Levelized Research Articles

Floating solar photovoltaics in the Mediterranean Sea: Mapping and sensitivity analysis of the levelised cost of energy

In this work, the levelised cost of energy (LCOE) from floating solar photovoltaics (PV) is calculated and mapped in the Mediterranean Sea. A breakdown of the factors that influence the LCOE is presented, including site-specific aspects such as distance to shore, water depth and solar resources. To address the uncertainties inherent to any novel technology, a sensitivity analysis is conducted, in which the effects on the LCOE of variations in its factors are quantified. With respect to the numerator of the LCOE (the costs), the results indicate that installation costs, which increase rapidly with distance to shore, play the main role. With respect to the denominator (the energy output), the substantial solar resources of the Mediterranean Sea translate into large annual energy productions overall – a clear advantage for the development of floating solar PV. Going into greater detail, LCOE values are found to be particularly sensitive to: (i) parameters directly linked to the production of energy, e.g., panel capacity and number of panels per structure; (ii) general project and project finance parameters, e.g., number of structures, project lifetime and discount rate; (iii) sources of costs, e.g., structure weight and installation of components. The lowest LCOEs occur in nearshore areas of Libya and Egypt. The Iberian Peninsula presents LCOE values in the range 340–380 €/MWh, and Italy, in the range 380–400 €/MWh. In the Aegean Sea there is high spatial variability, with LCOE values ranging from 320 €/MWh to 500 €/MWh. These results help to identify optimal locations for the deployment of floating PV in the Mediterranean Sea and indicate the key parameters for reducing its cost in future.

A novel multi-objective decision-making model to determine optimum resource and capacity configuration for hybrid electricity generation systems: A comparative case study in Türkiye

The rapid depletion of fossil fuels, their negative environmental impacts due to harmful carbon emissions, and the drawbacks of the sole use of intermittent renewable energy resources on system reliability necessitate the use of more advanced energy system technologies. As a result, hybrid electricity generation systems offer an innovative alternative to conventional energy systems. However, the technical complexity and variability of these systems require the application of multi-objective optimization techniques to determine the optimal sizing and system design. Therefore, in this study, we suggest a multi-objective decision-making (MODM) model that involves five conflicting objectives to find the optimal resource configuration and auxiliary source capacity allocation within the framework of the multi-source electricity production method in Türkiye. The MODM model aims to maximize the utilization of resource potentials and the jobs created, while simultaneously minimizing the levelized cost of energy (LCOE), construction duration, and carbon emissions. The MODM model was solved using fmincon and fgoalattain multi-objective optimization algorithms using the Goal Attainment Method in MATLAB and the model results were subsequently compared to the real-world data. According to the model results, the optimal capacity to be allocated for the auxiliary source units is 13,749.58 MWm, while the capacity allocated according to the real-world data as of March 2024 is 2495.49 MWm. In contrast to the model's prediction of 90.8 % solar-based auxiliary unit installations, 99.8 % of auxiliary units are based on solar PV in the actual case. Furthermore, hydro or geothermal-based auxiliary sources are not allocated any capacity, which is consistent with the actual situation. The capacity allocated for the wind (primary source) + solar (auxiliary source) configuration is 76.2 %, whereas in reality, it accounts for 65.6 % of the total installations. Consequently, the model findings suggest that the maximum capacity allocation is for the wind (primary source) + solar (auxiliary source) type hybrid electricity generation system.

Comparative study of an innovative coldly integrated pumped thermal electricity storage system: Thermo-economic assessment and multi-objective optimization

