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Due to the scarcity of fossil fuels and the potential for energy shortages, the use of energy-efficient devices is of utmost importance. There is an increasing trend in the utilization of heat pumps in air conditioning systems (heating/cooling) for both residential and commercial buildings. This article focuses on the analysis of the technical and economic aspects of gas engine heat pumps (GEHP) in various climates throughout Iran. The evaluation of this article revolves around two perspectives: that of the consumers and the government. The implementation of GEHP has been carefully considered from the consumers' perspective to ensure it does not have any negative effects on them. Additionally, from the government's point of view, the available resources are considered, and the supply of electricity and gas, along with their cost and energy consumption, are thoroughly investigated by the Ministries of Energy and Petroleum. The findings indicate that, from the consumers' perspective, the economic efficiency of GEHP can be up to 11 times higher than that of electric heat pumps (EHP). Moreover, from the government's viewpoint, GEHP leads to a reduction of over 92 % in electricity consumption, 5 % in gas consumption, and 92 % in annual expenses for the Ministry of Energy. Furthermore, the implementation of GEHP increases the income of the Ministry of Petroleum by 9.8 times. • Gas engine heat pumps (GEHPs) proposed to address electricity grid imbalance in Iran. • Consumer and government benefits of GEHPs across diverse Iranian regions analyzed. • Results show GEHPs reduce electricity consumption & costs for the Ministry of Energy. • GEHPs decrease gas consumption & boost revenue for the Ministry of Petroleum. [ABSTRACT FROM AUTHOR]

Quantifying greenhouse gas (GHG) emissions from electricity consumption presents a significant challenge due to the variable nature of the generation mix throughout the year and the complex dynamics of cross-border electricity trade. In this paper, we introduce an innovative methodology designed to accurately capture the hourly GHG emissions linked to electricity imports, and thus electricity consumption. Contrary to conventional approaches, our methodology identifies the relevant generation technologies in exporting countries which are activated for export. This selection is based on (i) the classification of the technologies according to their dispatch cost (merit order), and (ii) considers trade mechanisms from economic theory. We apply this methodology to Switzerland, a country characterized by a low-carbon electricity generation mix, which however heavily relies on imports from neighbouring countries, particularly during the winter months. Over the period from 2017 to 2021, we find that 88 % of Switzerland's domestic electricity demand is met by its own generation—primarily hydro and nuclear—while the remaining 12 % is imported, mainly from fossil-fuel-based sources. Consequently, the average annual GHG emission factor for electricity consumption in Switzerland is 98 g-CO2eq/kWh, with 29 % attributed to domestic generation and 71 % to imports. This figure is 40 % higher than the 70 g-CO2eq/kWh estimated using a conventional approach, which typically underestimates the specific impacts of electricity imports. The disparity between these approaches becomes even more pronounced when considering the seasonal and hourly variations in the electricity mix and the resulting emission factors. These insights are particularly crucial in the context of emerging electricity demands, such as heat pumps and electric vehicles, where accurate GHG accounting can significantly influence policy and investment decisions. • Novel methodology for computing hourly GHG emissions of grid electricity by integrating trade dynamics. • Method reveals significant emissions variations which are often overlooked in traditional approaches. • Provides CO2 signal for Swiss consumers to assess electricity impacts, crucial for heat pumps and EVs. [ABSTRACT FROM AUTHOR]

The electric submersible pump (ESP) is a compact multi-stage pump that is widely used in the oil industry. In this study, using the numerical simulations with entropy efficiency (EE) model, the high hydraulic loss region within the ESP hydraulic system is captured, and the energy degradation distribution within the internal flow field is investigated and its inter-stage variability is analyzed. The input power of the ESP hydraulic system is transformed into an entropy-reducing flow, and then the EE is defined to develop a connection between localized energy degradation and the efficiency of the hydraulic system. It was found that there were significant differences among the EEs of the three stages of the ESP hydraulic system. The EE of the first stage reaches 1.29 and 1.32 times that of the second and third (final) stage respectively under overload conditions. However, the overall energy characteristics of the hydraulic system are dominated by the energy dissipation in the second and third stage. In addition, The EE for characterization of pump performance is consistent with the existing research methods in the literature, but it has the advantage of quantifying the correlation between the localized flow field structure and the efficiency of the hydraulic system. This research can provide guidance for the design optimization of ESPs and performance evaluation of related equipment which has theoretical and practical significance. • Entropy-reducing flow quantifies the input energy of ESP hydraulic system. • Mathematical model of entropy efficiency (EE) is established. • Accuracy of numerical simulation is verified by high-accuracy experiments. • EE builds the link of local losses and total performance of fluid system. [ABSTRACT FROM AUTHOR]

