Electric Peak Shaving Research Articles

Low and Ultra-Low Temperature District Heating Equipped by Heat Pumps—An Analysis of the Best Operative Conditions for a Swiss Case Study

The manuscript analyses the management of low and ultra-low-temperature district heating systems (DHS) coupled with centralised and decentralised heat pumps. Operative conditions are defined in order to satisfy the heating needs without overloading the electric grid. The results are achieved by dynamic simulations, based on a real DHS located in southern Switzerland. At the building level, the heating needs are estimated considering real data and simultaneous energy simulations. Two DHS configurations, alternatives to the existing one, are simulated and suitable parameters for the management of the DHS are selected. The global performance of the two DHS is evaluated by KPIs also including the flexibility and the impact on the electric peak due to heat pumps. The achieved results are discussed providing suggestions for the stakeholders involved in DHS management for an optimal matching of the electric grid and thermal networks towards a reduction of the peak power. The rule-based control strategies defined allow the expected electric peak shaving and load levelling, conversely, the yearly energy consumptions are lightly increased and have to be further investigated. The outcomes demonstrate a global better performance of the ultra-low temperature DHS in terms of response to the applied control strategies and of energy savings.

Multi-criteria thermodynamic analysis of pumped-thermal electricity storage with thermal integration and application in electric peak shaving of coal-fired power plant

The development of efficient energy storage systems to compensate for the intermittency of renewable energy sources has become a key step in the widespread use of renewable energies. Pumped-thermal electricity storage, which has drawn wide attention in recent years, has the advantages of being unlimited by geographical conditions, high energy storage density and low costs. In this paper, a heat pump – organic Rankine cycle (HP-ORC) based storage system integrated with waste heat has been developed and analyzed to find the suitable operation parameters for the existing coal-fired power plant. The systematic exergy loss is calculated and the trade-off optimization between roundtrip efficiency and exergy efficiency is also performed to find the Pareto Front. It is concluded that the exergy losses of the sensible and latent heat stores account for 35% and 31% of the total exergy loss, respectively; when the heat source temperature is 110 °C, the roundtrip efficiency can reach 1.26. Furthermore, the two-objective optimization results show that when heat source temperature and maximum storage pressure are designed to be 87.1 °C and 3.6 MPa, roundtrip efficiency and exergy efficiency can reach 0.97 and 0.64, respectively. Under the optimization results, the maximum peak shaving capacity of the coal-fired power plant integrating Carnot battery can reach 94.4%.

Integrated Design and Control of Renewable Energy Sources for Energy Management

Growing population and expanding industry set off the demand for electrical energy and issues, such as the problem of peak load demand, emerge. To balance the supply and load demand problem, the energy management system has the vital role of Electric Peak shaving with the integration of microgrid into the utility grid. The combination of demand-side management with storable energy sources helps us resolve the matters concerned with the peak load demand. However, in a microgrid, whenever the distributed energy sources are interconnected, the DC bus link voltage will vary due to the inherent behavior of each source as they mainly depend on geographical conditions. This work proposes voltage droop control strategy to keep the DC bus link voltage at a constant value. Also, it gives an overlook of the present power sector scenario of India and a reassessment of the demand side management system and how it is utilized in electrical peak shaving.

Energy, Environmental and Economic Performance of an Urban Community Hybrid Distributed Energy System

Energy systems face great challenges from both the supply and demand sides. Strong efforts have been devoted to investigate technological solutions aiming at overcoming the problems of fossil fuel depletion and the environmental issues due to the carbon emissions. Hybrid (activated by both renewables and fossil fuels) distributed energy systems can be considered a very effective and promising technology to replace traditional centralized energy systems. As a most peculiar characteristic, they reduce the use of fossil sources and transmission and distribution losses along the main power grid and contribute to electric peak shaving and partial-loads losses reduction. As a direct consequence, the transition from centralized towards hybrid decentralized energy systems leads to a new role for citizens, shifting from a passive energy consumer to active prosumers able to produce energy and distribute energy. Such a complex system needs to be carefully modelled to account for the energy interactions with prosumers, local microgrids and main grids. Thus, the aim of this paper is to investigate the performance of a hybrid distributed energy system serving an urban community and modelled within the framework of agent-based theory. The model is of general validity and estimates (i) the layout of the links along which electricity is distributed among agents in the local microgrid, (ii) electricity exchanged among agents and (iii) electricity exported to the main power grid or imported from it. A scenario analysis has been conducted at varying the distance of connection among prosumers, the installed capacity in the area and the usage of links. The distributed energy system has been compared to a centralized energy system in which the electricity requests of the urban community are satisfied by taking electricity from the main grid. The comparison analysis is carried out from an energy, environmental and economic point of view by evaluating the primary energy saving, avoided carbon dioxide emissions and the simple payback period indices.

