A framework for data integration of offshore wind farms

Operation and maintenance play an important role in maximizing the yield and minimizing the downtime of wind turbines, especially offshore wind farms where access can be difficult due to harsh weather conditions for long periods. It contributes up to 25–30% to the cost of energy generation. Improved operation and maintenance (O&M) practices are likely to reduce the cost of wind energy and increase safety. In order to optimize the O&M, the importance of data exchange and knowledge sharing within the offshore wind industry must be realized. With more data available, it is possible to make better decisions, and thereby improve the recovery rates and reduce the operational costs. This article describes the development of a framework for data integration to optimize the remote operations of offshore wind farms.     

Life-cycle cost analysis of floating offshore wind farms

The purpose of this article is to put forward a methodology in order to evaluate the Cost Breakdown Structure (CBS) of a Floating Offshore Wind Farm (FOWF). In this paper CBS is evaluated linked to Life-Cycle Cost System (LCS) and taking into account each of the phases of the FOWF life cycle. In this sense, six phases will be defined: definition, design, manufacturing, installation, exploitation and dismantling. Each and every one of these costs can be subdivided into different sub-costs in order to obtain the key variables that run the life-cycle cost. In addition, three different floating platforms will be considered: semisubmersible, Tensioned Leg Platform (TLP) and spar. Several types of results will be analysed according to each type of floating platform considered: the percentage of the costs, the value of the cost of each phase of the life-cycle and the value of the total cost in each point of the coast. The results obtained allow us to become conscious of what the most important costs are and minimize them, which is one of the most important contributions nowadays. It will be useful to improve the competitiveness of floating wind farms in the future.     

Economic implications of pre- and post-combustion calcium looping configurations applied to gasification power plants

Gasification is a promising conversion technology to deliver high energy efficiency simultaneously with low energy and cost penalties for carbon capture. This paper is devoted to in-depth economic evaluations of pre- and post-combustion Calcium Looping (CaL) configurations for Integrated Gasification Combined Cycle (IGCC) power plants. The poly-generation capability, e.g. hydrogen and power co-generation, is also discussed. The post-combustion CaL option is a gasification power plant in which the flue gases from the gas turbine are treated for CO₂ capture in a carbonation–calcination cycle. In pre-combustion CaL option, the Sorbent Enhanced Water Gas Shift (SEWGS) feature is used to produce hydrogen which is used for power generation. As benchmark case, a conventional gasification power plant without carbon capture was considered. Net power output of evaluated cases is in the range of 550–600 MW with more than 95% carbon capture rate. The pre-combustion capture configuration was evaluated also in hydrogen and power co-generation scenario. The evaluations are concentrated for estimation of capital costs, specific investment cost, operational & maintenance (O&M) costs, CO₂ removal and avoidance costs, electricity costs, sensitivity analysis of technical and economic assumptions on key economic indicators etc.     

Failure rate,repair time and unscheduled O&M cost analysis of offshore wind turbines

Determining and understanding offshore wind turbine failure rates and resource requirement for repair are vital for modelling and reducing O&M costs and in turn reducing the cost of energy. While few offshore failure rates have been published in the past even less details on resource requirement for repair exist in the public domain. Based on ~350 offshore wind turbines throughout Europe this paper provides failure rates for the overall wind turbine and its sub‐assemblies. It also provides failure rates by year of operation, cost category and failure modes for the components/sub‐assemblies that are the highest contributor to the overall failure rate. Repair times, average repair costs and average number of technicians required for repair are also detailed in this paper. An onshore to offshore failure rate comparison is carried out for generators and converters based on this analysis and an analysis carried out in a past publication. The results of this paper will contribute to offshore wind O&M cost and resource modelling and aid in better decision making for O&M planners and managers. Copyright © 2015 John Wiley & Sons, Ltd.     

