A techno-economic probabilistic approach to superheater lifetime determination

In the commonly used approach, the lifetime of a superheater is estimated by characteristic values of the production parameters and the operating conditions. In this approach, a lower bound for a superheater lifetime is based on some arbitrary safety factor that does not necessarily reflect real life, where unexpected failures do occur. The method proposed here suggests coping with this reality, by employing a techno-economic probabilistic approach. It comprises the following two models: • A probabilistic time to failure evaluation model that considers the variability of the lifetime determining parameters. • A model to optimise values of technical parameters and operating conditions and to determine a superheater’s optimal replacement policy, based on life cycle cost considerations. The proposed probabilistic time to failure evaluation model can help to identify the most influential parameters for planning for a minimal probability of failure. It is applied to a unique problematic steel T22 superheater of rather specific parameters: corrosion rate, the Larson Miller Parameter (LMP), diameter and wall thickness. Sensitivity analysis has shown that the dominant factor affecting variation in superheater lifetime is the variation in the LMP, while the effect of the other parameters is quite marginal. Decreasing the standard deviation of the LMP (by keeping a more uniform material) lowered the probability of failure. This resulted in a practical recommendation to perform periodical checks of the parameter wall thickness. We also tested the effect of changing the nominal values of these parameters on the lifetime distribution. Hence, we suggest that the selection of the nominal values should be based on life cycle cost considerations; and propose a model to calculate, for any given combination, the average life cycle cost. The latter model, the optimal parameters combination model, optimises the combination of changes in all the superheater’s parameters by minimising the average life cycle cost associated with the superheater. Demonstrating the usefulness of the proposed approach, in a problematic case, suggests that it can be beneficially employed in the more general case whenever the planned lifetime of a design is threatened

Can solar tower plants withstand the operational flexibility of combined cycle plants?

The aim of this work is to investigate the level of reliability of a 100 MWe solar tower plant operating as a load-following plant using actual operational data of combined cycle power plants. Despite the low cost, the steam generator has been identified as the main cause of unavailability of solar tower plants due to fatigue failures of tube-to-tubesheet joints, which can lead to steam/water leakage into the heat transfer fluid circuit, putting the plant performance at risk. A methodology based on the ASME code and EN standards is proposed to predict the fatigue failures of critical welded points of the steam generator, such as tube-to-tubesheet joints and other T-joints. The results show that the forced outages due to failures of the steam generator lead to an energy penalty that ranges over 230-453 GWh over the plant lifetime. The associated annual degradation rate ranges over 0.123-0.244%. Three tube leakage repair strategies are compared: tube-to-tubesheet weld crack repair, tube plugging and tube plugging with steam generator replacement. The latter strategy was shown to be the best practice because the lowest levelized cost of energy was obtained. In addition, the design of heat exchangers with a minimum of 20% extra area is highly recommended to not compromise the plant operation due to tube plugging. Last, the load-following operation of the solar tower plant increases the levelized cost of energy by approximately 1.6% in the case of tube repair and approximately 0.8% in the case of tube plugging with steam generator replacement.This research is partially funded by the Spanish government under the project RTI2018-096664-B-C21 (MICINN/FEDER, UE) and the fellowship "Programa de apoyo a la realización de proyectos interdisciplinares de I + D para jóvenes investigadores de la Universidad Carlos III de Madrid 2019-2020" under the project ZEROGASPAIN-CM-UC3M (2020/00033/001)

