Advanced low carbon power systems - the advanced zero emissions power plant

The global warming issue is becoming more and more important in the public opinion, because its effects on everyday life of the entire mankind are starting to become appreciable. On the next (2009) December will be held in Copenhagen the fifteenth United Nations Climate Change Conference which is expected to be crucial for the future choices to deal with the anthropogenic greenhouse gases issue. The power generation sector is one of the most important contributors to the emissions of greenhouse gases (of which the carbon dioxide is the main anthropogenic example), and it is facing in the last decades a problem that will exacerbate surely the already alarming effect on the global warming: the rapid increase of the world power demand. For these reasons the carbon capture topic is gaining nowadays a lot of attention, especially in the industrial sector, since it will be a strategic field for the power generation in the short-medium term. In fact, it is really likely that will be introduced soon a so-called “cap and trade” system, with the trading of pollution licences related to the CO2 emissions, as the USA president Obama has recently proposed to the Congress. This option would turn out in a completely new scenario in the power generation sector with novel, cleaner concepts being economically more attractive than the conventional ones. This project investigates the performance of a novel thermodynamic cycle with carbon capture, called Advanced Zero Emissions Power plant (AZEP), which has been analysed in the open literature just partially and superficially up to now. Since this project is part of a bigger one in which several carbon capture novel cycles options will be compared, the main objective is to provide a flexible, modular, modern computational tool, called eAZEP, developed from scratch. The second objective is the evaluation of the four main layouts of the AZEP concept as a stand alone power plant, assessing their inclination to be included in an unfired combined cycle featured with an Heat Recovery Steam Generator (HRSG). A final, third objective is the development of a routine for the off-design performance calculation to be included in on old pre-existing computational tool. The original contribution of this work to the knowledge on the topic comprises 1. the conception of two new layouts for the AZEP cycle (the Post Expan-sion Heat exchanger layouts); 2. the performance evaluation of the long term potential for the power plant; 3. a sensitivity analysis of the thermodynamic concept. The best suitable arrangements of the plant layout are identified together with the main parameters which influence their performance, both for the combined cycle perspective implementation and for the stand alone option. Thanks to the flexibility of eAZEP will be easy to consider, in a future work, a pretty wide number of alternative concepts and investigate more cycle parameters in order to broaden the conclusions obtained in this work. Moreover the combined cycle off-design new routine must be debugged and validated

The development of a tool to promote sustainability in casting processes

The drive of the manufacturing industry towards productivity, quality and profitability has been supported in the last century by the availability of relatively cheap and abundant energy sources with limited focus on the minimisation of energy and material waste. However, in the last decades, more and more stringent regulations aimed at reducing pollution and consumption of resources have been introduced worldwide and in particular in Europe. Consequently, a highly mature and competitive industry like foundry is expecting challenges that an endeavour towards sustainability can turn into significant opportunities for the future. A tool to undertake a systematic analysis of energy and material flows in the casting process is being developed. An overview of the computer program architecture is presented and its output has been validated against real-world data collected from foundries

Techno-economic environmental risk analysis of sustainable power systems.

Sustainable engine systems are undoubtedly one of the main topics at the centre of the recent scientific debate. A significant number of novel thermodynamic concepts, partly based on gas turbine engines, are available in the open scientific literature and have been scarcely investigated. Cranfield University has developed an integrated, modular, multi-disciplinary framework of computational software called Techno-economic Environmental Risk Analysis (TERA) to assess complex, thermodynamic cycles from an integrated point of view. The present study completes a TERA work on sustainable power systems in two steps. Initially, the entire TERA methodology is applied to the aviation field with the integration of a set of modules to investigate three novel, turbofan, aircraft engines. Namely, the mentioned concepts are featured by: a counter-rotating core for short range (GTCRSR), an active core for short range (GTACSR), and an inter-cooler for Long Range (GTICLR). The optimised design specifications of the GTCRSR engine show a reduction of more than 7% of block fuel in comparison to the reference engine, more than 6% for the GTACSR and almost up to 5% for the GTICLR. Subsequently, a library of electric power generation future technology concepts has been built to be merged in the TERA for energy framework, developing the relevant computational codes. The power plants chosen encompass different domains of the field and are: the Advanced Zero Emissions Power plant — AZEP (carbon capture and storage concept); a supercritical steam turbine power plant (for nuclear applications); a land-based wind farm working in synergy with a conventional power plant. Multiple, specific control strategies for the fossil fuel and nuclear power plant have been identified to handle the power output down to 60% of the design point for the AZEP and slightly below 80% for the nuclear cycle. Hourly performance simulations of typical days representative of each season of the wind farm in combination to conventional gas turbine engines have been investigated for different size (from 223 MW to 5 MW at full load).Engineering and Physical Sciences (EPSRC)PhD in Aerospac

