1,720,965 research outputs found
Dynamic modeling and thermal management of a Power-to-Power system with hydrogen storage in microporous adsorbent materials
No full textThe increasing penetration of distributed renewable energy sources involves the development of efficient energy storage solutions. Hydrogen is a viable alternative, or complement, to electric batteries for long-term and high-capacity storage. This article assesses the benefits of hydrogen storage in microporous adsorption materials at room temperature. The integrated Power-to-Power system dynamic behavior is modelled. We assessed the system performance looking at hydrogen adsorption in four porous materials (MSC-30, IRMOF-1, NU-110, and C/Be2) at room temperature for high-storage capacity. Hydrogen storage in an empty pressurized vessel by means of mechanical compression only is evaluated for comparison of the previous cases. The best performance in terms of tank volume size and round-trip efficiency are obtained by adopting adsorbent materials as follows: C/Be2 > IRMOF-1 > NU-110 > MSC-30 > empty storage. Indeed, under the same operating conditions, the volume size of the storage tank is reduced by 38 to 88% compared to the empty vessel, and the round-trip efficiency gain ranges between 0.6 and 2.8 percentage points according to the properties of the adsorbent material. Finally, by filling the storage tank with adsorbent materials the DOE targets are met at a pressure from 45% (MSC-30) to 83% (C/Be2) lower than in an empty tank
Digital Platforms for Renewable Energy Communities Projects: An Overview
Full text linkThe European Union energy policy agenda of achieving the transition to carbon neutrality has been established by an important legislative package called "Clean Energy for all Europeans". A novel approach introduced was to put the citizen at the center of the energy transition. On one side, by powering his freedom of action and, on the other side, by asking him an exceptional engagement in energy consumption reduction activities and in participating in the investments for new distributed Renewable Energy Sources (RES) power plants. The Renewable Energy Communities (REC) is the policy framework used to implement this strategy introduced by the Renewable Energy Directive Recast (RED II). In particular, RECs promote citizen’s active role by encouraging energy consumption reduction and energy demand flexibility while reducing the Not In My Bachyard (NIMBY) effect towards RES. Each member state is transposing the RED II directive, adapting it to national legislation and energy transition strategy. Pioneers countries like Italy have already started the experimentation of this framework and developing the first pilot projects. The citizens’ interest and their will to participate in REC projects indicate the need for supporting tools guiding them along all the project development stages: “design”, “creation”, and “operation”. This work presents three categories of supporting digital tools and platforms required to develop REC projects: Commercial, EU Founded and Freeware. We analyzed 30 tools, evaluating the services provided in each of the different stages of REC project implementation
Green synthetic fuels: Renewable routes for the conversion of non-fossil feedstocks into gaseous fuels and their end uses
Full text linkInnovative renewable routes are potentially able to sustain the transition to a decarbonized energy economy. Green synthetic fuels, including hydrogen and natural gas, are considered viable alternatives to fossil fuels. Indeed, they play a fundamental role in those sectors that are di cult to electrify (e.g., road mobility or high-heat industrial processes), are capable of mitigating problems related to flexibility and instantaneous balance of the electric grid, are suitable for large-size and long-term storage and can be transported through the gas network. This article is an overview of the overall supply chain, including production, transport, storage and end uses. Available fuel conversion technologies use renewable energy for the catalytic conversion of non-fossil feedstocks into hydrogen and syngas. We will show how relevant technologies involve thermochemical, electrochemical and photochemical processes. The syngas quality can be improved by catalytic CO and CO2 methanation reactions for the generation of synthetic natural gas. Finally, the produced gaseous fuels could follow several pathways for transport and lead to different final uses. Therefore, storage alternatives and gas interchangeability requirements for the safe injection of green fuels in the natural gas network and fuel cells are outlined. Nevertheless, the effects of gas quality on combustion emissions and safety are considered
Liquid-like hydrogen in the micropores of commercial activated carbons
No full textThe hydrogen adsorption properties of commercial activated carbon (aC) samples, in particular Nuchar SA-1500, Filtercarb GCC 8x30 and Filtercarb PHA, are evaluated at different temperatures (77 K, 196 K and ambient temperature) and pressure up to 80 bar. A comprehensive characterization is carried out by means of a volumetric Sieverts-type apparatus for hydrogen adsorption measurements and helium picnometry for the skeletal density evaluation, by nitrogen adsorption measurement for the evaluation of the surface area (BET) and pore size distribution (NLDFT), by Scanning Electron Microscopy (SEM) for morphology. All the adsorption data are evaluated by Langmuir/T oth isotherm model with a very high accuracy and the enthalpy of adsorption is calculated through the ClausiuseClapeyron equation. Comparison between the different samples is shown. The probed aC samples show interesting hydrogen storage capacity and reversible behavior up to many cycles with and without any thermal treatment in between. Our data point out the crucial role of the microporosity and ultra-microporosity in the adsorption process at low H2 pressures. The surfaces exhibit an average adsorption enthalpy around 6.5 kJ/mol while for the ultra-microporous sites a 14 kJ/mol value is found. The observed trapping behavior at 77 K is attributed to the ultra-microporous morphology of the porous structure in GCC and PHA samples. A further result is the evaluation of the hydrogen molar density in the micropores with size below 10 A, which is 30 mmol/cm3, a value very close to the liquid hydrogen one. These results could represent an interesting starting point for a real and efficient alternative method to the hydrogen storage using cheap and easy scalable materials
