Electrical thermal storage modeling: a tool to evaluate new opportunities and bids for residential users in a deregulated market (original) (raw)
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A physically based load model of residential electric thermal storage: Application to LM programs
2004
This paper describes and assesses a physically based load model of residential Electric Thermal Storage (ETS) devices, for both static and dynamic loads. This load model is based on an energy balance between the indoor environment, the dwelling constructive parameters, the ETS device, and the internal mass through a discrete state-space equation system. Therefore, detailed information about several physical magnitudes of the whole system are given along the time: ceramic brick temperature, electrical demand, heat fluxes, and indoor temperature. The main application of this load model has been oriented towards the simulation of the ETS device performances, in order to assess load management (LM) programs.
2003
Cool thermal energy storage could become one of the primary solutions to manage peaks, low load factors, electrical power imbalance between daytime and nighttime, and to offer the possibility to reduce electricity costs for the customer. This kind of storage uses off-peak power to provide cooling capacity by extracting heat from a storage medium. Typically these systems use refrigeration equipment to create at night a reservoir of cold liquid or solid material. During the day, the reservoir is tapped to provide cooling capacity. To evaluate the opportunities of storage it is necessary to have accurate load models. The problem of modeling of cool thermal storage is addressed in this work. The proposed load model rely on information about the physical characteristics of an hypothetical load at the residential sector of customers. Some simulation results are shown and some demand responsive alternatives are also proposed in the work.
Simulation Of Domestic Heat Demand Shifting Through Short-term Thermal Storage
Building Simulation Conference Proceedings
Heat demand management through demand shifting will be crucial to enable load balancing in a future electricity grid with large domestic heating loads. Using dynamic models, in IES-VE and TRNSYS, of a 2-bedroom dwelling with typical operational schedules, this research demonstrated that a mixture of active and passive Thermal Energy Storage (TES) within the existing building infrastructure could enable up to 4 hours of heat demand shifting, without significantly affecting the indoor thermal comfort. However, this is strongly dependent on the building having very good thermal mass and performance to increase the TES effectiveness and decrease the thermal comfort degradation. The research provides a good starting point for developing more accurate models, which could enable greater understanding of the techno-economic feasibility of domestic scale TES, and the impact on the efficacy and benefits by variables such as household demography, building size, type and location.
2016
The ever-increasing installation of renewable electricity generation with volatile feed-in comes hand in hand with the challenge of matching generation and demand at all times, and induces the need for energy storage and more flexible demand. Thereby, the large and predictable thermal demand of the building stock could contribute flexibility if electricity powered heating systems are used. This simulation based analysis indicates great potential for load shifting by the activation of structural thermal building mass with electric heating systems. Depending on the utilized system, load shifting of few hours and up to many days is feasible, with just limited impact upon user comfort. Further, storage efficiencies in range of 88 % to 96 % are detected.
Thermal energy storage in residential buildings : a study of the benefits and impacts
2017
Residential space and water heating accounts for around 13% of the greenhouse gas emissions of the UK. Reducing this is essential for meeting the national emission reduction target of 80% by 2050 from the 1990 baseline. One of the strategies adopted for achieving this is focused around large scale shift towards electrical heating. This could lead to unsustainable disparity between the daily peak and off-peak electricity loads, large seasonal variation in electricity demands, and challenges of matching the short and long term supply with the demands. These challenges could impact the security and resilience of UK electricity supply, and needs to be addressed. Rechargeable Thermal Energy Storage (TES) in residential buildings can help overcome these challenges by enabling Heat Demand Shifts (HDS) to off-peak times, reducing the magnitude of the peak loads, and the difference between the peak and off-peak loads. To be effective a wide scale uptake of TES would be needed. For this to ha...