Energy storage is an important means of solving the instability of renewable energy sources. As a novel energy-storage technology, thermally integrated pumped thermal electricity storage systems have gained considerable attention owing to their capacity to enhance the power-to-power efficiency of pumped thermal electricity storage systems by integrating low-grade heat sources. However, previous studies have predominantly focused on the integration of low-grade heat sources during the charging phase. In this paper, a novel coldly integrated pumped thermal electricity storage system that integrates liquefied natural gas on the discharge side is proposed. Seawater and R1233zd(E) were utilised as the system’s heat source and working fluid, respectively. The performance of the proposed system was compared with that of a previous thermally integrated pumped thermal electricity storage system that used geothermal energy as the heat source on the charge side. System models were constructed in MATLAB, and thermodynamic and economic comparative analyses were conducted. The Genetic Algorithm was adopted for the multi-objective optimisation of the two systems. The results indicate that, within given temperature ranges for thermal and cold storage temperatures, the proposed system exhibits a higher power-to-power efficiency and has a lower levelised cost of storage compared to the existing system. The optimal power-to-power efficiency and levelised cost of storage solutions obtained via multi-objective optimisation were 1.45, 0.297 $·kWh−1 and 0.807, 0.411 $·kWh−1 for the coldly integrated and thermally integrated pumped thermal electricity storage systems, respectively. The proposed system outperformed the thermally integrated pumped thermal electricity storage system under comparison in terms of thermodynamic and economic performance. The findings of this study shed light on the design and performance of coldly integrated pumped thermal electricity storage systems.

A study on the dynamic characteristics of alternative arrangements of floating wind farms with varying hub heights

Wind farms with multiple hub heights have the potential to effectively mitigate velocity deficits resulting from wake effects and reduce the levelized cost of energy (LCOE). While existing research has predominantly focused on studying wake effects on floating wind farms with identical hub heights, there is a notable absence of research on floating wind farms with multiple hub heights. Therefore, a comprehensive understanding of the impact of vertical arrangements on floating wind farms is essential. In light of this gap, this study examines the characteristics of two distinct arrangements of a semi-submersible floating wind farm with multiple hub heights. The configuration includes two 15 MW semi-submersible floating offshore wind turbines (FOWT) and two 5 MW semi-submersible FOWTs. A novel wind farm modeling tool utilizing dynamic wake meandering (DWM) is employed to investigate the power production performance, wake characteristics, global dynamic responses, and fatigue damage of crucial components of each individual FWT, associated with the two different arrangements. The paper presents a discussion of the advantages and disadvantages of the two arrangements, accompanied by a summary of the key findings. The insights gained from this research can serve as a foundational basis for improving the design and analysis processes of floating wind farms with various arrangements.

Performance and Parametric Studies of a Non-Compact Hybrid PV-CSP Power Plant Integrated by a Supercritical Rankine Cycle and an Electric Heater in Series

This study focuses on performing a parametric analysis of the non-compact concentrated solar power (CSP)-photovoltaic (PV) hybrid plant combined with an electric heater (EH) and a Supercritical Rankine Cycle as well as a multi-objective optimization of different technologies. The power plant sizing is evaluated in a baseload dispatch scenario of 165 MWe for a location in Seville and considering combinations of the PV installed power, CSP solar multiple (SM), thermal energy storage (TES) capacity and EH power. Studied parametric combinations are optimized for minimizing the Levelized Cost of Electricity (LCOE) and maximizing the capacity factor (CF), with the ultimate goal of achieving the Pareto front. The results of the study show that certain combinations, such as PV=450 MWe, SM=2, EH=250 MW, and TES=12 h, have a favourable balance between the LCOE and the CF (LCOE=0.0979 €/kWh, CF=0.702). In addition, the results obtained through the optimization process, in particular by considering the Pareto frontier, indicate that among the different technologies, the CSP-PV-TES-EH configuration has the lowest LCOE and the highest FC.

Techno-economic assessment of large-scale sedimentary basin stored–CO2 geothermal power generation

