Levelized cost quantification of energy flexibility in high-density cities and evaluation of demand-side technologies for providing grid services

Today, energy flexibility technologies at demand side have been increasingly used to provide energy flexibility services to power grids for enhancing their power balance and operation reliability. Various energy flexibility metrics have been proposed to assess the energy flexibility technologies in different applications and concerning different aspects, e.g., power and energy. However, an effective cost evaluation method is still lacking, particularly for applications at design and retrofit stages from the life cycle perspective, and for convenient comparison of different technologies. This study, therefore, proposes a novel cost evaluation index, namely levelized cost of energy flexibility. It is defined as the total cost per unit of energy flexibility capacity during the lifetime associated to a given technology. This index considers various operational constraints and cost items, especially from occupant-related perspectives. By using levelized cost of energy flexibility, the economic viabilities of six commonly used demand-side energy flexibility technologies are evaluated and compared for three typical grid services. The impacts of cost evolution and service activation requirements are also analyzed. Results show that the Heating, Ventilation, and Air Conditioning system is the most cost-effective technology for all the grid services concerned. The significant cost reduction of vehicle-to-grid technology would make electric vehicles become the most cost-effective technology. This index could facilitate investors to prioritize the energy flexibility enhancement measures in applications.