Photovoltaic operation and maintenance evaluation

An Electric Power Research Institute (EPRI) sponsored evaluation of the operation and maintenance (O&M) experience at seven selected photovoltaic installations in the United States is presented. The presentation of the actual O&M costs experienced by the seven sites, documentation of the largest problem areas, identification of failure causes, and projections of O&M costs for future installations are included     

Offshore wind turbine fault alarm prediction

Offshore wind operations and maintenance (O&M) costs could reach up to one third of the overall project costs. In order to accelerate the deployment of offshore wind farms, costs need to come down. A key contributor to the O&M costs is the component failures and the downtime caused by them. Thus, an understanding is needed on the root cause of these failures. Previous research has indicated the relationship between wind turbine failures and environmental conditions. These studies are using work‐order data from onshore and offshore assets. A limitation of using work orders is that the time of the failure is not known and consequently, the exact environmental conditions cannot be identified. However, if turbine alarms are used to make this correlation, more accurate results can be derived. This paper quantifies this relationship and proposes a novel tool for predicting wind turbine fault alarms for a range of subassemblies, using wind speed statistics. A large variation of the failures between the different subassemblies against the wind speed are shown. The tool uses 5 years of operational data from an offshore wind farm to create a data‐driven predictive model. It is tested under low and high wind conditions, showing very promising results of more than 86% accuracy on seven different scenarios. This study is of interest to wind farm operators seeking to utilize the operational data of their assets to predict future faults, which will allow them to better plan their maintenance activities and have a more efficient spare part management system.     

Capital improvement project evaluation: a hydroelectric generation economic perspective

Hydropower is a capital‐intensive energy source with low operations and maintenance (O&M) cost and essentially no fuel costs. Consequently, the levelized cost of energy methodology is a very sensitive component to investment costs and interest rates but less sensitive to economic lifetimes. Because current hydroelectric plants are classified as one of the least costly sources of power generation, there are, however, a wide assortment of site‐specific capital costs and capacity factors. Maintenance activities, predominantly fixed O&M costs, are unjustifiable fundamentals in the capital improvement scheme. The conduct of an explicit aging asset in the hydroelectric generation confines is determined by its previous performance and condition assessment. The asset repair, upgrade, and/or replacement strategies are derived from the documented condition valuations to facilitate specific requirements in the capital improvement program. Moreover, the routine evaluation of the equipment with essential inspections and testing delivers a comprehensive insight of its condition before expensive replacement initiatives are imposed. The application of these evaluation approaches and implements described in this paper are designed to aid the decision‐maker with invaluable information of the equipment condition. Copyright © 2015 John Wiley & Sons, Ltd.     

Simulation study of a large scale line-focus trough collector solar power plant in Greece

This paper deals with the technical feasibility and economic viability of a solar thermal power plant using parabolic trough collectors in Greece. The power plant is to be installed in the island of Rhodes and its power output will be 8.55 MW. Power plant simulation is carried out using TRNSYS software (STEC library) and economic issues of the project such as initial cost of investment, operation and maintenance (O&M) and energy costs will be analyzed. It was found that for the particular investment, considering a 75% of initial investment cost loan (with a 10-year period), the payback period will be approximately 13 years.     

S-Transform and its contribution to wind turbine condition monitoring

Condition monitoring (CM) has long been recognised as one of the best methods of reducing the operation and maintenance (O&M) costs of wind turbines (WTs). However, its potential in the wind industry has not been fully exploited. One of the major reasons is due to the lack of an efficient tool to properly process the WT CM signals, which are usually non-stationary in both time and frequency domains owing to the constantly varying operational and loading conditions experienced by WTs. For this reason, S-transform and its potential contribution to WT CM are researched in this paper. Following the discussion of the superiorities of S-transform to the Short-Time Fourier Transform (STFT) and Wavelet Transform, two S-transform based CM techniques are developed, dedicated for use on WTs. One is for tracking the energy variations of those fault-related characteristic frequencies under varying operational conditions (the energy rise of these frequencies usually indicates the presence of a fault); another is for assessing the health condition of WT gears and bearings, which have shown significant reliability issues in both onshore and offshore wind projects. In the paper, both proposed techniques have been verified experimentally, showing that they are valid for detecting both the mechanical and electrical faults occurring in the WT despite its varying operational and loading conditions.     

