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The forthcoming implementation of national policies towards hydrogen blending into the natural gas grid will affect the technical and economic parameters that must be taken into account in the design of building heating systems. This study evaluates the implications of using hydrogen-enriched natural gas (H2NG) blends in condensing boilers and Gas Adsorption Heat Pumps (GAHPs) in a residential building in Rome, Italy. The analysis considers several parameters, including non-renewable primary energy consumption, CO2 emissions, Levelized Cost of Heat (LCOH), and Carbon Abatement Cost (CAC). The results show that a 30% hydrogen blend achieves a primary energy consumption reduction of 12.05% and 11.19% in boilers and GAHPs, respectively. The presence of hydrogen in the mixture exerts a more pronounced influence on the reduction in fossil primary energy and CO2 emissions in condensing boilers, as it enhances combustion efficiency. The GAHP system turns out to be more cost-effective due to its higher efficiency. At current hydrogen costs, the LCOH of both technologies increases as the volume fraction of hydrogen increases. The forthcoming cost reduction in hydrogen will reduce the LCOH and the decarbonization cost for both technologies. At low hydrogen prices, the CAC for boilers is lower than for GAHPs; therefore, replacing boilers with other gas technologies rather than electric heat pumps increases the risk of creating stranded assets. In conclusion, blending hydrogen into the gas grid can be a useful policy to reduce emissions from the overall natural gas consumption during the process of end-use electrification, while stimulating the development of a hydrogen economy. [ABSTRACT FROM AUTHOR]

The present work aims to investigate the integration into renewable energy communities (REC) schemes of micro and mini- Combined Heat and Power (CHP) plants. In detail, it has been evaluated the minimum self-consumption (SC) share needed to even out the revenues coming from the energy efficiency certificates (EECs). In order to establish a SC based tariff for CHP plants a correlation between SC share and the tariff value has been assessed for different commercial plants. A 70% of SC share has been set as a minimum target, which is related to incentive rates of 53 and 39.5 €/MWh, for mini and micro-CHPs, respectively. These values are about 65% lower than the current tariffs set by ARERA (Italian Regulatory Authority for Energy, Networks and Environment) to reward the renewable energy SC. A real building and two CHP plants have been considered as reference case studies. A dynamic simulation has been carried out in order to analyse the proposed incentive scheme in a real application. Starting from a 3-D BIM model, the energy flows have been calculated over one year period. Finally, it has been demonstrated how a SC based tariff can significantly reduce the share of injected electricity into the grid, also promoting the thermal carrier sharing. In so doing, the renewable energy sources intermittency can be easily mitigated and balanced, avoiding additional burdens on public expenditure.

Climate change is a worldwide recognized problem, and its mitigation identified as one of the most significant challenges. The way to achieve this purpose is to reduce greenhouse gases (GHG) emissions through the energy system using renewables. The change from an energy system based on fossil fuels to renewable sources-based one is necessary on which the world community agrees. A photovoltaic thermal (PV/T) panel is a system that can produce both electricity and thermal energy simultaneously in one integrated system. This paper deals with hybrid energy systems, specifically a hybrid system to produce power and thermal energy from solar sources consisting of photovoltaic thermal modules. The hybrid system consists of 7 hybrid photovoltaic panels installed on the roof of the laboratory. This paper presents a study for experimental data obtained from a measurement campaign of the thermal and electrical behavior of a PV/T system in single and series models.

This 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.

The 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.

The deployment of distributed energy systems must take place paying attention to the self-consumption of renewable generation. Innovative sector coupling strategies can play that role linking local electricity and gas grids. The present work aims to evaluate the energy and economic feasibility of the Power-to-Methane strategy application in urban energy districts. A residential cluster was considered as a case study. Two PV configurations have been applied to evaluate the Substitute Natural Gas (SNG) production under different renewable excess conditions. Thereafter, the Power-to-Methane strategy was implemented by varying the system's size. Some significant configurations have been compared to each other in terms of energy and economics. Beyond a certain threshold limit, an increase in the photovoltaic size slightly enhances the effectively self-consumed energy. The Power-to-Methane strategy can exploit all the renewable excess once the system is properly sized, almost doubling the potential energy consumption reduction compared to the PV system alone. The SNG production cost is between 100 and 200 EUR/MWh in most configurations, which is competitive with the high natural gas prices on the European market. Therefore, decentralised SNG production can reduce the households' annual expenditures and it can mitigate the energy poverty conditions over the current energy crisis period. [ABSTRACT FROM AUTHOR]

