In the field of science and technology, nothing is black or white. Or in this case, green or red. We had just posted the growing trend in genetically modifying (GMO) plants as possible source of clean and renewable biofuel, which is the green part.

Now comes the red part. Professor Sir Peter Crane, director of the Royal Botanic Gardens in Kew, warned that mass production of biofuels is a dangerous thing. According to him, extensive production of biofuel crops could destroy remaining areas of rainforest as farmers try to cash in on "green" oil.

"There are big opportunities with biofuels, but there are big problems too," he said. "It's not a free lunch."

As more and more countries join the bandwagon because of increasing prices of fossil fuel, Sir Peter calls for a much more sustainable way of producing biofuel crops. Instead of opening new tracts of rainforests to make room for the green fuel, he suggests utilizing land that's already degraded or not valuable for conservation or agriculture.

He also fears intensive biofuel production might force growers to increase the use of nitrogen-based fertiliser, pesticides and herbicides in order to get their level of production up. It could also strain irrigation systems in areas where water is scarce.

Sir Peter Crane is noted for his studies on living and fossil plants and large-scale patterns and processes of plant evolution. He was awarded a knighthood on June 12, 2004.