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Load-shifting is a demand-side management (DSM) strategy to support the efficiency of the electricity grid during hours of peak demand. Load-shifting at the appliance level is an interesting topic to review, since appliance usage is one of the main inputs of the load-profile analysis. More literature reviews on load-shifting at the appliance level are required, as this is a specific issue in the body of literature on load-profile research, though only a limited number of studies are available at this time. It is also essential to focus on appliance usage patterns to improve our understanding of the impacts and characteristics of different appliances. Existing studies on load-shifting have used commonly structured literature reviews; our work addresses the transparency of each stage and substage in the selection of the final list of studies. The findings show that efficiency has been achieved in installed-capacity reductions; costs, including those of emission reductions; and peak consumption reductions. The most frequently used method in load-shifting at the appliance level is to develop load-shifting optimization algorithms. This work contributes by providing a transparent process of drawing up a systematicity literature review as a source of knowledge and grounded theory. It also contributes to specific research on load-shifting at the appliance level by highlighting and discussing the key findings for the reader. In particular, it contributes to improving energy efficiency by describing load-shifting methods at the appliance level and identifying both controllable and uncontrollable appliances. This detailed literature review at the appliance level can make valuable contributions in support of decision- and policymaking by illuminating new dynamic systems specifically in load-shifting and in demand-side management in general for energy efficiency purposes. [ABSTRACT FROM AUTHOR]

In the last decade, pit thermal energy storage (PTES) systems have been used as a large-scale heat storage solution in district heating systems due to their low specific investment cost and high storage efficiency. Despite the existing knowledge on thermal energy storage (TES) technologies, their economic and environmental impacts have not been quantified in the literature, and very few studies have studied PTES as part of the energy system. For this reason, the energy system model Balmorel was used to quantify the impact of TES on the energy system, particularly PTES, and compare it to the tank thermal energy storage (TTES) alternative. The investigation was focused on Denmark and its neighboring countries. It was found that it was only the energy systems using TES that could achieve carbon neutrality by 2050. The main reason was the added flexibility due to the energy storage that allowed the system to have a 35% higher PV capacity, 10% higher wind capacity, and lower levels of curtailment. Additionally, systems with TES had 2.4 €/MWh lower average heat price (with 24% lower peak price). When comparing PTES with TTES, it was found that PTES systems were more advantageous, achieving a 1.5 €/MWh lower average price of heat. • Integration of thermal energy storage in energy systems using the Balmorel model. • Sector coupling was included by modeling the power, heat, gas, and transport sectors. • Thermal storage enabled 10% lower average heat price and 24% lower peak price. • Thermal storage allowed high renewable utilization, limiting dispatchable production. • The impact of pit storages on the energy system was quantified and compared to tanks. [ABSTRACT FROM AUTHOR]