Decarbonisation Of Heat Research Articles

Decarbonization of space heating in the Italian Alpine context: Thermo-economic assessment of the levelized energy cost of heating under alternative renewable scenarios

Decarbonization of space heating in the Italian Alpine context: Thermo-economic assessment of the levelized energy cost of heating under alternative renewable scenarios

Thermodynamic simulation of a water-injected twin-screw steam compressor

Abstract Decarbonisation of industrial heating and process steam generation is crucial for the mitigation of advancing climate change. High-temperature heat pumps can meet these demands while effectively integrating with renewable energy sources, outperforming traditional heating and boiling systems, especially when operating with natural refrigerants. Since compressor efficiency is critical for the effectiveness of heat pump systems, particular care is required in compressor design and specification. Detailed thermodynamic simulations of the compressor system are indispensable in this process. The compression of fluids with a negative saturation vapour curve leads to challenging temperature increases during compression, with substantial superheating of the working fluid. In this context, a promising approach is the injection of liquid working fluid into the compressing chambers for internal cooling. This introduces new complexity to compressor simulations for heat-pump applications. In this work, a novel two-phase approach for multi-chamber model simulations of positive displacement compressors is presented. Initially, a quasi-isentropic reference process for vapour compression with internal liquid injection is introduced and efficiency ratings are derived. Furthermore, the simulation process is described in detail, and comprehensive thermodynamic simulations of a water-injected twin-screw steam compressor are carried out.

Nurturing a New Industry Rooted in Geoscience: Stakeholder Insights on Minewater Thermal in Scotland

Heat decarbonisation is crucial for climate action and the transition to a sustainable society. Abandoned, flooded mines can be used to provide low-carbon heating and cooling for buildings or as thermal energy storage for district heating networks (“minewater thermal resources”). Due to the capital-intensive nature of the infrastructure required for minewater thermal, its use should be considered early in project development. Developers therefore need to be aware of the full range of low-carbon heating solutions to implement the most sustainable solutions. Through interviews with twelve key stakeholders in Scotland, this study aims to determine the level of awareness of this technology among stakeholders who require heat for their developments, and stakeholders who would be involved in the development or construction of such schemes. Our findings have implications for how the geoscience community could aid the development of a minewater thermal industry. Stakeholders perceived a range of advantages of minewater, including use as thermal storage and the co-location of minewater resources with heat demand. Perceived disadvantages included the high capital cost and pre-construction risks associated with determining the feasibility minewater resources. Building trust and confidence in minewater thermal technology was identified as a key factor for success. Issues relevant for low-carbon heat in general were also raised including, high retail cost of electricity, skills gaps and labour shortages. Geoscientists can identify prospective minewater resources and assess the risks associated with exploration, development and operation of that resource, contributing to building confidence and reducing up-front capital costs. Given the multidisciplinary nature of the heat decarbonisation challenge, geoscientists must be able to communicate clearly and transparently about the science underpinning resource estimates and risk mitigation measures. For minewater thermal projects to succeed, geoscientists must be equipped with skills, knowledge and understanding to embrace these wider roles in nurturing this nascent industry.

Quantifying vertical borehole heat exchanger sustainability from a geothermal resource perspective in the UK

Low-temperature geothermal energy is viewed as a renewable resource that could contribute to the decarbonization of residential heating in the UK. Here, we constrain the geothermal potential of the shallow subsurface to provide the heating requirements of a typical single-family house via a vertical borehole heat exchanger (BHE), to provide a preliminary framework for the heat resource licensing of such systems. Through analytical and numerical models, we calculate the heat balance for a typical house with a garden located in a Carboniferous sedimentary basin, which represents a large proportion of the UK land mass and the regions where energy poverty is more common. Neglecting the heat recharge via groundwater flow, our results indicate that geothermal, solar heat flux and radiogenic heat production can only replenish up to 5% of the heat extracted annually by a 100 m-long BHE in heat extraction-only mode. The lack of natural recharge causes the continuous expansion of the thermal footprint at an average rate of 18 m 2 a −1 over 30 years, considering a ground thermal conductivity of 2.2 W m −1 °C −1 , with the area cooled by 1°C extending beyond the current minimum BHE spacing guidelines of 6 m. In Scotland, reinjecting c . 35% of the yearly heat requirements, which could be accomplished through borehole thermal energy storage, is shown to safeguard against resource over-exploitation and interference risks between neighbouring users in the majority of the high-demand areas. In view of a large deployment of BHEs, it is crucial to incorporate such reinjection strategies into a regulatory framework to ensure a resilient and sustainable utilization of shallow geothermal resources.