Automatically weighted high-resolution mapping of multi-criteria decision analysis for sustainable manufacturing systems

A common feature of Multi-Criteria Decision Analysis (MCDA) to evaluate sustainable manufacturing is the participation (to various extents) of Decision Makers (DMs) or experts (e.g. to define the importance, or “weight”, of each criterion). This is an undesirable requirement that can be time consuming and complex, but it can also lead to disagreement between multiple DMs. Another drawback of typical MCDA methods is the limited scope of weight sensitivity analyses that are usually performed for one criterion at the time or on an arbitrary basis, struggling to show the “big picture” of the decision making space that can be complex in many real-world cases. This work removes all the mentioned shortcomings implementing automatic weighting through an ordinal combinatorial ranking of criteria objectively set by four pre-defined weight distributions. Such solution provides the DM not only with a fast, rational and systematic method, but also with a broader and more accurate insight into the decision making space considered. Additionally, the entropy of information in the criteria can be used to adjust the weights and emphasise the differences between potentially close alternativ

A tool to promote sustainability in casting processes: Development highlights

The validity of traditional manufacturing decision variables (i.e. cost, quality, flexibility and time) is questioned by some important challenges of our time: the scarcity of natural resources and environmental pollution. Increasing energy cost to extract and process natural resources, alongside regulatory pressures against pollution, pushes very mature and competitive processes like casting towards a holistic approach where sustainability contributes to strategic decisions together with the mentioned traditional manufacturing variables. As a contribution to this industrial necessity, a modular tool able to analyse material and energy flows in casting processes is under development. In particular, the ability to represent automatically Sankey diagrams of the flows recently implemented is described and validated

Cradle-to-grave lifecycle environmental assessment of hybrid electric vehicles

Demand for sustainable transportation with a reduced environmental impact has led to the widespread adoption of electrified powertrains. Hybrid electric vehicles (HEVs) and plug-in hybrid electric vehicles (PHEVs) produce lower greenhouse gas (GHG) emissions during the use phase of their lifecycle, compared to conventional internal combustion engine vehicles (ICEVs). However, a full understanding of their total environmental impact, from resource extraction to end-of-life (EOL), of a contemporary, real-world HEV and PHEV remains broadly elusive in the scientific literature. In this work, for the first time, a systematic cradle-to-grave lifecycle analysis (LCA) of a Toyota Prius XW50, as a HEV and PHEV, was used to comprehensively assess its environmental impact throughout its entire lifecycle using established lifecycle inventory databases. The LCA revealed that the gasoline fuel cycle (extraction, refinement, and transportation) is a major environmental impact “hotspot”. The more electrified PHEV model consumes 3.2% more energy and emits 5.6% more GHG emissions within the vehicle’s lifecycle, primarily owed to the manufacturing and recycling of larger traction batteries. However, when factoring in the fuel cycle, the PHEV model exhibits a 29.6% reduction in overall cradle-to-grave life energy consumption, and a 17.5% reduction in GHG emissions, in comparison to the less-electrified HEV. This suggests that the higher-electrified PHEV has a lower environmental impact than the HEV throughout the whole lifecycle. The presented cradle-to-grave LCA study can be a valuable benchmark for future research in comparing other HEVs and PHEVs or different powertrains for similarly sized passenger vehicles

