1,720,974 research outputs found
Techno-economic assessment of enhanced Biogas&Power-to-SNG processes with high-temperature electrolysis integration
Full text linkBiogenic energy sources are essential elements of the decarbonization pathways, but are strongly constrained by the limited availability. In this context, Biogas&Power-to-X technologies are strongly supported as a promising solution to foster renewable power generation and drive sector coupling opportunities. This work investigates enhanced Synthetic Natural Gas (SNG) production processes for the repurposing of biogas plants. As an alternative to combined heat and power applications via internal combustion engines, the Italian legislation is supporting biogas-to-biomethane upgrading, focusing on the transport market. The proposed integrated plant scheme is a flexible solution based on Power-to-Hydrogen and methanation, able to exploit both electric and gas grid connections, enhancing biomethane production. Advanced process schemes are studied combining solid oxide electrolysers that exploit the methanation waste heat as input thermal energy and flexible PEM electrolysers that improve the part-load operation. The calculated efficiency at max load is about 55% for the Power-to-Methane block and nearly 75% for the overall integrated plant. Results show limited sensitivity of efficiency to input power variations, making the system suitable for the recovery of surplus renewable power generation
SIMULATION OF THE HIPOWAR GAS-STEAM POWER GENERATION SYSTEM USING AMMONIA AS FUEL
Full text linkThis work presents a simulation activity on an innovative power generation cycle, developed within the EU Horizon 2020 project HiPowAR, using ammonia as fuel for an oxy-combustion process in a membrane reactor. The key advantages of the system are the low compression requirement, typical of steam cycles, and the large expander inlet temperature, typical of gas turbine cycles. The analysis explores the options of cooled or uncooled expander, either adopting a steam-cooled turbine made of conventional Ni-based alloys or using high temperature-resistant ceramic matrix composite (CMC) materials. The simulations show that, with a reactor outlet temperature of 1350°C, a cooled system could reach up to 48.2% efficiency, with limited additional advantages when further increasing the temperature. At the same temperature level, the uncooled system could instead achieve 52.5% efficiency, allowing also a substantial system simplification. However, since the expanded mixture contains nearly 90%mol steam, the use of CMC materials is made difficult by degradation issues and would require the development of suitable barrier coatings
A comprehensive multi-node multi-vector multi-sector modelling framework to investigate integrated energy systems and assess decarbonisation needs
Full text linkThe pathway towards decarbonised energy systems involves massive changes in adopted energy vectors, installed technologies, networks roles, and interaction capabilities. To investigate the combination of these effects, this work presents the OMNI-ES modelling framework (Optimisation Model for Network-Integrated Energy Systems), which offers a comprehensive approach to analyse multi-node, multi-vector, multi-sector energy systems. It adopts a detailed temporal and spatial resolution and implements multiple conversion options between energy vectors (electricity, hydrogen, natural gas, biomethane, biofuels, e-fuels, ...). The formulation solves the energy vector balances at each time step, taking into account sources, sinks, conversion processes, and storage systems. CO2 flows are also tracked, allowing the introduction of CO2 emission constraints that account for all contributions (fossil and biogenic, direct and indirect) and mitigation measures (capture, re-use, sequestration). In the article, OMNI-ES is applied to investigate an Italian scenario for 2050, adopting a regional (NUTS-2) resolution. The model output yields the cost-optimal energy system configuration that is capable to support the demand with net-zero CO2 emissions. Results show that the need for CO2 balance closure calls in several technologies, including massive renewable power generation (up to 20 times today’s capacities), storage systems (batteries, hydrogen, pumped hydro), biogenic sources (residual biomass and biomethane), and CO2 capture (both on fossil and biogenic sources). Networks emerge as critical elements, as the need to transport energy vectors saturates the expected capacities of grid infrastructures, especially in the case of hydrogen
Assessing the effectiveness of hydrogen pathways: A techno-economic optimisation within an integrated energy system
