Alessandro Bianchini

• PhD
• Professor (Associate) at University of Florence

Renewable energy production is one of the pillars of the decarbonization process for the electricity system. The use of hydrogen can also contribute to the decarbonisation of industrial sectors such as chemicals, steel production, heavy industry, and long-distance transports. In Italy, a significant growth in wind and photovoltaic production is alr...

Tilos, a Greek island in the Mediterranean Sea, hosts a pioneering hybrid energy system combining an 800-kW wind turbine and a 160-kWp photovoltaic (PV) field. The predominance of wind power makes the energy production of the island almost constant during the year, while the consumption peaks in summer in correspondence with the tourist season. If...

Darrieus-type vertical axis turbines are suitable for hydrokinetic applications, particularly when deployed in arrays within rivers and small watercourses. However, modelling their complex and unsteady hydrodynamic interactions, both among turbines and with channel boundaries and free water surface, remains a significant challenge. This study devel...

This study investigates the aerodynamic and wake dynamics of floating wind turbines under the combined influence of platform motion and dynamic blade pitch control. Specifically, it focuses on the dynamic induction control strategy employed to mitigate wake losses in wind farms. A series of wind tunnel experiments were conducted using a scaled mode...

Research is flourishing on how to model, mitigate, or even try to exploit the complex motions floating offshore wind turbines (FOWTs) are subjected to due to the combined loading from wind, waves, currents, and buoyancy effects. While preliminary studies made use of simplified inflows to focus attention on blade-flow interaction, recent evidence su...

The efficiency gains observed in a pair of closely spaced Darrieus turbines suggest the deployment of multiple turbines as an appealing solution for wind and, particularly, hydrokinetic applications, where the inflow direction is constant. The present study develops some design guidelines for closely spaced hydrokinetic Darrieus turbines by analyzi...

Floating offshore wind turbines represent a promising new technology in offshore renewables, but they are still in their early stages with few prototypes and limited performance data. As part of the NETTUNO research project, this study examines how platform movement affects the aerodynamics of a floating wind turbine rotor and connects its load res...

Accurate prediction of energy demand is necessary for efficient power system operation, particularly in energy systems with high renewable sources integration. This study compares different methods for predicting load demand using statistical regression. In particular, the goal is to provide insights on the differences between simpler AutoRegressiv...

To ensure that stall control performs correctly in wind turbines making use of this logic, having accurate airfoil data near and post the stall limit is crucial. Due to the scarcity of experimental data, Computational Fluid Dynamics (CFD) simulations are increasingly used to this end, although modelling stall is critical due to the impact of turbul...

Water shortage is one of the main problems for small, isolated islands, especially in the Mediterranean Sea. Water supply in those areas relies on maritime transport through tanker ships, especially during periods of high demand. However, this solution is unsuitable for isolated islands due to the high costs and environmental impact. This study aim...

Gas evolution and flow patterns inside an alkaline electrolyzer cell strongly affect efficiency, although such effects have not been explored in detail to date. The present study aims to critically analyze the dependence of cell performance on the multiphase flow phenomena, defining some key metrics for its assessment using CFD. Six performance ind...

Due to additional complexity and computational cost, most of the techno-economic analyses presented to date on hybrid energy systems overlooked the long-term performance decay of components. This study introduces a novel simulation approach that accounts for degradation effects while maintaining a reasonable computational cost, achieving a 88.5 % t...

Experimental testing at the test rig still plays a key role in the development of new centrifugal compressor designs for industrial applications. Although a wide set of different probes is used as per common practice, the overall impact of the probes? dimensions on the stage performance and rangeability is often assumed to be negligible. In this st...

Bringing floating offshore wind turbines (FOWTs) to a real industrial maturity and reducing the levelized cost of floating wind energy are key to significantly increasing the penetration of renewables in the energy mix of Mediterranean countries, especially if in combination with suitable energy storage systems, such as those involving green hydrog...

The potential of Darrieus-type Vertical Axis Turbines (VATs) in hydrokinetic applications, especially when deployed into arrays or clusters, has gained recognition in the field of distributed energy production. Due to the complex unsteady hydrodynamics of these turbines and the different flow scales involved, numerical studies to date have often fo...

Structural simulations are key for designing the wheel of a turbocharger’s turbine. These simulations enable the assessment of components’ durability and performance in demanding conditions such as extreme exhaust gas temperatures, facilitate the development of the cooling strategies that essential for managing excessive heat, and allow enhancing t...

Experimental testing at the test rig still plays a key role in the development of new centrifugal compressor designs for industrial applications. Although a wide set of different probes is used as per common practice, the overall impact of the probes’ dimensions on the stage performance and rangeability is often assumed to be negligible. In this st...

