Now people are concerned about the second-generation of biofuel crops–the crops that would be used to create cellulosic ethanol. Here’s what the NY Times says:

In the past year, as the diversion of food crops like corn and palm to make biofuels has helped to drive up food prices, investors and politicians have begun promoting newer, so-called second-generation biofuels as the next wave of green energy. These, made from non-food crops like reeds and wild grasses, would offer fuel without the risk of taking food off the table, they said.

But now, biologists and botanists are warning that they, too, may bring serious unintended consequences. Most of these newer crops are what scientists label invasive species — that is, weeds — that have an extraordinarily high potential to escape biofuel plantations, overrun adjacent farms and natural land, and create economic and ecological havoc in the process, they now say.

At a United Nations meeting in Bonn, Germany, on Tuesday, scientists from the Global Invasive Species Program, the Nature Conservancy and the International Union for Conservation of Nature, as well as other groups, presented a paper with a warning about invasive species.

“Some of the most commonly recommended species for biofuels production are also major invasive alien species,” the paper says, adding that these crops should be studied more thoroughly before being cultivated in new areas.

Controlling the spread of such plants could prove difficult, the experts said, producing “greater financial losses than gains.” The International Union for Conservation of Nature encapsulated the message like this: “Don’t let invasive biofuel crops attack your country.”