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The increasing decarbonisation of the power and heat sectors in Great Britain poses numerous uncertainties about the future of the gas network. An optimisation model was developed for investigating the operation of future low carbon electricity, gas and heat supply systems. The model was employed to quantify the impacts on the operation of the gas network in Great Britain of transitioning to low carbon power and heat. The modelling results show that the decarbonisation of the power and heat sectors affects the operation of the high and low pressure gas networks differently. A highly electrified heat sector, only slightly changes the gas load duration curve for the high pressure gas transmission network, but significantly affects the load duration curve for low pressure gas distribution networks. In addition, in a future energy system with a large capacity of variable wind and solar generation, and highly electrified heat supply, although the annual volume of gas supply decreases, the peak gas supply during low wind and cold spells remains the same or even exceeds the current figure. This is mainly due to gas-fired power plants operating to their maximum capacity to complement the wind resource and also supply electricity for heat pumps.

The increasing decarbonisation of the power and heat sectors in Great Britain poses numerous uncertainties about the future of the gas network. An optimisation model was developed for investigating the operation of future low carbon electricity, gas and heat supply systems. The model was employed to quantify the impacts on the operation of the gas network in Great Britain of transitioning to low carbon power and heat. The modelling results show that the decarbonisation of the power and heat sectors affects the operation of the high and low pressure gas networks differently. A highly electrified heat sector, only slightly changes the gas load duration curve for the high pressure gas transmission network, but significantly affects the load duration curve for low pressure gas distribution networks. In addition, in a future energy system with a large capacity of variable wind and solar generation, and highly electrified heat supply, although the annual volume of gas supply decreases, the peak gas supply during low wind and cold spells remains the same or even exceeds the current figure. This is mainly due to gas-fired power plants operating to their maximum capacity to complement the wind resource and also supply electricity for heat pumps.

Computer-based simulations of Organic Rankine Cycles (ORC) have been extensively used in the last two decades to predict the behaviour of existing plants or already in the design phase. For time-varying heat sources, researchers typically rely on either quasi-steady state or dynamic simulations. In this work, the two approaches are compared and the trade-off between them is analysed, taking as benchmark waste heat recovery with ORC from a billet reheating furnace. The system is firstly optimized in MATLAB® using a quasi-steady state approach. The results are then compared with a corresponding dynamic simulation in Dymola. In the case of waste heat from billet reheat furnace, the quasi-steady state approach can successfully capture the fluctuations in waste heat. For heat source ramps from 110% to 40% the nominal value in 30 s, dynamic effects lead to 1.1% discrepancies in ORC net power. The results highlight the validity of the quasi-steady state approach for techno-economic optimization of ORC for industrial waste heat and provide a valuable guideline for developers, companies and researchers when choosing the most suitable tool for their analysis, helping them save time and costs to find the most appropriate approach.

Computer-based simulations of Organic Rankine Cycles (ORC) have been extensively used in the last two decades to predict the behaviour of existing plants or already in the design phase. For time-varying heat sources, researchers typically rely on either quasi-steady state or dynamic simulations. In this work, the two approaches are compared and the trade-off between them is analysed, taking as benchmark waste heat recovery with ORC from a billet reheating furnace. The system is firstly optimized in MATLAB® using a quasi-steady state approach. The results are then compared with a corresponding dynamic simulation in Dymola. In the case of waste heat from billet reheat furnace, the quasi-steady state approach can successfully capture the fluctuations in waste heat. For heat source ramps from 110% to 40% the nominal value in 30 s, dynamic effects lead to 1.1% discrepancies in ORC net power. The results highlight the validity of the quasi-steady state approach for techno-economic optimization of ORC for industrial waste heat and provide a valuable guideline for developers, companies and researchers when choosing the most suitable tool for their analysis, helping them save time and costs to find the most appropriate approach.

