Vegetable fuel is fast becoming a concrete reality. In New Zealand, a passenger plane has successfully completed a two-hour test flight partly powered by jatropha oil.

Air New Zealand hailed the flight as a "milestone" in the development of sustainable fuels that could lower aeroplane emissions and cut costs.

One engine of the Boeing 747-400 was fueled by a 50-50 mixture of jatropha plant oil and standard A1 jet fuel.

A Virgin Atlantic test flight in February used fuel derived from a blend of Brazilian babassu nuts and coconuts.

The Jatropha plant is being promoted in many third world countries including India. If its use as a fuel source increases in the future, then farmers will have a great future, they are told.

Jatropha is a plant that can grow in marginal lands and common lands. Jatropha curcas grows almost anywhere, even on gravelly, sandy and saline soils. It can also thrive on the poorest stony soil and grow in the crevices of rocks.

When jatropha seeds are crushed, the resulting jatropha oil can be processed to produce a high-quality biodiesel that can be used in a standard diesel car, while the residue (press cake) can also be processed used as biomass feedstock to power electricity plants or used as fertilizer as it contains nitrogen, phosphorous and potassium.

The plant yields more than four times as much fuel per hectare as soybean, and more than ten times that of maize (corn). A hectare of jatropha produces 1,892 litres of fuel.