Techno-economic comparison of buildings acting as Single-Self Consumers or as energy community through multiple economic scenarios
Full text linkThe European Union has set ambitious targets to move towards a society with high penetration of renewable energy sources. In the forthcoming energy transition, Energy Communities (EC), i.e., legal entities where different actors, including citizens, cooperate in energy generation, storage and management, will play a crucial role. The present work simulates the energy flows and assesses the potential economic benefits of a cluster of buildings acting collectively as an energy community – a specific case study is set in northern Italy by comparing the EC performance with a configuration where customers act as Single Self-Consumers (SSCs). Pending the transposition of EU Directives to binding national laws, due by 2021, different supporting tariffs (economic scenarios) have been simulated in order to determine which scheme will support more effectively the integration of Energy Communities in the national energy market. Results show that ECs (i.e., customers acting collectively as energy prosumers) are able to accelerate the diffusion of building-integrated renewable energy sources (RES), resulting in higher overall self-consumption rates than SSCs. Self-consumed electricity generates savings on the energy bill of EC, and we calculated positive economic performance indicators for all the analysed economic scenarios. The sensitivity analysis carried out on system and transport charges of the electricity bill shows their remarkable impact on the economics making the EC less attractive for investors and citizens without proper supporting schemes
Evaluating uncertainty of shared energy in solar energy communities using a stochastic simulation framework
Full text linkAssessment methodology of promising porous materials for near ambient temperature hydrogen storage applications
No full textWith the rapid increasing of the available number of novel porous materials, a straightforward and low-cost testing methodology to assess those suitable for near ambient temperature hydrogen storage applications is needed. In this work, we developed a new assessment methodology to quickly identify those porous materials potentially suitable for near ambient temperature hydrogen storage applications. We introduced the usable capacity map showing why the absolute adsorption capacity at the temperature of 77 K is not a good indicator to compare the material's storage performance. In fact, some porous material that shows low usable capacity at 77 K appear to be better adsorbent at a higher temperature. Moreover, we demonstrated that using quick cyclic adsorption isotherm or TDS is possible to easily individuate those materials that are the most suitable for near ambient temperature applications. Therefore, as a general result, we showed that among the three commercial activated carbon, used here as case study, the one with the higher content of ultramicroporosity is the most promising because the optimum operating temperature shifts towards ambient temperature
Shared energy in renewable energy communities: The benefits of east- and west-facing rooftop photovoltaic installations
Full text linkRenewable energy communities (RECs) offer a promising perspective for decarbonizing the building sector. This is accomplished by enhancing the uptake, among others, of citizen-owned rooftop photovoltaic systems. A key challenge lies in ensuring that photovoltaic generation matches the needs of community members, i.e. maximizing shared energy index. Indeed, the shared energy depends on the consumption habits of individual members and the rooftop characteristics, such as orientation and inclination of available pitches, which influence the production curve. Therefore, clear guidelines on which roof pitches are most suitable for PV generation within RECs might be helpful during the design of such communities. In this paper, we investigate the optimal orientations and tilt angles for PV systems in REC design. We conducted a robust Monte Carlo simulation of an energy community comprising 60 users, 30 of which are equipped with rooftop PV systems for a total of 150 kWp installed. Our analysis revealed that pitches with West and East offer comparable, if not better, shared energy values than those South-facing, consequently mitigating peak power dispatched to the grid. Besides, shared energy remains quite constant across various tilt angles. These findings suggest that buildings with non-South-facing roofs should not be overlooked, but embraced in the design of renewable energy communities as they can contribute significantly to shared energy
Assessment of activated carbon fibers from commercial Kevlar® as nanostructured material for gas storage: Effect of activation procedure and adsorption of CO2 and CH4
No full textCarbon-based nanostructures are considered promising materials for gas storage thanks to robust structure, tunable porosity, lightweight, high thermal/chemical stability and easy production. This study reports the development of activated carbon fibers prepared from commercial Kevlar® through an innovative pyrolysis method, consisting of carbonization in inert ambient and subsequent physical activation in oxidizing atmosphere, using a unique apparatus. Varying three key parameters, time (range 60−240 min), temperature (range 1023−1123 K) and gas-flow (0.3/0.9/1.2 Nl/min of CO2), the correlation between the activation procedure and the resulting samples structure was evaluated. The best results in terms of microporosity and gas adsorption properties have been obtained by reducing the activation times of the material. Furthermore, the purpose has been to optimize the characteristics in terms of Specific Surface Area, Total Pore Volume and optimal Pore Size Distribution. The method made it possible to develop an adsorbent material with a high fraction of micropores up to 94 % of the total pore volume, straddling the supermicroporosity (0.7−2 nm) and ultramicroporosity (<0.7 nm) region. Such textural properties have resulted in high gases storage capacities, tested at different temperatures (280, 298, 314 K), with maximum uptake of 46 wt% for CO2 and almost 10 wt% for CH4. All produced samples were characterized by helium picnometry to estimate skeletal density, Scanning Electron Microscopy to obtain morphological information, porosimetry to know structural properties. The adsorption behaviour was tested using a Sievert-type apparatus in the pressure range of 0−15 bar for CO2 and 0−40 bar for CH4
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