/library/oar/handle/123456789/1181 Fri, 26 Dec 2025 03:23:01 GMT 2025-12-26T03:23:01Z /library/oar/handle/123456789/142217 Title: Using hydro-pneumatic energy storage for improving offshore wind-driven green hydrogen production — a preliminary feasibility study in the central Mediterranean Sea Authors: Pirotti, Oleksii; Scicluna, Diane; Farrugia, Robert N.; Sant, Tonio; Buhagiar, Daniel Abstract: This paper presents a preliminary feasibility study for integrating hydro-pneumatic energy storage (HPES) with off-grid offshore wind turbines and green hydrogen production facilities—a concept termed HydroGenEration (HGE). This study compares the performance of this innovative concept system with an off-grid direct wind-to-hydrogen plant concept without energy storage, both under central Mediterranean wind conditions. Numerical simulations were conducted at high temporal resolution, capturing 10-min fluctuations of open field measured wind speeds at an equivalent offshore wind turbine (WT) hub height over a full 1-year, seasonal cycle. Key findings demonstrate that the HPES system of choice, namely the Floating Liquid Piston Accumulator with Sea Water under Compression (FLASC) system, significantly reduces Proton Exchange Membrane (PEM) electrolyser (PEMEL) On/Off cycling (with a 66% reduction in On/Off events), while maintaining hydrogen production levels, despite the integration of the energy storage system, which has a projected round-trip efficiency of 75%. The FLASC-integrated HGE solution also marginally reduces renewable energy curtailment by approximately 0.3% during the 12-month timeframe. Economic analysis reveals that while the FLASC HPES system does introduce an additional capital cost into the energy chain, it still yields substantial operational savings exceeding EUR 3 million annually through extended PEM electrolyser lifetime and improved operational efficiency. The Levelized Cost of Hydrogen (LCOH) for the FLASC-integrated HGE system, which is estimated to be EUR 18.83/kg, proves more economical than a direct wind-to-hydrogen approach with a levelized cost of EUR 21.09/kg of H2 produced. This result was achieved through more efficient utilisation of wind energy interfaced with energy storage as it mitigated the natural intermittency of the wind and increased the lifecycle of the equipment, especially that of the PEM electrolysers. Three scenario models were created to project future costs. As electrolyser technologies advance, cost reductions would be expected, and this was one of the scenarios envisaged for the future. These scenarios reinforce the technical and economic viability of the HGE concept for offshore green hydrogen production, particularly in the Mediterranean, and in regions having similar moderate wind resources and deeper seas for offshore hybrid sustainable energy systems. Wed, 01 Jan 2025 00:00:00 GMT /library/oar/handle/123456789/142217 2025-01-01T00:00:00Z /library/oar/handle/123456789/141615 Title: On the use of measure-correlate-predict methodologies and energy demand forecasting to assess energy storage capabilities for offshore wind farms Abstract: Energy storage is crucial for the continued penetration of renewable energy. One of the most important reasons for this is that, for a given point of time, the availability of renewable energy resources rarely matches the demand for electrical energy. The integration of offshore windfarms with energy storage facilities, requires a capital-intensive investment which can only be justified by an adequate return on investment (ROI). Currently, Measure-Correlate-Predict (MCP) analysis is used to assess the viability of offshore windfarms while energy demand forecasting is normally used to manage and plan the electricity grid infrastructure. This research combined wind energy prediction methodologies with Energy Demand Forecasting (EDF) methodologies to size the energy storage capacity for an offshore windfarm and evaluated the economic feasibility. This research analysed various regression techniques for MCP analysis. Data from a Light Detection and Ranging (LiDAR) system were utilised. The study was extended to analyse the behaviour of a hypothetical floating windfarm, situated off the Northern Coast of the Island of Malta. The effect of using the different regression techniques for MCP analysis on the power output from the windfarm could therefore be evaluated. The second part of the research used a combination of ARIMA and regression techniques to forecast the energy demand over several years. The output from the windfarm was applied to a model which integrated the said windfarm to an Energy Storage System (ESS) and the electricity grid. Measurement matrices were used to compare the behaviour of the combined windfarm, ESS