Potential use of biofuels in aviation industry

Dr N Yogaratnam

In general, national policymakers and the public are becoming more concerned with climate change, global warming, greenhouse gas (GHG) emissions and the carbon footprint of our human activities. These considerations provide a guidepost to further the development of biofuel industries.

Aviation industry

The world’s airlines carry about 2.8 billion passengers and 46 million tons of freight per year. They will burn somewhere between 210 million and 220 million tons of fuel and generate 650 million tons of carbon emissions in the process. Strong growth, particularly in Asia, will see to it that those numbers keep rising.

Add to that the fact that the price of fuel is likely to keep rising and that the pressure to reduce fuel emissions has never been higher, and what you get is a huge increase in recent years in the airline industry’s efforts to develop biofuels capable of powering aircraft.

Sustainable biofuels

During the last decade, various studies and reports have investigated the potential for use of biofuels in aviation. More recently, EC-funded R&D projects have been initiated to map a way forward for the introduction of sustainable biofuels to help reduce dependence on fossil fuels in air transport and reduce GHG emissions by the air industry. Globally, various feed stocks and conversion technologies for production of biofuels for aviation are currently being investigated.

On October 6, 2011 a Boeing 757-200 operated by Thomson Airways carried 232 passengers from Birmingham Airport, UK to Arrecife, using a sustainable biofuel blend in one engine. The biofuel was supplied by SkyNRG, Netherlands, who is advised by an independent Sustainability Board consisting of two leading NGOs and a leading government scientific institute. For Thomson Airways, SkyNRG partners with US refiner Dynamic Fuels and uses used cooking Oil as a feedstock.

The Dutch airline KLM says it plans to use 50% biokerosene derived from recycled cooking oil (collected in the EU and refined in the US) on 200 flights between Paris and Amsterdam.

These flights illustrate the potential for further use of aviation biofuels, in combination with improved efficiency, to reduce emissions from aviation and reduce dependence on fossil fuels. The challenge now facing the airline industry is to source commercial quantities of sustainable biojet fuels.

EU Emission Trading Scheme (ETS)

It has been announced that all flights in and out of EU airports are to be included in the EU Emissions Trading Scheme for 2012 (a scheme based on a “cap and trade” system for emissions allowances). The decision to include international flights is being legally challenged by some US airlines. From 2013, at least half the total number of ETS allowances is expected to be auctioned. It has been argued that money raised should be reinvested in R&D&D in sustainable technologies. For example in the aviation sector, proceeds from ETS could potentially be used to support the demonstration of advanced biojet fuels at the industrial scale.

Flight Path Initiative

The EC, in coordination with Airbus, leading European airlines (Lufthansa, Air France/KLM, and British Airways) and key European biofuel producers (Choren Industries, Neste Oil, Biomass Technology Group and UOP), has launched an initiative to speed up the commercialization of aviation biofuels in Europe.

The initiative, labelled “European Advanced Biofuels Flight Path” is a roadmap with clear milestones to achieve an annual production of two million tonnes of sustainably produced biofuel for aviation by 2020. The “Biofuels Flight path” is a shared and voluntary commitment by its members to support and promote the production, storage and distribution of sustainably produced drop-in biofuels for use in aviation. It also targets establishing appropriate financial mechanisms to support the construction of industrial “first of a kind” advanced biofuel production plants.

The debate over increased use of biofuels in aviation should take into account technical, commercial, environmental and social issues. However, these need to be weighed up against the lack of alternatives to fossil fuels for use in aviation (i.e. if biofuels are not be used, how will planes be powered in future, and how would society address the severe economic and practical implications of a dramatic reduction in future air transport?).

Standards for renewable jet fuels

Renewable fuels can now be blended with conventional commercial and military jet (or gas turbine) fuel. The revised standard was approved on July 1, 2011. Through the new provisions included in ASTM D7566, up to 50 percent bioderived synthetic blending components can be added to conventional jet fuel. These renewable fuel components, called hydro processed esters and fatty acids (HEFA), are identical to hydrocarbons found in jet fuel, but come from vegetable oil-containing feedstock. The standard already has criteria for fuel produced from coal, natural gas or biomass using Fischer-Tropsch synthesis.

Future jet fuels

Hydrogen has also been suggested as an aircraft fuel of the future. In reality, hydrogen aircraft would require new engines and airframes, which are unlikely to be seen for at least several decades. Hence, at the present time novel liquid fuels are the only realistic alternative for commercial air transport. These include new fuels synthesized from gas (GTL) and coal (CTL) as well as those derived from biomass.

The potential use of synthetic jet fuels is just one of a wide range of long-term solutions being introduced or considered to reduce the sustainability of air transport. Biofuels are gaining increasing interest from airlines and airplane manufacturers.