Abstract This paper presents an economic and energy feasibility analysis of a renewable energy system for a small city in southern Italy to convert it to zero greenhouse gas city by 2030. The proposed energy infrastructure utilises different technologies: wind turbine, photovoltaic panels and biogas cogeneration plants to produce electric energy, and thermal solar panels, cogeneration and heat pumps to meet the thermal energy demand of the city. The electrification of transport sector is also considered. The whole city energy system is analysed by the EnergyPLAN software to evaluate streams combination and potential synergies between the different sectors. In order to improve the analysis, PhotoVoltaic technology has been simulated in TRNSYS environment, to obtain detailed prediction of this component of the energy infrastructure. The system behaviour was analysed considering different time bases: daily, weekly and yearly. The EnergyPLAN outputs include the aggregated yearly production and demands of all modelled energy conversion systems, as well as hourly values useful to identify the measures to make Altavilla Silentina nearly zero carbon city. Every measure identified becomes a new input in EnergyPLAN to evaluate its effect on city energy balance. The economic analysis has been performed to evaluate the electricity and thermal energy costs.

Abstract This paper presents an economic and energy feasibility analysis of a renewable energy system for a small city in southern Italy to convert it to zero greenhouse gas city by 2030. The proposed energy infrastructure utilises different technologies: wind turbine, photovoltaic panels and biogas cogeneration plants to produce electric energy, and thermal solar panels, cogeneration and heat pumps to meet the thermal energy demand of the city. The electrification of transport sector is also considered. The whole city energy system is analysed by the EnergyPLAN software to evaluate streams combination and potential synergies between the different sectors. In order to improve the analysis, PhotoVoltaic technology has been simulated in TRNSYS environment, to obtain detailed prediction of this component of the energy infrastructure. The system behaviour was analysed considering different time bases: daily, weekly and yearly. The EnergyPLAN outputs include the aggregated yearly production and demands of all modelled energy conversion systems, as well as hourly values useful to identify the measures to make Altavilla Silentina nearly zero carbon city. Every measure identified becomes a new input in EnergyPLAN to evaluate its effect on city energy balance. The economic analysis has been performed to evaluate the electricity and thermal energy costs.

Abstract Growth of urban population around the world and, particularly, within urban areas, has placed various pressing challenges on Food, Energy, and Water (FEW) such as food security, water safety as well as energy scarcity and so on. Current studies on urban FEW nexus are mainly focused on the correlation analysis of elements by pairs, while these works are developed separately. With respect to the methods, the existing researches mostly adopt the bottom-up approach, accounting for the direct relationship between the individual production sectors. While the associations between the internal elements of the system still lack of simulation. In this study, we aim at developing an online open access tool for cities, the Urban Circular Economy Calculator (UCEC), which enables to develop different circular economy scenarios associated to FEW management. UCEC v1.0 uses Beijing data as test case. In particular, more than 20 circular economy policies related on food, energy and water are selected and divided into 6 categories. Long-term simulations on the social, economic and environmental impacts are provided to test the trajectories of policy effects. Being an open access tool, UCEC can be used also for supporting participatory processes as an urban management instrument. The solution is economically and financially feasible, due to the low level of technical requirements. The necessity of such a tool is proved by the societal need of transition toward a low-carbon and sustainable framework, which can be effectively supported by the introduction of circular economy. This transition, such as the idea behind UCEC, should preserve (or even improve) the societal wellbeing, while increasing basic resources (i.e.: FEW) accessibility, security and preservation.

Abstract Growth of urban population around the world and, particularly, within urban areas, has placed various pressing challenges on Food, Energy, and Water (FEW) such as food security, water safety as well as energy scarcity and so on. Current studies on urban FEW nexus are mainly focused on the correlation analysis of elements by pairs, while these works are developed separately. With respect to the methods, the existing researches mostly adopt the bottom-up approach, accounting for the direct relationship between the individual production sectors. While the associations between the internal elements of the system still lack of simulation. In this study, we aim at developing an online open access tool for cities, the Urban Circular Economy Calculator (UCEC), which enables to develop different circular economy scenarios associated to FEW management. UCEC v1.0 uses Beijing data as test case. In particular, more than 20 circular economy policies related on food, energy and water are selected and divided into 6 categories. Long-term simulations on the social, economic and environmental impacts are provided to test the trajectories of policy effects. Being an open access tool, UCEC can be used also for supporting participatory processes as an urban management instrument. The solution is economically and financially feasible, due to the low level of technical requirements. The necessity of such a tool is proved by the societal need of transition toward a low-carbon and sustainable framework, which can be effectively supported by the introduction of circular economy. This transition, such as the idea behind UCEC, should preserve (or even improve) the societal wellbeing, while increasing basic resources (i.e.: FEW) accessibility, security and preservation.