As to the fuel injection system of electronic unit pump, of which fuel supply principles mainly be influenced by fuel supply camshaft. Due to the requirements of the diesel engine for the fuel supply system, a new method is presented to design the constant pressure injection fuel supply cam profile. First, design principles of the fuel supply camshaft profile according to the diesel engine combustion requirement are proposed and then the parametric equation for the camshaft profile can be obtained by the proposed principles which are analyzed through math method. At last, after the prediction and comparison of the designed camshaft profile, the conclusion shows that the fuel injection system designed by the proposed principle can satisfy the injection requirements of the diesel engine. Meanwhile, the parametric equations simplify the design process of camshaft profile so as to improve the reliability and the injection performance of the fuel supply system. [ABSTRACT FROM AUTHOR]

When an energy storage system (ESS) operates in cold conditions, the power and capacity of the battery critically fade. Therefore, an appropriate battery thermal management strategy (BTMS) is essential to prevent severe driving range loss at low ambient temperatures. However, none of existing studies considered the effect of BTMS on the driving range from a systematic perspective. Thus, we evaluated the trade-off between the performance enhancement by ESS heating and the additional energy consumption for ESS heating. We suggested and analyzed three BTMSs combined with a secondary heat pump: self-heating, active heating, and heat recovery. Active heating of the battery augmented the driving range of the EV by up to 18.8% over the self-heating strategy when the battery was used to full depletion, whereas the heat recovery strategy reduced the state-of-charge (SOC) decrease and thus increased EV driving range in nondepleted conditions. Furthermore, battery preheating with the heat pump achieved a temperature rise of 20 °C within an hour, consuming 38.4% less battery power than with conventional electric heater preheating. We expect this study contributes to the range extension of EV by suggesting the optimal BTMS depending on the driving conditions. • Experiments on the battery performance were conducted at low temperatures. • Battery thermal model was established and integrated with transient heat pump model. • Three strategies for battery thermal management were suggested. • Integrated thermal management model derived the optimal strategy under cold-start. [ABSTRACT FROM AUTHOR]

Accurately estimating the operational performance of electric coolant pump (ECP) can support long-term sensorless operational monitoring and reduce the cost and energy consumption of a vehicle thermal management system. However, there are some problems such as low estimation precision of theoretical model and back propagation neural network (BPNN) models, and the input parameters of existing studies are difficult to obtain at the ECP. In this study, a novel ISSA-BPNN estimation model is proposed that combines a hybrid strategy improved sparrow search algorithm (SSA) with the BPNN after hyperparameter optimization, and for the first time analyzes and uses the total power easily obtained as the input data of the model. Multiple experimental results show that the estimation precision and reliability of the proposed ISSA-BPNN model are much higher than those of the present theoretical models and BPNN methods. The average training time of the proposed ISSA-BPNN model is 226.9 s, and the average real-time operation time is about 5 ms, which meets the real-time application requirements. The proposed model is also applicable to the operational state estimation of other types of integrated pumps. • Operating state estimation of integrated pumps using easily accessible parameters. • High-performance Improved Sparrow Search Algorithm Based on Hybrid Strategy. • Swarm intelligence algorithm solves artificial neural network premature problem. • High precision pump operation performance estimation based on hybrid improved model. • Support long-term sensorless monitoring and reduce vehicle energy consumption. [ABSTRACT FROM AUTHOR]