One approach to reducing atmospheric carbon dioxide (CO2) emissions is to adopt carbon capture utilization and storage (CCUS) strategies. This is particularly crucial for countries to achieve their net-zero goal. In this study, we investigate the techno-economic viability of a proposed CCUS process that utilizes geologically stored CO2, associated with hydrogen (H2) production from fossil fuels, as a working fluid to extract geothermal energy from deep, large-scale, sedimentary storage formations. The process ensures permanent geological storage of all injected CO2 while generating adaptable geothermal power through supercritical CO2 turbine expansion, thus, bolstering revenue and reducing the final cost of blue hydrogen production. We simulate subsurface-wellbore fluid flow and heat transport for a representative 4-way closed anticlinal Arabian reservoir and optimize system power output, including a comprehensive and integrated economic analysis. We find that CO2 captured from an equivalent blue H2 production of ∼4.1 Mt./year can be injected at an annual rate of 0.92–1 million metric tons (Mt) per well, resulting in a cumulative sequestration of ∼1.15 gigatons (Gt) of CO2 over 11.5 years. To mitigate the risks of reaching the formation parting pressure at the crest of the anticline and ensuring sufficient CO2 saturation at the production wells, phased drilling schedules and pressure-controlled injection and production are essential. With horizontal production wells, our simulations generate an average geothermal net electricity of 164 MW. The base-case economic analysis reveals a Levelized Cost of Electricity (LCOE) of 77 $/MWh and a Net Present Value (NPV) of 480 million USD over 50 years. In contrast, vertical production wells double LCOE, and the project remains unprofitable throughout its life (negative NPV). Our economic sensitivity analysis further emphasizes how the capacity factor, electricity selling price, and drilling costs govern LCOE and NPV. On the other hand, discount rates and Opex fraction are influential yet uncertain parameters affecting the system's techno-economic outlook. Therefore, our study provides valuable insights into the benefits of geothermal energy production from over 1 Gt of stored CO2 and the associated economic landscape.

Comparison of Parabolic Troughs and Solar Photovoltaic as Solar Field Technology in Dispatchable Solar Power Plants

The use of thermal energy storage (TES) technologies, as means to provide dispatchability to thermally driven solar power production, has long stood as the main argument for the interest and potential competitiveness of Concentrated Solar Power (CSP) when compared to other non-dispatchable alternatives. Whereas reductions of the Levelized Cost of Electricity (LCOE) are observed for CSP in recent years, the notable LCOE reduction observed along this decade in large-scale solar photovoltaics (PV) plants is set to break the taboo of "power-to-heat-to-power" approaches, as its potential economic performance outcasts the associated thermodynamic inefficiency. The possibility of using available resistive heating technologies and components in PV-TES combinations, renders the configuration of a conventional CSP plant suitable for the replacement of a thermal conversion solar field by a photovoltaic field presenting further the possibility of delocalization and/or spatial distribution of the solar field (e.g. on a Carnot Battery configuration). As dispatchability no longer stands as an exclusive argument in favor of CSP over PV, the present article addresses the boundary conditions for the competitiveness of each technology as the champion of dispatchable solar power fields. The impact of both land and electrical heater costs variation in the variation of LCOE for PV-TES plants is much more modest than that observed for the impact of CSP solar field cost variations in the variation of LCOE for CSP plants, which leans for the latter and at present costs, towards better competitiveness for plant designs with a storage capacity in excess of 10.0 FLH (for GHI values in excess of 2100-2200 kWh∙m-2∙year-1).

How retailers can gain more profitability driven by digital technology: Live streaming promotion and blockchain technology traceability?

Live streaming in e-commerce often faces challenges like counterfeit products and high return rates. To mitigate this issue, retailers can adopt blockchain technology for product traceability to enhance consumer trust, i.e., blockchain-traceable products may be sold in live streaming. Our paper presents three analytical models under various return policies to explore how live streaming and blockchain technology interact in e-commerce. Retailers can invest in live streaming with influencers to attract consumers and in blockchain technology to reduce product returns, benefiting from a demand-enhancing effect and a price-enhancing effect, respectively. The retailer’s investment strategy between live streaming and blockchain technology depends on the interactions of these two effects, moderated by the retailer’s budget type, the market commission level of live streaming, and the traceability cost of blockchain technology. For budget-constrained retailers, live streaming and blockchain technology act as substitutes. When the commission level is low (high) and the traceability cost is high (low), the demand-enhancing (price-enhancing) effect dominates the price-enhancing (demand-enhancing) effect, thus the retailer invests in live streaming (blockchain technology) as a substitute for blockchain technology (live streaming). Conversely, for budget-unconstrained retailers, they may act as complements, prompting investment in both when commission levels and traceability costs are low. The retailer does not invest in either when both the commission level and traceability cost are high. We extend our results to a full refund policy to show the robustness of our result and find that it reduces the retailer’s incentive to invest in live streaming or blockchain technology.

