Beginner’s Guide 

to Aviation Biofuels

May 2009
Introduction Page 1

What are biofuels? Page 2

What are second-generation aviation biofuels? Page 4

Why use biofuels for aviation? Page 6

Biofuels for aviation – technical challenges Page 8

Biofuels for aviation – sustainability challenges Page 9

Flightpath to a biofuelled future Page 10

Biofuels for aviation – testing Page 12

Biofuels for aviation – the certification process Page 14

Biofuels for aviation – economic viability Page 16

From the fields to the wings Page 18

The next steps Page 20

Definitions Page 21

Contents 

Sources for diagrams and a reference version of this document are available at www.enviro.aero/biofuels

This brochure is for information purposes only. While every effort has been made to ensure the quality and accuracy of information in this brochure, it is made available without 

any warranty of any kind.

• Aviation provides the only rapid worldwide transportation network, is indispensable for 

tourism and facilitates world trade. Air transport improves quality of life in countless ways.

• Air transport moves over 2.2 billion passengers annually.

• The air transport industry generates a total of 32 million jobs globally.

• Aviation’s global economic impact (direct, indirect, induced and catalytic) is 

estimated at USD 3,560 billion, equivalent to 7.5% of world gross domestic product.

• Aviation is responsibly reducing its environmental impact.

• Air transport’s contribution to climate change represents 2% of man-made CO2

emissions and this could reach 3% by 2050, according to updated figures from 

the Intergovernmental Panel on Climate Change (IPCC).

• This evolution is based on a growth in aviation CO2

 emissions of 2-3% per year, with 

an annual traffic growth of 5%. The air transport industry is now working towards 

carbon-neutral growth – no increase in carbon emissions in spite of traffic growth – 

as a first step towards a carbon-free future.

• Aircraft entering today’s fleet are 70% more fuel-efficient than 40 years ago, 

consuming 3.5 litres per passenger per 100km. The Airbus A380 and the Boeing 787 – 

consuming less than 3 litres/100 km – compare favourably with small family cars.

The importance of aviation 
Beginner’s Guide to Aviation Biofuels: Page 1

In the early days of the jet age, speed and luxury were the drivers of intercontinental travel. 

Today, our engines are at the cutting edge of efficiency. Our aircraft are more aerodynamic 

and lighter than ever before. We are making huge improvements in our air traffic control 

efficiency, how we fly our aircraft and in developing more environmentally-friendly 

operations at airports. But we are still using the same fuel. That’s about to change.

The world is turning to governments and business to reduce the human impact 

on climate change. And the aviation industry is about to embark on a new journey. 

Sustainable biofuels are crucial to providing a cleaner source of fuel to power 

the world’s fleet of aircraft and help the billions of people who travel by air 

each year to lower the impact of their journey on our planet.

This guide looks at the opportunities and challenges in developing sustainable 

biofuels for aviation. To discover the other technology, operations and infrastructure 

improvements underway across the aviation industry, check out www.enviro.aero.

Introduction
Beginner’s Guide to Aviation Biofuels: Page 2

What are biofuels?

Theoretically, biofuels can be produced from any 

renewable biological carbon material, although the most 

common sources are plants that absorb carbon dioxide 

(CO2

) and use sunlight to grow. Globally, biofuels are 

most commonly used for transport, home heating, power 

generation from stationary engines, and for cooking. 

The two most common feedstock sources for making 

biofuels are plants rich in sugars and bio-derived oils.

Crops that are rich in sugars (such as sugar cane) or starch 

(such as corn) can be processed to release their sugar 

content. This is fermented to make ethanol, which can be 

used directly as a petroleum substitute or additive. These 

fuels, known as first-generation biofuels, are typically 

not suitable for use in aircraft, as they do not have the 

necessary performance and safety attributes for modern 

jet engine use.

However, bio-derived oil, commonly sourced from plants 

such as corn, soybeans, algae, jatropha, halophytes and 

camelina, is processed and can either be burned directly or 

converted by chemical processes to make high-quality jet 

and diesel fuels. These are known as second-generation 

biofuels and can be used for aviation (see page 4 for 

further information).

Biofuels – providing environmental benefits

Relative to fossil fuels, sustainably produced biofuels 

result in a reduction in CO2

 emissions across their 

lifecycle. Carbon dioxide absorbed by plants during 

the growth of the biomass is roughly equivalent 

to the amount of carbon produced when the fuel 

is burned in a combustion engine – which is simply 

returning the CO2

 to the atmosphere. This would allow 

the biofuel to be approximately carbon neutral over its 

life cycle. However, there are emissions produced during 

the production of biofuels, from the equipment needed 

to grow the crop, transport the raw goods, refine the 

fuel and so on. When these elements are accounted for, 

biofuels are still anticipated to provide an estimated 80% 

reduction in overall CO2

 lifecycle emissions compared to 

fossil fuels. For example, analysis of camelina feedstock 

use for aviation has shown even better results, with 

an 84% reduction in lifecycle emissions. Furthermore, 

biofuels contain fewer impurities (such as sulphur), which 

enables an even greater reduction in sulphur dioxide and 

soot emissions than present technology has achieved. 

Biomass thrives on carbon dioxide as it is grown, which 

makes it ideal for removing CO2

 from the atmosphere.

Biofuels – providing diversified supply

The airline industry’s reliance on fossil fuels means it is 

affected by a range of fluctuations, such as the changing 

price of crude oil and problems with supply and demand. 