Domestic thermal storage requirements for heat demand flexibility
2017
Future changes to the UK’s energy system, specifically radically increasing the deployment of renewable energy sources at all scales, will require much more flexibility in demand to ensure system stability. Using dynamic building simulation, this paper explores the feasibility of using thermal storage to enable flexibility in heat demand over a range of timescales: diurnal, weekly and seasonal. Time-varying space heating and hot water demand profiles for four common UK housing types were generated, accounting for different occupancy characteristics and various UK climates. These simulated heat demand profiles were used to calculate the necessary storage volumes for four heat storage options: hot water, concrete, high-temperature magnetite blocks and an inorganic phase change material. The results indicated that without first radically improving insulation levels to reduce heat demands, even facilitating diurnal heat storage would require low-temperature, sensible heat storage volume...
Simulation of domestic heat demand management using sensible and latent heat storage
Approximately one third of the energy consumption and CO 2 emission in the United Kingdom is in domestic buildings. Around 80% of the energy is used for space and water heating. Therefore, removing the CO 2 emission from heating is essential for meeting the 2050 target of reducing the overall CO 2 emission by 80% from a 1990 baseline. This could be done by using electricity for heating from renewable sources and low or decarbonised electricity generators. However, this could result in large disparity between the daily and seasonal peak to offpeak electricity demand, imposing tough challenges in the form of matching supply to demand. Thermal Energy Storage (TES) could help overcome these challenges, by de-coupling the temporal link between demand and supply, enabling demand shifting in time. To do this effectively, large uptake of the TES will be necessary. This research provides an insight into the heat demand shifting capability of domestic scale TES and the benefits it could deliver. This is done by dynamic modelling of a 1990's building with typical occupancy scenarios. The model simulates active and passive heat storage by using models of a hot water storage tank and Phase Change Material (PCM) based ceiling insulation. The results show that water tank size typically installed in homes and PCM wall layers can shift the heat demand by 3 hours whilst maintaining adequate level of thermal comfort. This research provides a good starting point for gaining greater understanding of the techno-economic benefits of TES, and how it could make domestic buildings more sustainable.
Thermal energy storage (TES) is an increasingly popular tool to level out the daily electrical demand and add stability to the electrical grid as more intermittent renewable energy sources are installed. TES systems can locally decouple high thermal loads from the operation of a heat pump or reduce the electrical energy demand of the heat pump by providing a more favorable temperature gradient. In addition, many policy makers and utility providers have introduced time-of-use (TOU) rate schedules for residential customers to better reflect the price of electricity generation and demand for specific times. TOU rate schedules price grid-provided electricity differently throughout the day depending on the region's climate, time of year, and electrical production portfolio. Large differences between on-peak and off-peak electrical prices may create an economic advantage for a residential customer to install a TES system. In this work, the economic and energy savings are calculated for a modeled 223 square foot residential building with water/ice-based TES using a TOU rate structure. The weather data is from Fresno County, CA, ASHRAE climate zone 3B, and a representative residential TOU utility rate structure from a utility provider in California was used. The simulation was carried out for cooling only during a week of extreme hot summer daytime temperature and the results showed that total energy consumption could be reduced by 14.5% with an 87.5% reduction in on-peak energy usage when the TES is installed. The cost of operating this system for space cooling was reduced by nearly 20% using the sample utility rate plan.
Thermal Energy Storage for Building Load Management: Application to Electrically Heated Floor
Applied Sciences, 2016
In cold climates, electrical power demand for space conditioning becomes a critical issue for utility companies during certain periods of the day. Shifting a portion or all of it to off-peak periods can help reduce peak demand and reduce stress on the electrical grid. Sensible thermal energy storage (TES) systems, and particularly electrically heated floors (EHF), can store thermal energy in buildings during the off-peak periods and release it during the peak periods while maintaining occupants' thermal comfort. However, choosing the type of storage system and/or its configuration may be difficult. In this paper, the performance of an EHF for load management is studied. First, a methodology is developed to integrate EHF in TRNSYS program in order to investigate the impact of floor assembly on the EHF performance. Then, the thermal comfort (TC) of the night-running EHF is studied. Finally, indicators are defined, allowing the comparison of different EHF. Results show that an EHF is able to shift 84% of building loads to the night while maintaining acceptable TC in cold climate. Moreover, this system is able to provide savings for the customer and supplier if there is a significant difference between off-peak and peak period electricity prices.