An Efficient Summer Operation Scheme for a Thermal Power Plant Air Cooling System based on Electric Peak Shaving

We proposed a novel efficient operation scheme for a thermal power plant's air-cooling system based on peak shaving, in order to cope with high ambient temperature in summer. We introduced an absorption-generation equipment with water/lithium working pairs into the air cooled condenser (ACC) to reconstruct the traditional thermal power plant, and established a dynamic thermodynamic model adopting Ebsilon code. We studied the thermodynamic performance variation of the reconstructed thermal power plant throughout a 24-hour cycle and found that the fluctuation ratio of the turbine back pressure decreased to 6% from 78%, which is beneficial for the stable and safe operation of the electric power system. The thermal performance improvement benefited from the exploitation of the heat transfer potential of ACC, which realized via cold duty schedule throughout the day, under different ambient temperature conditions. In this system, the generated power was higher at relatively high ambient temperature than that at relatively low ambient temperature, which solved the electricity demand-supply imbalance problem under high ambient temperature. Finally, the same optimization effects for power thermal plants with an indirect air-cooling system were obtained using the same operation scheme.

Multi-Objective Particle Swarm Optimization (MOPSO) for a Distributed Energy System Integrated with Energy Storage

Distributed energy systems are considered as a promising technology for sustainable development and have become a popular research topic in the areas of building energy systems. This work presents a case study of optimizing an integrated distributed energy system consisting of combined heat and power (CHP), photovoltaics (PV), and electric and/or thermal energy storage for a hospital and large hotel buildings located in Texas and California. First, simulation models for all subsystems, which are developed individually, are integrated together according to a control strategy designed to satisfy both the electric and thermal energy requirements of a building. Subsequently, a multi-objective particle swarm optimization (MOPSO) is employed to obtain an optimal design of each subsystem. The objectives of the optimization are to minimize the simple payback period (PBP) and maximize the reduction of carbon dioxide emissions (RCDE). Finally, the energy performance for the selected building types and locations are analyzed after the optimization. Results indicate that the proposed optimization method could be applied to determine an optimal design of distributed energy systems, which reaches a trade-off between the economic and environmental performance for different buildings. With the presented distributed energy system, a peak shaving in electricity of about 300 kW and a reduction in boiler fuel consumption of 610 kW could be attained for the hospital building located in California for a winter day. For the summer and transition seasons, electricity peak shaving of 800 kW and 600 kW could be achieved, respectively.

A Novel and Economical Rde-Based Approach for Investigating the Oxidation Evolution Reaction Activity of IrO2-Based Catalyst Coated Membranes

Polymer electrolyte membrane water electrolyzers (PEMWE) are clean and scalable energy conversion devices that can assist with electricity peak shaving and storage by converting electricity into hydrogen as an energy carrier 1. However, performance, durability and cost of these systems still require further improvements before they can be widely adopted. In particular, it is desired to have more efficient and lower cost oxygen evolution reaction (OER) electrocatalysts for the anode, because of the high cost and potential losses that are associated with this electrode2. Screening of catalyst materials, as well other expensive cell components (e.g., Ti current collectors and Ti endplates), is in general a slow and rather expensive process due to the inherent high costs of test cell equipment, and the difficulties associated with cell assembly3. Alternative methods based on commonly available and small laboratory-scale electrochemical test equipment, such as the rotating disk electrode, can facilitate the screening process. We present a novel and economical method for testing electrolysis CCMs and potential current collectors in a rotating electrode (RDE) setup. This method eliminates the difficulties which are often associated with ink preparation and sample drying which are encountered in thin film RDE (TF-RDE) testing. Very recently, we have successfully demonstrated this approach for evaluation of oxygen reduction reaction (ORR) electrocatalysts used in PEMFC applications4. The modified-RDE (MRDE) presented here allows a user to obtain very high current densities (~ 2 A cm-2) which is similar to those normally obtained with PEMWE hardware and test stations (Figure 1). Polarization measurements, kinetic analysis and accelerated degradation tests (ADT) have been performed with a commercial IrO2-based CCM using the MRDE, and are compared with those of PEMWE hardware results. The approach, methodology and the results will be presented at the meeting.

