Castro was right: as a green fuel, ethanol is a good idea, but the sort America produces is bad
Mentions biofuels subsidy study done for IISD's Global Subsidies Initiative:
"But corn-based ethanol, the sort produced in America, is neither cheap nor green. It requires almost as much energy to produce (more, say some studies) as it releases when it is burned. And the subsidies on it cost taxpayers, according to the International Institute for Sustainable Development, somewhere between $5.5 billion and $7.3 billion a year."
The article then presents ethanol from sugar cane as much better environmentally, and cellulosic ethanol as better still. While true from a narrow sense of the impacts from the crop production, they gloss over how producing these fuels at scale would still cause significant losses to habitat and biodiversity.