Methanol Worked Examples for the TEA and LCA Guidelines for CO2 Utilization

This document contains worked examples of how to apply the accompanying “Guideline for Techno-Economic Assessment of CO2 Utilization” and “Guideline for Life Cycle Assessment of CO2 Utilization”. The Guidelines can be downloaded via http://hdl.handle.net/2027.42/145436. These worked examples are not intended to be a definitive TEA or LCA report on the process described, but are provided as supporting material to show how the TEA and LCA methodologies described in the guidelines can be specifically applied to tackle the issues surrounding CO2 utilization. This document describes techno-economic assessment and life cycle assessment for methanol production. As methanol production via hydrogenation and PEM electrolysis of water to produce hydrogen are both at high technology readiness levels (TRL7+); a CO2 capture technology currently at a lower TRL (membrane separation at TRL3 or 4) was selected to demonstrate the differences that can be observed in the interpretation phase when working on TEA and LCA studies of processes with lower TRLs. It is acknowledged that there are many unknown variables with membrane capture, and it is not within the remit of this work to draw conclusions on their application. However, it is known that organizations wish to conduct TEA and LCA studies across a range of TRLs and therefore we hope to demonstrate here how this could affect the results. This document is one of several application examples that accompany the parent document “Techno-Economic Assessment & Life-Cycle Assessment Guidelines for CO2 Utilization”.Development of standardized CO2 Life Cycle and Techno-economic Assessment Guidelines was commissioned by CO2 Sciences, Inc., with the support of 3M, EIT Climate-KIC, CO2 Value Europe, Emissions Reduction Alberta, Grantham Foundation for the Protection of the Environment, R. K. Mellon Foundation, Cynthia and George Mitchell Foundation, National Institute of Clean and Low Carbon Energy, Praxair, Inc., XPRIZE and generous individuals who are committed to action to address climate change.https://deepblue.lib.umich.edu/bitstream/2027.42/145723/5/Global CO2 Initiative Complete Methanol Study 2018.pd

Techno-economical analyses of linear solar thermal electric plants for dispatchable power generation

