Energy Efficiency in Air Transportation

Arturo Benito, Gustavo Alonso

• Publisher: Butterworth-Heinemann
• Year: 2018
• ISBN:
  9780128125823
• Topic: Technology & Engineering
• Subtopic: Aeronautic & Astronautic Engineering
• Index: Technology & Engineering

Energy Efficiency in Air Transportation explores the relationship between air transportation and energy use, starting with an analysis of air transport energy sources and their potential development. The book examines how different elements of the air transport system make use of energy, with an analysis of various methods for optimizing energy consumption. The book covers the consequences of energy use in terms of economics, environmental impact and sustainable development, with a review of the existing and proposed regulatory measures addressing those factors.

Aeronautical and air transport engineers interested in aerial vehicle systems design, as well as public administrators and regulators concerned with energy efficiency or environmental issues in air transport, will benefit greatly from this comprehensive reference, which captures necessary background information along with the newest developments in the field.

• Examines new developments in energy efficiency in the air transport field
• Includes exergy analyses of aerial vehicles and systems
• Shows the environmental impact from fuel use including local air quality, consumption of non-renewable materials and contribution to climate change
• Discusses the CO2 emissions certification required by ICAO for new aircraft models

1

Introduction

Air transport is without any discussion one of the most relevant components of the social organization of our world. In 2017, there were about 4200 million of commercial air trips, more than one per every two-world inhabitants and the majority of the air traffic forecasts predict growth trends in the order of 5%–6% for the next 20 years, clearly higher than the expected economy increase rates.

The air cargo market is also important in a somewhat different way. In terms of weight, the demand is much smaller than in other transportation means, not reaching 0.1% of the ton-kilometer transported, but in terms of the value of the goods, it becomes close to 30% of all the import-export world market. The possibility of moving high-value components in a fast and safe way has modified the producers’ behavior and the consumers’ as well.

In economic terms, world airlines revenue went up to 754 billion USD, a figure that would put commercial aviation as number 19 of the World States Gross National Product (GNP) ranking, comparable with the Netherlands or Switzerland. However, the global effect is much greater, supporting 3.5% of global Gross Domestic Product (GDP), equivalent to 3.3 trillion USD, and summing up to 69.6 million jobs, if direct, indirect, induced, and catalytic effects are computed. This activity generated 126 billion USD in different taxes going to the national economies.

A very relevant factor is the increasing connectivity provided by air transport. In 2017, world airlines flew more than 20,000 unique city pairs, a figure more than double with respect to the year 1996. With a route structure showing a high level of interconnection in the airports acting as hubs and a growing number of intermodal relationship, modern air transport has a unique capability to put in contact the world population, serving its social and economic demands.

This upwards trend is confirmed by a number of other economic and behavioral evidences of our present society, as the widening of globalization, the growth of tourism, and the increasing interest for traveling of the new generations. All those phenomena needing of air transport to develop their maximum potentialities and requiring a continuous air transport offer enlargement in order to satisfy the existing and new developing demand. The strong and accelerated economic growth of some of the most populated countries, like China, India, Indonesia, or Brazil, is asking for the support of a well-balanced air transport network, able to support the domestic development and link it with the surrounding economies worldwide.

In comparison with the majority of activities in the services sector, including other transportation modes, commercial aviation is energy intensive and this feature makes mandatory the introduction of every mean to minimize its energy use due to economic, environmental, and sustainability reasons. The relative importance of these three elements has changed along the years, following the fluctuations of the world economy, the sociopolitical developments of different world regions, and the discovering of new scientific evidences on the evolution of the Earth climate. In any case, the global weight of the three factors has continued going up and putting more pressure on the different sector stakeholders: on manufacturers for developing more efficient technologies, to be adequately tested and brought into commercial service conditions; on operators for making the best possible use of those new vehicles in the general operative context; and on regulators for introducing new measures to optimize energy use and making a more sustainable operative landscape.

