RES). In achieving this goal, we first propose a technology superstructure for energy supply. The superstructure starts from different types of RES which are easily available in rural communities, including solar, wind, organic waste, and lignocellulose biomass. The RESs are processed in multiple technologies to meet energy demands of a rural community (chemical, thermal and electric powers). Using the model we identify the optimal system configuration and practical operational strategies. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to examine carbon dioxide (CO 2 ) separation process using membrane technologies. In achieving this goal, we develop an optimization model to design and integrate the CO 2 separation using multi-stage membrane technologies by maximizing the total profit calculated with the total capital and operating costs, and the expected revenue from the CH 4 selling. Using the proposed model, we are able to determine the optimal design and operation strategies of the individual membrane and compressor to meet the design specification (i.e., purity and recovery rate) in the scenarios of different CO 2 market prices. [ABSTRACT FROM AUTHOR]

Heat distribution via pre-insulated plastic bonded piping systems will become of major importance for covering the primary energy consumption of EU and will be of vital importance for the energy and heat turnaround. Utilizing efficiency potentials of combined heat and power (CHP) and integrating (industrial) waste heat and renewable energy contents within these grids, low temperature (and low-ex) heat sources might be exploited. Thus, energetic contents unsuitable for electrical energy supply are utilized in order to diminish greenhouse gas emissions and minimize primary energy needs. Distribution of heat requires accurate planning and network design for the expected service time of several decades. This applies for existing networks as well as for future networks. During planning and conception different load scenarios (of today and in future) must be considered. Since the design of existing networks was done in the past, this paper focusses on the requirements for the conception and planning of heating networks in the near future. Because of low temperature (and low-ex) heat sources, the expansion of district heating networks in EU will be linked to modifications in the network design and planning. A sensitivity analysis was carried out for relevant input parameters in low temperature networks. The analysis showed a significant influence of the conductivity of the bedding material as well as the overburden height on heat losses. For the given set of reference parameters, the energy efficiency potential of systems for heat distribution is approximately 10 %. [ABSTRACT FROM AUTHOR]

In this paper a gas-steam combined-cycle, partially fueled by syngas (produced in an embedded downdraft gasifier fed with pomace), is considered. In addition, an auxiliary combustion system is directly fed by ligno-cellulosic biomass. The thermodynamic model of the entire system is developed by means of the Cycle-Tempo software. The gasification process is supposed to occur at ambient pressure and air is used as gasifying agent. An optimization process has been introduced by means of the Design of Experiment (DoE) technique. The design variables and their corresponding ranges have been chosen by using a heuristic criterion. The power plant performance is represented by the thermal efficiency, _ ηI, the exergetic efficiency, ηII, the cost of electricity, COE, and the net return, Rnet. The DoE technique provided the so-called Pareto barrier, which isolates all the non-dominated solutions. [ABSTRACT FROM AUTHOR]

This paper focuses on the thermodynamic modelling and parametric optimization of an Organic Rankine Cycle (ORC) which recovers the heat stored in a thermal energy storage (TES). A TES with two molten-salt tanks (one cold and one hot) is selected since it is able to operate in the temperature range useful to recover heat from different sources such as exhaust gas of Externally Fired Gas Turbine (EFGT) or Concentrating Solar Power (CSP) plant, operating in a network for Distributed Generation (DG). The thermal storage facilitates a flexible operation of the power system operating in the network of DG, and in particular allows to compensate the energy fluctuations of heat and power demand, increase the capacity factor of the connected plants, increase the dispatchability of the renewable energy generated and potentially operate in load following mode. The selected ORC is a regenerative cycle with the adoption of a Heat Recovery Vapour Generator (HRVG) that recovers heat from molten salts flowing from the Hot Tank to the Cold Tank of the TES. By considering the properties of molten salt mixtures, a ternary mixture able to operate between 200 and 400 °C is selected. The main ORC parameters, namely the evaporating pressure/temperature and the evaporator/condenser pinch point temperature differences, are selected as variables for the thermodynamic ORC optimization. An automatic optimization procedure is set up by means of a genetic algorithm (GA) coupled with an in-house code for the ORC calculation. Firstly, a mono-objective optimization is carried out for two working fluids of interest (Toluene and R113) by maximization of the cycle thermal efficiency. Afterwards, a multi-objective optimization is carried out for the fluid with the best performance by means of a Non-dominated Sorting Genetic Algorithm (NSGA) in order to evaluate the cycle parameters which maximize the thermal efficiency and minimise the heat exchanger surface areas. Toluene results able to give the best trade-off between efficiency and heat exchanger dimensions for the present application, showing that by with respect to the best efficiency point, the heat exchange area can be reduced by 36% with only a penalty of 1% for the efficiency. [ABSTRACT FROM AUTHOR]