Following successful demonstration flights of commercial aircraft using various biofuel blends, the ASTM Aviation Fuel Subcommittee in June 2009 passed a new fuel specification that would enable the use of synthetic fuels (including biofuels) in commercial air transport.

This has opened the door to the potential large-scale production of jet fuels from a range of biomass feed stocks from Jatropha to MSW. For example, in April 2011, an Interjet Airbus A320, used a mix of 73% conventional jet fuel, and 27% Bio-SPK, processed by Honeywell UOP from Jatropha seeds provided by Global Energy as Renewables, and two other producers.

In the UK, British Airways plans to use 500,000 tonnes of waste to produce 16 million gallons of fuel at a plant in East London. The aim is to start production from 2014, creating up to 1,200 jobs. The plant would produce double the volume fuel needed for all flights from London City Airport (however this only represents 2% of flights from Heathrow). The plant will use Solena’s Plasma Gasification (SPG) technology, which can process 20-50% more waste than conventional gasification technologies.

In September 2008, the Sustainable Aviation Fuel Users Group (SAFUG) was formed to accelerate the development and commercialization of sustainable aviation fuels. Support and advice is provided by leading environmental organizations including the Natural Resources Defence Council and the Roundtable on Sustainable Biofuels (RSB). SAFUG members (including many of the world’s leading airlines) agree to contribute to robust sustainability and certification regimes via the RSB global multi-stakeholder process. All members subscribe to a sustainability pledge stipulating that any sustainable biofuel must perform as well as, or better than, kerosene-based fuel, but with a smaller carbon lifecycle.

UPS the world’s largest package delivery company has also indicated that it is considering use of biofuels to help meet its pledge to cut the carbon emissions of its airline by an additional 20% by 2020.

Studies and reports

A 2003 study by Imperial College - The Potential for Renewable Energy Sources in Aviation - investigated renewable alternatives to kerosene, the fuel currently used by jet aircraft. This concluded that bioethanol cannot be used for air transport due to its low energy density, and because it doesn’t combust effectively in `thin air’ at high altitude. The Imperial study also concluded that methanol and biogas are unsuitable for air transport for both technical and safety reasons. However, hydrogen, Fischer-Tropsch (FT) kerosene and biodiesel could all theoretically be used in aviation.

More recently, research has focused on production of `bio jet oil’ via a number of novel routes such as catalytic pyrolysis/refining and catalysis of plant sugars.

The 2007 report Alternative Technology Options for Road and Air Transport published by ETAG (European Technology Assessment Group) for the European Parliament, suggested that due to tighter operational and safety criteria for novel aviation fuels, biofuels will predominantly be used in the road transport sector for the foreseeable future. However, this assessment was made before the successful test flights of Boeing and AIRBUS aircraft, and the landmark ASTM Aviation Fuel Subcommittee decision to establish a specification for synthetic aviation fuels.

The establishment of SAFUG and increasing investments in biojet fuel R&D indicate that biofuels are now most definitely on the radar of major airlines.

In the UK, the Sustainable Aviation Strategy Group brings together researchers, airlines and other stakeholders contributing to a number of key documents proposing a way forward for sustainable air travel.

Feed stocks and conversion technologies

Second Generation biofuels derived from Jatropha and Camelina have been successfully blended with Jet fuel in demonstration flights.

Airbus has teamed with Honeywell Aerospace; UOP, a Honeywell Company; International Aero Engines (IAE); and JetBlue Airways to pursue development of a sustainable second-generation biofuel for use in commercial aircraft.

In August 2008, the world’s first algal based jet fuel was produced by Solazyme. It passed the most critical ASTM D1655 specification tests.

In January 2009, the Defence Advanced Research Projects Agency (DARPA) awarded Science Applications International Corporation (SAIC) a $25 million contract to develop an integrated process for developing Jet Fuel (JP-8 replacement) from algae.

A 100% renewable jet fuel produced by the Energy and Environmental Research Center (EERC), North Dakota University, under a $ 4 million contract with DARPA has been tested by the AFRL and met JP-8 specification criteria.

Arizona State University Laboratory for Algae Research and Biotechnology, Heliae Development, LLC and Science Foundation Arizona are also collaborating in the development of kerosene-based jet fuel derived from algae.

The Virent BioForming Process for catalytic conversion of plant sugars into liquid hydrocarbon fuels could also potentially be used to produce jet fuel from sustainable feedstocks.

SWAFEA

(A 26 month study (starting May 2009) with Sterling Pounds 5.1m funding from DG-TREN involving 19 partners from aviation and fuel industries, airlines, research and consultancy to develop a vision and road map for sustainable deployment of alternative fuels and energies in aviation.