Fuel cell based cogeneration: Comparison of electricity production cost for Swedish conditions

A good portion of greenhouse gas emissions is caused by the energy used in the built environment. Emission reduction goals may be achieved by combining cogeneration with fuel cells (FC). This paper investigates electricity production costs for FC based cogeneration systems with recent data for Swedish conditions. The types of FCs that are investigated are proton exchange membrane FC and molten carbonate FC. Based solely on cost, FC based cogeneration systems cannot compete with conventional systems. However, our results show that Molten Carbonate FC based cogeneration systems will be profitable by 2020. To compete with conventional systems, the capital cost, lifetime and efficiency of FCs must be improved. Creation of a reasonably broad market is essential since it will greatly help to reduce capital costs and operation and maintenance (O&M) costs, the dominating parts of the overall costs according to the analysis.     

Infinitesimal etendue and Simultaneous Multiple Surface (SMS) concentrators for fixed receiver troughs

In order to increase the cost-effectiveness of conventional parabolic trough (PT) fields it is essential to reduce Capital Expenditure (Capex) as well as Operations and Maintenance (O&M) costs, in particular the need for flexible hosing or rotating joints, which are used because the tubular receiver also tracks in a solidary way with the trough. One possible alternative is to design a different type of optic with the center of mass on the center of the tubular receiver, generating the possibility of it being fixed, thereby dispensing with flexible hosing or rotating joints, without penalizing its overall efficiency or even concentration. In this work, two possible optical solutions, combining parabolic-type primaries with second-stage non-imaging optics concentrators for fixed receivers, are presented. These concentrators are designed using the Simultaneous Multiple Surface (SMS) design method and the infinitesimal etendue limit. A performance comparison with a conventional PT in terms of optical efficiency, CAP (Concentration-Acceptance Product) and other performance data are also presented, including an estimate of the total amount of yearly collected energy (kW h/m² of entrance aperture) for one particular location – Faro (Portugal).     

A centurial history of technological change and learning curves for pulverized coal-fired utility boilers

Recent study of the history of technological change has provided better understanding of the driving forces for technological innovation, as well as quantitative estimates of historical rates of technical change. Although such results are widely used in long-term energy models to estimate future costs over time periods of up to a century, most studies of technological learning for major energy technologies are based on historical trends over time periods not longer than 20–30 years (often because of data limitations). Relatively few studies quantify longer-term (century-scale) trends. This study helps fill that gap by reviewing the history of pulverized-coal (PC) power plants, with a specific focus on the technological progress of PC boiler technology over the last century. Historical data for U.S. plants are used to develop long-term experience curves for the overall thermal efficiency of PC power plants, as well as the capital cost of PC boilers and non-fuel operating and maintenance (O&M) costs of PC plants. Despite a technology plateau experienced by PC power plants two decades ago, recent developments indicate that such plants will continue to improve and remain a competitive and important part of power generation technology portfolios.     

Numerical modelling of a bromide-polysulphide redox flow battery. Part 2: Evaluation of a utility-scale system

Numerical modelling of redox flow battery (RFB) systems allows the technical and commercial performance of different designs to be predicted without costly lab, pilot and full-scale testing. A numerical model of a redox flow battery was used in conjunction with a simple cost model incorporating capital and operating costs to predict the technical and commercial performance of a 120 MWh/15 MW utility-scale polysulphide-bromine (PSB) storage plant for arbitrage applications. Based on 2006 prices, the system was predicted to make a net loss of 0.45 p kWh⁻¹ at an optimum current density of 500 A m⁻² and an energy efficiency of 64%. The system was predicted to become economic for arbitrage (assuming no further costs were incurred) if the rate constants of both electrolytes could be increased to 10⁻⁵ m s⁻¹, for example by using a suitable (low cost) electrocatalyst. The economic viability was found to be strongly sensitive to the costs of the electrochemical cells and the electrical energy price differential.     

