Hybrid Systems Based on Solid Oxide Fuel Cells

Modelling and Design

Mario L. Ferrari, Usman M. Damo, Ali Turan, David Sánchez

• Publisher: Wiley
• Year: 2017
• ISBN:
  9781119039075
• Edition: 1
• Topic: Physical Sciences
• Subtopic: Energy

A comprehensive guide to the modelling and design of solid oxide fuel cell hybrid power plants

This book explores all technical aspects of solid oxide fuel cell (SOFC) hybrid systems and proposes solutions to a range of technical problems that can arise from component integration. Following a general introduction to the state-of-the-art in SOFC hybrid systems, the authors focus on fuel cell technology, including the components required to operate with standard fuels. Micro-gas turbine (mGT) technology for hybrid systems is discussed, with special attention given to issues related to the coupling of SOFCs with mGTs. Throughout the book emphasis is placed on dynamic issues, including control systems used to avoid risk conditions.

With an eye to mitigating the high costs and risks incurred with the building and use of prototype hybrid systems, the authors demonstrate a proven, economically feasible approach to obtaining important experimental results using simplified plants that simulate both generic and detailed system-level behaviour using emulators. Computational models and experimental plants are developed to support the analysis of SOFC hybrid systems, including models appropriate for design, development and performance analysis at both component and system levels.

• Presents models for a range of size units, technology variations, unit coupling dynamics and start-up and shutdown behaviours
• Focuses on SOFCs integration with mGTs in light of key constraints and risk avoidance issues under steady-state conditions and during transient operations
• Identifies interaction and coupling problems within the GT/SOFC environment, including exergy analysis and optimization
• Demonstrates an economical approach to obtaining important experimental results while avoiding high-cost components and risk conditions
• Presents analytical/computational and experimental tools for the efficient design and development of hardware and software systems

Hybrid Systems Based on Solid Oxide Fuel Cells: Modelling and Design is a valuable resource for researchers and practicing engineers involved in fuel cell fundamentals, design and development. It is also an excellent reference for academic researchers and advanced-level students exploring fuel cell technology.

Chapter 1
Introduction

Chapter Overview

1. World Population Growth, Energy Demand and its Future
2. World Energy Future
3. Introduction to Fuel Cells and Associated Terms
4. Gas Turbines
5. Coupling of Microturbines with Fuel Cells to Obtain ‘Hybrid Systems’
6. Conclusions

The current and future energy scenarios faced by the international community are discussed in this chapter, starting with a brief presentation of the energy landscape and related issues, including the increase in demand and environmental aspects. A list of possible solutions to existing and foreseen problems is presented and discussed, setting the framework to highlight the significant potential of fuel cells for future power generation. Following on from this, the performance characteristics of fuel cells are introduced, including an analysis of their different types and corresponding differential features. Additionally, attention is devoted to hybrid systems based on the coupling of high-temperature fuel cells and microturbines (mGTs).

1.1 World Population Growth, Energy Demand and its Future

A study carried out by the United States Census Bureau (USCB) [1] estimated that the world population exceeded 7 billion on 12 March 2012. Now, at the time of writing in August 2016 with the global population standing at about 7.4 billion [2], this figure is expected to continue rising over the coming decades [2]. As the world population grows, in many countries faster than the global average of 2%, the need for more and more energy is intensifying in a somewhat similar proportion, thus putting pressure on the natural resources available and existing infrastructures. This higher energy consumption is not only due to the growth in world population, but also to the improved lifestyles leading to a greater energy demand per capita (two features that inevitably come together). This is best exemplified by the fact that the wealthy industrialized economies comprise 25% of the world's population but consume 75% of the world's energy supply [3]. A recent study (from ref. [4]) shows that the total world consumption of marketed energy is expected to increase from 549 quadrillion British thermal units (Btu) in 2012 to 629 quadrillion Btu in 2020, and to 815 quadrillion Btu in 2040 – a 48% increase from 2012 to 2040 [4].

Indeed, the landscape of future energy demand and generation projected for the world seems rather bleak, as most nations, including the most developed ones, depend primarily on conventional energy sources such as oil, coal and gas to generate power not only for the domestic and industrial sectors but also for transportation. This dependency results in global warming, contributes to rises in fuel prices that constitute a burden on economies, and can lead to delays in energy production and supply [5, 6]. Furthermore, even if the global production of fossil fuels is currently sufficient to cover the world's needs, the exponential rise in the exploitation rate of this finite, fast-depleting resource would pose a risk to the future energy demand and generation balance [7–9]. In the long run this global dependence on conventional fuel sources for power production will prove problematic because the world will eventually fall short or run out of these resources. Renewable energy sources are often set forth as a feasible alternative to this fossil-fuel dominated world [10], although many of their inherent features, such as their low energy density, intermittency and geographical distribution, pose a number of challenges that remain to be solved today.

1.2 World Energy Future

Due to the heavy reliance of most nations worldwide on fossil fuels for power generation and transportation, the atmospheric concentrations of carbon dioxide and methane have increased by 36% and 148% respectively, compared with pre-industrial levels [11]. These levels are indeed much higher than at any time during the last 800,000 years, the period for which reliable data have been extracted from ice cores. This observation is further confirmed by less direct geological observations that also show that carbon dioxide concentrations higher than today were last seen about 20 million years ago. These findings suggest that the root cause for such high concentrations is anthropogenic, mainly hydrocarbon-based fuel burning (responsible for three-quarters of the increase in CO₂ from human activity over the past 20 years) and deforestation [11]. Other environmental f...