Biomass combined cooling, heating, and power (CCHP) systems promote energy efficiency and reduce overhead costs in bioenergy production. On the necessity of assessing the sustainability of bioenergy technologies, this study performs a comprehensive life cycle assessment (LCA) of small-scale biomass CCHP technologies regarding technical alternatives. The novelty stems from comparing configurations based on sustainability indicators, the energy payback time, and conflicting objectives (maximizing energy revenues and minimizing environmental costs). Accordingly, four configurations attributed to biomass conversion technologies (organic Rankine cycle (ORC) and gasifier) and cooling units (electric heat pump, absorption chiller) are considered for LCA modeling. The results reveal that the highest share of human health (70–85%), ecosystem quality (50–60%), climate change (60–80%) and resources (70–80%) in all configurations belongs to biomass conversion technologies. In terms of Global warming, impacts related to gasification-ICE-based configurations outweigh ORC-based configurations (30–47%) due to higher auxiliary energy demand in the gasification process. In contrast, the CCHP systems driven by ORC are more reliable in refunding primary energy in the short term, 2.4–2.8 years. As a final result, the gasifier coupled with the electric heat pump is the most optimum configuration due to higher energy profits and lower environmental costs. • A comparative life cycle assessment of four biomass CCHP configurations. • The prime movers are the most effective parameters respect to environmental issues. • Gasification-ICE-electric heat pump is favorable regarding sustainability indicators. • The fossil-based CCHP doubles overall impacts compared to the bioenergy plant. [ABSTRACT FROM AUTHOR]

The EU Commission raised the GHG emissions reduction targets from 40% to at least 55% by 2030, By the "Fit for 55" package. Member States have to review their national energy and climate plans (NECPs) in a short-time. In order to elaborate guidelines for the Italian NECP improvement, a methodology based on the Smart Energy Systems (SES) approach has been proposed. The reference scenario has been modelled in EnergyPLAN. A Sectors' Implementation Matrix, consisting of eight sectors and three implementation levels, has been developed and the configurations have been simulated by means of MAT4EnergyPLAN. The best scenario accomplishes the 55% emissions reduction targets along with a lowering in the annualised costs of Italian energy system. The RES capacity targets must be increased by further 33 GW for PV and 16.6 GW for WIND. High end-uses electrification degree represents the priority in the next decade, so as to easily and cost-effectively integrate the variable-RES. An integrated energy system and the sector coupling even take priority over the RES installation in order to minimise the energy system decarbonisation costs. Finally, the present work contributes to demonstrate the need for the SES approach in the planning of energy systems with large-scale RES integration. • Improving Italian energy strategy by means of Smart energy systems approach. • Simulations by means of MATLAB Toolbox for EnergyPLAN (MAT4EnergyPLAN). • District heating, individual heat pumps and electric vehicles are the priorities. • Sector coupling is crucial to decarbonise energy systems in a cost-efficient manner. • The Smart Energy Systems approach is essential for energy planning. [ABSTRACT FROM AUTHOR]

The performance of heat pumps in electric vehicles drops significantly at low ambient temperatures due to low suction density and high-pressure ratios. To resolve this issue, we proposed the kangaroo heat pump cycle (KC). It is an enhanced flash tank-based vapor injection heat pump cycle (FT-VIC) that adds a sub-cycle before the refrigerant enters the flash tank, which increases the injection mass flow rate and leads to a higher heating capacity. Thermodynamic cycle models were developed for the basic heat pump cycle, FT-VIC, and KC. Furthermore, their heating performances, the annual energy consumption, and life cycle climate performance (LCCP) were evaluated and compared while using R-1234yf as the refrigerant. Results show that as compared to the FT-VIC, the KC increases the heating capacity by 25.7% and 20.1% and reduces the coefficient of performance by 25.8% and 18.9% when the ambient temperature is −5 °C and −15 °C, respectively. Due to the additional weight of the sub-cycle, the LCCP of KC is on average 4.6% higher than that of FT-VIC. In conclusion, the KC can provide more heating capacity in extremely cold conditions with additional energy consumption but is still more efficient than relying on the low-efficient PTC heater to meet the target heating capacity. • Proposed kangaroo heat pump cycle to increase heating capacity by over 20%. • Calculated annual energy consumption of novel heat pumps for electric vehicles. • Calculated the life cycle climate performance of heat pumps for electric vehicles. [ABSTRACT FROM AUTHOR]

