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Item type:Publication, Access status: without files , Assessment of fuel property enhancement toward TRL advancement in biomass torrefaction(Elsevier, 2026-08-14); ; ; ; Publicationtype: Journal Article14 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Unsteady aerodynamics of large-scale floating offshore wind turbines in surge motion(Elsevier, 2026-03-15); ; ; ; Unsteady aerodynamic loads significantly influence the design and wake flow field of floating offshore wind turbines, especially due to wave- or vibration-induced tower top motions triggering various unsteady phenomena. Recent studies show that increasing turbine sizes amplify unsteady aerodynamic effects, as their impact typically grows with rotor diameter. This work combines recent findings from experiments and simulations on model-scale FOWT aerodynamics with new numerical analyses of large-scale rotors, providing a comprehensive understanding of unsteady phenomena occurrence and impact. Numerical analyses of the IEA 15-MW and 22-MW rotors undergoing surge motions characterise the combined influence of motion-induced unsteady phenomena on rotor thrust. Results indicate that unsteady effects can reduce thrust force variations by up to 40% at realistic surge periods. These findings contrast with prior model-scale rotor investigations, attributed to the specialised design of the model rotors. Comparisons between numerical methods — the dynamic blade element momentum method in OpenFAST and free vortex wake modules in panMARE and OpenFAST — reveal persistent differences in thrust predictions under both idealised and realistic conditions. This highlights that classical blade element momentum approaches require enhancement to accurately capture unsteady loads on large-scale floating offshore wind turbines at low wind speeds.Publicationtype: Journal Article43 50 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Deep eutectic solvent pre-treatment of residual biomass streams – Effects on anaerobic degradability(Elsevier, 2025-08-15); ; ; ; Cam, Miyase DenizThe suitability of residual biomass from biorefineries as biogas substrate, including the effect of DES pre-treatment on biogas potential and biomass composition was evaluated. Three different biomasses, i.e., cork dust, olive tree pruning, and common reed, were treated with a deep eutectic solvent (DES; i.e., choline chloride and formic acid, 1:2 M ratio, 1:10 (g mL−1) solid to solvent ratio) under various conditions. While being ineffective under less severe conditions, significantly increased biogas potentials were observed for all biomasses at 130 °C and 40 and/or 60 min of pre-treatment. Cork dust had the highest relative increase in biogas potential of 125 % (130 °C, 60 min). With an increase of 90 mLN gVS−1 (+21 %), olive tree pruning showed the highest absolute increase. Common reed demonstrated a notable increase of 12 %. Concurrently, kinetic modelling revealed shifts in degradation kinetics, such as altered lag phases and higher maximum biogas rates, hereby the Cone Model provided the best fit for the data. The change could be attributed to delignification and retention of the fermentable glucan fraction in the solid biomass. Despite considerable differences among the biomasses, the results underscore the efficacy of DES pre-treatment in enhancing the anaerobic degradability of residual biomass.Publicationtype: Journal Article32 24 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Near wake hydrodynamics and structural design of a single foil cycloidal rotor in regular waves(Elsevier, 2023-04); ; ; We present a hydrodynamic and structural model to design a single foil wave cycloidal rotor in regular waves. The hydrodynamic part considers potential flow and represents the foil as a point vortex. Unsteady effects are accounted for through Theodorsen's function. The structural part utilises beam theory to compute the bending moments and stresses on the foil of the cyclorotor. The validity of the hydrodynamic model is explored with the aid of CFD, and the CFD results are bench marked versus experimental measurements. Results show that the hydrodynamic model estimates the mean radial loading on the foil within 20%–25% in attached flow conditions, whilst it is accurate to predict the mean tangential loading only when operating close to stall, at maximum lift conditions. Because the optimal structural operation of the rotor is in attached flow conditions, and close to stall, we utilise the coupled model to design a rotor that operates optimally for a range of different sea conditions. We find that with careful dimensioning of the radius and span, power extraction in regular waves can be optimised, whilst the structural penalty is kept constant at the allowable stress level.Publicationtype: Journal ArticleScopus© Citations 4 67 128 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Numerical and experimental study of the hydrodynamic coefficients and power absorption of a two-body point absorber wave energy converterThis study compares the hydrodynamic coefficients of a two-body point absorber wave energy converter (WEC) model obtained by three methods, namely the experimental method, the finite volume method (FVM), and the boundary element method (BEM). The BEM and FVM numerical simulations of the WEC motion are done using ANSYS AQWA and OpenFOAM, respectively. An experimental method for the accurate calculation of the added mass, damping coefficient, and wave excitation force for the WEC is introduced. The experiments are carried out in a wave tank with a scaled-down WEC model. A comparison of the results shows that – although the BEM is computationally fast, inexpensive, and able to estimate the added mass of the WEC with a reasonable accuracy – it is not able to accurately calculate the damping coefficients. The power absorbed by the WEC is calculated using the hydrodynamic coefficients obtained by all methods. The results show that the viscous damping dramatically decreases the absorbed power. A practical range of dimensionless damping coefficients is proposed to estimate the viscous damping of a two-body point absorber WEC, based on the experimental and FVM results. The upper bound of the absorbed power is also discussed in this paper.Publicationtype: Journal Article51 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Capital expenditure and levelized cost of electricity of photovoltaic plants and wind turbines – Development by 2050(2022-02); ; Over the last decade, the levelized cost of electricity (LCOE) of solar and wind energy dropped extraordinary. Within this context, this paper aims to project the capital expenditures (CAPEX) of photovoltaic plants, onshore and offshore wind turbines for 2030 and 2050 by using the experience curve theory. Based on these, LCOE for 2020, 2030 and 2050 are estimated, investigated