Heat pumps emit more carbon than efficient fossil heating in new england because of dirty marginal power generation fuels

Today, there is a great demand for renewable energy sources, because the cost of natural energy resources and sanctions on installations that have a harmful impact on the environment are constantly increasing. More and more enterprises in Ukraine are moving to more advanced technologies to meet consumer needs. Thus, demand for the use of heat pumps as an alternative source of heat is increasing in Ukraine every day. One of the most promising areas for the use of heat pumps is the ventilation and air-heating systems for large-volume buildings. Energy efficiency increase of such systems can be achieved by combining heat pumps with different methods of heat recovery utilization. In this regard, a combined air heating and ventilation system with heat recovery recuperation and partial exhaust air recirculation is considered. The purpose of this study is to make thermodynamic analysis of the system and determine the influence of the external conditions, the type of building and the parameters of heat recovery devices on the energy efficiency of the heat supply system.The article deals with the thermodynamic and numerical analysis of the combined heat pump air heating and ventilation system with heat recuperation and exhaust air recirculation taking into account the parameters of the outside air and the type of the building. It is determined that, despite the decrease in energy efficiency of the heat pump air heating and ventilation system with the utilization of exhaust ventilation air with an increase in the relative costs of heat for heating in comparison with the costs of heat for ventilation, the specific costs of external energy per unit of produced heat remain low even at low ambient air temperatures. In this regard, the combined heat pump system is considered to be recommended as an alternative system for the heat supply of large objects.

Energy, exergy, economic and environmental studies on a nonflammable eco-friendly mixture for efficient heating in cold regions

The accounting methodology for renewable energy in the European Union’s (EU) renewable heating and cooling targets is often treated as a mere technical detail, yet it has profound implications for the effectiveness of climate policies. This paper highlights a critical misalignment within the Renewable Energy Directive (RED), which inadvertently disincentivises the deployment of more efficient heating technologies. By accounting for the energy harnessed to produce the useful heat, rather than the useful heat itself, the current metrics disproportionately credit the least efficient heating systems with generating the most renewable heat. An electric heat pump with a seasonal performance factor of 3 producing 100 units of renewable heat gets credited with 100 units of heat, despite using only 33 units of input energy, whereas a wood fireplace with an efficiency of 50% gets credited with 200 units of heat. The less efficient the device, the more renewable credits it receives for producing the same amount of useful heat. This misalignment undermines decarbonisation efforts by over-crediting inefficient technologies while failing to fully recognise high-efficiency solutions like heat pumps. This paper proposes revising the RED to account for useful energy output, ensuring a more accurate reflection of technology contributions. We also propose increasing the binding heating and cooling targets of 0.8 pp/year and 1.1 pp/year so that they reflect the needed contribution of the heating and cooling sector to reach the binding headline target of 42.5% by 2030. This shift would incentivise efficiency, better align with EU climate goals, and support the transition to a low-carbon heating and cooling sector in line with the 2030 emissions reduction target.

An assessment of efficient water heating options for an all-electric single family residence in a mixed-humid climate

Green ground source heat pump using various low-global-warming-potential refrigerants: Thermal imbalance and long-term performance

Energy analysis of heat pump water heaters coupled with air-based solar thermal collectors in Canada and the United States

The ORNL Heat Pump Model and an optimizing program were used to explore the limits of steady-state heating efficiency for conventional air-source heat pumps. The method used allows for the simultaneous optimization of ten selected design variables, taking proper account of their interactions, while constraining other parameters to chosen limits or fixed values. Designs were optimized for a fixed heating capacity, but the results may be scaled to other capacities. Substantial performance improvement is predicted compared to today's state of the art heat pump. With increased component efficiencies that are expected in the near future and with modest increases in heat exchanger area, a 28% increase in heating efficiency is predicted; for long-term improvements with considerably larger heat exchangers, a 56% increase is possible. The improved efficiencies are accompanied by substantial reductions in the requirements for compressor and motor size. The predicted performance improvements are attributed not only to improved components and larger heat exchangers but also to the use of an optimizing design procedure. Deviations from the optimized design may be necessary to make use of available component sizes and to maintain good cooling-mode performance while improving the heating efficiency. Sensitivity plots (i.e., COP as a function of one or more design parameters) were developed to explore design flexibilities and to evaluate their consequences. The performance of the optimized designs was compared to that of modified ideal cycles to assess the factors that limit further improvement. It is hoped that the design methods developed will be useful to designers in the heat pump industry.