Multi-software based dynamic modelling of a water-to-water heat pump interacting with an aquifer thermal energy storage system

Aquifer thermal energy storage systems may support the decarbonization of heating and cooling energy needs of urban areas, not only in heating-dominated countries but also in Southern Europe. In this framework, this work investigates the adoption of an electric-driven heat pump interacting with an aquifer and activating a small-scale district heating and cooling network serving a mixed-use district of eight residential and office buildings in Rome (Italy). The dynamic behaviour of aquifer was replicated using the GeoSIAM software. Energy conversion systems and users’ thermal and cooling loads were simulated in TRNSYS 18. The dynamic models were integrated using an iterative approach based on conditions regarding plant operation and injection temperature in wells. The proposed solution was compared from the energy and environmental perspective with a traditional system without aquifer. In addition, the balance between heating and cooling mode operation was assessed. The results obtained encourage the adoption of aquifer thermal energy storage systems in Central Italy. Indeed, the primary energy saving, and the carbon dioxide emissions avoided are equal to 18 %, whereas the imbalance between cooling and heating loads is limited to −5.2 %.

Optimisation of Integrated Heat Pump and Thermal Energy Storage Systems in Active Buildings for Community Heat Decarbonisation

The electrification of residential heating systems, crucial for achieving net-zero emissions, poses significant challenges for low-voltage distribution networks. This study develops a simulation model to explore the integration of heat pumps within active building systems for community heating decarbonisation. The model optimises heat pump operations in conjunction with thermal energy storage units to reduce peak demand on low-voltage networks by using real-time measured electricity demand data and modelled heat demand data for 76 houses. The study employs an algorithm that adjusts thermal storage charging and discharging cycles to align with off-peak periods. Three scenarios were simulated: a baseline with unoptimised heat pumps, a fixed threshold model, and an active building model with daily optimised thresholds. The results demonstrate that the active building model achieves a 21% reduction in peak demand on the low-voltage substation compared to the baseline scenario; it also reduces the total electrical energy consumption by 12% and carbon emissions by 17%. The fixed threshold scenario shows a 16% improvement in peak demand reduction, but it also shows an increase in energy consumption and emissions. These findings highlight the potential of active buildings to enhance the efficiency and sustainability of residential energy systems, marking a significant step toward decarbonising residential heating while maintaining grid stability.

A comparative analysis of policies and strategies supporting district heating expansion and decarbonisation in Denmark, Sweden, the Netherlands and the United Kingdom – Lessons for slow adopters of district heating

This paper undertakes a comprehensive comparative analysis of policy challenges and opportunities for the deployment of low-carbon DH. Through literature review and complementary qualitative analysis of interviews with key institutional stakeholders in the heating sector (n= 20) of Denmark, Sweden, the Netherlands, and the UK, the paper draws some important lessons on preconditions for successful roll-out of DH. We find that more governments must create appropriate conditions, provide more support, and speed up actions to enhance the role of DH in heat decarbonisation, to educate, encourage the adoption, and involve citizens, politicians, and other key stakeholders in the heat transition to DH. Amid the current energy price crisis, slow adopters must act fast to develop low-carbon DH networks to ensure the supply of secure, sustainable, and affordable heating sources. They would have to create appropriate conditions to reduce fossil-fuel path dependence, lock-out fossil fuel-based infrastructure and lock-in the diffusion and adoption of low-carbon DH.

