Exergetic Aspects of Renewable Energy Systems

Insights to Transportation and Energy Sector for Intelligent Communities

Evanthia A. Nanaki, George Xydis

• Publisher: CRC Press
• Year: 2019
• ISBN:
  9781351614023
• Edition: 1
• Topic: Physical Sciences
• Subtopic: Energy

Energy is essential to all human activities as well as critical to social and economic development. Sustainable energy planning encompassing the concept of smart cities has a high potential to significantly contribute to climate change mitigation. For improved energy efficiency, it is essential to find low carbon solutions for the urban environment. The integration and management of energy supply with predominant exploitation of local resources is examined through the fundamental concept of exergy. This book can assist in decision making, with regard to sustainable energy design both at a national and local level.

CHAPTER
1

Introduction

E. Nanaki¹ and G. Xydis²

¹ University of Western Macedonia, Department of Mechanical Engineering, Bakola & Sialvera, Kozani 50100, Greece

² Department of Business Development and Technology, Aarhus University, Birk Centerpark 15, 7400 Herning, Denmark

1.1 Energy, Climate Change, Smart Cities and Renewable Energy Integration

Energy is essential to all human activities as well as critical to social and economic development. Currently, the majority of energy systems are based on fossil fuel consumption leading to climate change and air pollution. Reducing energy use and increasing energy efficiency are crucial aspects for urban areas such as cities. Taking into consideration the fact that the worldwide population is growing, it is predicted that the fossil fuel consumption will keep on rising until 2050 [IEA energy outlook, 2017]. In this direction, many policies, such as the Paris Agreement, have been established. The Paris Agreement is characterized by a bottom-up approach to global cooperation, where each country delivers national inventories of greenhouse gases (NIR) and prepares Nationally Determined Contributions (NDC), which have to be adjusted and strengthened every five years [Doelle, 2016].

The Paris Agreement aims to keep global temperature rise this century below 2°C above pre-industrial levels and to pursue efforts to limit the temperature increase even further to 1.5°C. Nonetheless, in order to achieve 25% emissions reduction in 2040, opening the road to zero emissions in 2100, coordinated efforts of all stakeholders are imperative to take place. The introduction of renewable energy into the energy system of urban areas is a key element for the creation of smart and sustainable low carbon cities. In this direction, sustainable energy planning encompassing the concept of smart city has a high potential to contribute to the achievement of the European energy and climate targets.

Energy transition to zero carbon emission cities requires also energy use in a smart way, so as to reduce the energy degradation in terms of capacity to generate useful work. Thus, in order to improve the energy efficiency, it is essential to find low carbon solutions for the complex energy systems of urban environments (i.e. industrial, transport sector) that will increase cities’ overall energy and resource efficiency. Taken into consideration the fact that available standards do not provide integrated methods for the assessment of smart cities [ISO, 2014], the development of a comprehensive and holistic approach that will address policies for sustainable development and planning of smart cities is of great importance for climate change mitigation. It is noted, that in order to evaluate the energy and resource flows of different urban energy systems, it is necessary that these be analyzed not only within the city but also across city boundaries. Changes over time as a result of socioeconomic and technical strategies need to be examined and monitored, so as to quantify the progress towards the creation of low carbon cities and to visualize results in ways that are usable by stakeholders.

In this direction, exergy analysis is a useful tool for the evaluation of the effectiveness of different energy systems in smart cities. As per second law of thermodynamics, different forms of energy have different energy potential to generate useful work; therefore, exergy is used in order to measure the degradation of energy in conversion processes. Exergy analysis can be used, in order to identify how smartly energy is used. Until now exergy analysis has been applied in comparative analysis of countries, regions, economic, industrial as well as transportation sectors [Dincer and Rosen, 2013; Koroneos and Nanaki, 2008]. Nonetheless, the smartness of energy policies aiming to optimize their efficiency has not yet been investigated. Furthermore, many energy policies related to decision-making fail to take into consideration life-cycle impacts (both economic and environmental) of energy efficiency measures in the urban environment. Therefore, a holistic approach is necessary, in order to tackle climate change mitigation.