As demand for cleaner energy sources grows, geothermal operators must maximize production efficiency from geothermal reservoirs used for power and heat generation. One of the critical challenges shared between geothermal and oil and gas reservoirs is thermal short-circuiting, a phenomenon where cooler injected fluids bypass heat exchange processes by flowing directly to production wells via high-permeability pathways or dominant fractures. This issue, reported in projects such as FORGE and Soultz-sous-Forêts, leads to significantly reduced heat extraction efficiency, as fluid flow distribution within the reservoir is suboptimal. While several techniques have been deployed to address thermal short-circuiting, many have resulted in limited success or even adverse effects on production efficiency. Autonomous Flow control devices (AFCDs) offer a promising solution to these challenges. These tools, already proven in reservoir management for oil and gas wells, can optimize geothermal system efficiency by distributing fluid flow more uniformly, increasing contact between injected fluids and heated rock and enhancing heat absorption. This study explores the potential of autonomous flow control technologies in Enhanced Geothermal Systems (EGS) to address thermal short-circuiting and improve reservoir heat management. For the first time, this paper presents the functionality of autonomous flow control devices, designed to regulate the flow of cold and heated water plus steam, under laboratory conditions. Additionally, results from a comprehensive modelling practice that applies this technology to a geothermal system are discussed. The study simulates multiple possible scenarios which under those cold fluids are injected through an injection well into a naturally fractured and/or hydraulically fractured, high-temperature medium, while heated fluid is subsequently produced via a production well. The impacts of a few uncertain parameters and how the devices mitigate the risk associated with such uncertainties are also addressed. The results highlight that the integration of AFCDs significantly mitigates operational inefficiencies by ensuring uniform fluid distribution, reducing thermal short-circuiting, and maintaining stable reservoir conditions. Furthermore, autonomous flow control devices enable dynamic flow regulation, adapting to changing reservoir conditions in real-time. These advancements lead to delayed cold-water breakthrough for two years while improving thermal recovery by up to 16% and significantly improving economics of the projects. This study illustrates that incorporating AFCDs into geothermal systems represents a significant leap in geothermal reservoir management, offering enhanced heat efficiency, improved sustainability, and greater economic viability for geothermal energy projects. The findings underscore the importance of leveraging advanced flow control technologies to meet the growing global demand for renewable energy.

To overcome the limitations of unstable heat extraction power and low efficiency in current deep geothermal energy exploitation technologies, we propose a novel and sustainable approach using clustered U-shaped multi-branch wells (UMW). This method enables efficient heat exchange by circulating working fluid through U-shaped wells, where thermal energy is transferred between the working fluid and the reservoir via the wellbore wall, avoiding any material exchange. For the validation of UMW method, based on the high-temperature and high-pressure thermal conductivity tests using hot dry rock samples from the Gonghe Basin, we developed a UMW field-scale reservoir-wellbore coupling model to assess the efficient heat extraction processes and the potential generating power of Organic Rankine Cycle (ORC). The results highlight that high injection rates lead to rapid thermal breakthrough and a sharp decline in early-stage heat extraction power, indicating the need for careful optimization of operational parameters. The average heat recovery power of a single set of six branch wells over a 50-year operating cycle is ∼4.32 MW. The ORC power generation capacity was conservatively estimated at ∼284.4 kW over the first 21.5 years, and ∼144.6 kW over the 50-year period. Sensitivity analysis of injection rates and the number of branch wells further suggests that balancing short-term power and long-term thermal stability requires adjusting injection rates, the number of branch wells, well spacing, and branch well operational schematic. We also provide a partial quantitative relationship between ORC power and operational parameters (injection rate and the number of branch wells) for optimization. This study demonstrates the promising potential of the UMW method for sustainable deep geothermal energy development. Future research will focus on refining quantitative optimization strategies for injection rates and operational cycles to ensure efficient and long-term heat extraction while maintaining system stability.

Thermodynamic and heat transfer implications of working fluid mixtures in Rankine cycles

This paper studies the efficiency of ground source heat pump(GSHP) used in refrigeration and heating, comparing it with air source heat pump (ASHP) by means of theoretical analysis and experiment. The results were as follows, the cooling efficiency of GSHP in summer is higher than that of heating in winter because of the heat is transferred from high temperature to low temperature during cooling in summer, which can be compared to heat pipe; By calculating the power consumption of pump and fan, it is found that theoretically GSHP unit and system have higher heating efficiency than ASHP; The experiment shows that the daily average COP of the unit and the system is 4.22-4.62 and 3.26-3.55, respectively, both the unit COP and system COP of GSHP is higher than that of ASHP, which is consistent with the theoretical analysis.

