By James Kanter The New York Times

Some in the aviation industry say they could one day be flying the biggest jets across the planet without contributing to climate change — using biofuels.

They also say that it will be easier to convert planes to biofuels than land transport, because there are fewer planes than cars, trucks and buses, and there is a far less complex infrastructure to deal with, comprising only a few hundred airport fueling stations across the globe.

On Tuesday, Air New Zealand joined a clutch of other commercial airlines in testing out alternative fuels.

During a two-hour flight to and from Auckland International Airport, the Air New Zealand crew sought to test how the fuel, made from jatropha plants and blended 50:50 with Jet A1 fuel in the tank of one of four Rolls-Royce engines on a 747-400, stood up to use at high altitudes and in other demanding conditions.

Air New Zealand and the other companies participating the project were to “review all the results as part of our drive to have jatropha certified as an aviation fuel,” said Air New Zealand Chief Pilot Captain David Morgan, who was part of the test flight.

Using jatropha-based fuel still emits carbon dioxide, but the gas is typically recycled in the growing of the feedstock, so there is ostensibly no additional CO2 added to the atmosphere.

Even so, critics have taken issue with biofuels, which they say could drive expanded deforestation, or would compete with food commodities, raising food prices across the board — particularly for poor families and poor communities.

Aviation industry officials say that they are committed to using sustainable biofuels that do not threaten food supplies for land or water as part of their alternative fuel tests. “A major part of the industry’s future carbon emissions reduction plans rely on the ability for aircraft to shift towards biofuels,” according to the industry.

Air New Zealand said the jatropha it sourced and refined for its test flight came from Malawi, Mozambique, Tanzania and India, and was from seeds grown on environmentally sustainable farms. The airline said each jatropha seed produces between 30 and 40 percent of its mass in oil and that jatropha can be grown in a range of difficult conditions, including arid and otherwise non-arable areas, leaving prime areas available for food crops.

Air New Zealand also explained that the criteria for sourcing the jatropha oil required that the land was neither forest land nor virgin grassland within the previous two decades. The quality of the soil and climate was such that the land was not suitable for the vast majority of food crops. Furthermore, the farms the jatropha was grown on were rain-fed, not mechanically irrigated.

The New York Times