This paper introduces URB io , an interactive optimization framework for the planning of urban systems. Addressing the elusive nature of urban planning and its need to cope with more technical sectors, the framework allows urban planners to generate and evaluate many alternative urban configurations, while focusing their attention on the most promising ones. First, addressing the need for integrated urban modeling approaches, a Mixed Integer Linear Programing (MILP) optimization model representing both urban and energy system components was developed. Second, an interface based on parallel coordinates and georeferenced maps is proposed to effectively communicate the optimization results to decision makers, revealing tradeoffs and synergies between competing objectives. Interaction with the parallel coordinates charts further allows planners to steer consecutive optimization runs based on their preferences and experience. The framework is applied to an urban development project in Switzerland to demonstrate its usability and relevance. [ABSTRACT FROM AUTHOR]

Effective planning and control of district energy systems must account for numerous complexities and uncertainties, requiring advanced computational tools. This paper introduces the Ehub Modeling Tool, an open source software package for preliminary design optimization of district energy systems. Using automated code generation techniques that directly translate raw data descriptions of a given district into executable optimization code, the tool simplifies and accelerates the process of developing and executing district energy system optimizations, and visualizing/interpreting results. Example applications of the tool in research and education are described. [ABSTRACT FROM AUTHOR]

The energy demand of cities is highly influenced by urban planning parameters such as urban density and land use. These parameters are mostly determined during early stages of planning. However, the relationships between urban planning parameters and energy systems of districts are rarely incorporated. This paper aims to identify trade-offs between urban density, land use and share of renewable energy sources (RES). For this, we used a Mixed Integer Linear Programming formulation. The model is applied to a real case study of urban planning in Singapore. The results show that when the required share of RES increases from 20% to 70%, the maximum achievable density (floor area ratio) decreases from 32.2 to 2.9 with purely residential land use. While maximizing the self-consumption of electricity produced by PV panels, the resulting land uses are more diverse. These results provide urban planners with constraints from the perspective of energy performance of a district. [ABSTRACT FROM AUTHOR]

Building energy consumption accounts for a large proportion in the total social energy consumption and solar energy plays an important role in the building renewable energy system. A novel hybrid power gas heat pump system integrated with photovoltaic is put forward in this paper. An optimization design based on life cycle assessment for the solar assisted hybrid power gas heat pump system (SHPGHP) is proposed in consideration of three main environmental impact factors: human health, ecosystem quality and resources. The normalized environmental impact for the system during the whole life cycle is chosen as the objective to minimize the life cycle environmental impact. The influence of main independent decision variables is employed including the photovoltaic ratio, transmission ratio and mixing degree. Results show that the optimal photovoltaic ratio is 0.4. The system's environmental impact potential increases with the increase of transmission ratio and decreases with the increase of mixing degree. [ABSTRACT FROM AUTHOR]

Cogeneration and trigeneration systems can contribute to the reduction of primary energy consumption and greenhouse gas emissions in residential and tertiary sectors, by reducing fossil fuels demand and grid losses with respect to conventional systems. The cogeneration systems are characterized by a very high energy efficiency (80 to 90%) as well as a less polluting aspect compared to the conventional energy production. The integration of these systems into the energy network must simultaneously take into account their economic and environmental challenges. Moreover, the electricity distribution service can motivate the users of these systems by buying their residual electrical and thermal products. In this case, the "smart-grid" is the interface that manages the client-network interaction.In this paper, we will find the best cogeneration power that had to be integrated in the Lebanese electricity grid using a new decision-making technique. [ABSTRACT FROM AUTHOR]

The 4th Generation of District Heating (4GDH) is a complex agglomeration of heat providers, distributors, and consume must be automatically, continuously managed and coordinated. It is a complex system of systems; a definition which we al Maier's architecting principles for systems-of-systems as collaborative systems. Wrapped in the idea of system of systems reality that the 4GDH systems' descriptions and specifications are not currently all known. Nonetheless, the transition 4GDH is actual. We propose the use of two frameworks to secure a smooth metamorphosis and assure systems' opei maintenance, and evolution. The two frameworks are the Arrowhead Framework and the OPTi Framework. The first one system integration through Service Oriented Architecture (SOA) and the second one offers the overall system optimizatk respect to all stakeholders. This paper uses the Model Based Systems Engineering (MBSE) tool SysML to model a heating complex's structures and behaviors from the concept level down to the sensors and actuators within a district substation where we apply the SOA technology based on the open Arrowhead Framework. We focus on the Arrow! Framework's core services, i.e. Service Registry, Authorization and Orchestration to clearly describe the interactions between the different service providers and consumers. Going back up from the sensors to the systems, it is clear that SOA is the architecture that will empower the 4GDH. [ABSTRACT FROM AUTHOR]

In this paper, we discuss the design (seismometers’ types and layout) of seismic monitoring network that monitors microseismic events induced by CO 2 injection and natural earthquakes that occurs around the CO 2 injection site. We also elucidate CO 2 injection and occurrences of microseismic events. Firstly, we tested a monitoring network at the Large-scale CO 2 injection site in the U.S.A to obtain lessons learnt. Then, we review case studies of microseismic monitoring at the two CO 2 injection sites. Finally, we discuss and propose the monitoring network that meets our requirements based on findings from the monitoring experiment and case studies. [ABSTRACT FROM AUTHOR]