Heat pumps stand out because they are energy efficient heating and cooling devices and able to reduce global CO2 emissions to as much as 6%, which is one of the largest potentials for a single technology. This paper discusses the results of studies carried out by the International Energy Agency Heat Pump Centre (HPC) concerning the international status of residential heat pump technology, markets, as well as efforts for accelerating the use of heat pumps in buildings. The impact of heat pump policy instruments is analyzed.

Geothermal energy and in particular low temperature re- sources, have a rising worldwide importance. Ground-Source Heat Pumps (GSHP) have been used increasingly because they are among the cleanest and most energy efficient heating and cooling systems for buildings. Simulation models can be applied for a more effective use of the subsoil for geothermal purposes. In fact they are useful tools for the design of efficient systems considering also the need to avoid abnormal temperature distributions in soil and aquifers. In the hydrogeology field MODFLOW/MT3DMS are the most widespread programs to face environmental problems and to fore- cast quantity and quality impacts on groundwater resources. Al- though MODFLOW/MT3DMS are used to represent open circuit heat pumps, they are hardly used to represent borehole heat exchang- ers (BHE). The aim of this study is to simulate BHEs through two computer codes. The first one is TRNVDSTP, coupled to TRNSYS, which is often used in GSHP design in pure conduction cases. A methodology to take groundwater flow into account was added to TRNVDSTP, but a validation is still missing. The second one is MODFLOW/MT3DMS, suitable for groundwater flow and transport models, but whose reliability in BHE simulation is today unknown. The two software have been compared in terms of predicted ex- changed energy and temperature distribution in the aquifer.

This study describes the development of the optimal control strategies of eight parallel heat pumps in an existing building. The building consists of seven floors above ground and two floors underground with a total floor area of 22,440 m2. The chilled water generated by each of the eight parallel heat pumps runs through a common primary pipe to multiple air-handling units in the building. Because only one flowmeter and two thermometers (entering and exiting) are installed in the primary pipe, the heat removal rate and efficiency of each heat pump are unknown. The existing control of the heat pumps is as follows: if the chilled water return temperature in the primary pipe becomes greater than a predetermined temperature, the controller increases the number of operating heat pumps. The heat removal rate and efficiency of each heat pump were first identified using a Gaussian process (GP) machine-learning algorithm to develop the optimal control strategy of the eight heat pumps. Two GP models, one for estimating the heat removal rate and the other for estimating the coefficient of performance (COP), were developed based on the measured data for 27 days in July at the sampling time of 15 min. After developing the GP models, the authors applied a COP-based sequencing control strategy to the eight parallel heat pumps. The new optimal control strategy is to switch on the heat pumps in order from highest to lowest COP. Compared with the existing control logic, the new optimal control can reduce energy consumption by 20.9%.

District heating systems play a pivotal role in providing efficient and sustainable heating solutions for urban areas. In this sense, district heating systems that use geothermal resources have been gaining prominence in recent years, due to the non-intermittent nature of their application, among many other reasons. The present study investigates the thermal performance of novel coaxial pipes in comparison to conventional pipes within district heating distribution networks supplied by geothermal energy. Through experimental simulation and analysis, key thermal parameters such as heat transfer efficiency, thermal losses, and overall system effectiveness are evaluated through laboratory tests developed on a scale model. Experimental analysis concludes that, at a laboratory scale, heat energy efficiency can be improved by around 37% regarding the traditional geothermal distribution network. This improvement translates into a significant economic and environmental impact that has a direct influence on the viability of this type of system in different application scenarios. The results highlight the potential benefits of coaxial pipe designs in enhancing heat transfer efficiency and minimizing thermal losses, thus offering insights for optimizing geothermal district heating infrastructure for improved energy efficiency and sustainability. The novelty of this study lies in the innovative design and experimental validation of coaxial pipes, which demonstrate a 37% improvement in heat energy efficiency over conventional pipe designs in geothermal district heating systems, offering a breakthrough in optimizing heat transfer and minimizing thermal losses.