Sustainable biofuels could be an attractive alternative as 

their production is not limited to locations where fossil fuels 

can be drilled, enabling a more diverse geographic supply. 

In theory, biofuel feedstock can be grown in many places 

around the world, where the aviation industry needs it. 

And while, as for petroleum, there will be major producers 

of biofuel feedstock and it will likely be transported to where 

it can best be used, it is also likely that local smaller scale 

supply chains will be established.

Key points about biofuels

• Produced from renewable biological resources 

such as plant material (rather than traditional 

fossil fuels like coal, oil and natural gas).

• Absorbs carbon dioxide from the atmosphere as 

the plant matter (biomass) is grown, which is 

then released back into the atmosphere when 

the fuel is burnt.

• First-generation biofuels have been used for a 

number of years for transport, home heating, power 

generation from stationary engines, and cooking.

• Second-generation biofuels are derived from 

new sources that do not compete for resources 

with food supplies and can be used in aviation.

Biofuels are produced from renewable 

biological resources such as plant material.

The production of sustainable biofuels 

is flexible and biofuel feedstock can be grown 

in many places around the world according 

to the aviation industry’s needs and demands.
Beginner’s Guide to Aviation Biofuels: Page 3

Extraction CO2

Refining

Transport

Distribution

at airports

Flight

Transport

CO2

CO2

CO2

CO2

CO2

Lifecycle emissions from fossil fuels Lifecycle emissions from biofuels

Biofuels – providing economic 

and social benefits

Fuel is one of the biggest operating costs for the aviation 

industry. The changing price of crude oil also makes it 

very difficult to plan and budget for operating expenses 

long-term. Sustainable biofuels may offer a solution 

to this problem since their production can be spread 

worldwide, and across a number of different crops, thereby 

reducing airlines’ exposure to the fuel cost volatility that 

comes with having a single source of energy.

Biofuels can also provide economic benefits to parts 

of the world that have large amounts of marginal or 

unviable land for food crops, but are suitable for growing 

second-generation biofuel crops. Many of these countries 

are developing nations that could benefit greatly from 

a new industry such as sustainable aviation biofuels.

Refining

Distribution

at airports

Flight

Feedstock growth

Processing 

Transport

Proc

ansport

essing 

CO2

CO2

CO2

CO2

CO2

Sustainably produced biofuels 

result in a reduction in CO2

emissions across their lifecycle.

At each stage in the distribution chain, carbon dioxide is emitted through energy use Carbon dioxide emitted will be reabsorbed as the next generation of feedstock is grown.

by extraction, transport, etc.
Beginner’s Guide to Aviation Biofuels: Page 4

What are second-generation 

aviation biofuels?

The production of first-generation biofuels (derived from 

food crops such as rapeseed, sugarcane and corn – which 

can also be used as food for humans and animals) has 

raised a number of important questions. These include 

questions about changes in use of agricultural land, 

the effect on food prices and the impact of irrigation, 

pesticides and fertilisers on local environments. 

In addition, some of the first-generation biofuels, 

such as biodiesel and ethanol (produced from corn) 

are not suitable fuels for powering commercial aircraft. 

Many of these fuels don’t meet the high performance 

or safety specifications for jet fuel.

Learning from the experience of other industries, 

the aviation industry is therefore looking at second-, 

or next-generation, biofuels that are sustainable. 

This new generation of biofuels is derived from non-food 

crop sources. Second-generation biofuels can also be 

mass grown in a range of locations, including deserts 

and salt water. 

Each of the second-generation feedstocks being 

investigated for aviation use has the potential to deliver 

large quantities of greener and potentially cheaper fuel. 

It is unlikely, however, that the aviation industry will rely 

on just one type of feedstock. Some feedstocks are better 

suited to some climates and locations than others and 

so the most appropriate crop will be grown in the most 

suitable location. It is likely that aircraft will be powered 

by blends of biofuel from different types of feedstocks 

along with jet fuel.

Potential second-generation 

biofuel feedstocks

Jatropha is a plant that produces seeds containing 

inedible lipid oil that can be used to produce fuel. Each 

seed produces 30 to 40% of its mass in oil. Jatropha can 

be grown in a range of difficult soil conditions, including 

arid and otherwise non-arable areas, leaving prime land 

available for food crops. The seeds are toxic to both 

humans and animals and are therefore not a food source.

Camelina is primarily an energy crop, with high lipid 

oil content. The primary market for camelina oil is as 

a feedstock to produce renewable fuels. The left over 

"waste" from the oil extraction can also be used as feed 

for chickens in small proportions. Camelina is often grown 

as a rotational crop with wheat and other cereal crops 

when the land would otherwise be left fallow (unplanted) 

as part of the normal crop rotation programme. 

It therefore provides growers with an opportunity to 

diversify their crop base and reduce mono-cropping 

(planting the same crop year after year), which has been 

shown to degrade soil and reduce yields. 

Algae are potentially the most promising feedstock for 

producing large quantities of sustainable aviation biofuel. 

These microscopic plants can be grown in polluted or 

salt water, deserts and other inhospitable places. They 

thrive off carbon dioxide, which makes them ideal for 

carbon capture (absorbing carbon dioxide) from sources 

like power plants. One of the biggest advantages of algae 

for oil production is the speed at which the feedstock can 

grow. It has been estimated that algae produces up to 15 

times more oil per square kilometre than other biofuel 

crops. Another advantage of algae is that it can be grown 

on marginal lands that aren’t used for growing food, such 

as on the edges of deserts. 

