Let's use farmland for food, not fuelBefore I write bad things about biofuels, let me first say that I don't think they are always a bad idea; if a biofuel can be shown to be significantly energy positive (more energy comes out than was used to make it) and doesn't cause all kinds of other problems, like using precious arable land, increase the price of food, or pollute in other ways (fertilizer...), then I'm all for it. Biofuels will also probably be the best way to power certain things in a carbon-neutral way, at least until we figure out how to make electric airplanes.
But as things stand, while there are many people working on next-generation biofuels that could meet the criteria above, the vast majority of the biofuels made in the U.S. are not particularly green. Most are ethanol-based, made with corn, and depending on which study you trust, it's not clear that they are energy-positive, or even energy-neutral in some cases.
That's why it's so crazy that the U.S. is still making so much of the stuff and mandating by law that a certain amount be blended in the country's fuel supply. It's pretty much inexplicable from an environmental point-of-view, and the more likely explanation is that this is a hand-out to farmers (who are as good with lobbyists as they are with tractors).
So with that in mind, it's bad news that the EPA - who should be defending the environment - has come out with a new mandate that requires an increase in the total volume of renewable fuel use by the end of 2016 to 18.11 billion gallons, an 11% increase from 2014.
But why are biofuels not working? As we explained in this post, the math simply doesn't work most of the time. Biofuels are basically a way to turn sunlight into fuel. But photosynthesis is only a few percents efficient (often just 1%), and then the refining process to harvest the crops and then extract their sugars and turn them into liquid fuel further reduces efficiency. You then take that ethanol and burn it into an internal combustion engine that is maybe 20-30% efficient, and you end up with a tremendous amount of wasted energy... And you've used up farmland that could instead have grown food for human consumption, increasing food prices by reducing supply.
If the goal is to turn sunlight into energy that we can use for transportation, to displace fossil fuels, biofuels compare very badly with solar panels that are closer to 20% efficient, and electric motors, that are closer to 80-90% efficient.
For more details on why biofuels are not a good way to harvest the sun's energy, check out this post, which explains the math from Nobel-Winning photosynthesis expert Hartmut Michel.