The efficiency gains observed in a pair of closely spaced Darrieus turbines are suggesting the deployment of multiple turbines as an appealing solution for wind and, particularly, hydrokinetic applications, where the inflow direction is constant. The present study develops some design guidelines for closely spaced hydrokinetic Darrieus turbines by...

Dynamic stall is a phenomenon of primary interest in the design of modern wind turbines, whose long, and unprecedently flexible blades are exposed to continuous variations of the angle of attack due to the incoming non-uniform flow. Despite the importance of an accurate modelling of dynamic stall for a proper aeroelastic design of the rotor and the...

The Actuator Line Method (ALM) is gaining popularity in wind turbine simulations, as it can better handle some of the challenging operating conditions experienced by modern machines, such as highly turbulent inflows, severe aero-elastic forcing, and complex rotor-to-rotor interactions. However, it still falls behind other medium-fidelity methods su...

An accurate reconstruction of the Atmospheric Boundary Layer (ABL) is key for the estimation of energy production and loads in modern wind turbines since, at current rotor heights, the vertical structure of the ABL is heavily influenced by thermal stratification effects. The wind power community usually accounts for these effects by semi-empirical...

The Actuator Line Method (ALM) is gaining popularity in wind turbine simulations, as it can better handle some of the challenging operating conditions experienced by modern machines, such as highly turbulent inflows, severe aero-elastic forcing, and complex rotor-to-rotor interactions. However, it still falls behind other medium-fidelity methods su...

The study presents a systematic comparison between two of the most-credited dynamic stall models for wind turbine applications: the original Beddoes-Leishman (BL) model and the newly-developed IAG. The scope of such comparison, supported by experimental data, is to shed new light on the actual suitability of current dynamic stall models for their i...

A correct estimation of fatigue and ultimate loads on the structure is key for wind turbine design and certification. In a greater perspective, wind turbines are large structures placed in the natural environment and are thus subject to environmental loads that are stochastic in nature. In the case of offshore turbines, the design space is even vas...

Accurate estimation of the oncoming wind is key to ensure an accurate control of any wind turbine. The wind speed is commonly measured with an anemometer located on the nacelle; hence, the measurement is influenced by the rotor and the nacelle itself and needs to be corrected so as not to incur inaccurate energy yield assessments. This study introd...

Stall regulation turbines still represent the preferred solution for small wind turbines. In stall-controlled rotors the controller plays a key role but, differently from pitch-based ones, no open-source controller was available to date. The study presents the UNICO (UNIfi research COntroller) controller, which has been specifically developed for v...

Wind energy is almost unanimously thought to be a key catalyst in enabling a rapid transition from fossil fuels to a system based largely on renewable power. If the history of wind energy in the last fifty years has been to a large extent a success, it still needs to progress to respond to the new challenges coming from the upscaling of the rotors...

Blade element momentum (BEM) theory is the backbone of many industry-standard wind turbine aerodynamic models. To be applied to a broader set of engineering problems, BEM models have been extended since their inception and now include several empirical corrections. These models have benefitted from decades of development and refinement and have bee...

Floating offshore wind is widely considered to be a promising technology to harvest renewable energy in deep ocean waters and increase clean energy generation offshore. While evolving quickly from a technological point of view, floating offshore wind turbines (FOWTs) are challenging, as their performance and loads are governed by complex dynamics t...

To ensure a higher penetration of wind energy in local and national energy mixes, power variability induced by wind fluctuations needs to be limited. In this study, three power smoothing approaches are proposed and compared to the conventional unconstrained behavior. The first method makes use only of a state-of-the-art Li-Ion battery (BESS), while...

To realize the projected increase in worldwide demand for floating offshore wind, numerical simulation tools must capture the relevant physics with a high level of detail while being numerically efficient. This allows engineers to have better designs based on more accurate predictions of the design driving loads, potentially enabling an economic br...

The actuator line method (ALM) is increasingly being preferred to the ubiquitous blade element momentum (BEM) approach in several applications related to wind turbine simulation, thanks to the higher level of fidelity required by the design and analysis of modern machines. Its capability to resolve blade tip vortices and their effect on the blade l...

Aeroelasticity is recognized as the key enabler that allowed for the massive upscaling of wind turbines in the last decade, leading to long, slender, and flexible blades that equip rotors with lower specific power and unprecedented energy conversion capabilities. In this study, a selection of case studies with increasing size, specifically the NREL...

The realization of mathematical, multi-physics models for alkaline electrolyzers is crucial for advancing this technology. Lumped parameter models offer shorter simulation times, compared with other approaches, and practical industrial applications. If electrochemical models provide the polarization curve, the hydrogen production rate, and the devi...