Data-driven robust optimisation of hydrogen infrastructure planning under demand uncertainty using a hybrid decomposition method

In the race towards “Net-zero”, hydrogen has emerged as one of the key alternatives to carbon-based fossil fuels for a sustainable decarbonisation. This work studies the spatially explicit multi-period hydrogen infrastructure planning under demand uncertainty that contributes to the heat decarbonisation in Great Britain. Demand uncertainty surrounding future hydrogen supply chains poses challenges to cost optimisation and system security, so uncertainty-resilient policies are required to ensure robust operations. In this work, we employ data-driven robust optimisation to develop a framework for uncertainty-aware representative days explicitly characterised by polyhedral uncertainty sets. The proposed framework is applied on a multi-period mixed-integer linear model with dual temporal resolution which aims to determine the optimal yearly investment decisions and hourly operational decisions for the hydrogen infrastructure planning under demand uncertainty. To efficiently solve the large-scale two-stage adaptive robust optimisation problem, a hybrid decomposition algorithm is developed based on a two-step hierarchical procedure and the column-and-constraint generation method, which can significantly reduce the computational complexity. The optimisation results highlight how uncertainty can result in the total cost increase, and verify the advantages on controlling solution conservatism in the adaptive robust optimisation compared to the static robust optimisation.

A multi-valve flexible heat pump system with latent thermal energy storage for defrosting operation

There has been growing interest in using air-source heat pumps as an alternative to potentially replace fossil-fuel-based heating technologies for heat decarbonisation. One of the technical issues that hinders the wide uptake of air source heat pumps is the decreasing energy efficiency caused by frequent defrosting operations under low ambient temperatures. Currently, the most widely used defrosting method is the reverse-cycle defrosting but this operation would have to interrupt the heating supply during the defrosting process. The authors recently proposed, developed, and demonstrated a flexible heat pump concept that recovers partial of the subcooled heat from the hot refrigerant exiting the condenser and stores it in an integrated thermal storage. The stored heat could later be used to save compressor power and defrosting applications. In this paper, we proposed an innovative method by using a multi-valve design of the flexible heat pump to achieve the defrosting function. In this new concept, defrosting is achieved by condensing the refrigerant inside the evaporator and simultaneously ensuring uninterrupted heating during the heat storage discharge process. A model has been established to study the heat pump performance during a full charge/discharge cycle of the storage. Results indicated that with R410a, R134a and R1234yf, the proposed flexible heat pump has the potential to respectively save up to 11.2%, 10.8% and 13.2% of compressor power, in comparison with a heat pump using the conventional reverse cycle defrosting method. Concurrently with the defrosting operation, the same heating capacity is ensured without interruption by the flexible heat pump.

Comparative analysis of solar-powered heat pump systems for decarbonization of process heating and cooling applications: Case of milk pasteurization

The dairy processing industry is heavily dependent on fossil fuels for heating applications at different temperature levels and contributes to greenhouse gas (GHG) emissions. Besides, process cooling, product refrigeration, and storage are mainly reliant on vapour compression refrigeration technologies. This study investigates the performance of solar photovoltaic (PV) and solar thermal (ST) powered heat pumping technologies for simultaneous heating (at 75 °C) and cooling (at 2 °C) applications in a selected typical thermal process in a dairy processing plant (milk pasteurization). An ammonia/water absorption heat pump (AHP) and a two-stage R717 vapour compression heat pump with an open intercooler (VCHP) are used in the present study. The VCHP and AHP are powered by market-available solar PV modules and ST collector technologies. The electrical COP and exergy COP of the VCHP were about 4.710 and 0.535, respectively. The AHP operates at a thermal COP and exergy COP of 0.979 and 0.301 when the driving hot water and absorber cooling water inlet temperatures are 160 °C and 30 °C. The grid-connected PV-VCHP system and ST-AHP with natural gas-fired auxiliary heater operate at an annual solar fraction of 0.533 and 0.572, respectively, for a typical weather condition in Barcelona (Spain).

