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Biofuels: their emergence and implications for sustainability in aviation


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The global aviation industry is facing complex and unpredictable market conditions with fluctuating oil prices and the adverse environmental impact of aircraft operations. Since the regulatory approval for biofuels, the first biojet fuel flight test in 2007, using a blend fuel, was a remarkable step towards having more test and schedule flights up to the year of 2014. The purpose of this paper is to engage this new alternative energy with the issues that airlines associate with sustainability, mainly focusing on aircraft operations and profitability. The key findings suggest that the uses of alternative energy need to be in parallel to the reliability and maintainability of the aircraft system, so that the adoption of biofuels can be effective.
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Biofuels: their emergence and implications
for sustainability in aviation
H. Noh1,2, G. Alonso1, S. Nair3 & Y. Dahdi1
1Universiti Kuala Lumpur of Malaysian Institute Aviation Technology,
2ETSI Aeronauticos, Universidad Politecnica De Madrid, Spain
3Umeå School of Business and Economics, Sweden
The global aviation industry is facing complex and unpredictable market
conditions with fluctuating oil prices and the adverse environmental impact of
aircraft operations. Since the regulatory approval for biofuels, the first biojet fuel
flight test in 2007, using a blend fuel, was a remarkable step towards having more
test and schedule flights up to the year of 2014. The purpose of this paper is to
engage this new alternative energy with the issues that airlines associate with
sustainability, mainly focusing on aircraft operations and profitability. The key
findings suggest that the uses of alternative energy need to be in parallel to the
reliability and maintainability of the aircraft system, so that the adoption of
biofuels can be effective.
Keywords: air transport, alternative energy, biofuels, aircraft maintenance,
1 Introduction
According to IATA [1], airline passenger numbers are expected to rise by 31%,
from 2.98 billion passengers carried in 2012 to 3.91 billion by 2017, with the
Asia/Pacific region as the main contributor to this growth.
The growth of the industry is linked to an increase in the total emissions, which
contribute to climate change. There has been several studies on climate change
due to aviation since the late 60s and the early 70s (Kuhn [2]). The research was
triggered by the potential stratospheric ozone (O3) depletion, which was increased
by the emissions from supersonic aircrafts (SMIC [3]). Later, the effects of
nitrogen oxide were realized, which dramatically increased other research, ISSN 1743-3541 (on-line)
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Energy and Sustainability V: Special Contributions 103
programs to identify the emissions and their effects from aviation. These include
CO2 emissions emission of particulate matter, the effects of contrails, and other
aviation-induced cloudiness contrails (Steven and Merklein [4]).
The airline industry has recently started the adoption of alternative energy.
Many terms have often been used to identify the classification of biofuels; “the
first generation”, “the second generation”, and even “the third generation”. This is
further divided into two groups: conventional biofuels (first generation) and
advanced biofuels (second and third generations), as shown in figure 1 (IATA [5]).
Figure 1: Conventional and advanced biofuel. Source: IATA 2009 [5].
Among these three biofuel generations, the distinguishing element is the
technological advancement in terms of yield from biomass and the fuel efficiency.
Many investigations and research have taken place and many more are still in the
development phase. This is to ensure that this alternative biofuel can meet the
supply and demand for future use. The advantages and the disadvantages lie in the
biomass itself, which determines the projection for its readiness level for being in
the global market (ICAO [6]). Developing a biojet fuel that is clean and cheap has
become a concern of high priority within the aviation industry. The main problems
encountered regarding land availability and sustainability mean that it is not
prudent at this time to assume that in 2050 biofuels could account for more than
10% of global aviation fuel (Rosillo-calle et al. [7]). But recent research suggests
that value from renewable energy technologies can be created and captured
sustainably and innovatively by green business models (Nair and Paulose [8]).
Airlines need to adopt the new biofuels, but the most essential part is to ensure
that it can be used effectively and affordably in aircraft operations and
maintenance. In this case, it is crucial for the airlines to utilize the biofuels with
affordable maintenance costs in order to ensure that the engine systems can
continually and safely perform their functions with reliability. The Maintenance
Review Board (MRB) will need to evaluate the changes in the maintenance
program to check whether the tasks need to be eliminated or reinstated. In some
cases, the maintenance program needs to be adjusted with the introduction of new
48 102 127 202
1,200 1,500
ConventionalBiofuel AdvanceBiofuel
Algae A 10g/m2/day at 15%
Algae B 50g/m2/day at 50%, ISSN 1743-3541 (on-line)
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104 Energy and Sustainability V: Special Contributions
elements to ensure its reliability and to conduct analysis in case of system failure
or components failure (Sundaram et al. [9]).
