Browsing by Author "Hart, Phil"
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Item Open Access Comparative study between S-N and fracture mechanics approach on reliability assessment of offshore wind turbine jacket foundations(Elsevier, 2021-06-14) Shittu, Abdulhakim Adeoye; Mehmanparast, Ali; Hart, Phil; Kolios, AthanasiosThis paper investigates from a structural reliability assessment (SRA) perspective the fatigue reliability using the S-N curve approach compared with the fracture mechanics (FM) approach for a typical welded offshore wind turbine (OWT) jacket support structure. A non-intrusive formulation was developed for an OWT jacket support structure in 50 m deep water, consisting of a sequence of steps. First, stochastic parametric 3D (three-dimensional) Finite Element Analysis (FEA) simulations are performed, taking into account stochastic variables such as wind loads, wave loads and soil properties using facilities within the software package ANSYS. Secondly, the FEA results are post-processed using an Artificial Neural Network (ANN) response surface modelling technique deriving the performance functions expressed in terms of stochastic variables. Finally, the First Order Reliability Method (FORM) is applied in calculating the reliability index values of components. The developed framework was applied to elucidate the fatigue damage process, including the small to long crack transition amongst other stages, for structural steels used for OWT jacket applications. The FM formulation investigated includes a crack growth formulation based on the bilinear crack growth law, considering both segments of the crack growth law as non-correlated and correlated in calculating the reliability index (RI). Sensitivity analysis results showed a strong dependence of the structure's reliability levels on the uncertainties of the crack growth law constants measured in terms of coefficient of variation (COV). Also investigated, was the reliability of the structure reassessed and updated in the presence of assumed structural health monitoring/ condition monitoring (SHM/CM) data. The results from the case study revealed that fracture reliability is highly sensitive to the initial crack size. It is recommended to apply the S-N curve method at the design stage while the FM approach applied towards the end of the design life as the structure approaches failure.Item Open Access Data underpinning research article "Optimising Renewable Energy Integration in New Housing Developments with Low Carbon Technologies"(Cranfield University, 2021-02-09 00:33) Chowdhury, Jahedul; Ozkan, Nazmiye; Hart, Phil; Varga, Liz; Hu, YukunThis file includes data for energy demand and generation profile for different house types in the UK. It also contains data for daily average solar irradiance for typical UK weather conditions that were used for calculating PV outputs.Item Open Access Decommissioning strategy to reduce the cost and risk-driving factors in the offshore wind industry.(Cranfield University, 2021-05) Adedipe, Tosin; Hart, Phil; Shafiee, MahmoodWith the increasing number of wind turbines approaching their end of life, there has to be a decommissioning strategy in place as the removal of these assets is not as direct as reverse installation. Offshore asset decommissioning involves technical, financial, operational, safety, policy, and environmental considerations on handling offshore marine assets at their end-of-life, with phases from the planning to site clean-up and monitoring. Offshore decommissioning activities cost significantly more than onshore; thus, adequate financial and safety provisions are essential, and more research required in this area. Decommissioning projects have hitherto been performed on a small scale, but with large-scale aging structures, they must be optimised for lowered costs and risks. In terms of planning, execution and costs, there have been significant cost overruns on decommissioning projects, which are not profit-generating projects. These forecasted large-scale decommissioning activities also have associated risks. Although risk management is a well-researched area, there is limited literature on offshore wind decommissioning risk management. This research thus, applies risk management methods and strategies to develop a robust decommissioning risk framework. In addition, to improve decommissioning processes and technologies, there is a need to develop new protocols for decommissioning. This research identifies potentials for computational simulations and automations that need to be developed to identify and manage the highest cost and risk-drivers. This study seeks to close the research gap in understanding how to decrease decommissioning costs and risks. This research addresses potential opportunities in cost and risk estimation research, impact analysis and reduction frameworks that can be adapted to decommissioning activities specific to the offshore wind industry.Item Open Access Design and planning of energy supply chain networks.