and electricity grid, based on the actual and predicted data from the various regression techniques used for the MCP analysis and EDF. This created a matrix of results which was used to determine the optimal combination of regression techniques used for MCP analysis and EDF, following which, the optimal capacity of the ESS was established. The long-term behaviour of the windfarm and the of the energy storage system were also predicted. The Levelised Cost of Energy (LCOE) for the windfarm and the Levelised Cost of Storage (LCOS) for the Energy Storage System were also calculated, using different windfarm scenarios, and analysing the error due to the use of the MCP and EDF methodologies. This research therefore established a methodology for combining MCP and EDF to determine the optimal capacity of an ESS which was coupled to an offshore windfarm and the electricity grid. The error in establishing this capacity was determined. The end result was the determination of the LCOE of the windfarm and the LCOS of the ESS based on the combination of MCP analysis and EDF, together with the error introduced due to the use of the two methodologies. Description: Ph.D.(Melit.) Sun, 01 Jan 2023 00:00:00 GMT /library/oar/handle/123456789/141615 2023-01-01T00:00:00Z /library/oar/handle/123456789/141568 Title: The role of hydrogen in the growth of amorphous hydrogenated carbon Authors: Revelle, David; Mule’ Stagno, Luciano; Lin, Shuhan; Feldman, Bernard J. Abstract: We have investigated the role of hydrogen atoms, ions, and molecules in the growth of amorphous hydrogenated carbon by plasma chemical vapor deposition. By varying the ratio of CH4 to H2 in the feedstock, we varied the concentration of hydrogen atoms, ions, and molecules in the plasma. We observed that with increasing hydrogen concentrations in the plasma, the film growth rate decreases, the hydrogen concentration in the grown film decreases, and the optical bandgap decreases. We interpret these results in term of increased hydrogen etching of the carbon-hydrogen bonds that terminate the growing graphite-like crystallites. This leads to larger graphite-like crystallites, lower hydrogen concentrations in the growing film, and consequently, smaller optical bandgaps. Fri, 01 Jan 1993 00:00:00 GMT /library/oar/handle/123456789/141568 1993-01-01T00:00:00Z /library/oar/handle/123456789/141562 Title: Archetype definition for analysing retrofit solutions in urban areas in Europe Authors: De Carli, Michele; Carnieletto, Laura; Di Bella, Antonino; Graci, Samantha; Emmi, Giuseppe; Zarrella, Angelo; Baseggio, Nicola; Belliardi, Marco; Rossi, Leonardo; Mule’ Stagno, Luciano; Badenes, Borja; Urchueguía, Javier; Sanner, Burkhard; Cadelano, Gianluca; Bernardi, Adriana Abstract: Ground Source Heat Pumps (GSHP) are gaining interest for many applications and a very difficult task is to look at their affordability in urban environments with limited spaces. For this reason, the EU project GEO4CIVHIC has been funded. In order to set up different cases with different levels of retrofit and try to generalize results, the project focuses the activity on archetypes, i.e. buildings which may represent the usual type of building which may be found more frequently in urban environments around Europe. The analysis of the archetypes has been based on literature review and analysing the existing databases of buildings in Europe. The work allowed to determine a reference building for single family house and a building representing an apartment block for multi-users. In this latest case two types of possible uses have been examined: residential building and office building. In order to set up different levels of retrofit and cost-effective solutions, three different climates have been defined: warm climate, mild climate and cold climate. The climatic conditions do not only affect the energy demand of the building and the peak power needed for heating and cooling, but also determine different ways of buildings' construction and define different levels of insulation. Last but not least, the buildings have been also subdivided into existing buildings, i.e. built up from 1960 to 2000 and historic buildings, i.e. buildings earlier than 1960. The paper presents the first step of the research which permitted to define the different archetypes, their dimensions and way they are constructed. Moreover, the different simulations allowed to define the energy needs of the buildings as well as the peak power for heating and cooling. This allows to create a matrix for the different levels of retrofit solutions which will be associated to related costs for a cost-benefit analysis to check the most achievable solutions. Tue, 01 Jan 2019 00:00:00 GMT /library/oar/handle/123456789/141562 2019-01-01T00:00:00Z