Halophytes are salt marsh grasses and other saline 

habitat species that can grow either in salt water or 

in areas affected by sea spray where plants would not 

normally be able to grow.

(See page 17 for a map outlining where these feedstocks 

could be grown.)

Second-generation biofuels use a sustainable resource to 

produce a fuel that can replace traditional jet fuel, while 

not consuming valuable food, land and water resources.

Second-generation biofuels for aviation:

• use a sustainable resource to produce a fuel 

that can be considered as a replacement 

for traditional jet fuel, while not consuming 

valuable food, land and water resources;

• can be mass grown in locations almost 

worldwide, including in deserts and salt water;

• include bio-derived oil, sourced from feedstocks 

such as jatropha, camelina, algae and halophytes;

• have the potential to deliver large quantities of 

greener fuel for aviation at more stable prices – 

although aviation will not rely on just one type 

of feedstock.
Beginner’s Guide to Aviation Biofuels: Page 5

Jatropha Camelina Algae Halophytes

Key advantages of second-generation biofuels for aviation

• Environmental benefits: sustainably produced biofuels result in a reduction in 

CO2

 emissions across their lifecycle.

• Diversified supply: second-generation biofuels offer a viable alternative to fossil 

fuels and can substitute traditional jet fuel, with a more diverse geographical 

fuel supply through non-food crop sources.

• Economic and social benefits: sustainable biofuels provide a solution to the price 

fluctuations related to fuel cost volatility facing aviation. Biofuels can provide 

economic benefits to parts of the world, especially developing nations, that have 

unviable land for food crops that is suitable for second-generation biofuel crop 

growth.

What a load of rubbish 

One of the other feedstock avenues being explored is the use of biological waste 

material. There are ongoing experiments into the use of such varied waste as 

wood products, paper, food scraps, forestry waste, agricultural residues, industrial 

residues, animal by-products, sewage, municipal solid waste and even tyres, 

which through various processes can potentially be turned into jet fuel. These may 

provide feedstock sources to complement the specially grown biofuel supply and 

could also prevent an estimated 577 million tonnes of waste from entering landfill 

sites annually. 

Sustainable biofuels could be just a few years 

away from introduction to commercial flights.
Beginner’s Guide to Aviation Biofuels: Page 6

Why use biofuels for aviation?

The aviation industry has seen huge growth since its 

beginning. Today, more than two billion people enjoy 

the social and economic benefits of flight each year. 

The industry worldwide provides jobs to some 32 million 

people and has a global economic benefit of around 

7.5% of world gross domestic product. The ability to fly 

conveniently and efficiently between nations has been 

a catalyst for the global economy and has shrunk cultural 

barriers like no other transport sector. But this progress 

comes at a cost.

In 2008, the commercial aviation industry produced 

677 million tonnes of carbon dioxide (CO2

). This is around 

2% of the total man-made CO2

 emissions of more than 

34 billion tonnes. While this amount is small compared 

with other industry sectors, such as power generation and 

ground transport, these industries have viable alternative 

energy sources currently available. For example, the 

power generation industry can look to wind, hydro, 

nuclear and solar technologies to make electricity without 

producing much CO2

. Cars and buses can run on hybrid, 

flexible fuel engines or electricity. Electric-powered trains 

can replace diesel locomotives.

The aviation industry has identified the development of 

biofuels as one of the major ways it can reduce its greenhouse 

gas emissions. Biofuels provide aviation with the capability to 

partially, and perhaps one day fully, replace carbon-intensive 

petroleum fuels. They will, over time, enable the industry 

to reduce its carbon footprint significantly.

Building light and heat (20%)

Other electricity and heat (12%)

Other industry (2%)

Chemicals (6%)

Cement (5%)

Road (13%)

Air (2%)

Other transport (2%)

Other energy (10%)

Industrial processes (3%)

Land use change and forestry (25%)

Source: World Resources Institute 2002

Global CO2 emissions 

Developing sustainable biofuels for 

aviation will:

• provide the aviation industry with an alternative 

to petroleum-based fuels;

• enable the industry to reduce its carbon 

footprint by reducing its greenhouse gas 

emissions;

• allow it to draw upon a variety of different fuel 

sources;

• be easier to implement than for other transport 

modes.

Biofuels provide the aviation industry with 

the capability to partially, and perhaps one day 

fully, replace carbon-intensive petroleum fuels.
Beginner’s Guide to Aviation Biofuels: Page 7

This graph shows the total tonnes of CO2 emissions 

attributable to commercial aviation and a forecast for 

the coming years. However, the forecast emissions are 

simply based on a ‘business-as-usual’ scenario, not taking 

into account any major advances in technology or the 

introduction of biofuels.

The decrease in emissions between 2008 and 2009 

can partially be attributed to a fall in traffic due to the 

recession. However, 2% of this reduction comes from 

efficiency increases.

Total tonnes of CO2

 emitted by aviation over the last 10 years and forecast to 2012

0

200

400

600

800

1,000

F = Forecast

Mt /CO2

Aviation efficiency – 

technology will only take us so far

The progress the aviation industry has made in reducing its 

impact on the environment is remarkable. The aerodynamics 

of aircraft, the performance and efficiency of modern 

engines and the operational improvements by airlines, 

airports and air traffic systems have all combined to make 

aircraft more than 70% more fuel-efficient over the past 

40 years. The industry will continue to make technology 

improvements in the way aircraft are constructed and how 

they are flown, with some significant improvements in 

progress. But while cutting-edge technology means aircraft 

are now more fuel-efficient than many cars per passenger 

kilometre, the forecast growth in the number of people 

flying will see the industry’s emissions continue to rise 

unless other means to reduce emissions are found. 