The variability of energy production from renewable sources remains the main issue hampering their larger penetration in current energy grids. While batteries have been proven to work well in many applications, their cost and environmental footprint are opening room for alternative systems. In this study, the innovative isothermal compressed air en...

This study reports the results of the second round of analyses of the Offshore Code Comparison, Collaboration, Continued, with Correlation and unCertainty (OC6) project Phase III. While the first round investigated rotor aerodynamic loading, here, focus is given to the wake behavior of a floating wind turbine under large motion. Wind tunnel experim...

Hybrid energy systems comprising renewables (mainly wind and solar) and storage systems are increasingly welcome to serve small communities or areas, such as small islands. In particular, the present study deals with the hybrid power station of Tilos, a little island located in the Greek Dodecanese, which includes a 800 kW wind turbine, a 160kWp PV...

The accurate evaluation of thermally-induced stresses is of particular importance for life-cycle analysis of modern turbochargers. Conjugated heat-transfer (CHT), steady-state calculations represent the state-of-the-art, whose temperature distribution is usually imported into a structural solver as a thermal load for carrying out thermo-structural...

In the case of floating wind turbines (FOWTs), international design standards currently leave a larger degree of freedom to engineers in the specification of the boundary conditions for turbine simulation and certification. This is due to fact that FOWTs are still a young technology, and standards are still evolving. To analyze offshore wind turbin...

As research and industrial interests around FOWTs has grown, an aspect that has recently emerged is the fact that, because a floating foundation is inherently more compliant than a fixed one, in many instances tower resonance frequencies are effectively shifted upwards. While onshore wind turbine towers are typically designed with a soft-stiff appr...

To realize the projected increase in world-wide demand for floating offshore wind, numerical simulation tools must capture the relevant physics with a high level of detail while being numerically efficient. This allows engineers to have better designs based on more accurate predictions of the design driving loads, potentially enabling an economic b...

The evaluation of thermally induced stresses is key for life-cycle analysis of turbochargers and the use of conjugated heat transfer (CHT) steady-state calculations coupled with structural analyses represents the state-of-the-art. In case of transient analyses, the different timescales of convective and conductive heat transfer mechanisms lead to h...

Blade Element Momentum (BEM) theory is the backbone of many industry-standard wind turbine aerodynamic models. To be applied to a broader set of engineering problems, BEM models have been extended since their inception and now include several empirical corrections. These models have benefitted from decades of development and refinement and have bee...

Consensus is arising on considering floating offshore wind as the most promising technologies to increase renewable energy generation offshore. While evolving fast from a technological point of view, Floating Offshore Wind Turbines (FOWTs) are challenging, as their performance and loads are governed by complex dynamics that are a result of the coup...

The Actuator Line Method (ALM) is being increasingly preferred to the ubiquitous Blade Element Momentum (BEM) approach in several applications related to wind turbine simulation, thanks to the higher level of fidelity required by the design and analysis of modern machines. Its capability to resolve the vortex-like structures shed at the blade tip (...

Due to geographical constraints, the energy supply of communities living on small Mediterranean islands has always been an issue. Renewables potentially represent a game changer, but the power production from wind turbines and solar panels is heavily dependent on weather conditions, making the match between electrical production and demand much mor...

Bringing floating offshore wind turbines (FOWTs) to a real industrial maturity and reducing the levelized cost of floating wind energy are key to significantly increase the penetration of renewables in the energy mix of Mediterranean countries, especially if in combination with suitable energy storage systems, such as those involving green hydrogen...

Wind energy is foundational for achieving 100 % renewable electricity production, and significant innovation is required as the grid expands and accommodates hybrid plant systems, energy-intensive products such as fuels, and a transitioning transportation sector. The sizable investments required for wind power plant development and integration make...

The deployment of multiple closely-spaced Darrieus turbines has recently gained interest in the academic and industrial sectors due to their potential to increase power output and wake recovery. However, the computational cost of accurate three-dimensional, blade-resolved CFD analyses rapidly becomes unfeasible as long as multiple rotors are added,...

The study presents a combined experimental and numerical analysis of the impact of external losses in defining the real performance of a model stage. This is of particular importance in the early-validation phase, where novel solutions going beyond the state of the art need to be verified for the first time. Due to the number of simulations to be c...

Mediterranean islands have always struggled with power supply, with the high cost of electrical submarine cables prompting the pursuing of energy self-sufficiency with renewable energy sources (RES). Despite being clean and sustainable, RES are intermittent and unpredictable, hence the integration of a storage system is crucial to match load with p...

