On the face of it, it's most encouraging that biofuels will be at the top of the agenda when George Bush touches down in Sao Paolo on Thursday to meet his Brazilian counterpart, Luiz Inacio Lula da Silva. For years, environmentalists have complained of the industrialised world's "addiction to oil", to use Mr Bush's own words. The US President has now clearly grasped the message that his gas-guzzling compatriots need to wean themselves off fossil fuels - and not simply because the oil-rich Hugo Chavez of Venezuela is so hostile to America. Mr Bush understands that, with or without Mr Chavez, to continue consuming fossil fuels at the present breakneck speed is not an option.

Hence the biofuel "summit" in Sao Paolo, where the two countries that make the bulk of the world's ethanol - from sugar cane in Brazil and corn in the US - are likely to seal an "ethanol alliance". The terms of this accord will probably be aimed at boosting sugar-cane production in Latin America to meet a rising demand for ethanol in the US that America's farmers can't meet.

It's not just Mr Bush who is eyeing the potential for a world energy revolution in the endless fields of sugar cane surrounding Sao Paolo. Businesses are already excited, and are pumping huge sums into the development of renewable alternatives to oil, which include soybean-based biodiesel and other ethanol variants made from wood chips. In short, the ethanol business is booming. Moreover, the ambitious targets the US has set for ethanol production mean the boom has only just begun. Mr Bush has ordered a five-fold increase in American use of biofuels by 2017, which means a target of 35 billion gallons a year.

It's an exciting, almost dizzying thought, that the humble corn stalk or sugar cane may hold the solution to the looming energy crisis. So what's the catch? This is the hard part. Of course it's good that the leader of America, a Texas Republican to boot, has finally understood that the US, as the world's biggest single consumer of energy, has got to change its energy source.

The problem is that many Americans, and Europeans for that matter, seem to think it is just a matter of flicking a switch: one moment fossil fuel, the next moment, sugar cane-plus-corn. Lifestyle - unaltered. Sadly, that's not enough.

Ethanol may sound like the kind of "friendly" energy the world has been waiting for. But for ethanol production to rise to the levels Mr Bush is hoping for, huge amounts of the world's remaining forests will have to be cut down and turned over to corn or sugar cane.

The existing hectarage devoted to agriculture will not be remotely large enough to produce the quantity of fuel needed. In other words, paradoxically, a growing reliance of renewable energy may accelerate the destruction of the rainforests we so desperately need to moderate the planet's temperature. Besides, according to the World Conservation Union, growing corn uses far more energy than the finished fuel produces.

There is another downside to the ethanol boom. As demand rises, the price of the cereals from which it is partly made soars as well. Tortilla prices in Mexico are already surging as a result of ethanol demand in America. This threatens the precarious livelihoods of many of the world's poorest people.

To simply shift from fossil fuel use to ethanol is not going to get us out of our dilemma. It's not going to "save the planet", or not alone. That will require a sharp reduction in fuel consumption, too. The question is whether Mr Bush, other world leaders, or the public, for that matter, have taken this fact on board.
(The Independent, 05/03/2007)