Hydrocarbon fuel is the only option 

for aviation... for now 

At this stage, there is no foreseeable new technology to power 

flight beyond hydrocarbon fuels. Hydrogen can be burned in 

a turbine engine for aviation. However, there are significant 

technical challenges in designing a hydrogen-powered aircraft 

for commercial aviation and in producing enough hydrogen 

in a sustainable way to supply the indutries needs. The use 

of sustainable biofuels can provide the air transport industry 

with a near-term solution to provide a fuel with a lower 

environmental impact than petroleum-based fuels.

Implementing biofuels for aviation – 

easier than for other transport modes

The supply of fuel to the commercial aviation industry is on 

a relatively small scale and less complex than for other forms 

of transport. For this reason, it is anticipated that it will be 

easier to fully implement the use of sustainable biofuels in 

aviation than in other transport systems. For example, there 

are 161,768 retail petrol stations in the United States alone. 

This compares to a relatively smaller number of airport fuel 

depots: 1,679 airports handle more than 95% of the world’s 

passengers. 

Similarly, there are around 580 million vehicles on the road 

today, compared to around 23,000 aircraft. And while many 

of those road vehicles are owned by individuals or families, 

there are only around 2,000 airlines in the world. 

The integration of biofuels into the aviation system is 

potentially a lot easier than it would be in a more dispersed, 

less controlled, public fuel delivery system.

2012F

670

2011F

635

2010F

615

2009F

619

2008

677

2007

673

2006

653

2005

637

2004

621

2003

576

2002

578

2001

596

2000

595

1999

561

1998

542

The use of sustainable biofuels can provide the air transport 

industry with a near-term solution to provide a fuel with 

a lower environmental impact than petroleum-based fuels.
Beginner’s Guide to Aviation Biofuels: Page 8

Biofuels for aviation – 

technical challenges 

Second-generation biofuels must have the ability 

to directly substitute traditional jet fuel for aviation 

(known as Jet A and Jet A-1) and have the same qualities 

and characteristics. This is important to ensure that 

manufacturers do not have to redesign engines or aircraft 

and that airlines and airports do not have to develop 

new fuel delivery systems. At present, the industry is 

focused on producing biofuels from sustainable sources 

that will enable the fuel to be a “drop-in” replacement 

to traditional jet fuel. Drop-in fuels are combined 

with the petroleum-based fuel either as a blend 

or as a 100% replacement.

Some first-generation biofuels, such as biodiesel and 

ethanol, are not suitable fuels for powering commercial 

aircraft. Many of these fuels don’t meet the high 

performance or safety specifications for jet fuel. 

Recent advances in fuel production technology have 

resulted in jet fuel produced from bio-derived sources 

that not only meets but exceeds many of the current 

specifications for jet fuel. 

Jet fuel specifications

Criteria Explanation Jet A-1 specification

Secondgeneration

biofuel

✓

Flash 

point

The temperature 

at which the fuel 

ignites in the engine

to cause combustion 

to occur (°C)

38°

minimum

✓

Freezing 

point

The temperature at 

which the fuel would 

freeze (°C)

-47°

✓

Combustion 

heat

The amount of energy

that is released during

combustion, per kilo 

of fuel (MJ/kg)

42.8 MJ/kg

minimum

✓ Viscosity The thickness of the 

fluid or ability to flow 

(mm2

/s)

8.000 

max

✓

✓

Sulphur 

content

The amount of 

sulphur in the fuel 

(parts per million)

0.30

Density How heavy the fuel 

is per litre (kg/m3

) 

775-840

Technical requirements for aviation 

biofuels

• A high-performance fuel that can withstand 

a range of operational conditions.

• A fuel that can directly substitute traditional 

jet fuel for aviation.

• A fuel that does not compromise safety.

• A fuel that meets stringent performance targets.

Second-generation biofuels must have 

the ability to substitute traditional jet fuel 

for aviation (known as Jet A and Jet A-1) 

with the same qualities and characteristics.
Beginner’s Guide to Aviation Biofuels: Page 9

Biofuels for aviation – 

sustainability challenges

Many first-generation biofuel sources, such as ethanol 

produced from corn, compete for valuable land with food 

crops and can contribute to deforestation and pressure on 

freshwater resources. The aviation industry is committed 

to using only biofuels that are grown in a sustainable way 

that do not compete for land or water with food crops.

The aviation industry is seeking biofuels made from crops 

that:

• are fast growing, non-food plants that don’t take up 

productive arable land which would otherwise be used 

for food production;

• do not require excessive supplies of pesticides, fertiliser 

or irrigation and do not threaten biodiversity;

• provide socio-economic value to local communities;

• result in a lower carbon footprint on a total carbon 

lifecycle basis and provide an equal or higher energy 

content than the current petroleum-based traditional 

jet fuel, Jet A-1, used by the industry.

Ensuring that a fuel meets these key criteria 

is an important part of making sure any biofuel really 

does meet the sustainability goals of the industry. 

