"Biofuels" have shown great promise in weaning the world away from the use of petrofuels. They're less polluting, renewable, and all that acreage (primarily corn and soybeans) will go a long way toward absorbing that excess CO2 in the atmosphere.

Not so fast, say critics in the science community. First of all, they say, there's no proof that "biofuels" are any better than their fossil-fuel counterparts when it comes to greenhouse emissions. The other concern is what it may do the planet's ecology. The rush to plant additional acreage for biofuel production could put rainforests at risk, deplete fresh water supplies, deprive wildlife of habitat and eventually, affect the world's food supply. 

It comes down to deciding whose needs are greater: the 800 million people all over the world who own and drive automobiles, or the billions of others who survive on a day and already spend half their income feeding themselves.

Biofuels are not a new concept. Ford's famous "flivver," the Model T, was originally designed to run on alcohol, while the Diesel engine was designed to run on vegetable oil. Economics, as usual ended those ideas - back at the beginning of the last century, petroleum-based fuels were easier and cheaper to produce. The oil crises of the 1970's got many countries rethinking the idea.

Currently, Brazil is the leader in biofuel production and technology. Brazil produces about 10% of its biofuel needs with 3% of its arable land. Unfortunately, most other countries do not have Brazil's amount of tillable land, and/or are unable to produce similar crops that lend themselves to ethanol production.

For example, for the U.S. to meet 10% of its ethanol requirements would require ten times as much of its farmland as Brazil.  Some of the reasons: Brazilians typically drive far less than their U.S. and European counterparts. Their climate is also more conducive to the most suitable crops - namely sugar cane - and their population density is substantially lower. 

Most of the Northern hemisphere is not suitable for sugar cane, therefore most ethanol would be produced from corn. According to Lester Brown, veteran commentator and food politics activist, the corn required to fill an SUV tank with bioethanol just once could feed one person for a year.

Representatives of the UN Food and Agriculture Organization say the conversion of corn to ethanol is responsible for a sharp decline in world grain stocks and a spike in grain prices in the first half of 2006.

Eric Holthusen, a senior official with oil giant Shell, said that the use of food crops for making fuel while people were starving was "morally inappropriate". You can click on the chart above to see some of the statistics on this potentially troubling issue.