Conceptual design and techno-economic assessment of integrated solar combined cycle system with DSG technology

Direct steam generation (DSG) in parabolic trough collectors causes an increase to competitiveness of solar thermal power plants (STPP) by substitution of oil with direct steam generation that results in lower investment and operating costs. In this study the integrated solar combined cycle system with DSG technology is introduced and techno-economic assessment of this plant is reported compared with two conventional cases. Three considered cases are: an integrated solar combined cycle system with DSG technology (ISCCS-DSG), a solar electric generating system (SEGS), and an integrated solar combined cycle system with HTF (heat transfer fluid) technology (ISCCS-HTF).This study shows that levelized energy cost (LEC) for the ISCCS-DSG is lower than the two other cases due to reducing O&M costs and also due to increasing the heat to electricity net efficiency of the power plant. Among the three STPPs, SEGS has the lowest CO₂ emissions, but it will operate during daytime only.     

An interval-parameter minimax regret programming approach for power management systems planning under uncertainty

In this study, an interval-parameter minimax regret programming (IMRP) method is developed for supporting the power management systems planning under uncertainty. This method incorporates techniques of interval linear programming (ILP) and minimax regret programming (MRP) within a general optimization framework. The developed IMRP could deal with multiple policy scenarios associated with different costs and risk levels without making any assumptions. It can analyze various economic consequences for all of the possible scenarios through minimizing the maximum cost regret values. The IMRP approach can successfully reduce the worst regrets incurred under the pre-regulated targets. Moreover, it can deal with uncertainties and complexities expressed as interval numbers. A case study of power management systems planning is then presented for demonstrating applicability of the developed approach. The results indicate that many decision alternatives are generated based on the interval solutions which can help decision makers identify the desired system designs with minimized economic cost loss and system-failure risk under uncertainty. The trade-off between system regret and security-failure risk can be handled effectively through this method. And the generated solutions can also provide multiple electric power generation patterns and capacity expansion schemes under the optimal strategy obtained through the developed IMRP method. It is indicated that the proposed method is efficient to provide the decision makers with available plans in actual operation of power management systems.     

The development of natural gas and hydrogen pipeline capital cost estimating equations

Natural gas pipeline cost data collected by the Oil and Gas Journal (O&GJ) [1] for interstate pipelines constructed from 1980 through 2017 were used to develop capital cost estimating equations that are a function of pipeline diameter, length, and U.S. region. Equations were developed for material, labor, miscellaneous, and right-of-way costs, the four cost components in the O&GJ data, for six different regions of the United States (U.S.). Each equation is a function of pipeline diameter and length.Adjustment mechanisms were then developed for converting the natural gas pipeline equations into equations for estimating the costs of hydrogen pipelines. These adjustments were based in part on an analysis completed by the National Institute for Standards and Technology (NIST) [2,3]. The results of this work were used to update cost models in the Hydrogen Delivery Scenario Analysis Model (HDSAM) [4], developed by Argonne National Laboratory for the U.S. Department of Energy's Hydrogen Program. Our analysis shows a wide range of pipeline cost across different U.S. regions, especially with respect to labor and right-of-way costs. The developed cost formulas for hydrogen pipelines are both important and timely as hydrogen is being considered as a zero-carbon energy carrier with the potential to decarbonize all energy sectors, and the cost of hydrogen transportation is essential for techno-economic analysis of its potential use in these sectors.     

Optimal energy management strategy of fuel-cell battery hybrid electric mining truck to achieve minimum lifecycle operation costs

Proton exchange membrane fuel cell (PEMFC) electric vehicle is an effective solution for improving fuel efficiency and onboard emissions, taking advantage of the high energy density and short refuelling time. However, the higher cost and short life of the PEMFC system and battery in an electric vehicle prohibit the fuel cell electric vehicle (FCEV) from becoming the mainstream transportation solution. The fuel efficiency-oriented energy management strategy (EMS) cannot guarantee the improvement of total operating costs. This paper proposes an EMS to minimize the overall operation costs of FCEVs, including the cost of hydrogen fuel, as well as the cost associated with the degradations of the PEMFC system and battery energy storage system (ESS). Based on the PEMFC and battery performance degradation models, their remaining useful life (RUL) models are introduced. The control parameters of the EMS are then optimized using a meta-model based global optimization algorithm. This study presents a new optimal control method for a large mining truck operating on a real closed-road operation cycle, using the combined energy efficiency and performance degradation cost measures of the PEMFC system and lithium-ion battery ESS. Simulation results showed that the proposed EMS could improve the total operating costs and the life of the FCEV.     

