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Alternative Fuels and Biofuels for Aircraft Development

Periodic Report Summary 2 - ALFA-BIRD (Alternative fuels and biofuels for aircraft development)

Project context and objectives:

ALFA-BIRD is a project co-funded by the European Union (EU) in the Seventh Framework Programme (FP7) for research and technological development (RTD), started in July 2008. ALFA-BIRD is an research and development (R&D) project aiming at viable technical solutions. Its objective is to investigate and develop a variety of alternative fuels for the use of in aeronautics, motivated by the need to ensure a sustainable growth of the civil aviation, regarding the impact of fossil fuels on climate change and in the context of oil prices that are highly volatile and increasing in the long term.The main challenge in the project work is developing fuels that meet the very strict operational constrains in aviation (e.g. flight in very cold conditions), and are compatible with current civil aircraft, which is a must due to their long lifetime of almost 50 years. To address this challenge, ALFA-BIRD gathers a multi-disciplinary consortium with key industrial partners from aeronautics (engine manufacturers, aircraft manufacturers) and fuel industry, and research organisations 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 five new fuels will be performed with tests in realistic conditions.

It covers a number of areas, including:
- study of possible alternative fuels for use in aviation;
- chemical analysis of the 'best' fuel;
- improved formulation of biofuels;
- new injection systems;
- modelling of injection and combustion;
- compatibility with aircraft fuel systems;
- production of new fuels.

The first fuel selection matrix has been designed around three main axes, covering a wide range of possible alternative fuels from short term to long term:
- paraffinic fuels, with hydrotreated vegetable oils and synthetic fuels (XtL), in a short / middle term vision;
- naphthenic fuels, representative of new production processes such as coal or biomass liquefaction in a middle term vision;
- oxygenated fuels, such as higher alcohols or furanic compounds, in a long term vision.

Several tests including the standard characterisation of the 12 blends were used for the final selection of the 4 fuels that are currently tested in the second phase (tests on engine components). The 4 fuels selected are FSJF, FT-SPK, a blend of FT-SPK and 50 % naphthenic cut, and a blend of FT-SPK and 20 % hexanol. This fuel matrix offers the possibility to evaluate the potential of different chemical families which are paraffinic compounds, naphthenic compounds and oxygenated compounds. This is also representative of a short, middle, and long term view.

The information collected during the tests will be used to prepare the environmental and economical impact assessment, which will be the basis for the elaboration of the future strategy for the use of alternative fuels for aircraft.

In terms of management, the project has a slight delay, due to the late provision and selection of the alternative fuels. The steering committee is well aware of the situation and has estimated at the last physical meeting of the period (on 5 July 2011) that this delay should not have a major impact on the achievement of the final objectives.

ALFA-BIRD is collaborating with several other European and international projects:
- SWAFEA study (DG TREN);
- DREAM, SP5 (FP7 project);
- CAAFI (United States (US) initiative);
- OMEGA & ECATS (national projects).
Representatives of all these projects have been invited to the ALFA-BIRD annual meetings in July 2009, 2010 and 2011, and will be invited again at the next one, to continue scientific exchanges.

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Project results:

- Subproject 1 has fully achieved its objectives and technical goals for the period. The subproject 1 is dedicated to the overview of potential alternative fuels for aircraft. The work is divided in four work packages (WPs):
WP1.1 on fuel survey and economy;
WP1.2 on the analysis and characterisation;
WP1.3 on the analysis of the production and distribution chain; and
WP1.4 on new alternative fuel production.

The state-of-the-art called 'Overview of potential alternative fuels' was published. As planned originally in the ALFA-BIRD project, the fuel selection process is divided into two steps. The consortium has now completed the two steps, which consisted in evaluating 12 blends in terms of their quality as jet fuel based on standard characterisation only and to select the 4-5 most promising fuels. These 12 blends were: FSJF for fully synthetic jet fuel, FT-SPK for Fischer-Tropsch-synthetic paraffinic kerosene, blends of FT-SPK with naphthenic cut, hexanol, furane or FAE , in different amounts.

These results were used for the selection of the four fuels which have been tested in the second phase, (tests on engine components). The 4 fuels selected are FSJF, FT-SPK, a blend of FT-SPK and 50 % naphthenic cut, and a blend of FT-SPK and 20 % hexanol. This fuel matrix offers the possibility to evaluate the potential of different chemical families which are paraffinic compounds, naphthenic compounds and oxygenated compounds. This is also representative of a short, middle, and long term view.The work followed with detailed characterisation of the fuels, with a study about fuel production, storage and distribution and also with the investigation of the possibility to produce, at the lab-scale, specific bio-fuels according to the constraints of aeronautics and yields compatible with a realistic industrial transposition.

- Subproject 2 has achieved most of its objectives and technical goals for the period with relatively minor deviations. In subproject 2, the objective is to assess the suitability of the selected alternative fuels for the aircraft.

Concerning the WP 2.1: Injection and combustion, many efforts have been done during the reporting period and, although there is some still some delay with respect to the initial time table, the objectives should be reached by the end of the project. The main achievements concern the experimental characterisation of the evaporation behaviours of the fuels (task 2.1) the experimental characterisation of their combustion properties, the experimental study of the soot emission, the update of the detailed chemical kinetics models (task 2.2) and the experimental characterisation of the pollutant emissions and lean-blow out limits using an industrial burner at atmospheric pressure (task 2.3).