Assessment of Colombian renewable energy auctions policy: Enabler or barrier for concentrating solar power plants

Auctions are an alternative for introducing renewable energy (RE) projects into electricity markets at competitive prices. Colombia added 2.2 GW capacity of RE through this mechanism. Nevertheless, 94% of the awarded generation is allocated between 12 a.m. and 5 p.m. because of a lack of low-cost storage. Integrating concentrating solar power plants (CSP) could be relevant in tackling this issue. Therefore, a preliminary step is to determine if Colombian instruments benefit the deployment of CSP and trigger the discussion about its future in the country. In this work, we evaluate how auction mechanisms and fiscal incentives (FI) influence the Levelized Cost of Electricity (LCOE) and Internal Rate of Return (IRR) for two CSP configurations. The results indicate that FIs reduce capital expenditures between 17.11% and 19.45%, reaching similar LCOEs to those reported internationally. However, energy prices higher than USD 150/MWh are required to achieve an adequate IRR. Regarding the auction design, it is observed that a “security criterion” leads to a significant loss of competitiveness for CSP as it neglects its possibility to support demand at night. Policy suggestions are provided for a level playing field where low-cost solutions can coexist with dispatchable renewable power generation.

Economic and Environmental Analyses of an Integrated Power and Hydrogen Production Systems Based on Solar Thermal Energy

This study introduces a novel hybrid solar–biomass cogeneration power plant that efficiently produces heat, electricity, carbon dioxide, and hydrogen using concentrated solar power and syngas from cotton stalk biomass. Detailed exergy-based thermodynamic, economic, and environmental analyses demonstrate that the optimized system achieves an exergy efficiency of 48.67% and an exergoeconomic factor of 80.65% and produces 51.5 MW of electricity, 23.3 MW of heat, and 8334.4 kg/h of hydrogen from 87,156.4 kg/h of biomass. The study explores four scenarios for green hydrogen production pathways, including chemical looping reforming and supercritical water gasification, highlighting significant improvements in levelized costs and the environmental impact compared with other solar-based hybrid systems. Systems 2 and 3 exhibit superior performance, with levelized costs of electricity (LCOE) of 49.2 USD/MWh and 55.4 USD/MWh and levelized costs of hydrogen (LCOH) of between 10.7 and 19.5 USD/MWh. The exergoenvironmental impact factor ranges from 66.2% to 73.9%, with an environmental impact rate of 5.4–7.1 Pts/MWh. Despite high irreversibility challenges, the integration of solar energy significantly enhances the system’s exergoeconomic and exergoenvironmental performance, making it a promising alternative as fossil fuel reserves decline. To improve competitiveness, addressing process efficiency and cost reduction in solar concentrators and receivers is crucial.

Energy comparison and cost estimation of pressure-retarded osmosis using spiral wound membrane

Advancements in Pressure Retarded Osmosis (PRO) technology are enhancing the feasibility of evaluating its economic viability against other renewable energy production methods. This is done using the Levelized Cost of Energy (LCOE) as a metric. The study focuses on three PRO scenarios designed to minimize environmental impact and promote sustainable energy. These scenarios utilize a spiral-wound membrane module combined with hyper-saline solutions from Reverse Osmosis (RO) and wastewater from demineralization processes. Experimental results using a commercial spiral-wound membrane in the PRO system yielded LCOE values of USD 0.0702/kWh for a draw solution (DS) concentration of 36.2 g/l, USD 0.0563/kWh for 44.2 g/l, and USD 0.0721/kWh for 51.8 g/l. The study also evaluated environmental viability by considering the cost of CO2 emissions. This comprehensive comparison highlighted PRO's competitiveness with fossil fuels, showing it to be a reasonable alternative to coal and oil but less practical than natural gas. Specifically, the environmental analysis revealed that PRO is approximately 25.2 % more competitive than coal and 9.76 % more competitive than oil but 27.16 % less competitive compared to natural gas in terms of CO2 emission costs. This underscores the importance of considering carbon emission mitigation in energy generation.

