Addressing the growing concerns of climate change necessitates the decarbonisation of energy sectors globally. Heating is the largest energy end-use, accounting for almost half of total energy consumption in most countries. This paper presents an extensive review of previous works on several aspects of heat pumps, including their role in the decarbonisation of the heating sector. In addition, themes related to recent technological advances of heat pumps, as well as, their roles in terms of adding flexibility to renewable-rich systems and carbon abatement are examined. Challenges and barriers facing large-scale deployment of heat pumps are identified. Generally, as the share of renewables in the energy mix increases, heat pumps can play a role in addressing a multitude of problems induced by climate change. The potential of heat pumps to abate emissions, however, is highly dependent on the type of technology, location and electricity mix. Heat pumps can be a source of flexibility in the power system and can upgrade waste heat to provide low-cost heating in district heating networks. They are environment friendly and provide a viable pathway for decarbonising the heating sector. However, economic, regulatory, structural and infrastructural barriers exist, which may hinder heat pump integration rate.

Heat pumps and our low-carbon future: A comprehensive review

With building electric demand becoming increasingly dynamic, and a growing percentage of intermittent renewable power generation from solar photovoltaics and wind turbines, the power grid is facing increasing challenge to manage the real time balance between the supply and demand. With advancements in smart sensing and metering, smart appliances, electric vehicles, and energy storage technologies, demand side management of residential buildings can help the grid to improve stability by optimizing flexible loads. This paper reviews recent studies on residential building demand side management, with a focus on characterization and quantification of energy flexibility covering various types of flexible loads, metrics, methods, and applications. The reviewed studies showed four levels of applications: building level (45%), district or community level (29%), system level (19%), and building sector level (7%). Shifting loads is the dominant flexibility type in 60% of applications, followed by shedding (19%), generation (16%), and modulating (6%). Depending on the technology and application scope, flexible operations have a wide range of performance, with peak power reductions of 1%~65%, energy savings up to 60%, operational cost reduction of 1%~48%, and greenhouse gas emission reductions of up to29%. More than half (51%) of the studies employed control strategies to achieve flexibility; among those 72% used optimal controls, while 28% used rule-based controls. About 58% of the studies used mathematical formulation to quantify energy flexibility. Most studies were based on simulation, while less than 15% of the studies had measurements from experiments or field tests. The review reveals research opportunities to address significant gaps in the existing literature: (1) establishing a common definition and performance metrics for energy flexibility of buildings that are technology and application agnostic, (2) developing an ontology to standardize representation of flexibility resources for interoperability, (3) integrating occupant impacts into the quantification and optimization of energy flexibility, and (4) developing requirements and credits of energy flexibility in building energy codes and standards. Findings from the review can inform future research and development of energy flexible buildings which are essential to a reliable and resilient power grid.

Energy flexibility of residential buildings: A systematic review of characterization and quantification methods and applications

Development of grid-responsive buildings: Opportunities, challenges, capabilities and applications of HVAC systems in non-residential buildings in providing ancillary services by fast demand responses to smart grids

https://backend.orbit.dtu.dk/ws/files/203389023/EcoGrid_2.0_A_large_scale_field_trial_of_a_local_flexibility_market.pdf

Bernard J. Jansen

Papers

Large-scale demonstration of precise demand response provided by residential heat pumps