This paper focuses on the optimal operation of integrated electrical and water energy networks at the distribution level considering the demand response program. In this manner, the water network with various components including reservoirs, tanks, fixed and variable speed pumps, and control valves is modeled. Newton-Raphson method is adopted to solve the water flow problem. This technique, unlike existing methods, can be applied to any network with any type of topology, whether radial, circular or hybrid. The electrical network is also modeled with the relevant constraints and coupled with the water network to supply the required electrical power. The optimization problem in a practical energy system, including a standard IEEE 33-bus electrical network, and the North Marin water network has been solved by a teaching learning-based optimization algorithm as a parameter-free method. The objective is to minimize the total operation cost. With the participation of the water network in a demand response program, the optimal charging and discharging of tanks, and pumps scheduling has been carried out, which consequently has led to operation cost reduction. In addition, numerical results have proved that the utilization of variable speed pumps can reduce about 7% of the total costs. • Integrated operation of electrical and water distribution networks is investigated. • Newton Raphson's method is developed for any type of water network topology. • Tanks and various electric pumps are scheduled to reduce power consumption. • An optimization method and demand response program are used for optimal operation. • The superiority of variable speed pumps in water network operation is addressed. [ABSTRACT FROM AUTHOR]

To reduce CO 2 emissions, the European Commission aims at having 100 Positive Energy Districts (PEDs) planned, developed or established by 2025. A PED annually exports more energy than it imports from the local grid. Because of Europe's diversity, this study aims to indicate where in the EU and under which tariff circumstances an electrified PED will likely thrive most. To do so, the work uses a tailor-made, mixed-integer linear programming model to optimise electrified PED solutions and compare them to the respective status quo for various representative zone-tariff parameter combinations. Results indicate that the optimal potential for PEDs is in southern Europe, with a dynamic electricity tariff and where previously no district heating was used. Under those circumstances, the PED concept could save around 84% of carbon emissions, while being more economical over the project horizon. Pricing of CO 2 emissions of energy services additionally nudges towards PED implementation. By limiting the power exchange of the PED with the grid, some of the negative grid impacts can be reduced. This study provides an essential insight into where in Europe a PED could be a sensible addition compared to where other decarbonisation approaches might be more beneficial. • Optimisation of electrified, multi-energy Positive Energy Districts. • PV, battery, heat pump and electric boiler-based system. • Europe-wide potential analysis according to climate and tariff structures. • Grid power connection assessment to restrict negative impact. • Advantage of southern districts with dynamic electricity tariffs and CO 2 cost. [ABSTRACT FROM AUTHOR]

Electric submersible pump (ESP) is the core artificial lift equipment to pump production oil from underground or deep sea to the surface. Its energy efficiency significantly affects global oil market and energy consumption. To explore the effects of the impeller meridian profile on the hydraulic performance, a typical multi-stage ESP with medium specific speed was taken as the research object. Based on the statically determinate control of the shroud and hub profiles, eight parameters of the impeller meridian profile were selected as the key factors. By taking head and efficiency as optimization targets, 27 schemes were designed according to the Taguchi approach. The effect analysis method was employed to determine the primary and secondary order of the parameters. The linear relationship between the meridional parameters and the optimization target was analyzed based on regression analysis. The results show that the design of the intersection line of the front and rear shrouds in the impeller meridian has great effects on the ESP performance. The optimal model shows a significant improvement on both of efficiency and head compared with the original model. The head increases 3.5% and the efficiency increases 6.1%. This study provides new inspiration to optimize the hydraulic design of ESPs to achieve higher efficiency and lower energy consuming. [Display omitted] • The impeller meridian profile was optimized by Taguchi approach successfully. • The numerical methods were verified by experimental measurements. • Improvement of performance and flow filed were confirmed by numerical simulation. [ABSTRACT FROM AUTHOR]

Combined heat and power (CHP) plants are operating under more fluctuating working conditions due to the increasingly inconsistent demands for heat and power and integration of renewable energy. This paper proposes to use an electric heat pump (EHP) to decouple heat and power and save energy by recovering waste heat from the cooling water. The thermodynamic model of the CHP unit under dynamic working conditions is established, and the dynamic EHP model based on an efficiency factor is proposed. The heat-power decoupling and energy - saving potential with different heat and power outputs and the heat pump DH ratio (χ HP) are analyzed for a CHP unit as a case study. Absorption heat pump (AHP) and EHP - based waste heat recovery systems are also compared. The results indicate that the heat-power decoupling potential is bigger when χ HP and the heat demand are increasing. The energy - saving effect is clearer by increasing the coefficient of performance (COP), χ HP , or both. AHP and EHP can help the system obtain a certain level of heat-power decoupling and energy - saving effects, but these effects of the AHP - based system are smaller than that of EHP, especially under the working conditions of high heat demand and low power demand. • A heat-power decoupling method with waste heat recovery using large HP is proposed. • Thermodynamic model for CHP unit in dynamic working conditions is developed. • Integration of HP-based waste heat recovery system can bring energy-saving benefits. • Heat-power decoupling and energy saving with EHP is better than that with AHP. • The energy saving effect is improved by increasing COP or heating ratio of HP. [ABSTRACT FROM AUTHOR]