蓄電・蓄熱を考慮したスマート化実証 （その3）PTR方式でのデマンドレスポンスに関するピークカット効果と光熱費削減効果の検証

蓄電・蓄熱を考慮したスマート化実証 （その3）PTR方式でのデマンドレスポンスに関するピークカット効果と光熱費削減効果の検証

Benefits of demand-side response in combined gas and electricity networks

Active demand side response (DSR) will provide a significant opportunity to enhance the power system flexibility in the Great Britain (GB). Although electricity peak shaving has a clear reduction on required investments in the power system, the benefits on the gas supply network have not been examined. Using a Combined Gas and Electricity Networks expansion model (CGEN+), the impact of DSR on the electricity and gas supply systems in GB was investigated for the time horizon from 2010 to 2050s. The results showed a significant reduction in the capacity of new gas-fired power plants, caused by electricity peak shaving. The reduction of gas-fired power plants achieved through DSR consequently reduced the requirements for gas import capacity up to 90 million cubic meter per day by 2050. The cost savings resulted from the deployment of DSR over a 50-year time horizon from 2010 was estimated to be around £60 billion for the GB power system. Although, the cost saving achieved in the gas network was not significant, it was shown that the DSR will have a crucial role to play in the improvement of security of gas supply.

Design of a PCM to air heat exchanger using dimensionless analysis: Application to electricity peak shaving in buildings

In this paper, a phase change material (PCM) to air rectangular heat exchanger is studied for an objective of electricity peak shaving. First, a set of dimensionless numbers are derived from physical equations to understand the storage device behaviour: 1/BiFo, Bi/St and Ste. Second, these numbers are used to select the PCM based on the thermophysical properties of the material. Finally, the storage device is pre-designed by a proper analysis of the remaining dimensionless numbers. With the methodology developed in this paper, it is possible to efficiently design solutions from the specification requirements of the storage system.

Battery storage system for residential electricity peak demand shaving

This article presents the modeling, simulation, and sizing results of battery energy storage systems for residential electricity peak shaving. Realistic 5min time-step electricity profiles were input to an energy storage model with the objective of reducing the peak electricity demand seen by the electricity grid. The model simulates and provides performance results of a range of battery and inverter sizes specific to a variety of residential houses. The results suggest typical system sizes range from 5kWh/2.6kW for low electricity intensity homes to 22kWh/5.2kW for electricity intense homes with electric space heating. Based on the resulting storage system cycling profile and data provided by other researchers, the battery life is estimated to be in the range of 10–20 years for this application.

Rational Use of Energy in the Industrial Sector Served by The Medellín Public Utility, Colombia

ABSTRACT This article describes the methodology and results of the Rational Use of Energy Program carried out in 29 industries in Medellin, Colombia. Higher energy savings than the ones expected were found in the companies audited. Potential savings are around 24 percent in thermal energy, 11.4 percent in electricity, and 29 percent in electric peak shaving. Recommended actions included adequate operation of processes and equipment, satisfactory maintenance practices, and the implementation of new technologies. An important result is that about 50 percent of all savings could be carried out without investment. A strategic plan has been developed to verify the implementation of the recommendations and the achievement of the improvements. The program was carried out by the Energy and Thermodynamics Group of the Universidad Pontificia Bolivariana, a research center similar in its functions and structure to the Industrial Assessment Centers in the U.S.A. The program was sponsored by Empresas Publicas de Medel...