Corn ethanol's popularity has come and mostly gone in the U.S., but the 60% of global ethanol use that's sugar based is still marching on. The low net energy problem of corn ethanol (EROEI about 1.3) may be fixed by the cellulosic ethanols being worked on, but meanwhile, the near oil-like net energy of sugar ethanol, as produced by Brazil anyway, make this renewable fuel the oil replacement of choice. Ethanol solves the CO2 problem because, as your high school chemistry should remind you, plants absorb CO2 and give off oxygen. When plants are burned for fuel, they give off CO2, so they are about carbon neutral.
The problem for sugar is that where it is most needed (like North America) it's hardest to grow. And where they can grow excess tons of grains in general, including lots of sugar, they don't have the advanced economy to use it all as fuel. There is a pronounced inverse relation here that was charted by Stuart Staniford recently:
The blue blobs are the world's population centers and, as you can see, they tend to be very agriculturally oriented people who use very little energy. At the other end of the curve are the industrialized nations where there are fewer people but they use much more energy. One can envision a happy, massive export/import situation emerging for something like sugar that can effectively replace oil.
There is clear link developing between oil and sugar:
As the correlation table shows, there was no correlation until the oil price climb began around 2001.
Jim Rogers was quoted at an investors' conference about a year ago as saying, "Buy all the sugar you can". He likes agriculture in general, but sugar in particular. I don't know how much of this ethanol link he is seeing in that, but I can understand why he is busy buying up farming operations around the world, saying that it will be the farmers, not the leveraged buyout artists, who will be driving the Maseratis of the future.