In order to bridge the above mentioned gaps, this book addresses, through a holistic approach - future energy needs of smart cities. The transportation as well as the energy system of the future has to be intelligent, sustainable and completely integrated in the multi-modal logistics chain of the future.

For this reason, the methods of exergy analysis as well as of life cycle analysis are being employed, in order to support smart city planning, in terms of evaluating the exergy efficiency of renewable energy systems that are going to be integrated to the electricity market and managed on the exploitation of resources within smart cities. In order to improve the energy efficiency of complex energy systems (i.e. transportation, built environment), it is imperative to find low carbon solutions. For this reason, this book also throws light on the correlation of the exergy concept in relation to the energy and transportation sector aiming to increase the efficiency of this sector in relation to its surroundings, within the concept of this city. In this direction, exergy analysis is combined with life cycle analysis.

The basics of exergy analysis as well as of sustainable smart cities are presented; however the fundamental concept of exergy applied to the above mentioned sectors is the basic axis of this book (Fig. 1.1). Transportation in urban environment and interaction with the intelligent energy systems is studied. Exergy analysis is used within regional planning; referring to sustainable spatial design (improved use of energy flows, energy demand, e.g.). Moreover, possibilities through intelligent energy systems implemented are presented for energy conversion, distribution and storage to increase the integration of sustainable energy to the system and deliver energy to the end user under the most suitable scheme. An exergy planning approach focuses towards that direction and examines smart grids, electricity markets and how much they interact with each other. Big Data, Deep Learning, and Nexus Platforms are recruited to demonstrate the amount of data being wasted from a number of processes at an urban scale and collect them, organize and utilize them under a “smart city v2.0” version. In addition, the term of Bi-directional exergetic efficiency (BiXef) is introduced so as to measure not only how efficient a resource is, but mainly if it is as efficient when needed.

Fig. 1.1. Flow chart of the book

Color version at the end of the book

1.2 Motivation for the Book

Intelligent Energy Systems within the scope of smart cities are gaining recognition as alternative ways through which a low carbon society can be pursued. This term is drawing increasing attention from urban planners and decision-makers as it emphasizes the need for enhancing cities’ capacities to cope with the heterogenous challenges of cities and their future development and climate change. Therefore, a holistic approach to urban development is of great significance, especially in the case of contemporary cities, and what this entails in terms of sustainability and the integration of its environmental, social, and economic dimensions. Theoretical knowledge, and available research tools such as exergy analysis, should contribute to make urban development smartly more sustainable. Based on the above mentioned, the motivation for this book lies in the following areas:

• The significance of the interdisciplinary field of smart cities as it requires a multi-disciplinary approach starting from conceptual designs (modeling) to the implementation of this within the city.

• The determination of what has been done until now in the area of optimization of complex energy systems within smart cities.

• The presentation of an overview of key concepts, theories, and discourses in regards to exergy analysis and energy systems within smart cities.

• The assessment and synthesis of the existing information in line with the concept of exergy analysis.

• To provide a solid background and theoretical foundation for exergy analysis and renewable energy systems within smart cities.

• To identify the gaps in the existing research that this book is endeavoring to address, positioning this book in the context of previous research and creating a research space for it.

• To produce a rationale and establish the need for this study and thus justify its originality.

• To bridge the gap between academic understanding of exergy analysis and ecosystem functions and municipal planning of organizational structures.

1.3 Aim and Objectives of the Book

The concept of sustainable energy planning is interconnected via the method of exergy analysis with the smart cities’ perspective. In this direction, this book constitutes a valuable tool that can be helpful to stakeholders and decision-makers in the process of regional planning, referring to sustainable spatial design. Thus, it aims to help in decision making, especially with regards to national and sustainable energy designs, and demonstrates how intelligent energy systems can best be utilized. The book’s objective is to provide useful insight to policymakers, urban planners, engineering consultancies, scientists, researchers, students as well as citizens interested for optimization of energy systems within intelligent energy urban areas.