There are a number of organisations investigating 

ways to certify the sustainability credentials of biofuel 

supplies. It is also vital that farmers don’t replace food 

crops on fertile land with biofuel crops, simply to make 

more money. It is essential that stringent criteria are 

applied so that airlines can buy biofuels from truly 

sustainable sources.

Developing sustainable biofuels

The aviation industry is interested in developing 

fuels that can be mass produced at a low cost 

and high yield with minimal environmental 

impact. These biofuels should be made from crops 

that are fast growing plants that don’t take up 

productive arable land; do not require excessive 

farming techniques or threaten biodiversity; 

provide socio-economic value to local communities 

and importantly result in a lower carbon footprint.

The aviation industry is 

committed to using only 

biofuels that are grown 

in a sustainable way 

that do not compete for 

land or water with food crops.
Beginner’s Guide to Aviation Biofuels: Page 10

2009 2010 2011 2012 2015 

<1% 1% 

Test flights

Lab tests and 

analysis

Biofuelled commercial flights

Establish mass distribution systems

from refineries and blending facilities 

to airports

Build production plants,

refineries and blending facilities

Produce feedstock

Find the right parts

of the world to grow

the crops

Certification

Flightpath to

a biofuelled

future

Indicative proportion of biofuel to be 

“dropped-in” to the aviation fuel supply.

Find the right parts

of the world to grow

Build pro

refinerie

Produce feedstock

B

r

Biofuelle

sh mass di

2009

Test flig

from refi

to airpo

Build production

Establis
Beginner’s Guide to Aviation Biofuels: Page 11

2020 2030 2040

15% 30% 50%

Over time, as more feedstock is cultivated, 

more refineries come online and more biofuel 

is blended into fuel for commercial flights.
Beginner’s Guide to Aviation Biofuels: Page 12

Biofuels for aviation – 

testing

Safety is the aviation industry's top priority. Given 

this and the specific requirements of any fuels used in 

aircraft, the process for testing potential new fuels is 

particularly rigorous. Through testing in laboratories, 

in equipment on the ground, and under the extreme 

operating conditions that the aviation industry requires, 

an exhaustive process determines those biofuels that are 

suitable for aviation.

In the laboratory

Researchers develop a biofuel that has similar properties 

to traditional jet fuel, Jet A-1. The aircraft and engine 

manufacturers and other systems suppliers then run 

compatibility tests. This is important because fuel is 

used for many purposes inside the aircraft and engine, 

including as a lubricant, cooling fluid and hydraulic fluid, 

as well as for combustion.

On the ground 

Tests look at specific fuel consumption at several power 

settings from ground idle to take-off speed, which is 

then compared to performance with traditional Jet A-1. 

Tests are also completed on the amount of time it takes 

for the engine to start, how well the fuel stays ignited in 

the engine and how the fuel performs in acceleration and 

deceleration. Finally, an emissions test determines the 

gaseous emissions and smoke levels for the biofuels.

In the air

Once the lab and on-the-ground testing have been 

completed, the fuel is ready to be tested on aircraft under 

normal operating conditions. A number of airlines have 

provided aircraft for biofuel flight trials designed to:

• provide data to support fuel qualification and 

certification for use by the aviation industry;

• demonstrate that biofuels are safe and that they work; and

• stimulate research and development into biofuels.

During a flight, pilots perform a number of ordinary and 

not-so-ordinary tests to ensure the fuel can withstand 

use under any operating condition. 

Biofuels testing is imperative to 

determine suitability for aviation

• The aviation industry has a rigorous testing 

process to maintain the highest standards of 

safety.

• This means that biofuels must undergo dozens 

of experiments in the laboratory, on the ground 

and in the air.

• This exhaustive process determines those 

biofuels suitable for aviation.

Safety is the aviation industry's 

top priority. Given this and the 

specific requirements of any fuels 

used in aircraft, the process 

for testing potential new 

fuels is particularly rigorous.
Beginner’s Guide to Aviation Biofuels: Page 13

Start Taxi Take-off Quick 

accelerations/

decelerations

Shutdown 

and restart

Repeat engine 

restarts and 

simulated go-around 

engine acceleration 

on landing

Landing

Before

With biofuel 

and 

Jet A-1 mix

After

The data recorded 

is analysed 

by engineers

During

Flight trials – evaluation of engine performance during all phases of flight: including a number of extraordinary "manoeuvres" (e.g. shutting down the engine in-flight 

and ensuring they can restart)

This flight profile is an example of one of the biofuel trials conducted in early 2009.
Beginner’s Guide to Aviation Biofuels: Page 14

Biofuels for aviation – 

the certification process

Following the success of flight trials, biofuels need 

to be certified as safe and appropriate for commercial 

use. The aviation industry is working closely with fuel 

specification bodies, such as the American Society 

for Testing and Materials (ASTM) International 

and the UK’s Defence Standards Agency.

The approval process has three parts: the test 

programme; the original equipment manufacturer 

internal review; and a determination by the specification 

body as to the correct specification for the fuel. 

The approval process looks at a minimum of 11 key 

properties, including energy density, freezing point, 

appearance, composition, volatility, fluidity and many other 

characteristics which would make it fit for aviation use.

The target is to certify aviation biofuels by 2013, although 

there is now a possibility that a 50/50 blend of biofuels 

mixed with Jet A-1 fuel could be certified before 2011. Due 

to recent advances in research and technology, aviation 

biofuel might be available for commercial use within five 

years, once the feedstock production process has been 

set in motion. 

