1,720,979 research outputs found
How national decarbonisation scenarios can affect building refurbishment strategies
Full text linkEnergy transition is radically changing national energy systems. Nevertheless, the dynamics of this transformation are not considered by end-users in the design of building systems. The present work aims at assessing how the renewable share increase, in both electricity and gas grids, can affect building energy performance. To do this, building energy performance indicators, taking into account growing renewable shares, have been proposed. Four national decarbonisation scenarios have been considered. In a case-study in Italy, conventional boilers, heat pumps, combined heat and power plants and hybrid systems have been analysed. Heat pumps turn out to be the best option if the renewable penetration in the power grid is higher than 40%. The substitute natural gas deployment can increase the competitiveness of cogeneration systems, but not enough to represent the best configuration. National decarbonisation scenarios significantly affect the primary energy and emissions savings of building refurbishment strategies. Conventional indicators, taking primary energy factors as fixed, lead to correct assessment for the reference year, but are unable to describe the actual building energy performance over the system lifetime. Depending on the scenario, the average specific primary energy consumption ranges in 17% and 55% lower than the one assessed with conventional analyses
High-efficiency solution for an open-loop desiccant assisted solar cooling system by integrating trans-critical CO2 heat pumps. A comprehensive techno-economic assessment
Full text linkSolar cooling systems are classified into open and closed loop cycles. The latter is superior in terms of reliability and commercialization. However, the former, due to unique features to provide sensible and latent cooling separately is still under development. This work proposes a potential improvement in terms of energy performance in solar-assisted open loop cycles. The cooling system is composed of desiccant wheel, indirect evaporative coolers that require regeneration power. Such power is provided by a cutting-edge technology named trans-critical CO2 heat pump, running mostly by photovoltaic modules. Four different configurations are dynamically simulated inside MATLAB SIMULINK environment for the year interval. Based on the main simulation results, the renewable energy share of at least 50% for both electric and thermal is achieved. It could be increased up to 77% electric and 100% for thermal share. Furthermore, the parameters to optimize the cooling system performance are the heat pump COP, the recovery heat exchanger effectiveness, and the regeneration air mass flow rate. Generally, the innovative cooling system behaviour is affected by climate variations. Hence, the COP of the CO2 heat pump is starting from 2.3, which could be improved up to 6.5. It is clearly higher than the available benchmark
The potential role of trans-critical CO2 heat pumps within a solar cooling system for building services: The hybridised system energy analysis by a dynamic simulation model
No full textThe rotary desiccant wheels application in the air conditioning systems are used for the air dehumidification by means of hygroscopic layers for water vapor adsorption. Nevertheless, external heat sources are required for water desorption to close the air treatment cycle. This paper investigates on the possibility to integrate in that cycle a new component, such as the trans-critical CO2 heat pump, to reduce the contribution of external thermal sources. In so doing, the high temperature waste heat discharged by the heat pump hot sink can be fruitfully exploited. Additionally, a PV array has been added to the typical layout based on the solar collectors, in order to assure the heat pump electrical driving. The energy analysis is carried out by calculating the energy performance indicators of the whole cooling system, simulating it by a dynamic model built in the MATLAB SIMULINK environment. Specifically, an air handling unit has been properly sized to supply cooling load to a reference conference hall of 1200 m3, with changes in boundary conditions (i.e. solar radiation, daily temperature and relative humidity variations). Indeed, three different cities representing the most typical Italian climatic zones, have been considered for assessing the proposed technical option suitability
Recent progresses in H2NG blends use downstream Power-to-Gas policies application. An overview over the last decade
Full text linkThis paper attempts to give a broad overview on technologies progress status, effects, perspectives, and issues associated to H2NG widespread applications. It deepens and completes the content of previous reviews by including hitherto unreviewed aspects as far as possible. To do so, a holistic approach has been used by surveying technical, energy, environmental, economic and safety issues related to the hydrogen mixtures’ use. This review aims to provide support for a broader understanding of the problem, starting from the simple list of mixtures properties up to their impact on both NG pipelines and end-use devices. Hydrogen injection affects several blend characteristics and gas network parameters. Mixing limits are also related to Wobbe index variations and safety aspects due to the flashback risk. Numerous works have shown that hydrogen fractions of 10% allow parameters to be kept within acceptable ranges, and up to 20% are not related to significant risks
Power-to-gas as an option for improving energy self-consumption in renewable energy communities
No full textRenewable Energy Communities (RECs) have been introduced by the Renewable Energy European Directive (REDII) in order to allow their members to collectively produce, consume, store and sell renewable energy. With the distributed generation deployment, the electricity injection into power grids has to be limited. Thereby, the RES management has to maximise the local energy self-consumption (SC). The present work deals with Power-to-Gas (PtG) application for blending hydrogen in the local gas grid for maximising the energy-SC, comparing it with traditional electric batteries (PtP). Moreover, this study investigate how SC-based tariffs for RECs can represent an indirect incentive for hydrogen production. To do so, a case study, consisting of 200 dwellings, has been analysed. Four PV configuration have been considered for evaluating different RES excess conditions. PtP and PtG systems have been implemented and compared each other. The hydrogen production cost has been assessed exploiting the renewable electricity incentive scheme
Adsorption gas Heat Pump fuelled with hydrogen enriched natural gas blends: The analytical simulation model development and validation