This book addresses the concept of exergy analysis within sustainable energy planning and contributes to the literature regarding optimization of energy systems within smart cities. Methodologies and theoretical foundations of exergy analysis as well as case studies within the concept of smart cities are presented. Furthermore, the book aims to point out that a combination of efficiency measures, intelligent load management and local renewables, can contribute to a decarbonized urban energy future. In the book, several scales within the city are addressed, ranging from the efficiency of renewable energy systems to complex energy systems such as the transportation sector.

1.4 Structure of the Book

The book discusses the exergetic aspects of renewable energy system in the key areas of transport and energy sector, within the concept of smart cities. The book is structured into six sections that are briefly described here below.

In Chapter 2, the background and the method of exergy analysis is presented. It establishes the fundamental notion of energy – exergy and thermodynamics with application on Renewable Energy Systems. The chapter provides the necessary background for understanding these concepts, as well as basic principles, general definitions and practical applications and implications. Case studies (solar energy, wind energy and hybrid energy systems) are provided to point out aspects of energy, entropy and exergy. The scope of this chapter is to emphasize on the role of exergy analysis as a tool for the creation of a sustainable energy future by increasing the energy efficiencies of processes utilizing sustainable energy resources.

Chapter 3 points out the need for the improvement of the performance of smart cities via a holistic system operation, which shall lead to increased efficiencies of the system and reduced operational costs. By improving the efficiency in urban areas via a holistic approach, will lead to increased performances of all urban related activities squeezing as much as possible the operational costs, and goes a lot further than just the optimization of electricity markets. However, optimizing electricity markets is the starting point for city planners and decision-makers towards achieving cleaner investments and monitor at the end a unified smart city operation.

Chapter 4 then deals with available Alternative Fuel Vehicles and the renewable energy sources that can be employed for the creation of a low carbon transport sector within smart cities. The chapter focuses on the key challenges for smart mobility consideration in smart city – in terms of economic and environmental assessment. The main questions are which transport systems will be used in the future – in terms of cost and environmental efficiency. It is argued that alternative vehicle technologies within smart cities have to be considered as part of an integrated energy system. Based on real data from the vehicle industry, the total cost of ownership as well as the life cycle environmental impacts of different powertrains are assessed.

In Chapter 5, transport energy demand is discussed. The interrelation between urban environment and the transportation sector as well as between climate change and the need for sustainable transport systems is presented. Optimization of the transport sector is proposed via the method of exergy analysis. The optimization is then applied to Greece’s transportation sector. Using detailed data for the period 1980-2016, the efficiency of the transport system is assessed. The assessment includes a detailed transport system analysis - in terms of energy and exergy efficiency - and discusses how the system (road, rail, aviation and navigation) can be optimized with the integration of alternative fuels (i.e. electricity and biofuels).

Chapter 6 focuses on the Urban Nexus Platform which should serve as a tool for organizing small scale resources within a city level by measuring efficiencies within one energy system. The platform will optimize the true potentials of new energy technologies using artificial intelligence and deep learning. An index, measuring when a resource within a city/neighborhood is needed or not, is introduced. In addition, this index quantifies how much of the resource is needed. The Bi-directional exergetic efficiency (BiXef) is introduced to measure not only how efficient a resource is, but mainly if it is as efficient when needed. This approach, when adopted, will change the way we evaluate global resources.

In Chapter 7, the uncertainty of spatial planning within the concept of smart cities is asses...

Table of contents

• Cover
• Title Page
• Copyright Page
• Dedication
• Preface
• Table of Contents
• 1. Introduction
• 2. Basics of Renewable Energy Systems Exergetics
• 3. Electricity Markets and Renewable Energy Sources – A Smart City Approach
• 4. Economic and Environmental Assessment of the Transport Sector in Smart Cities
• 5. Transportation and Urban Environment – Exergetics
• 6. Exergy Analysis of Intelligent Energy Systems in the Built Environment
• 7. Spatial Planning and Exergy – Design and Optimization
• Index
• Color Plate Section