Green hydrogen is among the most promising energy vectors that may enable the decarbonization of our society. The present study addresses the decarbonization of hard-to-abate sectors via the deployment of sustainable alternatives to current technologies and processes where the complete replacement of fossil fuels is deemed not nearly immediate. In...

This paper provides a summary of the work done within Phase III of the Offshore Code Comparison Collaboration, Continued, with Correlation and unCertainty (OC6) project, under the International Energy Agency Wind Technology Collaboration Programme Task 30. This phase focused on validating the aerodynamic loading on a wind turbine rotor undergoing l...

In recent years, Darrieus turbines have received increasing attention by both the industrial and the academic sector due to their advantages for both wind and hydrokinetic applications. Experimental and numerical investigations showed that the interaction between closely spaced Darrieus rotors can lead to a significant increase in their efficiency....

This study reports the results of the second round of analyses of the OC6 project Phase III. While the first round investigated rotor aerodynamic loading, here focus is given to the wake behavior of a floating wind turbine under large motion. Wind tunnel experimental data from the UNsteady Aerodynamics for FLOating Wind (UNAFLOW) project are compar...

The present study investigates the feasibility of coupling the intermittent electric power generation from a wind farm with alkaline electrolyzers to produce green hydrogen. A physically accurate model of commercial electrolytic modules has been first developed, accounting for conversion efficiency drop due to modules’ cool down, effects of shutdow...

Availability of reliable and extended datasets of recorded power output from renewables is nowadays seen as one of the key drivers to improve the design and control of smart energy systems. In particular, these datasets are needed to train artificial intelligence methods. Very often, however, datasets can be corrupted due to lack of records connect...

Wind energy is anticipated to play a central role in enabling a rapid transition from fossil fuels to a system based largely on renewable power. For wind power to fulfill its expected role as the backbone – providing nearly half of the electrical energy – of a renewable-based, carbon-neutral energy system, critical challenges around design, manufac...

The availability of accurate numerical tools for predicting the energy consumption of recreational crafts is pivotal in view of reducing the environmental impact on local waters. A computationally efficient digital twin capable of accurately predicting the boat resistance is thus required to account for the energy fluxes. In the study, an improved...

Cryogenic piston pumps are commonly found in cryogenic systems to pressurize low-temperature liquefied fuels, such as liquified natural gas (LNG) or hydrogen, which are then gasified and stored in high-pressure vessels. The main challenges to be tackled in the design of these machines concern the low operating temperatures, high discharge pressures...

Offshore wind turbines are subject not only to varying wind conditions during their lifetime, but also sea conditions. Therefore, in addition to wind speed, other sea-related quantities need to be considered to characterize a specific installation site. International standards suggest that, at a minimum, significant wave height, peak spectral perio...

In the study, an extended sensitivity analysis is presented, which was aimed at properly tuning the parameters of an algorithm based on the Discrete Wavelet Transform (DWT) for use in power smoothing of utility-scale wind turbines coupled with batteries. More specifically, a twofold implementation is proposed, so that the proposed algorithm can ope...

For many years, wind turbine blade experts have based their designs on airfoil polars obtained with panel methods. These are quick to be set and sufficiently robust. On the other hand, their accuracy intrinsically decreases after stall, where simple post-stall extrapolation functions are introduced. Also, the complex shapes of wind turbine blade ai...

Small wind turbines (SWTs) have known alternate fortune but can now play a key role in distributed production to foster energy transition. Among the typical features of small machines, the use of stall regulation is a distinctive one, since the ubiquitous variable speed pitch regulation used in utility-scale rotors is hampered by space constraints...

The installation of new renewable power plants in Italy is currently hindered by various concurrent factors, the length of the authorization process above all. The average time to authorize a wind farm is about five and a half years, mainly due to the binding judgment of the EIA (Environmental Impact Assessment). Italy however is now in a phase whe...

Weather routing (WR) systems are widely adopted in the maritime transport since safety of goods and saving of fuel are crucial for shipping companies. However, the need of protecting the local coasts and reducing CO 2 emission is making WR attractive even for the market of leisure boats, especially if comfort and safety are also accounted. In the p...

Replacing the bulk of grey hydrogen needed by industrial processes with a green one is one of the challenges of energy transition. In this study, the problem is analyzed from the perspective of a pre-determined amount of hydrogen to be delivered to hard-to-abate industries (steel mills and chemical industries) and produced by a wind farm converted...

To date, the most industrially developed technology to produce green hydrogen is represented by alkaline water electrolysis (AWE). To improve on design and efficiency of these devices, however, multiphysics simulations based on Computational Fluid Dynamics (CFD) are needed, able to account for electrophysical phenomena and multiphase flows. Focusin...