Abstract: Centrifugal pumps are widely used in cooling water systems to transport cooling water to its users. They are installed in the header line of the feed pipe, constituting a main pump network. The pressure head of the main pumps must be large enough to satisfy the pressure heads of all coolers. The pressure drop of parallel branch pipes must be balanced by reducing the opening of valves for some coolers, incurring an energy penalty on some pumps. To attain energy savings, this paper proposes an auxiliary pump network whereby auxiliary pumps are installed in parallel branch pipes. A superstructure-based mathematical model is developed to optimize the total cost of the main and auxiliary pump networks. The optimal number of auxiliary pumps and their installation locations are determined by solving the model with a simulated annealing algorithm. The effectiveness of the model is tested by a case study based on the cooling water network of a refinery. [Copyright &y& Elsevier]

Abstract: This paper examines and compares the cost-effectiveness to energize pumping systems in remote areas on northern Chile by means of photovoltaic systems, diesel engines and grid extension. Variables such as the distance to the power grid, the voltage grid, the prices of electricity and fuel, and the required investments, are taken into account. The comparison is made for wide range of variable values, distances and pumping requirements. The results obtained are useful for choosing the best alternative for the power supply of pumping systems in wells in Northern Chile. [Copyright &y& Elsevier]

Excessive preheating energy consumption is a persistent issue in natural gas expansion power plants. In this paper, a novel system is proposed to solve this problem by using multi-stage expansion and gas engine-driven heat pumps (GHP). A dynamic model based on phase equilibrium theory is established to predict hydrate formation. A control strategy with continuously variable transmission (CVT) for optimizing engine efficiency is investigated through simulation and experiment. Finally, the efficiency and economic performance are compared among GHP, electric heat pump (EHP), and cogeneration (CHP) in a case study. The results show that the engine efficiency of CVT is 4.89% higher than that for multi-level transmission. Compared to single-stage expansion, multi-stage design can reduce preheating temperature by 46%, preheating load by 4.41%, and improve the performance coefficient (COP) of GHP 1.4-fold. The COP of GHP is 33.38% higher than that of EHP, and the primary energy ratio (PER) is 1.81 times that of CHP accordingly. The annual average profit margin for GHP is 1.89 times that of CHP and 7.15 times that of EHP. Thus, the proposed system has significant energy savings and economic advantages. • A new system integrated with multistage turbine and gas-engine heat pump is proposed. • A dynamic model with phase equilibrium theory is used to predict hydrate formation. • Multistage expansion can reduce preheating temperature and load by 46% and 4.41%. • The proposed system owns extremely lowest preheating cost and highest profit margin. • Such system has high heating efficiency, engine efficiency, and primary energy ratio. [ABSTRACT FROM AUTHOR]

Clean heating is a powerful solution for satisfying the building heat demand by synergizing energy efficiency and carbon emission. For satisfying the newly increased heat load, this paper constructs an alternative integrated electricity and heat energy system (IEHES) to consider different clean heating supply modes, namely electrical-heating mode (EH, electric boiler or electric heat pump), CHP unit with high back-pressure turbine heating mode (HBP–CHP), and auxiliary heat source heating mode (AHS, coal-fired boiler or gas-fired boiler). An optimal configuration planning and dispatch model is proposed for comparing the performance of the three heating modes. Wherein, a new comprehensive energy-carbon price is proposed as the optimization objective to minimize this system's total production costs and carbon emission costs. The results show that the HBP-CHP mode is the optimal solution when the heat load growth rate λ is lower than 14%, followed by the electric heat pump heating way under the EH mode. However, the HBP-CHP mode will limit the flexibility of the IEHES when λ is larger than 8%. Therefore, we propose a combined heating mode by introducing the electric heat pump into the HBP-CHP heating mode that facilitates the flexibility of the IEHES and brings the optimal system coal-saving effect. • Proposed an optimal dispatch model of the integrated electricity and heat energy system. • Constructed a new comprehensive energy-carbon price as the optimization objective. • Introduced three kinds of heating-supply modes to satisfy the increased heat load. • Recommended a new combined HBP-CHP with electric heat pump heating mode. [ABSTRACT FROM AUTHOR]

