Sustainable flight

An Air New Zealand Boeing 747-400 jetliner is to make a so-called 'sustainable flight' powered by biofuels in early December this year.

During the flight, one of the airplane's four Rolls-Royce RB211 engines will be powered in part using biofuels derived from jatropha, which was converted to biojet fuel using proprietary fuel processing technology from UOP, a Honeywell company.

As part of the fuel verification process, Rolls-Royce's UK technical team conducted laboratory testing to ensure that the fuel would be compatible with its jet engines while meeting the necessary performance requirements.

Because of the unique environment in which aviation operates, stringent criteria are in place to ensure that any alternative fuel meets or exceeds current jet fuel requirements. Advance testing for the Air New Zealand flight showed that the jatropha-based biofuel met all critical specifications, including a freeze point at -53^oF (-47^oC) and a flash point at 100^oF (38^oC).

'Laboratory testing showed the final blend had excellent properties, meeting and in many cases exceeding the stringent technical requirements for fuels used in civil and defence aircraft,' said Chris Lewis, Rolls-Royce company specialist for fuels. 'The blended fuel therefore meets the essential requirement of being a "drop-in" fuel, meaning its properties will be virtually indistinguishable from conventional fuel, Jet A1, which is used in commercial aviation today.'

To process the jatropha crude, the team relied on UOP's fuel processing technology. During processing, hydrogen is added to remove oxygen from the biomass, resulting in a bio-derived jet fuel that can be used as a petroleum replacement for commercial aviation.

Jatropha, which can be grown in a broad range of conditions, produces seeds that contain inedible lipid oil that is extracted and used to produce fuel. Each seed produces 30 to 40 per cent of its mass in oil. Plant oil used to create the fuel for the Air New Zealand flight was sourced from non-arable lands in India and south eastern Africa (Malawi, Mozambique and Tanzania).

Boeing is working with airlines and engine manufacturers to gather biofuel performance data as part of the industry's efforts to revise the current American Society for Testing and Materials (ASTM) standards to include fuels from sustainable plant sources.