Offshore wind turbine reliability and operational simulation under uncertainties

The fast‐growing offshore wind energy sector brings opportunities to provide a sustainable energy resource but also challenges in offshore wind turbine (OWT) operation and maintenance management. Existing operational simulation models assume deterministic input reliability and failure cost data, whereas OWT reliability and failure costs vary depending on several factors, and it is often not possible to specify them with certainty. This paper focuses on modelling reliability and failure cost uncertainties and their impacts on OWT operational and economic performance. First, we present a probabilistic method for modelling reliability data uncertainty with a quantitative parameter estimation from available reliability data resources. Then, failure cost uncertainty is modelled using fuzzy logic that relates a component's failure cost to its capital cost and downtime. A time‐sequential Monte Carlo simulation is presented to simulate operational sequences of OWT components. This operation profile is later fed into a fuzzy cost assessment and coupled with a wind power curve model to evaluate OWT availability, energy production, operational expenditures and levelised cost of energy. A case study with different sets of reliability data is presented, and the results show that impacts of uncertainty on OWT performance are magnified in databases with low components' reliability. In addition, both reliability and cost uncertainties can contribute to more than 10% of the cost of energy variation. This research can provide practitioners with methods to handle data uncertainties in reliability and operational simulation of OWTs and help them to quantify the variability and dependence of wind power performance on data uncertainties.     

Multi-objective optimization of an experimental integrated thermochemical cycle of hydrogen production with an artificial neural network

In this study, an experimental lab-scale copper-chlorine (Cu–Cl) cycle of hydrogen production is examined and optimized in terms of exergy efficiency and operational costs of produced hydrogen. The integrated process is modeled and simulated in Aspen Plus incorporating the reaction kinetic parameters with a sensitivity analysis of a range of operating conditions. An artificial neural network (ANN) method with machine learning is used to generate a mathematical function that is optimized based on a multi-objective genetic algorithm (MOGA) method. A sensitivity analysis of variations of each design parameter for both the objective functions and the effectiveness of exergy performance relative to operational costs of produced hydrogen is demonstrated. The sensitivity analysis and optimization results are presented and discussed.     

Comparative analysis of battery electric,hydrogen fuel cell and hybrid vehicles in a future sustainable road transport system

This paper compares battery electric vehicles (BEV) to hydrogen fuel cell electric vehicles (FCEV) and hydrogen fuel cell plug-in hybrid vehicles (FCHEV). Qualitative comparisons of technologies and infrastructural requirements, and quantitative comparisons of the lifecycle cost of the powertrain over 100,000 mile are undertaken, accounting for capital and fuel costs. A common vehicle platform is assumed. The 2030 scenario is discussed and compared to a conventional gasoline-fuelled internal combustion engine (ICE) powertrain. A comprehensive sensitivity analysis shows that in 2030 FCEVs could achieve lifecycle cost parity with conventional gasoline vehicles. However, both the BEV and FCHEV have significantly lower lifecycle costs. In the 2030 scenario, powertrain lifecycle costs of FCEVs range from $7360 to $22,580, whereas those for BEVs range from $6460 to $11,420 and FCHEVs, from $4310 to $12,540. All vehicle platforms exhibit significant cost sensitivity to powertrain capital cost. The BEV and FCHEV are relatively insensitive to electricity costs but the FCHEV and FCV are sensitive to hydrogen cost. The BEV and FCHEV are reasonably similar in lifecycle cost and one may offer an advantage over the other depending on driving patterns. A key conclusion is that the best path for future development of FCEVs is the FCHEV.