In this paper, we try to look at how the biofuels have been adopted in aviation
and what implications their use has for promoting sustainability in aviation. We
also try to examine how the adoption of biofuels will affect aircraft operations and
2 Biojet fuel evolution
Airlines fly across continents and need to refuel anywhere and so the goal is to
establish local biofuel value chains on every continent. Such global supply chains
require the infusion of huge amounts of capital, which can be achieved only
through policy initiatives by airline alliances that combine aircraft manufacturers,
allied industries, regulatory organizations, and various governments. The
initiatives in this field include the Brazilian Alliance for Aviation Biofuels
(ABRABA); the European consortium of airlines and bio-fuel conversion
technology providers led by Airbus; an Australian consortium led by Qantas, the
Sustainable Aviation Fuel Users Group (SAFUG), which features 21 airlines, three
aircraft manufacturers, and a bio-fuel conversion technology provider; and the
Sustainable Way for Alternative Fuel and Energy in Aviation (SWAFEA) of the
European Commission. These alliances are characterized by a wide variety of
involved stakeholders, including the airlines, the aircraft manufacturers, airports,
biofuel companies, petroleum companies, NGOs, governmental agencies and
funding agencies.
Figure 2 shows how the different stakeholders are playing a role in changing
the global aviation biofuel industry. Table 1 gives more information on what
carrier; type of biofuel; aircraft and destination details of the present airlines use
of biofuels in the Asia-Pacific region.
Figure 2: The commercial flight progress around the globe since 2008 up to
September 2014., ISSN 1743-3541 (on-line)
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Energy and Sustainability V: Special Contributions 105
Table 1: Asia-Pacific biofuel flight progress.
20% one
Air New
Jatropha 50% one
Two hour flight test
JAL Camelina,
Alage blend
50% one
B 747-
Demo flight
Air China
Jatropha 50% of one
Beijing airspace
Airways TG
Castor seed One engine B777-
Bangkok–Chiang Mai
Qantas Cooking Oil 50% A330 Sydney–Adelaide
ANA Cooking Oil 10% blend B737 Evertt’s Paine Field (KPAE)
to Haneda Airport (HND)
Jetstar Cooking Oil 50% Blend Dream-
3 Biojet fuel adoption
The most important factor in the adoption of biofuels is going to be their cost with
respect to using aviation kerosene. Fossil fuel use is increasing and their reserves
are being depleted that will lead to fuel shortages in the near future. Airlines not
only consider the fuel price, but also the implications the new fuel has on
sustainability and cost gains in terms of operations and maintenance.
The alternative fuel being produced using (F–T) process was certified for
aviation usage by ASTM International Standard D7566 in September 2009
(ASTM [10]). A 50% blend of (F–T) synthetic fuel with conventional fuels is
currently used by few biojet fuel flight tests for use in commercial aviation. On
July 1, 2011, ASTM approved the jet fuel product slate of Hydro processed Esters
and Fatty Acids (HEFA) under alternative fuel specification ASTM D7566 (IATA
[11]). HEFA fuel that meets this specification can be mixed with conventional jet
fuel, up to a blend ratio of 50% (Liu et al. [12]). HEFA is currently the leading
process for producing renewable jet fuel and several airlines that use this
technology including Aeroméxico, Air China, Air France, Finnair, Iberia, KLM,
Lufthansa and United (IATA [13, 14]).
In January 2009, the involvement of the Commercial Aviation Alternative Fuel
Initiative (CAAFI), a research and development initiative involving various
participants from Europe and the US, moved towards an established effort that the
US Air Force and an Airbus proposal may possibly be brought together as a single
Fuel Readiness Level (FRL), as shown in table 2 (CAAFI [15])., ISSN 1743-3541 (on-line)
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106 Energy and Sustainability V: Special Contributions
Table 2: Fuel readiness level on the ICAO environment report 2010.
FRL DESCRIPTION TOLL GAT – progress updates
1, 2 Basic Principles Observed and
Technology Concept Formulated
Biofuel technologies including processes
were identified
3, 4 Proof of Concept
Process validation
No agricultural land required for growth
of feedstock (e.g. biofuels from algae or
biofuels grown with water from low-
carbon desalination) may develop to
change this picture and be fully optimistic
5, 7 Preliminary Technical Evaluation –
Fuel Approval
ASTM D7566 approved
Full-Scale Technical Evaluation Biofuel flight test/schedule flight
conducted successfully since 2008
(Appendix 1)
8, 9 Commercialization Validated
Production Capability Established
Internationally adaptation through
methodology acceptance/ technically
feasible and economically viable. E.g. full
scale operational – SkyNRG-KLM
This development is very intense as the legislation for price and potential new
carbon emissions affects the fossil fuels. At the same time, the growing global
demand for air travel has led to collective motivated research to obtain more
sustainable alternative fuels (ATAG [16]).
3.1 Biofuel adoption and aircraft maintenance issues
A turbine engine uses air as its working fluid, in the same way that blood does in
our body. Every movement of the moving part needs a dynamic relationship
regards all systems such as aircraft fuel and the metering system, lubrication and
seals system, and the aircraft cooling system. Starting from the air intake, up until
exhaust nozzles, complete combustion and actual combustion can be seen in figure
3 [17, 18].