This paper proposes a cost-effective, robustly practical solution for a high-efficient electro-hydraulic actuator (EHA) for linear drives. The solution addresses the challenges of high costs and limited efficiency that limit the application of EHA for the electrification of many off-road vehicles. Based on a variable-speed electric motor and a low-cost technology for a fixed-displacement pump, the proposed solution is suitable for a compact implementation and it is capable of energy regeneration under overrunning load conditions. Two different architectures—an open circuit and a closed circuit one—are considered to determine the most practical and efficient configuration as well as the control features. Both architectures minimize throttling losses associated with the conventional regulation of hydraulic actuators. Actuator velocities below the minimum and beyond the maximum allowable pump flow rate are achieved in both architectures using a proportional valve that bypasses the pump flow. The paper describes the design methodology as well as the simulation and experimental activities performed to verify the control strategies as well as energy efficiency. Considering an EHA system of about 20 kW, a complete efficiency map of the system is determined for all the possible four quadrants of operation thus including both resistive and overrunning loads, where energy recuperation is implemented. Simulation and experimental results show that the energy efficiency of the hydraulic systems can reach 84.7% in resistive phases. In assistive phases, the hydraulic system can recover up to 81.8% of the actuator energy. The comparison between open-circuit and closed-circuit structures shows the advantages of the former in terms of energy efficiency. The proposed solution is suitable for electrified hydraulic actuation systems, in both industrial and mobile applications. With the advantages of the low cost of the hydraulic unit and high energy efficiency, it is particularly suitable for mobile applications such as construction machines, that are recently experiencing a significant electrification trend. • A cost-effective electro-hydraulic actuator is proposed with high efficiency. • The solution uses fixed-displacement pump and variable-speed electric motor. • Low-speed actuation is allowed by the usage of bypass valve in the architecture. • The efficiency of the system is verified by both simulation and experiments. • Four-quadrant efficiency maps demonstrate energy performance. [ABSTRACT FROM AUTHOR]

Development of unified electrical and thermal power flow model is critical for effective analysis of integrated power and thermal systems (IPTSs), where existing electric-analogy thermal circuit models of thermal systems are not analogous to that of power systems in physics, and heat transfer constraints of heat exchange facilities (HEFs) are usually simplified with inaccurate assumptions. Inspired by the irreversibility of transport phenomena, this work redefines the thermal resistance of HEFs and proposes a heat current model to comprehensively reflect heat transfer, migration and storage characteristics, which is in consistent with electrical power flow model and yields multi-energy flow model of IPTSs that can be solved using existing power system simulators. A multi-time scale hybrid simulation algorithm is further proposed and applied in simulating an urban IPTS. Results depict the developed method takes consideration of heat transfer characteristics of HEFs and secondary heating network accurately, which are ignored in traditional methods. Besides, introducing electric heat pumps as complementary heat sources to change the operation mode of combined heat and power plant from heat-led to power-led reduces 820.3 MWh wind curtailment by consuming 140.9 MWh electricity, where a 505.6 MWh heat stored in pipelines due to heat migration delay is fully exploited. Image 1 • Develop heat current model for heat transfer, migration and storage processes. • Heat current model is consistent with power flow model of power system in physics. • Proposed multi-energy flow model can be solved by existing power system simulator. • Obtain temperature variations considering nonlinear heat transfer constraints. • Applying auxiliary electrical heat pump effectively accommodates renewable energy. [ABSTRACT FROM AUTHOR]

Existing power systems are facing new challenges in maintaining the security of the power system as the penetration of variable renewable energy technologies, such as variable speed wind turbines, increase. System non-synchronous generation replaces conventional generators as penetration of renewable generation increases. This affects system rotational inertia and limits the number of online thermal generators that can provide frequency stability services and system-wide areas voltage stability. This evolution has resulted in some changes to existing grid codes and new ancillary services. Furthermore, it could provide opportunities to address the security of the system utilizing modern smart technologies, e.g. smart loads, heat pumps and electric vehicles. The aim of this paper is to evaluate the impacts of large-scale renewable power generation on power system dynamics from the perspective of the power system operator. It focuses on the grid codes implications and challenges specifically. Synthetic inertia response opportunities from smart loads, electric vehicles and energy storage technologies and dispatching wind farms during frequency excursions are analyzed and thoroughly discussed. The key finding is that rethinking in the development of grid code requirements and market mechanisms are needed if a power system based on 100% power electronic renewable generation is to be achieved. This type of power system would need a range of technologies to provide the types of ancillary (i.e. system) services required, as none of the technologies alone can tackle all the challenges presented. • First thorough study of impact of converter-based renewable generation on grid system dynamics. • Crucial for energy storage and smart appliances to respond in less than 500 ms to reduce trip risk. • Anti-islanding RoCoF relays should be set for 0.5 Hz/s for a window of 500 ms • Frequency limitations in renewable dominant countries are typically between 49.8 Hz and 50.2 Hz. • New fast frequency services to large disturbances are within 500 ms to 2.0 s from an event start. [ABSTRACT FROM AUTHOR]