In this specific transportation mode, the problem is more acute due to the absence of short/medium term alternatives to the use of oil products (kerosene and high octane gasolines) as standard fuels. Longer-term options, like liquid hydrogen, would require a drastic change in the system structure and look very far away in time. While ground and sea transport may access gas, electric, solar, wind, or even nuclear energy, the air mode is just starting to analyze batteries, solar panels, and fuel cells as possible auxiliary energy providers and the only medium-term technically feasible alternative source appears to be the kerosene obtained from biological feedstock. However, its present price in today’s market conditions makes this option unfeasible, unless regulatory actions are taken to introduce these substances in the industry through mandatory or economic incentive measures.

All aforementioned circumstances taken into account, it seems pertinent to gather in a book those many different aspects of the energy efficiency in air transport. Not only to provide answers to questions coming from diverse areas of the sector but also, perhaps, to propose some new research items that may appear in the next future, as results of the advanced technology now in preliminary status. This book intends to provide the necessary background information, together with the newest developments in a very dynamic field of knowledge, and become a useful tool for air transport professionals, decision makers, and university students wishing to specialize in this area or to find interesting data to be used in other different but related research tasks.

The structure of the book starts with this introductory section (named as Chapter 1), and follows with other nine chapters, covering the energy efficiency aspects of the three main elements of the air transport system (aircraft, air space, and airports) design and operation, and their respective impacts on environment and sustainability. The volume closes with a very wide and exhaustive list of references that have been used along the different chapter expositions.

The second chapter intends to describe the framework in which the air transport energy consumption is inserted. It starts with a wide panorama of the world present energetic situation, showing the primary energy production sources and the main consumption elements, with a reference to the most likely future developments. An overwhelming majority of the fuel used in air transport is coming from crude oil distillation, taking the form of kerosene, but there are other minor fuel sources, like organic feedstock, waste, or carbon that may be important in the future. This chapter describes, in technical and economic terms, the existing and potential sources and the similitudes and differences with other transportation means, indicating the world oil consumption share of the air transport and the comparative efficiency in competitive or uncompetitive trips.

Chapter 3 describes the core structure of the air transport system, detailing its main components and their respective importance for the optimization of energy consumption. The air transport mode is defined by three basic elements: commercial transport aircraft, the air space used for their flights, and the infrastructure required to supporting their operations, like airports and air traffic management (ATM) facilities. The large majority of energy consumption is coming from the aircraft operation and the chapter covers the composition of the 28,000-strong commercial aircraft fleet, with a brief description of existing aircraft and engine types and the prospective future programs. The other two stakeholders have a substantial influence in the global result as well. Airports, in particular, have a different energy balance and offer more chances to use alternative energy sources and achieve a zero‑carbon footprint, but the way in which they manage their traffic has a large effect in the fuel consumption by the operators. In the case of ATM, it is obvious its decisive influence on optimizing the trajectory and flight regime of the operations in order to optimize the energy bill. Over these three elements, the regulatory system has an obvious relevancy because a great number of operational regulations have direct effects on the energy use and the operational efficiency.

The design of commercial aircraft and the effects of different elements design in fuel efficiency are the issues dealt with in Chapter 4, divided into four subchapters: aerodynamics, propulsion, structures, and systems, corresponding to a typical subdivision of the aircraft architecture. In each one of them, the main existing and proposed features to reduce energy consumption are detailed, including in service and in development applications, and medium-long term expectations, like nonconventional aircraft or engine configurations. A second part of this chapter provides some information on the evolution of the energy efficiency in the last years, in relation with the aircraft-type replacement. A final section reviews some of the most important technological programs going ahead in Europe and United States.

Chapter 5 moves to the daily operation of commercial aircraft and the fuel efficiency consequences of the preparation of commercial service flight planning, with the relative importance of different parameters, like flight speed, aircraft weight, flight track, or cruise altitude. The repercussions of last-minute unexpected events on the flight plan and the different possibilities of managing those circumstances are also discussed. An analysis of most commonly used optimization policies at the moment of elaborating the flight plan, including the application of Cost Index, tankering, redispatch/reclearance, and flight management system (FMS), helps to go from the theory to the airline practice of each individual flight dispatch.

Next chapter presents the detailed fuel efficiency effects of each flight phase (ground operations, take-off, climb, cruise, descent, approach, landing, and taxi) and the optimization procedures, including the elements depending on the airport procedures and air navigation services operation. Trajectory optimization and the application of the ATM instructions are also contemplated and discussed.

