Five or six years ago it seemed like biofuels really might be it, a serious replacement for all that nasty oil powering, well, roughly one-third of our lives. Renewable, capable of being made pretty much anywhere in some form, liquid (and therefore familiar), biofuels seemed to be, if not a green panacea, very, very good.
But fast forward to 2013 and you’ll rapidly pass through a period of deep green soul searching, and the realization that most biofuels from the so-called first generation either created as many problems environmentally as they solved, didn’t reduce emissions as much as claimed (some actually increasing them), or caused or as least contributed to serious social problems. Or all of the above.
Which doesn’t mean we ought to be writing off biofuels entirely. It’s just that a green technology that once seemed a simple solution, is far, far more complex issue than was originally thought.
It’s All About the Feedstock
Some terminology, for those that are coming to this for the first time: One thing you need to understand is the difference between first-generation and second-generation biofuels.
Ethanol, made from corn or another food crop, is considered a first-generation biofuel; cellulosic ethanol, made from agricultural, wood, or yard waste, is a second-generation biofuel. I’ve never seen a specific, strictly defined definition between first- and second-generation biofuels, but the terms are generally used to define established technologies (even if not really widely deployed) in former case, versus emerging technologies in the latter. Over the past several years, biofuel companies, as well as backers in government, have touted the wonders of second-generation biofuels, too often though as something perpetually just over the horizon of commercial viability.
Some more important terminology: You’ve no doubt heard by now of ethanol and biodiesel. Without getting into the chemical differences between them, they require different types of engines to burn them, and require different infrastructure to distribute them than fossil fuels—due to a variety of factors beyond the scope of this piece.
Then there are so-called drop-in biofuels. These are biofuels, often made from the same feedstocks as ethanol or biodiesel, that are identical on a chemical level to petroleum-based gasoline or diesel fuel. This means they can be used in engines without any sort of modification and, crucially for oil distributors, can be distributed using the existing distribution network.
Now we get to the crux of the issue, memorize this: A biofuel is only as green as the feedstock used to make it, and there are wide variations in this. In other words, you simply can’t say that ethanol is environmentally friendly, or biodiesel is a sustainable fuel, without knowing what was used to make it.
What feedstocks have the least and most environmental impact?
A study last fall coming out of Switzerland’s Federal Laboratories for Material Science and Technology found that, when burned, virtually every feedstock currently being cultivated results in some reduction in greenhouse gas emissions, compared to petroleum-based fuels—though some offer less than a 5% reduction.
But it all goes downhill from there, with the environmental impact in other areas actually being much worse than fossil fuels, for a frightening number of potential biofuel sources. In particular, eutrophication of both fresh and salt water sources, as well as negative impacts on land use (it takes land to grow biofuels…) were both more than two-thirds worse with all the biofuel feedstocks considered.
Sources that fared well in the survey: Jatropha, grown as hedges, in East Africa; sugar beets, grown in Switzerland. The problem here is that jatropha cultivated in the way with least environmental impact isn’t scalable to the commercial level. And, well, sugar beets aren’t on the top of many companies list of biofuel sources.
Algae wasn’t considered in this particular survey, but other surveys have shown that algae has great potential for greenhouse gas reduction (though this varies depending on how it’s grown), with less of the negative environmental side effects.