Laut Prognosen wird im Zeitraum von 2018 bis 2023 voraussichtlich 1000 GW neue Stromerzeugungskapazität aus erneuerbaren Energien errichtet, die aber zum größten Teil aus intermittierenden Stromerzeugungstechnologien wie Fotovoltaik und Wind bestehen wird, was das Integrationspotenzial im globalen Stromversorgungssystem einschränkt. Bei Solarthermischen Kraftwerken mit thermischer Energiespeicherung dagegen kann die Stromerzeugung von der variablen Verfügbarkeit der Ressource Sonnenenergie entkoppelt werden, wodurch deutlich geringere Einschränkungen hinsichtlich des Intergrationspotenzials bestehen. Bereits die erste Generation solcher Kraftwerke hat die technische Machbarkeit und die Vorteile dieser Technologie nachgewiesen. Allerdings weist diese erste Technologiegeneration noch zahlreiche Nachteile auf, die ihre Wettbewerbsfähigkeit beeinträchtigt, vor allem auf Grund der physikalischen Eigenschaften des eingesetzten Wärmeträgermediums und der Grundauslegung des hydraulischen Kreislaufs. Weitere Wärmeträgermedien, wie Salzschmelze oder Flüssigmetall, helfen diese Nachteile zu überwinden, insbesondere im Zusammenhang mit sogenannten "Direkt" Kraftwerkskonzepten, bei welchen das selbe Wärmeträgermedium sowohl im Solarfeld als auch im Energiespeicher, also innerhalb eines hydraulischen Kreislaufs, eingesetzt wird. Solche neuen Kraftwerkskonzepte wurden allerdings noch nicht in kommerziellen Kraftwerken mit linienfokussierenden Sonnenkollektoren (wie linear-Fresnel oder Parabolrinne) eingesetzt, weshalb hier weitere Untersuchungen erforderlich sind. Diese Arbeit untersucht den Einfluss ausgewählter Konfigurationsparameter von linienfokussierenden Kraftwerken mit Salzschmelze als Wärmeträgermedium nach dem "Direkt" Kraftwerkskonzept auf deren Stromgestehungskosten und vergleicht dieses Kraftwerkskonzept mit dem Stand der Technik und weiteren Kraftwerkskonzepten mit Flüssigmetall als Wärmeträgermedium. Zu diesem Zweck wurde eine neue Simulationsumgebung entwickelt, um einen Kraftwerksbetrieb über den Zeitraum eines Jahres mit relativ hoher Zeitauflösung (ein bis fünf Minuten) zu simulieren, um den Stromertrag und die Kosten des Kraftwerks genauer berechnen zu können. Zur Verifizierung der Berechnungsergebnisse dieses Modells wurde ein Abgleich mit genaueren Modellen und Daten aus der Fachliteratur vorgenommen, woraus eine relative Ungenauigkeit hinsichtlich der Simulationsergebnisse des Stromertrags von weniger als 5% geschätzt werden kann. Mit diesem Simulationsmodell wurden technisch-wirtschaftliche Analysen der Hauptkonfigurationsparameter von einem linear-Fresnel Kraftwerk mit "Direkt" Kraftwerkskonzept und Salzschmelze durchgeführt, die unter anderem gezeigt haben, dass (a) der Bedarf an thermischer Energie, die erforderlich ist um zu vermeiden, dass die Salzschmelze im Solarfeld gefriert, weniger als 1% des Ertrags der thermische Energie aus dem Solarfeld beträgt, weshalb es nur einen vernachlässigbaren Einfluß auf die Stromgestehungskosten hat; (b) Kraftwerke, die eine Nennleistung von mehr als 200 MW haben, als zwei getrennte Kraftwerke mit jeweils reduzierten Nennleistungen gebaut werden sollen, weil andernfalls die Wärme- und Druckverluste im Solarfeld erhebliche Einbußen im Stromertrag verursachen; (c) eine Nord/Süd Ausrichtung des Solarfelds erhöhte jährliche Stromertragswerte für Standorte mit einem Breitengrad unter 35\degree~bringt, für andere Standorte dagegen eine Ost/West Ausrichtung besser ist und (d) optimale Werte hinsichtlich der Stromgestehungskosten bei einem Nutzungsgrad des Kraftwerks zwischen 60% und 75% (je nach Standort) erreicht werden, was dafür spricht solche Kraftwerke als Mittellastkraftwerke einzusetzen statt als Grundlastkraftwerke. Die Vergleichsanalysen haben gezeigt, dass (a) die Stromgestehungskosten bei dem "Direkt" Kraftwerkskonzept mit Salzschmelze im Vergleich zu thermo-Öl-Kraftwerken, die dem Stand der Technik entsprechen um mindestens 57% reduziert sind und (b) die Stromgestehungskosten bei Kraftwerken mit Flüßigmetall als Wärmeträgermedium, hauptsächlich wegen einer geringeren Dichte, geringerer Wärmekapazität und höherer spezifischer Kosten, um mindestens 25% höher sind

Nuclear Power

We are fortunate to live in incredibly exciting and incredibly challenging time. Energy demands due to economic growth and increasing population must be satisfied in a sustainable manner assuring inherent safety, efficiency and no or minimized environmental impact. These considerations are among the reasons that lead to serious interest in deploying nuclear power as a sustainable energy source. At the same time, catastrophic earthquake and tsunami events in Japan resulted in the nuclear accident that forced us to rethink our approach to nuclear safety, design requirements and facilitated growing interests in advanced nuclear energy systems. This book is one in a series of books on nuclear power published by InTech. It consists of six major sections housing twenty chapters on topics from the key subject areas pertinent to successful development, deployment and operation of nuclear power systems worldwide. The book targets everyone as its potential readership groups - students, researchers and practitioners - who are interested to learn about nuclear power

Nuclear Power - Deployment, Operation and Sustainability

We are fortunate to live in incredibly exciting and incredibly challenging time. Energy demands due to economic growth and increasing population must be satisfied in a sustainable manner assuring inherent safety, efficiency and no or minimized environmental impact. These considerations are among the reasons that lead to serious interest in deploying nuclear power as a sustainable energy source. At the same time, catastrophic earthquake and tsunami events in Japan resulted in the nuclear accident that forced us to rethink our approach to nuclear safety, design requirements and facilitated growing interests in advanced nuclear energy systems. This book is one in a series of books on nuclear power published by InTech. It consists of six major sections housing twenty chapters on topics from the key subject areas pertinent to successful development, deployment and operation of nuclear power systems worldwide. The book targets everyone as its potential readership groups - students, researchers and practitioners - who are interested to learn about nuclear power