Integrated smartly controlled energy networks have the potential to deliver significant reductions in carbon emissions, improve air quality and reduce energy costs for end-users across the world. This paper introduces a novel methodology for the development of integrated thermal, power and mobility 5th generation (5G) smart energy networks. The proposed 5G concept builds on state of the art by connecting flexible electricity demands such as heat pumps, and electric vehicles to intermittent, renewable and secondary energy sources and storage using artificial intelligence to facilitate optimal control and to maximise revenue and carbon savings. The proposed innovative method is being applied in central London through the development of two independent 5G smart energy schemes. The proposed schemes will incorporate a range of different renewables and secondary energy sources, for example, waste heat from local data centres and the London Underground that will supply a large proportion of the energy demand of the overall district network capacity. Both networks will operate at close to ambient temperature, approximately 15–25 °C as a so-called 'ambient loop' system, with individual heat pumps for each end-user or building connected to the network. The system also integrates thermal and electrical storage to create additional flexibility for the network and smart control for demand-side management. A smart management system flexibly controls individual assets such as heat pumps and electric vehicles in response to price signals reflecting the intermittency of renewable energy sources on the electricity grid. The ambient district thermal loop will distribute low carbon energy to a range of end users. Results presented in this paper provide an understanding of capital costs associated with integrated smart energy systems and the relative performance of individual technologies in a complex system using a techno-economic modelling approach. Overall, this paper demonstrates that the implementation of the 5G concept results in lower energy costs to consumers while at the same time transforming a large existing urban area to a near zero-carbon energy system in terms of heating, cooling, electricity and transport. [ABSTRACT FROM AUTHOR]

In order to integrate large shares of variable renewable energy sources, district heating can play an important role. Furthermore, in order to increase the efficiency of district heating systems, interconnecting adjacent system could be socio-economically justified. In order to assess the economic and environmental consequences of the latter, a mixed linear integer optimization model was developed with the endogenous decision on the potential interconnectors. The case study was carried out for the city of Zagreb, Croatia. The results showed that all three studied interconnections are economically viable, while the socio-economic cost was 29.2% lower in the case of the implemented interconnectors, all other capacities being equal. Moreover, the optimal thermal energy storage capacity was found to be equal to 25 and 24 days of average heating demand in two alternative scenarios. Finally, compared to the reference case, the CO 2 emissions could be lowered by 15.3%.CO 2 savings derive mainly from better utilization of low carbon capacities after interconnecting the systems, as well as from installation of heat pumps and electric boilers. [ABSTRACT FROM AUTHOR]

Vapor injection heat pumps have been proposed for cabin heating in electric vehicles (EVs) to improve the performance and reliability under severe weather conditions. However, the geometric optimizations of the injection-port and internal heat exchanger (IHX) in vapor injection heat pumps designed for EVs have rarely been investigated. The objective of this study is to investigate the effects of the injection-port angle and IHX length in a vapor injection heat pump for use in EVs at various startup conditions. The heating performance of a vapor injection heat pump with R134a is measured by varying the IHX length from 100 to 400 mm and injection-port angle from 320° to 440° at various cabin temperatures. The effects of the IHX length and injection-port angle are analyzed in terms of coefficient of performance (COP) and heating capacity. The optimum IHX length and injection-port angle for the maximum COP are determined to be 300 mm and 400°, respectively. • An IHX type vapor injection heat pump for EV is investigated. • Experiments are conducted under various startup conditions. • Effects of design parameters on the heating performance are analyzed. • The optimum injection-port angle and IHX length are suggested in terms of COP. [ABSTRACT FROM AUTHOR]