ALFA-BIRD

ALFA-BIRD gathers a multi-disciplinary consortium that aims to develop the use of alternative fuels in aeronautics, with key industrial partners from aeronautics (engine manufacturer, aircraft manufacturer) and fuel industry, and research organizations covering a large spectrum of expertise in fields of biochemistry, combustion as well as industrial safety. Bringing together their knowledge, the consortium will develop the whole chain for clean alternative fuels for aviation. The most promising solutions will be examined during the project, from classical ones (plant oils, synthetic fuels) to the most innovative, such as new organic molecules. Based on a first selection of the most relevant alternative fuels, a detailed analysis of up to 5 new fuels will be performed with tests in realistic conditions.

BioTfuel

BioTfuel is a 112.7 million Euro joint project launched by five French partners and Uhde. BioTfueL aims to integrate all the stages of the BTL process chain and bring them to market. The project includes the construction and operation of two pilot plants in France to produce biodiesel and biokerosene (bio-jet fuel) based on biomass gasification. The plants are scheduled to go into operation in 2012.

Clean Sky JTI

The Clean Sky JTI is one of the largest European research projects ever, with a budget estimated at Sterling Pounds 1.6 billion, equally shared between the European Commission and industry, over the period 2008 - 2013. This public-private partnership will speed up technological breakthrough developments and shorten the time to market for new solutions tested on Full Scale Demonstrators. “Clean Sky will demonstrate and validate the technology breakthroughs that are necessary to make major steps towards the environmental goals set by ACARE - Advisory Council for Aeronautics Research in Europe - the European Technology Platform for Aeronautics and Air Transport and to be reached in 2020:”

* 50% reduction of CO2 emissions through drastic reduction of fuel consumption
>* 80% reduction of N2O (nitrogen oxide) emissions
* 50% reduction of external noise

A green product life cycle: design, manufacturing, maintenance and disposal and recycling This will be achieved by technologies in areas such as loads and flow control, Aircraft Energy Management, N2O and CO2 reduction, rotorcraft, regional aircraft, trajectory management, smart fixed-wing aircraft, etc.

Demonstration flights

In Spring 2011, Interjet and Airbus conducted the first jatropha-based biofuel test flight in Mexico. An The Airbus 320 jet successfully flew from Mexico City International Airport to Angel Albino Corzo of Tuxtla Gutierrez airport in the southern State of Chiapas. One of the aircraft’s two engines was fuelled with a 30 percent blend of biojet fuel by Honeywell UOP.

In June 2010, the first flight by an airplane using algal biofuels was demonstarted by EADS at the Berlin Air Show. EADS has partnered with IGV GmbH in the development of algae-based biofuels. An IGV photobioreactor, which multiplies microalgae, was also exhibited at the Berlin Air Show.

In February 2008, Virgin Atlantic carried out a test flight of a Boeing 747 Jumbo from London to Amsterdam with a 20% blend of coconut and babassu oil in one of the aircraft’s fuel tanks. However, the company concedes that there are no immediate plans to use similar mixtures in commercial flights.

Also in February 2008, an Airbus A380 used a 40% blend of GTL (gas to Liquid) in a flight from Bristol to Toulose, paving the way for future use of BTL. “Analysis of data from the A380’s historic flight powered by an alternative fuel derived from gas (GTL) has shown that use of the GTL blend had no adverse impact on the engine, aircraft systems or materials, and that it behaved like conventional kerosene.”

In December 2008, a blend of 2nd Generation biofuel from Jatropha was used in one Rolls Royce engine for a two hour test flight of an Air New Zealand Boeing 747-400.

Bio-Derived Synthetic Paraffinic Kerosene (Bio-SPK) has been used by Boeing in flight tests of several different aircraft between 2006 and 2009. Performance was as good as (or better than) Jet A fuel.

In January 2009, Japan Airlines (JAL) used a 50:50 blend of Jet A fuel and 2nd generation synthetic kerosene, mainly produced from Camelina, in one Pratt and Whitney engine of a Boeing 747-300.

National initiatives

In June 2011, a group of 20 airlines, aviation companies, universities and biofuel producers launched AIREG the Aviation Initiative for Renewable Energy in Germany. It aims at coordinating research activities and fostering the market introduction of “climate friendly” aviation fuels.

Conclusion

Bio-fuels are being seen as an essential element of the plan to cut down on the aviation industry’s carbon footprint. In addition, the bio-fuel industry could create employment and potentially even reduce travel woes burdened by high and increasing airfare.

(Reference: Biofuels for Air Travel, European Biofuels Technology ,January, 2012)