Quantifying peak heat demand in neighbourhoods: A UBEM approach and its implications for residential heating electrification in the UK—A case study of Newcastle upon Tyne

Developing Urban Building Energy Models (UBEM) to manage heat decarbonisation at the neighbourhood level is both crucial and challenging. Our study addresses key research challenges: quantifying peak heat energy demand and developing reliable and replicable urban energy demand microsimulations. We applied our UBEM approach to a case study area of 228 houses served by the Ridgeway New Low Voltage (LV) electrical substation in Newcastle upon Tyne, to estimate the difference between existing peak heat and electricity demand at this scale. Results show that peak heat demand is 5 to 14 times greater than peak electricity demand, significantly exceeding estimates from national studies. Furthermore, our work follows a comprehensive validation framework, comparing our simulation results against all relevant and available UK datasets. This comparison demonstrates that our model is an overall good fit at the declared Level of Detail. However, our paper identifies significant challenges, particularly in validation, that need to be addressed to improve the reliability and usability of future UBEMs. Finally, we reflect on all our findings and make policy recommendations, as we believe addressing the issues raised in this paper is vital for enabling area-based planning of residential heating electrification, particularly in the UK.

Decarbonization of Heating and Cooling Systems of Buildings Located Nearby Surface Water Sources: Case Study

The study was carried out to evaluate theoretically and in laboratory conditions the capacity of a hybrid heating and cooling system that sustainably uses thermal energy extracted from surface waters in order to decarbonize buildings located near water sources. The novelty of the research consists in the realization of two experimental systems, one for the rapid evaluation of the performance of the water–water heat pump heating system and one for the evaluation of the operating behavior of a cooling system with fan coil units. Starting with the heating and cooling demand, and the climatic and hydrological local characteristics, a hybrid system model for the heating and cooling of the analyzed building was established and implemented. The forecasted energy consumption and CO2 emissions for the operation of the new equipment were compared with the historical values of the old systems with which the building was equipped (thermal energy supply from the district heating and cooling system with an air conditioning unit). Also, the results were extrapolated for forecasting the energy potential of the surface waters. The study highlights a percentage reduction in annual energy consumption of 67.71% and CO2 emissions of 80.13% through the implementation of the hybrid system.

Role of power-to-heat and thermal energy storage in decarbonization of district heating

The sector integration of the heat and electricity sectors promotes the flexibility of the energy system. This, together with the already almost carbon dioxide-free electricity supply in Finland, facilitates the environmental transition to a carbon-neutral heating system. In this study, pathways to decarbonize the district heating system in Åland (an autonomous region of Finland) are explored. Especially, the roles of different power-to-heat technologies, e.g., heat pumps and direct electric heating, and thermal energy storage are investigated in the decarbonization of the district heating system. The focus is on studying the impact of varying prices in electricity markets on the operation of climate-neutral district heating systems. For this, three scenarios were modeled over the five years of 2018–2022 with varying demand and electricity market prices by using the modeling software PLEXOS. The study showed that electricity prices, but also reserve market prices, have a very significant impact on the operation cost and profit of a district heating system. Overall, electrification has the strong potential to reduce emissions cost-effectively in a district heating system, but it also makes the system vulnerable to electricity price volatility. It can be concluded that thermal energy storage and reserve market participation are crucial for protecting against cost increases and reducing investment risk.

