Positive findings from long-term biofuel tests at Lufthansa
German Aerospace Center (DLR) scientists confirm suitability of bio-synthetic kerosene in routine airline operations
After testing bio-synthetic fuel on 1,187 scheduled flights, Lufthansa Vice President Aviation Biofuel Joachim Buse presented the initial findings of detailed technical analysis of the long-term trial in Berlin today. “Bio-kerosene can, as expected, be utilised without any problems in flight operations. All the technical investigations were positive and we were able to prove that bio-kerosene does not generate more pollutant emissions than conventional jet fuel,” said Buse. Manfred Aigner, Director of the German Aerospace Center (DLR) Institute for Combustion Technology, observed: “Our measurements have demonstrated that bio-kerosene emissions are at least equivalent to those from conventional fuel.” During the burnFAIR research project, a Lufthansa Airbus A321 flew eight times daily between Hamburg und Frankfurt from 15 July to 27 December 2011. One engine was powered half-and-half by a mixture of biofuel and conventional fuel.
An overview of the key findings:
DLR exhaust gas measurements
During the long-term trial, researchers at the DLR Institute for Combustion Technology scrutinised the pollutants in the exhaust gas from the aircraft engines. They mounted a sensitive probe behind both engines of the Lufthansa Airbus A321 (D-AIDG) and conducted the exhaust gases through a tube to the analysis instruments. “Similar levels of nitric oxide and carbon monoxide were measured in both engines,” noted DLR Institute Director Manfred Aigner.
Analysis of aircraft components
On conclusion of the test flights, the Airbus powerplants were subjected to boroscopic tests. The findings from detailed investigation of sediment and changes to the seals of both tanks were entirely positive. No sign was found of any abnormal behaviour resulting from the use of biofuel.
Fuel-carrying parts and wing tanks
In order to return the aircraft to normal scheduled service quickly, the major fuel-bearing parts between tank and engine were dismantled. These parts and the sensors were checked for sediment and functionality in the subsequent weeks. Their behaviour in respect of function and tightness was perfectly normal. As expected, the parts were in very good shape. No deposits were found in the inspection of both fuel tanks, either.
Engine Condition Monitoring
During the test-phase, the routine messages from the aircraft on the major engine parameters were increased and the data subjected to additional evaluation. The findings: The fuel flow rate on the engine powered by the bio-kerosene mix was about one per cent lower than that on the engine powered by conventional fuel. Thus less fuel was consumed. The reason is that the energy density of the bio-kerosene mix was on average about one per cent higher than that of conventional fuel.
Throughout the long-term burnFAIR biofuel testing project, Lufthansa enjoyed the support of strong partners. The Federal Ministry for Economics and Technology (BMWI) invested around 2.5 million euros in the project as part of its aviation research programme (LuFo). Aside from other activities, scientists at the German Aerospace Center (DLR) conducted emission measurements directly at the engines and evaluated all the findings in cooperation with Lufthansa experts.
More details on the project at www.puresky.de.
Deutsche Lufthansa AG
Media Relations Lufthansa Group