Full text linkWith the world still far off-track from averting relentless global warming, and most countries struggling in meeting their self-imposed goals, hydrogen can potentially play a crucial role in tackling the major challenge of decarbonising the global economy in the framework of a sustainable development. Capable to store, carry, and convert energy in a variety of ways, hydrogen can be a versatile tool to exploit fully the potential of renewable energy sources. Using a holistic approach within a techno-economic optimisation, this study aims at analysing quantitatively the effect of different possible energy pathways employing hydrogen, taking the Italian energy system as a case study, assuming a progressive growth in both renewable power generation capacity and electric mobility in private transport. Results confirm the beneficial impact of hydrogen and identify three hydrogen-based pathways in the optimised energy scenarios: production of synthetic natural gas to partially replace natural gas in the grid and both direct hydrogen consumption and production of synthetic liquid fuel in the heavy transport sector. Direct hydrogen injection in the gas grid plays a negligible role instead. At most, CO2 emissions can be reduced by 49 % within the investigated scenarios, with an increase in annual costs of 8 %
Analysing the pace of the energy transition under different cumulative CO2 budgets
No full textUnder the pressing need for decarbonisation, most industrialized countries are targeting net-zero CO2 emissions by mid-century. The pathway to the net-zero configuration is as important as the final goal, since a lack of containment of the cumulative CO2 emissions may enhance climate impact effects and force larger efforts for negative emissions. The main objective of this article is to investigate the effects of cumulative CO2 emission budgets in shaping the long-term transformation of national energy systems, using Italy as a case study. By comparing three scenarios with different budgets, the analysis provides insights into their impact on technology deployment, infrastructure development, and timing of decarbonisation actions. The analysis is developed with the open-source model FENICE (Future Energy traNsition multI-seCtor model), which is here fully presented for the first time. It provides a comprehensive multi-period approach to analyse multi-vector energy systems with multi-node and multi-sector resolutions. Based on the oemof framework, FENICE considers the five main energy carriers (electricity, hydrogen, fossil and biogenic CH4, liquid fuels, biomass), detailing their transmission infrastructures and tracking the CO2 flows. Results confirm the expected surge of renewable energy sources in all scenarios, combined with programmable technologies (power generation or energy storage) as well as carbon capture. Energy infrastructures emerge as key enablers of decarbonisation, facilitating renewables installation and highlighting the relevance of their detailed modelling. Under low CO2 budgets, the system development is impacted by installation rate limits and the urgency of new measures forces large negative emission contributions, leading to diverse CO2 pipeline designs and transport dynamics
Come aumentare l’efficienza energetica di uno stabilimento industriale con sistemi SOFC-SOEC
No full textThe role of hydropower in decarbonisation scenarios
Full text linkAn increased penetration of renewable energy sources is essential for the energy transition. A major role will be played by wind and solar, as they are widely available. Hydropower is another crucial resource, currently covering large shares of power generation (e.g., Norway, Italy, Brazil). Despite little expected growth, in a context of increasing electrification, improved integration of hydropower can play a critical role thanks to programmable operation. This work addresses the modelling of hydropower flexibility in energy system models and analyses the impact of hydropower operation on CO2 emission-constrained scenarios. To implement the study, a detailed dataset of the Italian programmable hydroelectric plants is created, using open-source information, covering location, rated power, and storage capacity. Inflow timeseries are derived from historical operational data. These new sets of data are employed in OMNI-ES (a multi-node, multi-sector, and multi-vector energy system model) to study optimal configurations and operation of the Italian energy system in decarbonisation scenarios, such as net-zero-CO2 and Fit-for-55 targets. Considering different operational strategies and multiple historical reference years (impacting the inflow), results demonstrate significant changes in hydropower behaviour and highlight its relevance as zero-carbon resource in terms of both power and energy output, influencing the installation of other technologies
Design of hybrid power-to-power systems for continuous clean PV-based energy supply