Test the biofuels 

in the aircraft

Engine

and aircraft

manufacturer

quality process 

Specification 

body testing 

and certification 

Entry into

commercial

flight service

Certification of biofuels for aviation use

• Once flight trials are successfully completed, 

biofuels need to be certified for commercial use.

• This is the role of the fuel specification bodies 

responsible for testing aviation fuels according 

to key criteria before the fuel is certified for 

commercial use.

• The certification approval process looks at a 

minimum of 11 key performance properties.

• The target is to certify biofuels as safe for 

aviation use by 2013, but latest information is 

that certification could be completed before 2011.

Following the success of flight trials, 

biofuels need to be certified as safe 

and appropriate for commercial use.
Beginner’s Guide to Aviation Biofuels: Page 15

The target is to certify biofuels as safe for 

aviation use by 2013, but latest information is 

that certification could be completed before 2011.
Beginner’s Guide to Aviation Biofuels: Page 16

Biofuels for aviation – 

economic viability

The fossil fuel industry has a 100-year head start 

compared to sustainable biofuels, which are still 

emerging technologically. A concerted effort by 

governments is required to foster these promising 

renewable options to help drive their long-term viability.

Supporting this case are two major trends developing 

in the economics of fuel. 

First, fossil fuels are forecast to become increasingly 

scarce and as a result will become more expensive. 

Second, advanced biofuels that stem from sustainable 

feedstocks will become less expensive as the relevant 

science and business models mature. It is estimated 

that 85% of biofuel production costs relates to the 

cost of the feedstock. As technology to harvest and 

process these feedstocks progresses and as they become 

available in commercial quantities, the price will drop. 

Owing to their renewable nature, these feedstocks can 

continue to be produced, over and over again.

The price of oil can vary substantially, falling from a high 

of USD$147 per barrel in June 2008 to $40 in December 

2008. This makes it difficult to project when biofuels 

would be competitive, but there are strong indications 

Key oil-producing regions of the world

Circles represent current oil reserves

Economic viability of biofuels for aviation

• Sustainable biofuels will become economically 

viable and compete with petroleum-based 

fuels as costs are lowered by improvements in 

production technology and through economies 

of scale in production.

• They may also provide valuable economic 

opportunities to communities who can develop 

new sources of income – including in many 

developing nations.
Beginner’s Guide to Aviation Biofuels: Page 17

that biofuels would become cost-comparable with 

traditional jet fuel, Jet A-1 by around 2020.

However, there may be costs to using fossil fuels in 

addition to the price of the fuel itself. Legislation passed 

by the European Union in 2008 to include aviation in the 

EU’s emissions trading scheme (ETS) will add a carbon 

cost to aviation, requiring airlines to pay for their carbon 

emissions from 2012. 

It is possible that emissions trading schemes will also 

be developed in other parts of the world. This makes 

alternative fuel technologies, which reduce emissions 

compared to traditional jet fuel, especially attractive. 

Under the European ETS legislation, biofuel use is zerorated for emissions. Other policies could reduce tax levels 

on low-carbon fuels such as biofuel. The United States 

and other governments are on course to make significant 

investments in sustainable biofuel development.

Many companies are developing ways to refine advanced 

biofuels, including the use of bacteria and other natural 

processes, cheaper conversion and refinement, or the use 

of less costly feedstocks, including waste products.

Optimum land for growing sustainable 

aviation biofuels

● Algae

● Jatropha

● Camelina

Circles indicate potential locations for biofuel feedstock 

growth (indicative estimate)

Biofuels may provide valuable 

economic opportunities to 

communities who can develop 

new sources of income – including 

in many developing nations.
Beginner’s Guide to Aviation Biofuels: Page 18

From the fields to the wings

Now that biofuels for aviation are a confirmed viable 

option and the certification process is underway, one of 

the biggest challenges is cultivating the required quantity 

of feedstocks. The worldwide aviation industry consumes 

some 1.5 to 1.7 billion barrels of Jet A-1 annually (about 

250 billion litres, or 70 billion gallons). Analysis suggests 

that a viable market for biofuels can be maintained when 

as little as 1% of world jet fuel supply is substituted by 

a biofuel (or, put another way, 10% of the world’s aircraft 

fleet is running on a mix of 10% biofuel and 90% Jet A-1).

So, when will the industry be able to reach that point? 

If the certification process goes well, it could be as early 

as 2015. Some parts of the industry are aiming to operate 

the fleet using 25% biofuel by 2025, which would be 

increased to 30% by 2030. However, for these targets 

to be reached, it is necessary to produce sustainable 

feedstocks in commercial-scale quantities.

Growing biofuel feedstock

Second-generation biofuels can be grown in fairly harsh 

conditions, requiring little or no fresh water and soil that 

is not at a premium for food crops. So how much land will 

it take to grow enough feedstock to supply the world’s 

airline fleet with biofuel?

Most of the potential biofuel feedstocks can be grown 

as normal crops. They just need to be planted and cared 

for, cultivated and harvested before being processed. 

Jatropha can be grown on the land surrounding other 

crops, as a natural barrier on the edge of fields. It can 

also be grown on wasteland and in areas where other 

crops would not survive.