(Cranfield University, 2019-10) Murele, Oluwatosin Christiana; Hanak, Dawid P.; Hart, PhilDuring a period of transformation towards decarbonised energy networks, maintenance of a reliable and secure energy supply whilst increasing efficiency and reducing cost will be key aims for all energy supply chain (ESC) networks. With the knowledge that about 80% of global energy is obtained from fossil fuels, appropriate design and planning of its supply chain networks is inevitable. Notwithstanding, renewable energy sources, such as biomass, solar, wind and geothermal, will also play important roles in the future ESCs as climate change mitigation becomes an increasingly important concern. To achieve this aim, energy systems optimization models were derived; (i) for the simultaneous planning of energy production and maintenance in combined heat and power (CHP) plants for overall cost reduction, with results obtained benchmarked against data from industry; (ii) for biomass integration into ESC networks for emissions reduction and benchmarking it against data from literature and the governing equations solved for optimality using the General Algebraic Modelling System (GAMS) software. Further, energy survey questionnaires were developed using the Qualtrics online survey tool and same disseminated to individuals in some counties of the United Kingdom (UK) with the aim of proposing strategies for improved renewable energy (RE) embracement in the UK energy mix. The case study of the coal-fired CHP plant predicted a 21% reduction in annual total cost in comparison to the implemented industrial solution that follows a predefined maintenance policy, thereby, enhancing the resource and energy efficiency of the plant. Additionally, the optimization model for integrating biomass into energy supply chain networks indicated that a reduction in the emissions level of up to 4.32% is achievable on integration of 5-8% of biomass in the ESC with a 4.57% increase in the total cost of the ESC network predicted at biomass fraction of 7.9% in the mixed fuel, indicating that the cost increment in a biomass and coal co-fired plant can be offset with the introduction of effective carbon pricing legislation.Item Open Access Energy transition at local level: analyzing the role of peer effects and socio-economic factors on UK solar photovoltaic deployment(Elsevier, 2020-11-03) Balta-Ozkan, Nazmiye; Yildirim, Julide; Connor, Peter M.; Truckell, Ian; Hart, PhilA growing literature highlights the presence of spatial differences in solar photovoltaic (PV) adoption patterns. Central to forward planning is an understanding of what affects PV growth, yet insights into the determinants of PV adoption in the literature are limited. What factors do drive the adoption at local level? Are the effects of these factors geographically uniform or are there nuances? What is the nature of these nuances? Existing studies so far use aggregate macro datasets with limited ability to capture the role of peer effects. This paper considers some established variables but also broadens the base of variables to try to identify new indicators relating to PV adoption. Specifically, it analyses domestic PV adoption in the UK at local level using data on the number of charities as a proxy to capture the opportunities to initiate social interactions and peer effects. A geographically weighted regression model that considers the spatially varying relationship between PV adoption and socio-economic explanatory variables reveals significantly more variability than the global regression. Our results show that charities and self-employment positively influence PV uptake while other socio-economic variables such as population density has bidirectional impacts.Item Open Access A holistic risk management framework for renewable energy investments(Elsevier, 2022-03-04) Abba, Yahajja Zara Ibrahim; Balta-Ozkan, Nazmiye; Hart, PhilPrivate investments are critical enablers to achieving energy access for over 770 million people worldwide. Despite decreasing capital costs, investments in renewable energy (RE) projects in developing countries are low due to unattractive risk-return profiles. Through understanding key risks drivers and their interactions, actionable insights can be drawn to mitigate investment risks, making energy more accessible. This paper reviews RE risks and methods used for risk assessment and mitigation for developed and developing countries with a focus on Sub-Saharan Africa countries (SSA). The review finds that while risk analysis and evaluation mainly employed semi-quantitative multicriteria decision analysis (MCDA) and