Low carbon power generation from the combination of natural gas, biomass and CCS

The transition from coal to natural gas is a key element of the decarbonisation of the global economy. The fact that natural gas supports renewables in terms of electricity generation and even storage is influencing long term energy policy to an affordable power decarbonisation. Therefore, the role that natural gas will play might be crucial if carbon capture and storage (CCS) or biomass is to be implemented into the power system. This work aims to find a holistic solution for the combination of gas, biomass and CCS in terms of cost and emissions. Three configurations were studied; Biomass Integrated Combined Cycle (BIGCC), Hydrogen Thermal Combined Cycle (HTCC) and Externally Fired (EF). The potential of each process to capture CO2 was calculated as well as the likelihood of achieving carbon neutral or negative emissions at a certain cost. Finally the main parameters influencing the net emissions and cost were identified through a global sensitivity analysis. Key conclusions from the work are the following: (1) With a reasonable biomass blending rate (16% to 47%) it is possible to achieve neutral emissions. (2) Biomass and CCS systems always will deliver negative emissions, if biomass supply chain CO2 emissions are lower than 900 kg/tBM and capture rate higher than 50%. (3) Biomass combustion with CCS (EFccs100) has a higher probability of capturing more than a tonne of CO2 per MWh. (4) Capacity factor was a common key parameter among technologies. (5) All configurations with more than 50% blending had a 67% likelihood of reaching costs lower than $100/tCO2av (6) If the whole BECCS CO2 emissions are considered, i.e., including supply chain emissions, instead of the single power plant CO2 emissions, there will be c.50$/tCO2 ).Open Acces

Marine Power Systems

Marine power systems have been designed to be a safer alternative to stationary plants in order to adhere to the regulations of classification societies. Marine steam boilers recently achieved 10 MPa pressure, in comparison to stationary plants, where a typical boiler pressure of 17 MPa was the standard for years. The latest land-based, ultra-supercritical steam boilers reach 25 MPa pressure and 620 °C temperatures, which increases plant efficiency and reduces fuel consumption. There is little chance that such a plant concept could be applied to ships. The reliability of marine power systems has to be higher due to the lack of available spare parts and services that are available for shore power systems. Some systems are still very expensive and are not able to be widely utilized for commercial merchant fleets such as COGAS, mainly due to the high cost of gas turbines. Submarine vehicles are also part of marine power systems, which have to be reliable and accurate in their operation due to their distant control centers. Materials that are used in marine environments are prone to faster corrosive wear, so special care also should be taken in this regard. The main aim of this Special Issue is to discuss the options and possibilities of utilizing energy in a more economical way, taking into account the reliability of such a system in operation

Solar thermal plant impact analysis and requirements definition study

The technology and economics of solar thermal electric systems (STES) for electric power production is discussed. The impacts of and requirements for solar thermal electric power systems were evaluated

Alternative Energy Sources

The search for alternative sources of energy is an attempt to solve two of the main problems facing the modern world. Today's resources are mainly based on fossil flammable substances such as coal, oil, and natural gas. The first problem is related to the expected and observed depletion of deposits, not only those available but also less accessible. Another is related to global warming from emissions of greenhouse gases (mainly carbon dioxide) as well as emissions of other pollutants in the atmosphere. Mitigating the harmful effects of fossil fuel use is an obvious challenge for mankind. This Special Issue includes articles on the search for new raw materials and new technologies for obtaining energy, such as those existing in nature, methane hydrates, biomass, etc., new more efficient technologies for generating electricity, as well as analyses of the possibilities and conditions of use of these resources for practical applications