While algae can grow in almost all types of water, 

including seawater, on wastewater ponds and in 

lakes, they grow fastest in algae incubators called 

photo bioreactors, or in special ponds to enhance 

1. Algae: 68,000 sq km

2. Ireland: 70,000 sq km

3. Montana: 380,000 sq km

5. Camelina: 2,000,000 sq km

6. Jatropha: 2,700,000 sqkm

7. Australia: 7,617,930 sq km

4. World annual corn crop: 809,000 sq km

1 2 3 4 5 6 7

Bringing biofuels from feedstock to jet 

fuel supply

• This will require the production of sufficient 

sustainable raw materials and the industrial 

capability to process and refine it into fuel. 

• The worldwide aviation industry consumes 

some 1.5 to 1.7 billion barrels of traditional 

jet fuel annually. 

• Analysis suggests that a viable market for 

biofuels can be maintained when as little 

as 1% of world jet fuel supply is substituted 

by a biofuel.

• Some estimates indicate that biofuels will be 

commercially viable when they reach 1% of the 

total jet fuel supply.

Land area equivalents required to produce enough fuel to completely supply the aviation industry

These diagrams represent 

a conservative estimate 

of the amount of land 

that would be needed to 

completely replace the 

amount of traditional jet 

fuel currently used with just 

one of these sources (as 

well as a comparison with 

different land areas). 

It is unlikely that aviation 

will rely on just one type of 

biofuel, so a combination of 

these and other sources will 

be used. 
Beginner’s Guide to Aviation Biofuels: Page 19

the amount of carbon dioxide and sunlight they 

can capture to grow. 

Increasing the productivity through advanced methods, 

while decreasing the cost-to-unit ratio, is one of the 

major challenges facing the scaling up of algae feedstock 

production.

Processing

Once the crop has been harvested, oil needs to be 

extracted from its biomass. The feedstock is pressed, 

which produces oil and a leftover substance: the meal. 

In many cases this meal can also be used. The solid waste 

left from the processing of jatropha, for example, can be 

used as fuel for burning on fires and in stoves. The meal 

Jatropha Solid

waste

Oil

Refined into biofuels

Used for other solid fuel purposes

Raw material Pressing process End-result

Camelina

Etc.

Algae

from algae oil production can be used for fertiliser, animal 

feed and other purposes, and camelina meal can be used 

as animal feed.

Refining the bio-oil

The bio-oil can then be refined into renewable jet fuel 

using conventional hydro-processing technology 

applied in petroleum refineries around the world 

today. The process first removes oxygen from the 

feedstock oil. The product is then further refined 

through isomerisation, a process by which one 

molecule is cracked open and re-arranged to form 

another shape of molecule, to meet the specifications 

needed for jet fuel. 

Blending of fuels and delivery to the aircraft

Once it is refined, the biofuel needs to get to the aircraft 

tank, initially as a drop-in blend with traditional jet fuel. 

Because the industry is pursuing biofuels that can be 

blended with existing fuel supplies, the industry can start 

using the new fuel as it becomes available, in increasing 

quantities, as a "drop-in" to traditional fuel.

As the aviation industry and potential fuel suppliers 

go through the process of certification and production 

development, they will also be investigating how to 

deliver the vast quantities of fuel to the world's airports. 

During the years when blending of biofuel and traditional 

Jet A-1 fuel takes place, a blending may be undertaken at 

a biofuel refinery, a petroleum-fuel refinery, at a separate 

facility, or even at the airport fuel facility itself.

One of the biggest challenges in developing biofuels is 

cultivating the quantities of feedstock needed to produce it 

and developing the facilities to process and refine the fuel.

Processing: turning raw feedstock into oil
Beginner’s Guide to Aviation Biofuels: Page 20

The next steps

With the testing process nearing completion and 

an accelerated certification programme underway, 

sustainable biofuels could be just a few years away from 

introduction to commercial flights. The aviation industry 

has set itself the task of developing a set of sustainability 

criteria – to ensure that the biofuels it is being supplied 

are genuinely sustainable and have no negative impact 

on the communities that grow them. The main hurdles 

are in attracting investment for biofuels production 

and distribution and ensuring that the industry has 

access to this biofuel stock, at a price that is costcompetitive with traditional jet fuel.

The industry has called on governments to assist 

potential biofuel suppliers to develop the necessary 

feedstock and refining systems – at least until 

the fledgling industry has achieved the necessary 

critical mass. 

The positive incentives required include:

• Assistance in identifying the most suitable areas 

in which to grow these crops.

• Support in starting the farming and production of algae 

– building of facilities, hiring labour resources, buying 

seeds and setting up any irrigation components.

• Incentives for companies to develop the processing 

and refining capacity needed to turn raw feedstock 

into biofuel crude oil and then into biojet fuel.

• Positive fiscal and legal frameworks to facilitate 

the economic viability of these new types of fuels 

so that airlines can use them as quickly as possible.

While these are not minor hurdles, they are not 

insurmountable. The history of aviation is marked 

by people achieving extraordinary things, despite 

the conventional wisdom of the time telling them 

it couldn’t be done.

The aviation industry is now on the verge of another 

extraordinary step – but it is a challenge that the entire 

industry needs to take on together. The industry is 

committed to sustainable biofuels use in commercial 

flights to become a reality by 2012 and a significant 

supply of biofuel in the jet fuel mix should be a reality 

before 2020.

It is now up to dedicated stakeholders across the aviation 

sector, with help from governments, biomass and fuel 

suppliers to ensure that the low-carbon, biofuelled future 

for flight becomes a reality.