system dynamics (SD) methods for developing countries, qualitative methods were used to identify mitigations. The methods assessed technical and economic risks at a minimum, while MCDA and SD methods can assess social, political, and policy risks. The efficacies of mitigations were tested using SD and quantitative methods such as agent-based modelling and Monte Carlo simulation. The paper further introduces a ‘holistic multi-dimensional investor risk management framework’ which can be used to identify actions to improve investment risks in a structured manner. The framework addresses four fundamental limitations observed in the existing literature, recognising that RE risks are complex and involve multidisciplinary perspectives having interactions and feedbacks with other risks, actors, and their actions. This review provides a valuable reference to investors, policymakers, and researchers, providing a catalogue of risks, methods deployed in literature, including a framework to identify impactful actions to improve risk levels.Item Open Access Impact of design parameters on the dynamic response and fatigue of offshore jacket foundations(MDPI, 2022-09-18) Marjan, Ali; Hart, PhilThe lifetime of offshore foundations is governed by a combination of harsh environmental conditions and complex service loads. The fatigue limit state (FLS) analysis needs to be performed in the time domain to capture the complex phenomenon. This study aims to investigate different parameters and design modifications that can impact the design life of an offshore jacket foundation. An OC4 jacket foundation is designed in industrial software from DNV and reduced to a super-element model. The super-element model is connected to an NREL 5-MW wind turbine designed in Bladed. The time-series loads are used to compute the fatigue damages faced by the foundation during the service life. The impact of soil non-linearity, marine growth, scour size, the mass of the transition piece, and the grouted connection’s design on the dynamic response and fatigue damages are compared. A 30% increase in life was observed by replacing the concrete transition piece with a lightweight steel configuration. The fatigue damages were considerably greater for the inclined pile in the leg grouted connection than for the leg in the pile concept. The study provides a different perspective by analysing the effect of design parameters and design changes in the complex and computationally expensive time-series domain.Item Open Access Integrating biomass into energy supply chain networks(Elsevier, 2019-11-13) Murele, Oluwatosin C.; Zulkafli, Nur I.; Kopanos, Georgios M.; Hart, Phil; Hanak, Dawid P.During a period of transition towards decarbonised energy networks, maintaining a reliable and secure energy supply whilst increasing efficiency and reducing cost will be key aims for all energy supply chain (ESC) networks. Renewable energy sources, such as biomass, will play an important role in future ESCs as climate change mitigation becomes an increasingly important priority. This paper seeks to address these requirements by presenting an optimisation model for the design and planning of biomass integration into the ESC networks. A supply chain model was derived and the governing equations were solved using the General Algebraic Modelling System software (GAMS) to achieve an optimal solution. The results of the study indicate that a reduction in the emissions cost of up to 4.32% is achievable on integration of 5–8% of biomass into the ESC network. However, a 4.57% increase in the total cost of the ESC network was recorded at the biomass fraction in the mixed fuel of 7.9%, with the fixed assets cost having the largest impact on the total cost of the ESC network. It has been shown that the cost increment in the assets and operational costs of a biomass and coal co-fired combined heat and power plant can be offset by the cost reductions obtained from reduced carbon dioxide emissions. Economic arguments for dual-fuel plants, therefore, require the introduction of effective carbon pricing legislation. It is concluded that such policy implementations can be effective at mitigating the effects of climate change and would assist in achieving a global carbon neutral economy.Item Open Access Optimising renewable energy integration in new housing developments with low carbon technologies(Elsevier, 2021-01-14) Gil, Gemma Oliver; Chowdhury, Jahedul Islam; Balta-Ozkan, Nazmiye; Hu, Yukun; Varga, Liz; Hart, PhilSince buildings account for more than one-third of final energy use, it is important to integrate renewable energy sources for new housing developments to reduce demand for grid energy and carbon emissions. This research investigates the potential of solar PV, energy storage, and electric vehicles in new housing developments