regarding their sensitivities and compared to fossil fuel based power plants. CAPEX projections amount to 250 to 430 €2020/kWel (2030) and 170 to 330 €2020/kWel (2050) for photovoltaic plants, 940 to 1,210 €2020/kWel (2030) and 820 to 970 €2020/kWel (2050) for onshore wind turbines and 1,730 to 2,570 €2020/kWel (2030) and 1,420 to 2,360 €2020/kWel (2050) for offshore wind turbines. Based on these results the LCOE of photovoltaic plants are estimated to drop up to more than 70 % (2050), while for wind turbines reductions up to 50 % (2050) are calculated. The highest sensitivity of the LCOE was identified for a variation of the CAPEX and annual full load hours. The comparison of the LCOE with fossil fuel operated power plants showed that the considered renewable options can obtain significant lower LCOE.Publicationtype: Journal Article447 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Technical and environmental analysis on the power production from residual biomass using hydrogen as energy vector(2021-09); ; ; Decarbonization of energy by using renewable sources is a global need to tackle climate change. Herein, we report on the techno-environmental analysis of the use of sugarcane press-mud, a residual biomass, as feedstock to produce power in a fuel cell by using hydrogen (H2) as energy vector. Technical analysis was performed by using experimental and Aspen plus simulation results whereas environmental analysis was assessed through life cycle assessment. Raw bioethanol was used as H2 source, which was purified by three different technologies, i.e., flash, mash, and rectification columns. Mash column was selected as the suitable process to purify bioethanol for producing H2 and power, mainly ascribed to the reduction of bioethanol impurities that increases H2 yield, reduces energy demand, and mitigates the environmental impact in terms of global warming potential and acidification potential. This technology presented an energy efficiency of 56 %, a renewability factor of 1.24 and a carbon footprint of 1.21 kg CO2 kWh−1. Additionally, the use of residual biomass showed environmental benefits in comparison with the use of first-generation bioethanol from sugarcane molasses. Therefore, using sugarcane press-mud as power source in rural areas can diversify the energy sources to move towards a decarbonized economy.Publicationtype: Journal Article70 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Autoclave pre-treatment of foliage – Effects of temperature, residence time and water content on solid biofuel propertiesFoliage is a biogenic material occurring outside the tropical areas typically in autumn. This material is mostly not used for the production of energy because foliage is often characterized by a very high moisture and ash content as well as adhering impurities. Cleaning and drying are very energy-intensive; i.e. the additional energy used for drying is often in no relation to the possible energy yield. In such cases, heat-induced autoclave pre-treatment could be used to improve the solid biofuel properties of the foliage with regard to a subsequent energetic utilization. Here the effects of temperature, residence time and initial water content during autoclave pre-treatment were determined for foliage. The results show that such an autoclave pre-treatment can significantly improve higher heating value by 15 %, grindability, drying behaviour and concurrently reduces moisture content up to 30 wt% and equilibrium moisture content over 40 wt%. Thereby, the investigated effects can only insignificantly reduce the amount of inorganic components and should be separated before autoclave pre-treatment. The optimum operating conditions identified in this study also indicate that temperatures of 170 °C, at residence times of 3 h and an initial water content of the foliage of 50 wt% lead to an improvement of the solid biofuel properties.Publicationtype: Journal Article57 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Laboratory-scale additive content assessment for aluminum-silicate-based wood chip additivation(2021-02); ; This paper analyzes the aluminum-silicate-based additivation of wood chips with regard to the retention of the ash and particulate matter (PM) forming element potassium (K) in high-temperature stable ashes. In terms of additivation, two types of the aluminum-silicate-based additive kaolin are used. The wood-additive-samples are analyzed in detail with respect to the ash content, the recovery rate of the ash and PM forming element K, the crystalline phases of the high-temperature stable ashes and the achieved additivation efficiency by means of an experimental as well as a theoretical approach. Based on the obtained findings, a general suitability of wood chips for additivation can be derived. Thereby, assessing the additive content solely based on stoichiometric calculations considering the alkali element content in the biomass and applying generalized safety factors from the literature turned out to be not advisable during the present study. Instead, the presence of alkaline earth elements originating from the biomass and the actual additivation process need to be considered as well. Given the composition of the wood chips in the present study and the applied additivation process, advisable additive contents between 1.49 wt%a.r. and 3.53 wt%a.r. were determined based on theoretical calculations.Publicationtype: Journal Article49 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Life cycle assessment (LCA) of the energetic use of bagasse in Iranian sugar industrySugar production from sugar cane in Iran has been increased steadily in recent years. The same is true for bagasse remaining after sugar extraction from the sugar cane stalks as one of the main co-products. Nowadays, the residue is mostly disposed and thereby causes environmental concerns. But bagasse can be used for the provision of heat and/or electricity within the sugar refineries. The present study examines and compares the cradle-to-gate life cycle impacts of the energy generation from bagasse along with cane trash based on combustion, gasification or anaerobic digestion (AD) exemplarily in Iran. The paper shows that the three conversion options for bagasse are characterized by quite different environmental key figures. In tendency the combustion option shows the most promising figures compared to gasification and AD especially when considering the potential of exporting the surplus electricity to the grid and also savings of greenhouse gas emissions. However, gasification and biogas production can be potentially characterized by a much better environmental performance in some impact categories. Additionally, the market maturity of the combustion option is much better than the other two options along with also its data availability and reliability.Publicationtype: Journal Article151