No full textThe increasing penetration of intermittent renewable sources, fostering power sector decarbonization, calls for the adoption of energy storage systems as an essential mean to improve local electricity exploitation, reducing the impact of distributed power generation on the electric grid. This work compares the use of hydrogen-based Power-to-Power systems, battery systems and hybrid hydrogen-battery systems to supply a constant 1 MWel load with electricity locally generated by a photovoltaic plant. A techno-economic optimization model is set up that optimizes the size and annual operation of the system components (photovoltaic field, electrolyzer, hydrogen storage tanks, fuel cell and batteries) with the objective of minimizing the annual average cost of electricity, while guaranteeing an imposed share of local renewable self-generation. Results show that, with the present values of investment costs and grid electricity prices, the installation of an energy storage system is not economically attractive by itself, whereas the installation of PV panels is beneficial in terms of costs, so that the baseline optimal solution consists of a 4.2 MWp solar field capable to self-generate 33% of the load annually. For imposed shares of self-generation above 40%, decoupling generation and consumption becomes necessary. The use of batteries is slightly less expensive than the use of hydrogen storage systems up to a 92% self-generation rate. Above this threshold, seasonal storage becomes predominant and hybrid storage becomes cheaper than batteries. The sale of excess electricity is always important to support the plant economics, and a sale price reduction sensibly impacts the results. Hydrogen storage becomes more competitive when the need for medium and long terms energy shift increases, e.g. in case of having a cap on the available PV capacity
The role of hydropower in decarbonisation scenarios
Full text linkAn increased penetration of renewable energy sources is essential for the energy transition. A major role will be played by wind and solar, as they are widely available. Hydropower is another crucial resource, currently covering large shares of power generation (e.g., Norway, Italy, Brazil). Despite little expected growth, in a context of increasing electrification, improved integration of hydropower can play a critical role thanks to programmable operation. This work addresses the modelling of hydropower flexibility in energy system models and analyses the impact of hydropower operation on CO2 emission-constrained scenarios. To implement the study, a detailed dataset of the Italian programmable hydroelectric plants is created, using open-source information, covering location, rated power, and storage capacity. Inflow timeseries are derived from historical operational data. These new sets of data are employed in OMNI-ES (a multi-node, multi-sector, and multi-vector energy system model) to study optimal configurations and operation of the Italian energy system in decarbonisation scenarios, such as net-zero-CO2 and Fit-for-55 targets. Considering different operational strategies and multiple historical reference years (impacting the inflow), results demonstrate significant changes in hydropower behaviour and highlight its relevance as zero-carbon resource in terms of both power and energy output, influencing the installation of other technologies
Design and partial-load operation of a reversible Solid Oxide Cell system with molten salts thermal storage
No full textThe increasing penetration of renewable energy sources in the electricity mix requires efficient storage solutions on the seasonal scale. Reversible Solid Oxide Cell (rSOC) systems are receiving increased attention as viable options to fulfil this requirement. In this work, a MW-scale rSOC system capable of working over a large operating window is studied via modelling on Aspen Plus®. To ease the thermal integration, a molten salt thermal storage is coupled to the system, enabling heat recovery in fuel cell mode, which is then exploited for water evaporation in electrolysis mode. The rSOC stack is designed to operate exothermically in the electrolysis mode at nominal load. In both modalities, the air mass flow rate is regulated to control the stack temperature, while limiting the in-out gradients within 100°C. At nominal load, the system achieves an electrical efficiency of 52% in fuel cell mode and of 87% in electrolysis mode. The operation at low partial loads, due to the decrease of the air flow rate, requires an additional high-temperature heat source to guarantee the heat integration. In this regard, the adoption of an electrical resistance in electrolysis mode and a hydrogen-fed combustor in fuel cell mode are selected as viable solutions to amplify the operating range of the system. As a results, the system can be operated down to the 30% of the stack nominal power in both modalities, where the system achieves an electric efficiency of 44% and 80% in fuel cell and electrolysis mode, respectively
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