Full text linkThis study deals with the implementation of an analytical model to simulate the energy performance associated to a commercial Gas adsorption Heat Pump, when H2NG (Hydrogen Enriched Natural Gas) blends are used as fuel. In detail, a water source heat pump manufactured by Robur (GAHP-WS) has been used as a reference device for building the simulation model within the MATLAB-Simulink environment. Thereafter, the simulation results have been validated by the experimental campaign, testing on field and in actual operating conditions the heat pump. Specifically, the model has been developed by implementing the WaterAmmonia mass and energy balances for each component. It is able to evaluate fuel consumption, efficiency in terms of GUE, required thermal power from the cold heat sink as well as the water outlet temperature at the evaporator, once the heating load is used as the main input. The experimental campaign for the model calibration and validation has been carried out over the winter season. Additionally, the heat pump performance has been detected when it operates to supply hot water at 60 °C and 55 °C, and it is fuelled with growing hydrogen fractions, starting from 0% vol., 5% vol. up to 10% vol. In the end, the standard errors as well as the relative ones affecting the main output parameters have computed for the validation process. From the outcomes it emerges that the average relative standard error related to all load conditions is lower than 2.5% for natural gas operation. On the contrary, it ranges between 2.5% and 4% when H2NG at 5% and 10% by volume have been burnt
Heading towards 100% of renewable energy sources fraction. A critical overview on smart energy systems planning and flexibility measures
Full text linkThe growing penetration of non-programmable energy sources will largely contribute to intensify the renewable capacity firming issues. Providing a higher systems flexibility, i.e. the ability to match the supply and the demand sides as much as possible, is the main challenge to cope with, by adopting new energy planning paradigms. In this framework, different combined strategies, aiming at efficiently integrating that large amount of variable RES (VRES), have to be implemented. In the recent years, the Smart Energy Systems (SES) concept has been introduced to overcome the single-sector approach, promoting a holistic and integrated vision. By that approach, it is possible to exploit synergies between different energy sectors so as to identify the best technical options to globally reduce the primary fossil energy consumption. Starting from a quantitative and qualitative analysis of the most recent international studies dealing with the SES approach, the aim of this paper is to critically review and analyse the role of the main potential flexibility measures applied in the energy planning sector. In detail, Power-to-X and Demand Side Management (DSM) application have been considered, highlighting strengths and weaknesses of such strategies to accomplish the ambitious target of 100% renewable. From this literature review, it emerges how a single strategy adoption is not enough to guarantee the required flexibility level for the whole energy system. Indeed, the best configuration can be attained by integrating different options matching all the external constraints
Urban energy transition: sustainable model simulation for social house district
Full text linkEnergy communities (EC) play a crucial role in driving the transition towards renewable energy sources within urban areas. This study focuses on the implementation of EC within linear mass housing in Rome, with particular attention given to the Tor Bella Monaca district. The research proposes and simulates six energy community distinct scenarios using the Urban Modelling Interface (UMI) and Simulink in order to advance understanding of this topic. These scenarios evaluate the integration of photovoltaic systems, heat pumps, and energy storage systems to determine their comprehensive effect on renewable energy production, CO2 emission reduction, and the enhancement of self-consumption. The study findings show that higher electrification levels in an energy community lead to greater consumption of renewable energy and reduced reliance on the grid. The integration of heat pumps and energy storage further enhances energy consumption and self-sufficiency creating sustainable energy models in urban environments. With an increase in self-consumption factor and self-sufficiency factor of 0.15–0.30 and 0.11–0.13, respectively, depending on the scenario. The research highlights the importance of a thorough assessment of technology sizing and integration in order to enhance self-consumption and decrease CO2 emissions. It proposes investigating the incorporation of both thermal and electrical storage to optimize self-consumption. Finally, the simulated scenarios underwent flexibility analyses to determine the precise energy flow capacity and the optimal setting identified through economic evaluation
Synergy between smart energy systems simulation tools for greening small Mediterranean islands
No full textSeveral islands around the world are facing common challenges in terms of high energy costs, local CO2 emissions, security of supply and system stability. In EU, many islands have become sites of energy innovation, where betting on Renewable Energy Sources is a winning choice to meet their energy needs. In this framework, renewable energies play a key role for supporting the transition of small islands to an autonomous, cleaner and low-carbon energy system – in line with the overall EU Energy Union package and EU2030 goals. This study examines the suitability of using hybrid energy system comprising photovoltaic systems, wind turbines, biomass and diesel generators to meet the electricity demand of Favignana Island, to increase the penetration of renewables in the local electricity grid. Additionally, the energy scenarios simulation aimed at identifying foreseeable energy-environmentally improvements associated to the mutual merging of further energy sectors, such as transportation and heating sector. Consequently, the renewable capacity firming issues can be strongly mitigated by integrating new energy demand components. Thus, this work shows in a systemic overview all the outcomes related to the different energy mix layout, with varying the RES share values compatibly with the local grid electrotechnical constraints. Furthermore, this paper studies the impact that the introduction of electric vehicles into the island car fleet will have on the energy system. The smart energy system's components and sizes have been studied both from an energy and an economic point of view by means of two different software (i.e. EnergyPLAN and HOMER)
High-temperature green hydrogen production. A innovative- application of SOEC coupled with AEC through sCO2 HP
No full textThis study evaluates a potential coupling between AEC and SOEC through a CO2 heat pump unit that works in super-critical conditions. In such a way, thermal power requested by SOEC can be provided by recovering heat loss from AEC via the CO2heat pump. The coupled configuration is characterized by renewable electric input. Hence, the power is provided for electrolysis without more external thermal resources. The energy, economic and environmental impacts of such intervention have been determined and compared with SOEC in solo mode. The layout is created and simulated in a MATLAB SIMULINK environment. The simulation results show a potential improvement in the total energy efficiency of the whole system without an external heat resource, up to 68%, which is higher than 65% of SOEC itself, thanks to the heat recovery section that is correlated with sCO2 HP contribution. LCOH varies widely depending on SOEC size from around 2.59 €/kgH2 up to 9.27€/kgH2
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