In work package 2 of the FLOATECH project a detailed validation and verification of the capabilities of QBlade-Ocean is carried out. A detailed description of the models used in the validation is provided in Deliverable 2.1 and results of the validation that was carried out are presented in Deliverable 2.2. Some modifications to the models used in...

While most wind energy comes today from utility-scale machines, small wind turbines SWTs can still play a role in off-grid installations or in the context of distributed production and smart energy systems. Due to cost reasons, SWTs (especially up to 100kW) are usually controlled via progressive stall of the blades. Accurate airfoils polars are the...

Among proposed solutions for power augmentation of Darrieus turbines, one of the most promising is represented by Radial Guide Vanes (RGVs) which can potentially increase both the velocity magnitude and the swirl of the incoming flow, without losing omni-directionality like in the case of diffusers. The main drawback of this technology is the incre...

While modern wind turbines have become by far the largest rotating machines on Earth with further upscaling planned for the future, a renewed interest in small wind turbines (SWTs) is fostering energy transition and smart grid development. Small machines have traditionally not received the same level of aerodynamic refinement as their larger counte...

Darrieus vertical-axis turbines are known for their complex aerodynamics connected to the continuous change in the angle of attack experienced by the blades, which often exceeds the static stall limit. Low fidelity tools such as the Blade Element Momentum Theory have been shown lately not to provide sufficient levels of accuracy, while the medium-f...

This report constitutes deliverable 2.2 of the FLOATECH project, funded under the European Union’s Horizon 2020 research and innovation programme under grant agreement No 101007142. For the detailed validation and verification of the capabilities of QBlade-Ocean in work package 2 (WP2) of FLOATECH, a detailed definition of the three considered mod...

This paper provides a summary of the work done within Phase III of the Offshore Code Comparison, Collaboration, Continued, with Correlation and unCertainty project (OC6), under International Energy Agency Wind Task 30. This phase focused on validating the aerodynamic loading on a wind turbine rotor undergoing large motion caused by a floating suppo...

Wind energy is anticipated to play a central role in enabling a rapid transition from fossil fuels to a system based largely on renewable power. For wind power to fulfill its expected role as the backbone—providing nearly half of the electrical energy—of a renewable-based, carbon-neutral energy system, critical challenges around design, development...

Upscaling is currently seen as one of the most promising techniques to lower the Levelized Cost of Energy of wind farms and is a trend that has been ongoing for many years. Floating wind turbines are still a quite novel technology. In this kind of application, the benefits of upscaling are potentially even greater than those that can be seen in lan...

While modern wind turbines have become by far the largest rotating machines on Earth with further upscaling planned for the future, a renewed interest in small wind turbines is fostering energy transition and smart grid development. Small machines have traditionally not received the same level of aerodynamic refinement of their larger counterparts,...

The Actuator Line Method (ALM) is an accurate and efficient tool for the simulation of Darrieus rotors, but fails to resolve the vortex-like structures shed at the blade ends. In order to investigate the reasons behind such issue, this study uses the ALM tool developed by the authors in the ANSYS® FLUENT® environment (v. 20.2) to simulate both a st...

Large, highly flexible wind turbines of the new generation will make designers face un-precedent challenges, mainly connected to their huge dimensions. To tackle these challenges, it is commonly acknowledged that design tools must evolve in the direction of both improving their accuracy and turning into holistic, multiphysics tools. Furthermore, th...

This wind tunnel study investigates the aerodynamic effects of mini Gurney flaps (MGFs) and their combination with vortex generators (VGs) on the performance of airfoils and wind turbine rotor blades. VGs are installed on the suction side aiming at stall delay and increased maximum lift. MGFs are thin angle profiles that are attached at the trailin...

Oscillating water column (OWC) devices are the technical solution more favourably considered for a significant future exploitation of the energy potential of sea waves. While theoretically quite simple, these systems are indeed rather complex in terms of correct tuning between the caisson and turbine. Recent studies showed that only a holistic appr...

This paper describes the results of an extended experimental campaign, reporting surface pressure measurement over one of the blades of the Berlin Research Turbine (BeRT), placed in a closed-loop wind tunnel facility. BeRT is a three-bladed horizontal axis wind turbine with a 3 m rotor diameter. The focus is, on the one side, on the three-dimension...

Leading edge erosion of wind turbine blades is still an important challenge for wind energy professionals, both at research and industrial level. While the efficiency and durability of materials and coatings are improving rapidly, it is important to explore innovative solutions at the aerodynamic design level to mitigate the adverse effects of surf...