Direct coupling of pressurized gas receiver to a brayton supercritical CO2 power cycle in solar thermal power plants

Three layouts of Brayton supercritical CO2 power cycles directly coupled to the receiver are proposed for Generation 3 solar power plants: conventional recompression, recompression with partial cooling, and recompression with intercooling. To achieve direct coupling, the solar heat is introduced downstream of the turbine, where CO2 pressure is lower. A higher temperature rise diminishes the receiver's dimensions, thus increasing its energy efficiency. It also lowers the average working temperature since the maximum temperature is fixed at 700 °C, thereby reducing losses. However, optical efficiency decreases as the receiver size diminishes. Both intercooling and partial cooling layouts further increase the cycle's net efficiency, which reduces the receiver's size, following similar trends observed with an increase in temperature rise. Considering all these effects, various factors push in opposite directions, affecting overall efficiency and costs. This competitive interplay results in overall efficiencies ranging from 30.26 % to 31.58 % and Levelized Costs of Electricity (LCOEs) between 162.47 €/MWh and 166.81 €/MWh. In conclusion, similar outcomes in terms of energy and economics are achieved with the three layouts, suggesting the simplest layout (recompression) as the most advisable. If thermal storage is incorporated, partial cooling becomes preferable due to its significant increase in the receiver's temperature rise.

Techno-economic optimization of hybrid renewable energy system for islands application

This study evaluates the effects of time resolution on the optimization results of a renewable energy system for an off-grid island. The assessment uses a multi-objective genetic algorithm (MOGA) applied to Tilos Island in Greece. Three objective functions—levelized cost of electricity (LCOE), renewable ratio (RR), and profit—are considered across four distinct scenarios with six variables representing the number of renewable technologies. These cases are implemented using three time resolutions: minute-by-minute, 15-minute, and hourly. A significant difference in results is observed based on the time resolution used. With hourly data optimization, 100 % renewable energy coverage is achievable at Tilos’ current diesel generator cost (0.46 $/kWh). However, using minute-by-minute data, renewable energy coverage ranges from 85.87 % to 95.64 %, depending on the scenario. The primary reason for this discrepancy is the volatile nature of demand and power generation on Tilos Island. The analysis further indicates that the differences between minute-by-minute and hourly optimization diminish as the volatility of the input data to the algorithm decreases.

A comparative configuration and decision of main restrictions of a renewable energy powered campus micro grid: A case study

Higher education institutes are representative of small cities. Availability of building level data enables categorizing the models according to load profile instead of developing one model for whole communities, which is a gap in literature.In this study, hourly electricity consumption data of 34 buildings measured in Selcuk University is utilized to develop optimum Zero energy campus (ZEC) model. ZEC models developed until now used data of whole campus. In this study, campus and building level ZEC models are compared using PV/Wind/Biomass/Hydropower with/without battery.Biomass is found as a good option for high annual electricity consumption (AEC) buildings whereas using more than two type of renewable systems was better for low AEC. Required system size was found to be smaller at campus level design. However, renewable factor (RF) was higher at building level design which decreased levelized cost of electricity (LCOE). Therefore, the main limitation of ZEC is found as electricity selling price. Campus level design will be cost effective in case of electricity selling price to be the same or more then purchasing price. As a result of this study hourly load profile and electricity selling/purchasing prices are found to be the main decision criteria’s on optimum HRES design.