Abstract High Renewable Energy Sources (RES) share in energy systems entails environmental advantages in its use but drawbacks in its distribution, management and effectiveness. The interconnection between electricity, heat and transport sector seems to be a comprehensive answer. Its actual link is on-going and, currently, involves electricity and heat. Indeed, Power to Heat (P2H) is the strategy of meeting the heating demand by supplying electricity to feed Heat Pump (HP). Their higher efficiency compared to fossil fuel boilers requires a further check in the quality of the heating demand to meet, i.e. the temperature levels. Great part of current building stock calls for High Temperature (HT) Heat which is not affordable by HP maintaining their Coefficient of Performance. To face this issue, RES can be used to produce synthetic fuels for feeding existing energy systems, the so-called Power-to-Gas option. In this way, greening the fuel supply can be seen as the best option for meeting HT heating demand while, Medium and Low Temperature are met by HP. Therefore, two technological scenarios, P2H and its combination with P2G, are presented and assessed in three reference Urban Energy Systems. The authors investigated on the impact of RES share increase from 25% up to 50% in the electricity mix with the objective function of Primary Energy Consumption (PEC). The outcomes of twenty-four energy scenarios, eight for each Reference City were assessed also through the value of delivered Renewable Heat. Finally, the leverage effect of P2G on the system is evaluated in terms of renewable heat contribution. Highlights • Merging heat and electricity sectors for renewable capacity firming. • Review of established electricity-driven Heating Technologies from low to high supply temperatures. • Three Reference Urban Energy Systems were modelled with varying the RES share. • Gains in PEC from Power-to-Heat and Power-to-Gas in Urban Heating Systems. • The interaction between P2G and P2H implies higher renewable heat delivery. [ABSTRACT FROM AUTHOR]

In recent months, gas prices have reached unprecedented levels, hurting the European economy and exacerbating energy poverty conditions. This paper deals with investigating measures for a rapid reduction in the Italian natural gas (NG) consumption. The aim is to assess and quantify energy, economic, social and environmental impacts of different strategies to be implemented promptly. Several solutions, such as utility and residential PV systems, Wind plants, biomethane, green hydrogen and heat pumps, have been analysed. Different implementation levels of such solutions have been simulated in combination with each other by means of the MATLAB Toolbox for EnergyPLAN. The NG Abatement Cost (NGAC) has been calculated. That indicator allows an immediate evaluation of economic benefits comparing it with current and future NG spot prices and potential import alternatives. The NGAC of the best strategies is between 40 and 70 €/MWh depending on the amount of achieved savings. Less than 80 billion in total investment leads to a NG reduction of 75 TWh/year at an average abatement cost of about 70 €/MWh. That entails an employment impact of 640,000 temporary jobs and 30,000 permanent jobs along with an emission reduction of 21.5 Mt CO2 /year. Under the highest implementation of such measures, future average NG spot prices higher than 50 €/MWh allow to reduce GHG emissions implying decarbonisation costs lower than 80 €/t CO2. Furthermore, three Carbon Abatement Cost curves by changing the NG prices have been elaborated. The findings of this work show how current high NG prices can be an opportunity to speed up the transition process towards decarbonised energy systems. • Strategies for reducing the Italian Natural Gas consumption in the short term. • Assessment of energy, economic, social and environmental impacts. • Simulations by means of the MATLAB Toolbox for EnergyPLAN. • Evaluation of the abatement cost of Natural Gas consumption. • Assessment of decarbonisation costs as a function of the Natural Gas spot price. [ABSTRACT FROM AUTHOR]

Abstract: Energy conversion from hydrogen represents a viable contribution to sustainable development. For this reason several authors have investigated clean hydrogen production and its end uses. One end use is a hydrogen storage system with a fuel cell to mitigate grid instabilities inherent to renewable power generation or intermittent reactive loads. Another end use is burning hydrogen in internal combustion engines for motive transport or remote power generation. Blending hydrogen with traditional hydrocarbon fuels is also possible. The aim of this paper is to assess the opportunity for realizing a small-scale renewable hydro methane production system in Italy. The system is completely integrated in an electrical and thermal smart grid. For this reason, a techno-economic feasibility analysis on hybrid systems was carried out to quantify the carbon avoidance cost associated with blended hydrogen fuels. Twelve different scenarios were simulated with the HOMER software and the optimal system configuration was identified by applying the levelized cost of hydrogen (LCOH) as evaluation criterion. Furthermore, a sensitivity analysis was applied to explore potential fiscal policy scenarios. The simulation results show that the lowest LCOH (8.041 €/kg) was achieved with a 5 Nm3 electrolyser capability (operating for about 4000 h/yr) and a grid connected 160 kWp PV array when hydrogen was produced only during the winter season. Instead considering the same operating hours and modifying the hydrogen production daily and monthly profile (i.e. hydrogen production from May to September) the best results were obtained (LCOH = 0 €/kg). An analysis of carbon avoidance costs showed the optimal hydrogen mixture of approximately 23% by volume to provide the best economic and environmental trade-off. Finally, if the hydrogen cost is equal to 1.5587 €/kg a null over price for decarbonisation is achievable. To obtain this result a dedicated incentive scheme to encourage the hydrogen production should be developed by Italian Government. [Copyright &y& Elsevier]

Highlights: [•] Renewable hydrogen production for natural gas enrichment as a good transition solution toward hydrogen economy. [•] Theoretical energy analysis carried out on CHP fueled by hydromethane blends. [•] Environmental analysis on different hybrid system configuration. [•] Individuation of best methodology for specific emissions assessment related this unconventional CHP power plant. [ABSTRACT FROM AUTHOR]