Once testing has been undertaken, the 

aviation industry knows that biofuels 

can work and certification is complete, 

the hurdles that remain are:

• ensuring a steady supply of the feedstock 

is grown and then processed into biofuel;

• ensuring that the facilities are in place to refine 

and blend the biofuel into current jet fuel;

• ensuring that the cost is right, in order to 

compete with petroleum-based jet fuel;

• ensuring that aviation is allocated its share of 

biofuel supply despite competition for that 

supply with other forms of transport; and

• the industry is looking to governments to 

help with incentives for fuel suppliers to bring 

enough of the fuel to market.

The history of aviation is marked 

by people achieving extraordinary 

things, despite the conventional 

wisdom of the time telling 

them it couldn’t be done.

Sources for diagrams and a reference version of this document available at www.enviro.aero/biofuels
Beginner’s Guide to Aviation Biofuels: Page 21

Definitions

Alternative fuel: the general term to describe any 

alternative to petroleum-based fuels, including liquid 

fuel produced from natural gas, liquid fuel from coal 

and biofuels. While the aerospace sector is investigating 

some of the gas-to-liquid and coal-to-liquid fuel 

production processes, these are not generally considered 

to be significantly greener than current petroleum-based 

fuel supplies. Indeed, many of these products will produce 

far more CO2

 when their production is taken into account. 

Aviation is already making limited use of these fuels 

and this may increase in the future, but the real solution 

to reducing emissions is to leave all fossil fuels behind. 

Biofuels are therefore the answer for sustainable energy.

ASTM International: originally known as the American 

Society for Testing and Materials, this international 

standards organisation develops and publishes 

voluntary consensus technical standards for a wide 

range of materials, products, systems, and services. 

ASTM International works with aircraft and engine 

manufacturers, government authorities and fuel suppliers 

to set the standards for aviation fuels such as the 

required characteristics for Jet A-1 and, soon, biojet.

Biodiesel: diesel fuel produced from biomass. 

Not suitable for use in aviation.

Biofuel: fuel produced from renewable resources.

First-generation biofuels: biofuels produced from 

biomass that competes with food production and fresh 

water use, and/or causes deforestation or reduced 

biodiversity. Examples include sugar cane, corn and wheat.

Second-generation biofuels: sustainable biomass 

that is not a food source and does not impact the 

food supply chain or fresh water resources, or cause 

deforestation. Examples include jatropha, camelina, 

halophytes and algae. Also known as next-generation 

or sustainable biofuels.

Biojet fuel: jet fuel produced from bio-derived resources.

Biomass: any renewable material of biological origin 

(plants, algae, waste and so on).

Carbon footprint: net amount of carbon dioxide 

emissions attributable to a product or service (emissions 

from production and combustion, minus absorption 

during growth). For fossil fuels, the absorption of carbon 

dioxide occurred millions of years ago and so their carbon 

footprint is simply 100% of their carbon output.

Carbon neutral: being carbon neutral, or having a net 

zero carbon footprint, refers to achieving net zero carbon 

emissions by balancing a measured amount of carbon 

released with an equivalent amount sequestered or 

offset. Biofuels represent a step towards carbon neutrality 

because most of the CO2

 they release during combustion 

has been previously absorbed by growing plants and 

absorbed again afterwards as new plants grow. 

Carbon-neutral growth: where the same amount of 

carbon dioxide is emitted year on year. For the aviation 

industry this means being able to continue to increase 

passenger traffic and aircraft movements, while keeping 

aviation industry emissions at the same level.

Drop-in fuel: a fuel that is chemically indistinguishable 

from conventional jet fuel, so no changes would be 

required in aircraft or engine fuel systems, distribution 

infrastructure or storage facility. It can be mixed interchangeably with existing jet fuel.

Ethanol: a fuel produced from sugar-rich crops such 

as corn and sugarcane and used by ground vehicles. 

Not suitable for aviation use.

Feedstock: raw material from which fuels are produced.

Jet A: Commercial jet fuel specification for North America.

Jet A-1: Common jet fuel specification outside North 

America. (These two fuels are very similar and 

throughout this guide we used the term jet fuel to mean 

the fuel used by aviation).

Kerosene: the common name for petroleum-derived jet 

fuel such as Jet A-1, kerosene is one of the fuel sources 

that can be made by refining crude oil. It is also used 

for a variety of other purposes.

Greenhouse gases: emissions of gases such as carbon 

dioxide (CO2

), methane (CH4) and oxides of nitrogen 

(NOx

), arising from fossil fuel combustion and land-use 

change as a result of human activities. These gases trap 

the warmth generated from sunlight in the atmosphere 

rather than allowing them to escape back into space, 

replicating the effect glass has in a greenhouse.

Sustainability: the ability for resources to be used in 

such a way so as not to be depleted. For humans to live 

sustainably, the earth's resources must be used at a rate 

at which they can be replenished, providing economic 

growth and social development to meet the needs of 

today without compromising the needs of tomorrow.

Sources for diagrams and a reference version of this document are available at www.enviro.aero/biofuels
This Beginner’s Guide was made possible due to the kind 

support of:

Produced by the Air Transport Action Group 

with the assistance of:

Airbus, Airports Council International, Boeing, CFM 

International, Civil Air Navigation Services Organisation, 

GE Aviation, International Air Transport Association, 

Pratt & Whitney and Rolls-Royce

Air Transport Action Group

33 Route de l’Aéroport

P.O. Box 49

1215 Geneva 15

Switzerland

T: +41 22 770 2672

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