Household Thermal Energy Storage in the Context of Smart Grids Viability and Potential Impact of Small Residential Consumers in Demand-Side Load Balancing With The Use of Phase-Change Materials Luís S. Rodrigues, Jorge A. F. Ferreira, Vítor A. F. Costa Centre for Mechanical Technology and Automation, Department of Mechanical Engineering, University of Aveiro Aveiro, Portugal lrodrigues@ua.pt Abstract — A smart grid can be defined as an electrical network equipped with distributed and interconnected automation technologies, in order to: (i) increase the efficiency, (ii) minimize waste and emissions, (iii) make the most of the installed infrastructure, and (iv) maximize the utilization of available renewable energy sources. It is a holistic concept that involves all the energy chain, from producers to consumers [1–3]. The evolution towards smarter electrical grids is inevitable in the current global conjuncture of circumstances, among others: (i) the capacity limitations, high losses, and lack of reliability, caused by an ageing transport and distribution infrastructure; (ii) the increasing supply fluctuations induced by the growing penetration of renewable sources (mainly wind and solar); (iii) the increasing global demand from developing countries, etc... The main objective of grid management is to match supply and demand. Smart grid technologies help to achieve this goal by allowing control from the demand side, impossible to achieve with conventional/classical control models (which rely exclusively on supply modulation). For this purpose, smart grids incorporate the more recent advances in information and communication technologies (ICT) to gather and consolidate the relevant information from all the intervenient players in the energy chain. Demand-side load management (DSLM) has been, so far, exclusively assured by big consumers (e.g., industry, big office and/or commercial buildings, etc.). However, the participation of small residential consumers may become viable thanks to the dissemination of internet connectivity, the growing park of installed smart meters with telematic capabilities [4], the emergence of Internet of Things (IoT) technologies, the increasing number of electrical vehicles (EVs), and the profusion of microprocessor-controlled domestic appliances. Shifting the load from peak to off-peak periods depends primarily on the capacity of delaying/postponing consumption. This capability is significantly augmented by the possibility of local energy storage. Unfortunately, the large-scale use of electrochemical batteries for this purpose is hindered by their economic and environmental costs. By contrast, the use of phasechange materials (PCMs) for thermal energy storage (TES) is by far cheaper and environmental benign [5]. TES has, easily, the lowest specific cost (i.e., $/kWh) of any type of battery [6]. The use of PCMs can even provide roughly twice the specific capacity (i.e., Wh/kg) of the most common and less expensive lead-acid battery [7]. Arguably, the major limitation of TES is that the stored energy cannot be, realistically, converted back to electricity. This limits its scope to thermal applications – i.e., water heaters, refrigerators, freezers, and space heating, ventilation, and air conditioning (HVAC). However, this does not diminish its importance, since, in most homes, the highest energy consumption
results from water heating – which frequently coincides with peak hours – and, in many climates, from HVAC. Hence, together with refrigerators and freezers, domestic TES with PCMs will be, inescapably, part of a smarter energy management paradigm, towards a greener World. Keywords — Smart Grids; Load Shifting; Demand-Side Load Management (DSLM); Thermal Energy Storage (TES); PhaseChange Materials (PCMs). ACKNOWLEGEMENT
This work was supported by the FCT – Fundação para a Ciência e Tecnologia, the Portuguese national funding agency for science, research, and technology, via the grant number 2020.06120.BD. TOPIC 2) Technologies for the Wellbeing b. Innovative Technologies for Smart Cities. REFERENCES [1] I. Colak, “Introduction to smart grid”, 2016 International Smart Grid Workshop and Certificate Program, IEEE, 2016. [2] European Technology Platform SmartGrids, "Vision and Strategy for Europe’s Electricity Networks of the Future", Office for Official Publications of the European Communities, 2006. [3] EPRI, “Smart Grid Resource Center,” Electric Power Research Institute. [Online]. Available: https://smartgrid.epri.com/. [4] J. Zheng, D. W. Gao, and L. Lin, “Smart meters in smart grid: An overview,” in IEEE Green Technologies Conference, 2013. [5] A. Sharma, V. V. Tyagi, C. R. Chen, and D. Buddhi, “Review on thermal energy storage with phase change materials and applications,” Renew. Sustain. Energy Rev., vol. 13, no. 2, pp. 318–345, 2009. [6] I. Sarbu, C. Sebarchievici, "A Comprehensive Review of Thermal Energy Storage", Sustainability, vol.. 10, no. 2, p. 191, 2018. [7] Harald Mehling Luisa F. Cabeza, “Heat and cold storage with PCM”, 2013.
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