and their associated grid impacts by taking the UK’s Cambridge, Milton Keynes, Oxford arc as a case study. Using published data on electrical loads for different types of dwellings, energy demands for new housing developments with and without renewable and low carbon technologies are analysed using techno-economic modelling frameworks. Technical analysis includes sizing and optimisation of PV and storage while economic analysis covers cost-benefit analyses, by considering a range of existing and future tariffs and subsidy schemes including Standard, Economy 7 (cheaper electricity for seven hours at night), Feed-in tariff, and the Smart Export Guarantee. Results show that installing PV panels and storage systems not only reduces the dwellings’ grid energy demand by 31% in January but also helps the dwellings to become net exporters of green electricity to the grid in July and hence saves a substantial amount of money by taking advantage of Feed-in and Economy 7 tariffs.Item Open Access Sensitivity analysis of design parameters for reliability assessment of offshore wind turbine jacket support structures(Elsevier, 2022-02-17) Shittu, Abdulhakim Adeoye; Mehmanparast, Ali; Amirafshari, Peyman; Hart, Phil; Kolios, AthanasiosOffshore Wind Turbine (OWT) support structures are subjected to hostile environments, defined by highly stochastic loads and complex soil-structure interaction, and thus the need for a probabilistic approach towards design. The study carried out herein presents the sensitivity analysis of these inherent stochastic variables imposed on a complex OWT support structure via purpose-developed modular non-intrusive structural reliability assessment formulation. The results from this study reveal that the uncertainties in the wind speed is a structural design driving factor and the hydrodynamic load effects are secondary to this, for the ultimate (ULS) and Fatigue Limit States (FLS) while their relative sensitivities on the Serviceability Limit State (SLS) cannot be clearly distinguished but are seen to have a dominant impact. Also, it was inferred that incorporating correlation between the variables have a significant impact on the reliability of the structure in the ULS design.Item Open Access Structural fatigue assessment and optimisation of offshore wind turbine jacket foundations.(Cranfield University, 2023-08) Marjan, Ali; Huang, Luofeng; Hart, PhilOffshore Wind Turbine (OWT) is an expensive type of renewable energy system, and there is a continuous effort to lower the capital and operational costs. Jacket foundations are increasingly used in offshore wind due to their relatively light weight and adaptability in deep waters. However, the contemporary jacket designs are based on conservative practices from the oil and gas industry. There is still substantial room to optimise the jacket designs for offshore wind usage. This research aims to generate innovative jacket designs by applying a topology optimisation algorithm. The research demonstrates the use of advanced computational techniques to improve existing designs by enhancing structural integrity and fatigue life whilst reducing the mass. The research presents a comprehensive investigation of different parameters and design modifications that impact the design life of an existing jacket. An OC4 jacket foundation is employed, modelled in industrial software from DNV, and transformed into a super element model. The time-series loads obtained from Bladed are used to assess fatigue damages experienced during the foundation's service life. Furthermore, the research presents a topology optimisation method to retrofit an existing jacket foundation design by finding the optimum load path on the structure to enhance fatigue life and lower costs. The jacket's structural optimisation is performed by considering its dynamic response while adhering to the relevant international design standards. In particular, time-domain fatigue simulations were performed to assess the structural integrity of the topology- optimised jacket for the first time. As a result, a range of optimised models with various thickness and diameter options are presented, which are shown to be rational and verify the optimisation procedure. The research contributes a unique integrated topology optimisation framework, dynamic analysis, and time-domain fatigue simulations using industry-standard software tools, and achieved a mass reduction of 35.2% and simultaneously realized a 37.2% better fatigue life compared to the baseline model. The overall environmental load calculation, optimisation procedure and results provide useful practicalities for designing offshore wind turbine foundations and potentially facilitate the relevant industry's structural integrity and cost reduction.Item Open Access Structural reliability assessment