Accelerating renewable heat: Overcoming barriers to shared-loop ground source heat pump systems in the United Kingdom

Heat decarbonisation is needed rapidly and at scale to reach net-zero carbon emissions by 2050. Shared-loop ground source heat pumps (GSHPs) are an under-researched technology with potential to deliver clean heat at scale. These involve the installation of connected GSHPs for a group of homes, a whole street or apartment building, with shared use of deep boreholes, coupled with individual heat pumps installed in each property. However, a range of socioeconomic, political and technical barriers inhibit their mass deployment and there is a research gap surrounding potential policy, governance and financial support mechanisms to help overcome these. This study investigates the advantages and challenges associated with this technology, and reviews measures which could accelerate uptake. Analysis draws on 58 interviews with policymakers, industry stakeholders, users and non-users in the UK. Advantages include neighbourhood scale-deployment, with the potential to decommission local gas grids. Compared with air-source heat pumps, shared-loop GSHPs are more compact, less noisy, and more efficient, with lower running costs. However, they share many barriers associated with all heat pumps, and have higher up-front costs. A range of policy options are discussed which address the need for investor confidence, skills and training, information provision, and other incentives. Overall, carefully designed policy and financial support mechanisms could accelerate mass deployment of shared-loop GSHP technology, helping to reduce reliance on fossil fuels, boost energy security and reduce carbon emissions.

Are BSR Municipalities on Track for Energy Transition?

Climate neutrality targets and the growing decentralization of energy systems have substantially increased the role of municipalities in global energy transition. However, global shifts and national government demands have often left local public authorities unprepared to face numerous challenges related to local space planning, cost-effective integration, and decarbonization of electricity, heating, industry, and mobility. Therefore, there is a need to investigate the current state of municipal energy transition and analyze how municipalities face climate neutrality target achievement. This study conducts an integrated energy sustainability assessment to investigate the progress of the energy transition in six municipalities in the Baltic Sea region. A benchmarking approach is applied to compare the different levels of energy efficiency and decarbonization in the municipalities. The study reveals different energy consumption patterns of municipal buildings, which are influenced by various factors such as the type of building (educational, office, social facilities, etc.), the heat source (district heating or individual local heat source) and the energy efficiency management practices applied. In addition, a different trend in the installation of renewable energy capacity can be observed in municipalities in Latvia, Lithuania, Poland and Sweden. The study analyses the overall gap between the production and consumption of renewable energy to determine the storage potential and the role in the local energy transitions. The findings of this study highlight the key cornerstones in the current state of municipal energy transition, setting a foundation for better and more effective energy policy planning at national and local scales.

Real-time monitoring and optimization of a large-scale heat pump prone to fouling - towards a digital twin framework

Large-scale heat pumps are a promising technology for the decarbonisation of heat supplied in buildings and industries, provided they operate as expected. However, common faults like fouling and unplanned downtime periods can significantly affect their performance and availability. This could limit the widespread adoption of large-scale heat pumps over other heating technologies such as gas and electric boilers. Approaches described in the literature to optimize the operation of large-scale heat pumps often lack validation under real-world conditions and do not account for performance degradation due to faults. This work demonstrates a step towards utilizing digital twins to improve the energy performance of a commercial large-scale heat pump affected by fouling. A framework was proposed based on the real-time adaptation of digital twins, where a simulation model was calibrated online based on measurements from the heat pump in operation, which was then used for set point optimization. This enabled to determine optimal intermediate pressure set points in the heat pump operating under varying levels of fouling over time. The framework was tested on different periods of heat pump operation spread over ten calendar months. The results showed that the use of online calibration rather than a single calibration decreased performance estimation errors between 3 and 17 percentage points. Moreover, the set points determined by the online-calibrated model, along with a simpler polynomial model derived from it, showed improvements in the heat pump performance by up to 3%, depending on the level of fouling. The findings of this study demonstrated the potential to extend the proposed framework using digital twins to enhance the energy efficiency of large-scale heat pumps.