The importance of sound maintenance practices to optimize fuel use is analyzed in Chapter 7. The two main issues to consider are the systems for aircraft performance monitoring and the maintenance actions focused on improving fuel efficiency. Aircraft and engines performance monitoring is a valuable decision tool to follow the performance degradation and to evaluate the different possibilities of performance/reliability recovery actions to be added to the standard maintenance program. To put those actions into value, their potential fuel efficiency effects need to be compared, by the adequate tradeoffs with the changes in other operational conditions, like aircraft availability for commercial service, on-time performance, and global flight economy. This chapter makes also a smart tour around the maintenance actions with the most important effects on fuel efficiency, like engine refurbishment, aerodynamic cleanness, and weight reduction.

Chapter 8 pays a fast visit to the energy footprint of the air transport infrastructure. Although the share of energy consumption of airports and ATM facilities is very small, compared with the aircraft movements, and they have more possibilities of using alternative energy sources, their correct operation may have important repercussions in the flight optimization. The effects of infrastructure in energy use are divided into two parts: the first one deals with ATM developments to optimize flight tracks and reduce congestion, including the restructuration of the airspace and the international cooperation on flight tracking analysis under International Civil Aviation Organization (ICAO) surveillance. The second explores the use of energy in the airport facilities and the effects of airport operations both to the airlines and to the airport itself. This part reviews the airside of the airport, the ground one and the other transportation modes access to the facilities, with a final note on the airport carbon certification system.

The relationship between aviation energy efficiency and the environment protection is described in Chapter 9. The aviation environmental impact from energy use has two different parts: local effects (air quality, energy management facilities in the airports, landscape alteration) and global effects (consumption of nonrenewable materials, use of dangerous substances and, the most important, contribution to climate change). In addition to the technical actions exposed in the previous chapters, an analysis of the potential of market-based measures (taxes, charges, voluntary agreements, emissions offsetting, and emissions trading systems) to reduce this impact is performed. Due to the complicated regulatory framework of the aviation environment, a list of the most important regulatory bodies and the key laws and regulations is included, with a mention to the Environmental Management Systems and their energetic repercussions.

Chapter 10 deals with the most recent developments in the area of the efficiency certification. While a number of commercial aircraft features require a certification under the design state rules before entering into service, fuel efficiency had not been one of the certification parameters until now. However, after complicated and hectic six-year-long discussions, the 2016 ICAO General Assembly approved a CO₂ emissions certification requirement for new aircraft models, achieving type certification in 2020 and onwards, with a later extension to models in production. During the same meeting, ICAO also approved the implementation of the Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA), intended to keep net international civil aviation CO₂ emissions at a level not higher than the one produced in the year 2020. The technical bases of the certification system are described here as well as the general principles of the CORSIA system, but many detailed features are still in discussion within the ICAO Committee on Aviation Environmental Protection (CAEP).

2

Energy and air transport

Abstract

As an opening tool for the rest of the book, this chapter covers some of the main questions about the different types of energy sources available in present times, with their main characteristics, and which ones of them and in which form are they used for transportation services. After a rough comparison of transport modes energetic efficiency, the focus falls on air transport, describing the different types of aviation fuel and their most important attributes. The final part of the chapter contains a brief discussion on the future of some of the alternative aviation fuel presently on development or in study.

Keywords

Transportation energy; Transportation energetic efficiency; Alternative fuels

2.1 Energy and transportation

Transportation means moving massive things from one point to other and requires a certain amount of energy. The dimension of the energetic needs depends on the achieved momentum (mass and speed), the vehicle technology, the medium in which transport is done, the infrastructure qualities, and the legal regulation applicable.

Any transport consumes energy in the quantity demanded by those previously mentioned elements. This energy has a number of conditions to adapt itself to the type of movement of each different transportation mode. The final fuel product has to arrive to the engine in the most convenient condition and, at the same time, production and logistics should not be excessively complicated, expensive, or demanding a large amount of additio...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• 1: Introduction
• 2: Energy and air transport
• 3: The elements of the air transport system
• 4: Aircraft design
• 5: Flight planning
• 6: Operational procedures
• 7: Maintenance
• 8: Infrastructures
• 9: Energy efficiency and the environment
• 10: Efficiency regulation and certification
• References
• Index