Synergistic Integration of Multiple Wave Energy Converters with Adaptive Resonance and Offshore Floating Wind Turbines through Bayesian Optimization

We developed a synergistic ocean renewable system where an array of Wave Energy Converters (WEC) with adaptive resonance was collocated with a Floating Offshore Wind Turbine (FOWT) such that the WECs, capturing wave energy through the resonance adapting to varying irregular waves, consequently reduced FOWFT loads and turbine motions. Combining Surface-Riding WECs (SR-WEC) individually designed to feasibly relocate their natural frequency at the peak of the wave excitation spectrum for each sea state, and to obtain the highest capture width ratio at one of the frequent sea states for annual average power in a tens of kilowatts scale with a 15 MW FOWT based on a semi-submersible, Bayesian Optimization is implemented to determine the arrangement of WECs that minimize the annual representation of FOWT’s wave excitation spectra. The time-domain simulation of the system in the optimized arrangement is performed, including two sets of interactions: one set is the wind turbine dynamics, mooring lines, and floating body dynamics for FOWT, and the other set is the nonlinear power-take-off dynamics, linear mooring, and individual WECs’ floating body dynamics. Those two sets of interactions are further coupled through the hydrodynamics of diffraction and radiation. For sea states comprising Annual Energy Production, we investigate the capture width ratio of WECs, wave excitation on FOWT, and nacelle acceleration of the turbine compared to their single unit operations. We find that the optimally arranged SR-WECs reduce the wave excitation spectral area of FOWT by up to 60% and lower the turbine’s peak nacelle acceleration by nearly 44% in highly occurring sea states, while multiple WECs often produce more than the single operation, achieving adaptive resonance with a larger wave excitation spectra for those sea states. The synergistic system improves the total Annual Energy Production (AEP) by 1440 MWh, and we address which costs of Levelized Cost Of Energy (LCOE) can be reduced by the collocation.

Analysis of the thermodynamic performance of the SOFC-GT system integrated solar energy based on reverse Brayton cycle

Efficient power generation systems are an essential way to reduce carbon emissions. To avoid the complex effects of high-pressure conditions on the solid oxide fuel cell (SOFC) and gas turbine (GT) hybrid systems, while further improving energy efficiency. A SOFC-GT hybrid system based on the reverse Brayton cycle (RBC) is proposed, in which the SOFC operates at near atmospheric pressure conditions and GT expands below atmospheric pressure. Solar energy is integrated to further enhance system performance. Rigorous assessments of the novel system and the pressurized system are conducted utilizing energy, exergy and economic analysis. The sensitivity analysis of environmental parameters on the novel system's performance is performed. The results show that the novel system generates power and efficiency better than the conventional system when the GT compression ratio is 3 and 6, respectively. The power generation and exergy efficiency of the novel system at the design point is 60.47 % and 58.57 %, respectively. The largest exergy destruction occurred in the SOFC. The lowest exergy efficient components are the parabolic dish collector (PDC) and heat exchanger 2. The novel system is more cost-effective due to the higher lifetime of the SOFC, with the levelized cost of energy (LCOE) is 0.1418 $/kWh.

Economic Aspects of Aircraft Propulsion Electrification

Aircraft propulsion electrification is currently being considered by industry and academia as one of the most promising strategies to reduce air transport emissions and increase overall efficiency levels. In the past decade, several papers were published on this subject, with the majority indicating encouraging fuel burn benefits versus conventional, fossil-fuel-based propulsion systems when future technologies, novel aircraft configurations, and synergistic propulsive-airframe integration are employed. However, a much smaller effort has been applied to the economic aspects of hybrid and fully electric propulsion, which are crucial for a successful product introduction. The present paper describes the modeling of a baseline general-aviation-type aircraft and its propulsion system retrofit with electrified architectures, exploring different electrification strategies for a fixed airframe design. Analyses are performed at the aircraft level, comparing recurring and cash operating costs for several cost and durability scenarios. While considerable CO2 reductions may be achieved in some electrification strategies, aircraft performance is significantly penalized, and important improvements in economic figures of merit are needed in order to make electrified propulsion cost-competitive. Electrified architectures tend to increase costs: turboelectric increases recurring equipment costs, while hybrid-electric increases recurring and direct maintenance costs, especially at higher degrees of energy hybridization.