Energy and material efficiency metrics in foundries

Most of the current foundry processes are based on well-developed and established practices typical of mature technologies. Contemporary economic, environmental and societal developments have concurrently changed at an unprecedented rate the context where traditional metal casting methodologies have not really developed much over time. Consequently, significant challenges and opportunities arise. This work will present the founding metrics of a novel approach to metal casting with the development of a new philosophy (called “Small is Beautiful”) aimed at tackling the current pressures on the industry with a focus on energy and materials’ efficiencies and flexible production. Traditional and well-established parameters are presented and compared to new metrics defined from first principles and thermodynamic properties. All metrics are validated using industrial and scientific literature data of five sand casting plants melting different ferrous and non-ferrous alloys

Substitution of cast iron engine components with aluminium alloys: a life cycle perspective

Environmental sustainability is nowadays one of the most important global challenges. It is common that the amount of CO2 emissions is being used as a measure of the environmental impact of vehicles. As a result, manufacturers focus on producing lightweight car components in order to minimize the weight of the vehicles and maximize the fuel economy. As a consequence, car manufacturer designers have started to favour low density materials. However, it is usually the case that the energy footprint of the materials as well as the processes involved in the manufacturing of automotive components is often not assessed. This study focuses on the validity of the claim that lightweight materials are associated with enhanced environmental sustainability by making a full assessment of the energy consumption and CO2 emissions during the manufacturing and usage stages of diesel and petrol engine blocks made of cast iron and aluminium. For this purpose, inputs from over 100 world experts from across the automotive supply chain have been taken into consideration. Our results show that the usage of lightweight materials is often associated with higher energy consumption and CO2 emissions. More specifically, the 1.6L aluminium alloy engine block examined only seems to compensate for the additional energy consumed during their manufacturing process after 200,000 km of on-the-road driving compared to the one made of cast iron. Similar trends are observed for the CO2 emissions

Life cycle and energy assessment of automotive components manufacturing: The dilemma between aluminium and cast iron

Considering the manufacturing of automotive components, there exists a dilemma around the substitution of traditional cast iron (CI) with lighter metals. Currently, aluminum alloys, being lighter compared to traditional materials, are considered as a more environmentally friendly solution. However, the energy required for the extraction of the primary materials and manufacturing of components is usually not taken into account in this debate. In this study, an extensive literature review was performed to estimate the overall energy required for the manufacturing of an engine cylinder block using (a) cast iron and (b) aluminum alloys. Moreover, data from over 100 automotive companies, ranging from mining companies to consultancy firms, were collected in order to support the soundness of this investigation. The environmental impact of the manufacturing of engine blocks made of these materials is presented with respect to the energy burden; the “cradle-to-grave approach” was implemented to take into account the energy input of each stage of the component life cycle starting from the resource extraction and reaching to the end-of-life processing stage. Our results indicate that, although aluminum components contribute toward reduced fuel consumption during their use phase, the vehicle distance needed to be covered in order to compensate for the up-front energy consumption related to the primary material production and manufacturing phases is very high. Thus, the substitution of traditional materials with lightweight ones in the automotive industry should be very thoughtfully evaluate

Numerical simulation and evaluation of Campbell running and gating systems

The most common problems encountered in sand casting foundries are related to sand inclusions, air, and oxide films entrainment. These issues can be addressed to a good extent or eliminated by designing proper running systems. The design of a good running system should be based on John Campbell’s “10 casting rules”; it should hinder laminar and turbulent entrainment of the surface film on the liquid, as well as bubble entrainment. These rules have led to the establishment of a group of components such as high and low placed filters (HPF/LPF) and standard gate designs such as the trident gate (TG) and vortex gate (VG) which are incorporated in wellperforming running system designs. In this study, the potential of the aforementioned running system designs to eliminate air entrainment and surface defects has been investigated via means of computational fluid dynamics (CFD) simulations. The obtained results suggest that the use of filters significantly enhances the quality of the final cast product; moreover, all of the gating system designs appear to perform better than the basic running system (BRS). Finally, the five in total running and gating system designs have been evaluated with respect to their ability to produce good quality cast products (reduced air entrainment and surface defects) and their sustainability component (runner scrap mass)