A provincial analysis of centralized heating systems decarbonization in China's residential sector: History and future

Decarbonization of China's residential Centralized heating (RCH) is crucial for China's carbon peak and neutrality. To tap the decarbonization potential, from the perspective of heating production and consumption, this study uses Log-Mean Divisia Index to investigate the historical decarbonization of RCH. Meanwhile, this study novelty develops a bottom-up RCH CO2 emission forecast model, which can quantify technique renovation by building stock dynamics. The results indicate that 1) During the period of 2005–2019, RCH achieved 800.66 MtCO2 of decarbonization, and the heating consumption ends had a larger contribution (85.68 %) than heating production end. 2) Under Business-as-usual scenario (BAU), RCH will reach 208.41 MtCO2 by 2060. Other scenarios can reduce CO2 emissions by 52.38 % to 100 % below BAU. 3) In the future, the heating production end will have a larger decarbonization potential, and the best decarbonization strategy is non-fossil energy utilization. In summary, this study offers insights into the decarbonization of provincial RCH and can benefit the formulation of a reasonable provincial decarbonization responsibility and decarbonization pathway.

Assessing the relevance of energy indicators as sustainability screening metrics for the decarbonisation of industrial heat through electrification

Power generation faces the challenge of reducing its greenhouse gas emissions without shifting the burden to other environmental impacts. Energy and exergy-based environmental indicators have proven to some extent to be effective environmental proxies for the current energy mix but the robustness of this approach has barely been discussed in the frame of energy transition scenarios. Hence, the aim of this study is to analyse their relevance in the context of decarbonisation of industrial heat through electrification. To this end, we investigate the potential relationships between two different energy indicators and environmental indicators using life cycle assessment (Ecoinvent database, 16 environmental indicators, 2 energy indicators) for 28 pairs of energy sources shifting for the production of 1 kWh of electricity. For the reference French case, no similar trends across all sources of energy, for given environmental and energy indicators are found neither between all environmental and energy indicators. The extension to other cases is discussed, leading to the same conclusion. These results highlight the need for a multi-criteria assessment to evaluate the impacts of industrial heat in a context of intensive process electrification, which will be country dependent because of the various strategies in achieving net-zero electricity mix.

Use of Absorption Heat Pumps to Raise District Cooling Waste Heat Temperature for District Heating Supply in Tallinn: Technical and Economic Analysis

Abstract Decarbonisation of District Heating (DH) networks is essential to achieving the European Union’s climate goals. In this context, there is growing interest among DH stakeholders in the recovery and reuse of underutilised heat sources. Waste heat recovery from district cooling (DC) networks offers a compelling option that can be used as input for various heat pump integrated DH solutions. In this regard, absorption heat pumps (AHP) showcase a promising solution to elevate a lower-temperature waste heat source with reduced electricity consumption. However, AHPs are not widely applied in DH context, primarily due to the lack of suitable waste heat sources or the necessary conditions for their effective operation. This article aims to explore various configurations of AHP and their potential integration with DC plant waste heat for DH application. The potential for adopting AHPs to boost efficiency and lower carbon emissions is evaluated through a techno-economic examination of three distinct technological configurations. For Tallinn case study, it was observed that AHPs can be more efficient, reduce energy consumption, and achieve a lower LCOH while being combined with HP condenser cooling. This study is expected to provide a theoretical support for the positive impact of using AHPs to reduce the usage of fossil fuels in the Tallinn DH network.

Energy supply for the building stock of tomorrow – A case study

Reducing energy consumption and using renewable energy sources for the building operation is crucial to achieve lower overall greenhouse gas (GHG) emissions. In this case study we conduct a building energy system optimisation for a new residential district in Darmstadt, Germany under different boundary conditions using the optimisation software Sympheny. Boundary conditions of the year 2023 lead to similar results to the owner’s plan, which is mainly based on natural gas-fired cogeneration plants. However, different scenarios with predicted emission factors and energy prices for 2050 lead to a shift towards the usage of renewables. As planners tend to use current boundary conditions for their calculations, we assess the possibility of switching to a renewable heat supply after the expected life span of the cogeneration plants. The obstacles identified mainly concern the temperature level, but also the space that will not be accessible at that time. The results emphasise (1) that the decarbonisation of space heating in Germany goes hand in hand with the need to decarbonise the electricity grid and (2) the need for planners to start considering future developments as part of building energy system planning.