Performance Analysis and Techno-Economic Evaluation of Solar Energy Retrofitting for Coal-Fired Power Plant in Central Kalimantan Province

The power generation sector significantly contributes to climate change. Mitigation efforts are crucial to adhering to the global commitment to limit temperature increases below 2°C. One potential solution is retrofitting existing power plants with technologies that integrate renewable energy. This study explores the integration of solar energy into the operational processes of a coal-fired power plant in Central Kalimantan, replacing the extraction steam turbine in the high-pressure feed water heater No. 7. Using STEAG EBSILON for simulation, this research evaluates the power plant's performance before and after retrofitting in both power-boost (PB) and fuel-save (FS) modes under varying load conditions. The results demonstrate that thermal efficiency in both PB and FS modes increased by up to 2% compared to the base scenario. Specific fuel consumption decreased by 15.05 g/kWh in PB mode and 15.75 g/kWh in FS mode, leading to a reduction in coal consumption and CO2 emissions by 4.69% and 4.94% respectively. Additionally, the study observed that the solar percentage and solar-to-electricity efficiency increased as the load decreased. In FS mode, the solar electricity proportions at VWO, 100%, 75%, and 50% load rates were 5.23%, 5.53%, 7.76%, and 11.92%, respectively. The levelized cost of energy (LCOE) for solar electricity was calculated to be 431.82 IDR/kWh, with an expected investment return period of 5.87 years.

Strategic operation of electric vehicle in residential microgrid with vehicle-to-home features

The urgent need for innovative energy solutions to facilitate the transition to renewable energy and electric vehicles (EVs) is particularly critical in developing countries, where high emissions and grid reliability challenges persist. This study investigates an off-grid residential renewable energy system with stationary storage like battery and hydrogen, alongside an EV as mobile storage. A bi-level optimization framework is established considering stationary and mobile energy storage options and a strategy is proposed to implement Vehicle-to-Home (V2H) in off-gird settings. Three cases are studied, with optimal component sizing determined using an optimization tool integrated with MATLAB. Firstly, to determine the most cost-effective stationary storage alternative, Case 1 uses hydrogen and Case 2 employs a battery as storage. Then Case 3 integrates the optimal stationary storage with mobile storage using V2H technology enabling the EV to support household energy needs during peak times. Results highlight that combining stationary and mobile storage (Case 3) offers a 15.92% reduction in Total Net Present Cost (TNPC) and a 13.9% reduction in Levelized Cost of Energy (LCOE) compared with stationary storage alone. This off-grid system (Case 3) also outperforms the conventional grid economically and environmentally, offering 2.13× TNPC reduction and 7,813 kg/yr carbon emissions mitigation.

Investigation on vibration control of TetraSpar floating offshore wind turbine

The stability of offshore wind turbines during operation is crucial, and as an emerging technology, the TetraSpar floating offshore wind turbine demonstrates commendable stability. Moreover, it can effectively reduce the levelized cost of energy (LCOE) in production and installation. However, There is relatively scarce research on its dynamic response and reliability under complex ocean conditions. To reduce the vibration response of floating offshore wind turbines in complex marine environments and improve the stability of the turbines, it is necessary to establish a fully coupled dynamic model to study the multi-field coupled dynamic response and vibration control of the turbines. In light of this, this paper establishes a multi-physical field coupled dynamic model for TetraSpar floating offshore wind turbine through an F2A coupling framework, integrating aerodynamics, servo-elasticity, hydrodynamics, and mooring dynamics. The study analyzes the vibration suppression effects of different Tuned Mass Dampers (TMDs) on the wind turbine system. Using the two main response frequencies, 0.0367Hz and 0.57Hz, in the front and rear directions of the wind turbine as the tuning frequencies for TMD. The best vibration reduction effect was achieved by comparing multiple sets of TMD with different parameters. Analysis shows that TMD can significantly reduce the standard deviation of bending moment and tension of steel bars before and after tower foundation, with maximum values of 38.76% and 73.02%, respectively. At the same time, TMDs also impose a burden on wind turbines, such as a maximum increase of 2.23% in the average values of tower base bending moment, platform pitch, and tower top longitudinal displacement, which also slightly increase under extreme sea conditions. However, compared to the significant vibration suppression effect of TMD, it can be ignored.