Figure 3: Turbine engine diagram with combustion products., ISSN 1743-3541 (on-line)
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Energy and Sustainability V: Special Contributions 107
Maintenance comes after a great design. The ability to maintain and sustain the
components, parts, and engine in the case of biojet fuel is vital. An aircraft turbine
engine is very expensive compared to an automotive engine. Every single part
such as bearings and seals needs to captivate, and further research on aromatics
contents in the biojet fuel vs. normal kerosene fuel is still going on (Dufferwiel
[19], Daggett et al. [20]). Examples of turbine engine components and its
relationship towards biojet fuel maintenance is shown in table 3 (SAE [21], Lipa
[22], Woodward [23]).
Table 3: Turbine engine components and their relationship towards biojet fuel
Components Functions Relation to bio jet fuel maintenance
FUEL TANK The fuel tank located in both wing and
center of the fuselage. It holds the fuel for
power demand form the engine.
Inspection of the tank needs to be
evaluated for any seals property damage
and micro biological growth corrosions
that will lead to leak, cracking or pump
blockage due to lack of Aromatics-
substantial to add additives.
The fuel pump is located on the accessory
gearbox (AGB). The fuel pump
pressurizes and circulates fuel within the
fuel for fuel combustion.
The fuel flow needs to be tested for
minimum requirement of flow rate
(literally low for biojet fuel).
The fuel filter is located within the lower
section of the fuel pump and its corrugated
construction is designed to retain foreign
particles suspended in the fuel, and
prevent blockage their entry into the MEC.
Normal sediment possibility comes
from the tank or the biomass residue.
Fuel nozzles are installed into the
combustion case and are connected to a
fuel manifold and drain manifold.
Results from the decreasing fuel flow
rate led to a decrease in Fuel Nozzle
supply, which enhances disturbance on
complete combustion.
PMC Power Management Control, which
provides an electronic Adjustment of the
MEC to obtain optimum power settings for
take-off, climb, and cruise flight
conditions without constant adjustment of
the thrust lever by the flight crew.
Detailed data on new fuel enhance the
change in the details. Specific gravity
on the MEC position.
MEC Designed to control fuel flow variable
bypass valve (VBV) position, and
variable stator vane (VSV) position on the
engine. The MEC schedules the proper
amount of fuel during acceleration and
deceleration and regulates flow during
steady-state operation to maintain a set
core engine speed.
The specific requirements of fuel need
to be met and adjusted accordingly., ISSN 1743-3541 (on-line)
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108 Energy and Sustainability V: Special Contributions
3.2 Biofuel adoption and aircraft operations
Other than maintenance repair and overhaul (MRO), the airport infrastructure, air
traffic management (ATM), airline operations, end-of-life recycling are among the
main concerns in line with a broader scope for going green and sustainable in
aviation. For aircraft operations, teams from the IATA (Green Teams) are advising
all the members in terms of aircraft operation including fuel efficiency, covering
ground operations, flight planning and operations, fleet renewal programs and
aircraft upgrades with already certified improvements (Boeing [24]). In the year
2011, due to environment concerns, around 40 ground support vehicles in the
Amsterdam Schipol Airport were 100% powered by biodiesel. The commitment
in introducing more sustainable transport is necessary as electrical power is not
currently suitable for all type of vehicles.
While non-related to biofuel adoption, Air Traffic Management (ATM)
enhancement progress will enhance the reduction in aviation emissions where
IATA currently is working close with Civil Air Navigation Services Organization
(CANSO), Air Transport Action Group (ATAG), Radio Technical Commission
for Aeronautics RTCA, EUROCAE, Airlines Electronic Engineering Committee
(AEEC) and more (Ribeiro et al. [25]). Since the 1930s, changes in air navigation
systems have been introduced in a very systematic way. The primary concern on
top of all others will be the ‘safety’. Any changes, modifications or amendments
will be analyzed with extremely careful testing and consultation. Air traffic
management does not work alone. From ATM, two types of reduction can be
contributed; CO2 reduction and fuel consumption reduction. By the
implementation of projects in Single European Sky project by SESAR,
the average fuel consumption per flight can be reduced by up to 10%. The
implementation will be in between 2013 and 2030, where around 50 million tonnes
of CO2 can be avoided (IATA [26]).
4 Conclusion
Air transportation is adopting sustainability at different levels. Adopting biofuels
has been a major factor in this with major airlines involved in multiple initiatives
around the world. Airlines look at multiple factors such as costs, regulatory and
operational aspects, while adopting new fuels. We have looked at these issues
and have come to the conclusion that adopting biofuels has positive impacts on
the maintenance and operations of aircrafts. The cost benefits are long-term and
will have more positive impacts as petroleum fuels become scarce and the
environmental costs of using them become a major factor in cost benefit analysis
of airlines. Airlines should adopt biofuels in a major way as it leads towards their
long-term economic and environmental sustainability.
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