Concerning WP 2.2 (to ensure that the use of alternative fuels does not compromise the fabric of the engine), materials that may come into contact with alternative fuels were identified and selected. First, the materials to be evaluated, from within the engine and fuel control system, were identified (D2.2.1 fulfilled). Then, the elastomeric, metallic and non-metallic materials in the fuel system were selected. Due to the late fuel delivery, some tasks were also delayed, up to six months. Currently, the ordering of the samples is on the way.

Within WP 2.3: Experimental check of material compatibility and aircraft fuel system compatibility, the main focus in the reporting period was on the identification of the impact of alternative fuels on A / C systems, discussing numerous issues, with sealing, corrosion, pumping system, filtering, water compatibility, microbial contamination, gauging, permeability, and other issues among them as well as handling of fuel impact on A / C performance, as well as modification to the fuel system. The results of these studies were summarised in a document (D2.3.1) prepared by Airbus UK.

The main results achieved so far within WP 2.4 (activities started in month 12) was the elaboration of a review of the standards for aviation jet fuel, regulations (transportation, distribution, refuelling) and a code of practice in order to identify specific issues related to the production, handling and use of aircraft alternative fuels. The main objective of WP 2.4 is to serve for a focus point for the whole WPs of ALFA-BIRD. In these WPs, the collection, analysis and consolidation of all produced data regarding safety, and the potential impacts on the regulation and standardisation schemes will be considered, analysed and evaluated.

Subproject 3 has achieved most of its objectives and technical goals for the period with relatively minor deviations. The subproject 3: Technical synthesis to set new standard requirements for the alternative fuels and components has just started and has not yet produced any deliverable.

The WP 3.1 started on 1 July 2009. It appears that it might get difficult to evaluate the absolute impact of alternative fuels with regard to emission characteristics due to the selected new reference fuel CtL instead of kerosene (Jet-A1). Used and validated semi-empirical emission correlations are based on petroleum derived jet fuel. To adapt these emission correlations to new fuels, comparable experimental investigations on kerosene are necessary. Otherwise, it will become very difficult to detect the differences in the specific fuel emission characteristics. Consequently, there might possibly be no clear statement about the kerosene to alternative fuel effect. Fuel data preparation has started at Airbus F. The implementation of variable fuel properties and fuel dependent emission correlations within the engine performance software tool at DLR-AT is ongoing. No failures concerning critical objectives or any delays in schedule are expected.

The WP3.2 and in particular T3.2.1 aims at providing a comprehensive economic analysis of economy related impacts, has been only partly achieved in the reporting period. The following has been achieved:
- setting up the framework for economic impact analysis;
- the economical aspects of the scientific and technological impacts;
- the economical aspects of policy and regulation impacts has not been tackled in the reporting period (delay);
- the topic of economical aspect of sustainability in terms of lasting value of the impacts has not been tackled in the reporting period (delay);
- the economical aspects of impacts of research activities on various sets of actors, such as the research teams and their organisations, the immediate users and the society at large has been partly tackled in terms of Global Reporting Initiative (GRI) based indicators scheme prepared (please see online).

Potential impact:

The overall expected impact of ALFA-BIRD project is to contribute to a sustainable aviation thanks to the development of alternative fuels for aircraft.

For the consortium, a sustainable aviation means:
- keep European lead position for aircraft and engine industry (economical and social benefits - employment);
- continue to offer airline transport capabilities at an competitive economical cost and at an acceptable environmental impact;
- enable the eco-efficient circulation of people and goods in a global world, and within an enlarged Europe, facilitate contact and communication.

The ALFA-BIRD project is a contribution to the development of the use of alternative fuels for aircraft that sets the foundations of new technologies to power aircraft. It will constitute a step change in air transport in the long term and bring several benefits described hereunder.

Environmental benefits, mandatory for sustainable development:
- improvement of CO2 balance (life-cycle assessment);
- thanks to renewable energy resources (bio-fuels);
- thanks to optimal formulation of new alternative fuels;
- better performance in the engine during the combustion;
- propulsion performance including reliability, ignition delay, heat release rate, energy contents;
- emission performance: reduce NOx, SOx emissions, reduce soot production (improvement of injection reduce NOx emission, optimal fuel composition reduces soot emission, fuel without sulphur doesn't produce SOx).

Thus, ALFA-BIRD will also contribute to the objectives of the Clean Sky JTI, and both initiatives could be combined into a joint demonstration that would support European initiatives related to 'Green aircraft'.

The opportunity to fly a demonstrator (or, at least, to perform ground tests) with the alternative fuels selected in ALFA-BIRD should be considered within the 'Clean sky' project. Such experiment could lead to further developments towards operational use, and complement the implementation plan provided by ALFA-BIRD. Additionally, the demonstration could be a strong advertising initiative.

Strategic impact:
- reduction of the dependence from crude oil and development of an alternative supply chain to the CTL fuel on which US and China are investing, and GTL in Russia, Iran and Qatar;
- stay in the competition in the context of worldwide initiatives related to alternative fuels demonstrations for aircraft, especially in the US (Boeing with Virgin, US Air Force B52, Boeing with Brasil, CAAFI). As playing a leading role in the game, Sasol will bring an invaluable contribution to this objective.

Impact on European competitiveness:
- identification of new routes for cumulated benefits of low NOx technologies with alternative fuel combustion; this is an additional benefit to the recommendation from European Technology Platform from Aeronautic Industry (ACARE) to reduce NOx emission by 80 % by working mainly on engine.

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