Tariff-based load shifting for domestic cascade heat pump with enhanced system energy efficiency and reduced wind power curtailment

Research output: Contribution to journalArticle

Abstract

Cascade air-to-water heat pumps may have good potential for retrofitting UK domestic buildings because they can directly replace existing fossil-fuel boilers without the requirement of considerable modifications to heat distribution systems. A widespread uptake of these heat pumps, however, would pose challenges to the grid. Furthermore, wind power generation has increased in the UK to achieve the target of decreasing CO2 emissions by 2050, but there are high levels of wind curtailment due to the mismatch between electricity supply and demand. In this paper, a load shifting study for cascade heat pumps coupled with thermal energy storage addressing these issues is presented. The main objective is to find the best tariff-based schedule load shifting for cascade heat pumps, which can help to avoid peak demand periods while obtaining enhanced system energy efficiency with minimised running costs and reduced wind energy curtailment. How the retrofit performance of the cascade heat pumps with load shifting is further investigated. TRNSYS was used to simulate the system performance validated against experimental results. Northern Ireland (UK) was selected as the evaluated scenario. Simulation results showed that the tank temperature set point of 75 °C and the storage size of 1.2 m3 could wholly shift the cascade heat pumps’ operation to off-peak periods. The best times to start the cascade heat pumps to charge the storage were at 3 am and 2 pm for the morning and afternoon heating demands, respectively. Compared to oil boilers, the cascade heat pumps with load shifting could obtain lower running costs (16–34%) and carbon emissions (20–37%).

LanguageEnglish
Article number113976
JournalApplied Energy
Volume257
Early online date21 Oct 2019
DOIs
Publication statusPublished - 1 Jan 2020

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wind power
energy efficiency
Wind power
Energy efficiency
Pumps
Boilers
electricity supply
Hot Temperature
tariff
heat pump
carbon emission
Cascades (fluid mechanics)
Retrofitting
power generation
cost
distribution system
fossil fuel
Thermal energy
Fossil fuels
Energy storage

Keywords

  • Cascade air-to-water heat pump
  • Enhanced system energy efficiency
  • Reduced wind energy curtailment
  • Tariff-based load shifting
  • Thermal energy storage
  • TRNSYS simulation

Cite this

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title = "Tariff-based load shifting for domestic cascade heat pump with enhanced system energy efficiency and reduced wind power curtailment",
abstract = "Cascade air-to-water heat pumps may have good potential for retrofitting UK domestic buildings because they can directly replace existing fossil-fuel boilers without the requirement of considerable modifications to heat distribution systems. A widespread uptake of these heat pumps, however, would pose challenges to the grid. Furthermore, wind power generation has increased in the UK to achieve the target of decreasing CO2 emissions by 2050, but there are high levels of wind curtailment due to the mismatch between electricity supply and demand. In this paper, a load shifting study for cascade heat pumps coupled with thermal energy storage addressing these issues is presented. The main objective is to find the best tariff-based schedule load shifting for cascade heat pumps, which can help to avoid peak demand periods while obtaining enhanced system energy efficiency with minimised running costs and reduced wind energy curtailment. How the retrofit performance of the cascade heat pumps with load shifting is further investigated. TRNSYS was used to simulate the system performance validated against experimental results. Northern Ireland (UK) was selected as the evaluated scenario. Simulation results showed that the tank temperature set point of 75 °C and the storage size of 1.2 m3 could wholly shift the cascade heat pumps’ operation to off-peak periods. The best times to start the cascade heat pumps to charge the storage were at 3 am and 2 pm for the morning and afternoon heating demands, respectively. Compared to oil boilers, the cascade heat pumps with load shifting could obtain lower running costs (16–34{\%}) and carbon emissions (20–37{\%}).",
keywords = "Cascade air-to-water heat pump, Enhanced system energy efficiency, Reduced wind energy curtailment, Tariff-based load shifting, Thermal energy storage, TRNSYS simulation",
author = "Le, {Khoa Xuan} and Huang, {Ming Jun} and Christopher Wilson and Shah, {Nikhilkumar N.} and Hewitt, {Neil J.}",
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AU - Le, Khoa Xuan

AU - Huang, Ming Jun

AU - Wilson, Christopher

AU - Shah, Nikhilkumar N.

AU - Hewitt, Neil J.

PY - 2020/1/1

Y1 - 2020/1/1

N2 - Cascade air-to-water heat pumps may have good potential for retrofitting UK domestic buildings because they can directly replace existing fossil-fuel boilers without the requirement of considerable modifications to heat distribution systems. A widespread uptake of these heat pumps, however, would pose challenges to the grid. Furthermore, wind power generation has increased in the UK to achieve the target of decreasing CO2 emissions by 2050, but there are high levels of wind curtailment due to the mismatch between electricity supply and demand. In this paper, a load shifting study for cascade heat pumps coupled with thermal energy storage addressing these issues is presented. The main objective is to find the best tariff-based schedule load shifting for cascade heat pumps, which can help to avoid peak demand periods while obtaining enhanced system energy efficiency with minimised running costs and reduced wind energy curtailment. How the retrofit performance of the cascade heat pumps with load shifting is further investigated. TRNSYS was used to simulate the system performance validated against experimental results. Northern Ireland (UK) was selected as the evaluated scenario. Simulation results showed that the tank temperature set point of 75 °C and the storage size of 1.2 m3 could wholly shift the cascade heat pumps’ operation to off-peak periods. The best times to start the cascade heat pumps to charge the storage were at 3 am and 2 pm for the morning and afternoon heating demands, respectively. Compared to oil boilers, the cascade heat pumps with load shifting could obtain lower running costs (16–34%) and carbon emissions (20–37%).

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