of offshore wind turbine support structures subjected to pitting corrosion‐fatigue: A damage tolerance modelling approach(Wiley, 2020-07-12) Shittu, Abdulhakim Adeoye; Mehmanparast, Ali; Shafiee, Mahmood; Kolios, Athanasios; Hart, Phil; Pilario, Karl EzraThe structural integrity of offshore wind turbine (OWT) support structures is affected by one of the most severe damage mechanisms known as pitting corrosion‐fatigue. In this study, the structural reliability of such structures subjected to pitting corrosion‐fatigue is assessed using a damage tolerance modelling approach. A probabilistic model that ascertains the reliability of the structure is presented, incorporating the randomness in cyclic load and corrosive environment as well as uncertainties in shape factor, pit size and aspect ratio. A non‐intrusive formulation is proposed consisting of a sequence of steps. First, a stochastic parametric Finite Element Analysis (FEA) is performed using SMART© crack growth and Design Xplorer© facilities within the software package ANSYS. Secondly, the results obtained from the FEA are processed using an Artificial Neural Network (ANN) response surface modelling technique. Finally, the First Order Reliability Method (FORM) is used to calculate the reliability indices of components. The results reveal that for the inherent stochastic conditions, the structure becomes unsafe after the 18th year, before the attainment of the design life of 20 years. The FEA results are in very good agreement with results obtained from analysis steps outlined in design standard BS 7910 and other references designated as ‘theoretical analysis methods’ in this study. The results predict, for the case study, that the pit growth life is approximately 56% of the total pitting corrosion fatigue life. Sensitivity analysis results show that the aspect ratio of pits at critical size plays a significant role on the reliability of the structure.Item Open Access Systematic review of demand-side management strategies in power systems of developed and developing countries(MDPI, 2022-10-23) Usman, Rilwan; Mirzania, Pegah; Alnaser, Sahban W.; Hart, Phil; Long, ChaoBalancing electricity demand and supply remains a significant challenge for the power systems in developing countries, such as Nigeria. In Nigeria, there is a shortage of adequate power supply, and demand-side management (DSM) plays a minor role in the power balancing mechanism with load shedding being widely used. The paper aims to review and compare various existing and emerging DSM strategies in developing countries. An extensive and systematic review was conducted to evaluate potential solutions using DSM to increase the overall energy efficiency in the Nigerian electricity market. This study found that, although the technical and economic potentials of DSM vary in developed countries, the uptakes of DSM have been severely hampered hence preventing the full exploitation and utilisation of the full potential of DSM. The initiatives of a DSM model in Nigeria and other developing countries can play a significant role in addressing demand and supply challenges but an upgrade of the energy infrastructures, a reform of the market structure and the provision of financial incentives are required to allow for wide implementations of DSM strategies in developing countries.Item Open Access A through-life cost analysis model to support investment decision-making in concentrated solar power projects(MDPI, 2020-03-27) Shafiee, Mahmood; Alghamdi, Adel; Sansom, Christopher L.; Hart, Phil; Encinas-Oropesa, AdrianaThis research paper aims to propose a through-life cost analysis model for estimating the profitability of renewable concentrated solar power (CSP) technologies. The financial outputs of the model include net present value (NPV) and benefit-cost ratio (BCR) of the project, internal rate of return (IRR) and discounted payback period (DPBP) of the investment, and levelized cost of energy (LCoE) from the CSP technology. The meteorological data for a specific location in the city of Tucson in Arizona is collected from a network of automated weather stations, and the NREL System Advisor Model (SAM) is applied to simulate hourly energy output of the CSP plant. An Excel spreadsheet tool is designed to calculate, in a bottom-up approach, the financial metrics required for approval of CSP projects. The model is tested on a 50MW parabolic trough CSP plant and the results show an annual energy production of 456,351,232 kWh, NPV of over $64 million and LCoE of 0.16 $/kWh. Finally, a sensitivity analysis is performed to identify the factors which have the most significant effect on the economic performance of CSP technologies. The proposed model can provide valuable guidance to support the strategic planning and investment decision-making in CSP projects.