So today I’m sharing a study completed by some researchers here at Colorado State University, along with some folks at UI Urbana-Champaign using the DAYCENT model.
They basically asked what would happen if instead of using corn to make ethanol, we used switchgrass. This is an important question because close to 40% of the corn we grow is used to make ethanol + animal feed from the leftover dried distiller grains.
They found that replacing corn would reduce GHG emission, reduce nutrient leaching, and increase soil organic matter (SOC). These are all good things!
But can we get the same yield from the same land and still be better off? Unfortunately not. Not yet at least. While miscanthus did have higher yields, switchgrass didn’t, and neither would be able to replace the animal feed that is a byproduct of the grain to ethanol process. Best case scenario, as they present in the paper, is a partial replacement of corn with miscanthus. With miscanthus going to ethanol, we can return some of the corn to the food supply (still leaving a 3% gap from current production).
Why did I say not yet earlier? Part (or most) of the reason for this failure is because we are trying to compare a crop that has been the focus of breeding efforts for decades (plus thousands of years of traditional farmer breeding) to a wild species with literally no attempts to improve its agronomic characteristics. This is a big point that I think needs to be made. All of these new technologies from algae, to cellulosic will require at some point for us to optimize the biology of these systems, as we have done with agriculture for food production. Recent efforts (including some of our upcoming projects) hope to change this, but breeding takes time and money through dedicated long term projects.
Notably, they include a discussion of Indirect Land Use Change (ILUC), but claim that land use would not change as a result of the switch on existing lands. Presumably this corn to switchgrass/miscanthus switch would be driven by policy, but somewhere somehow we need to produce the animal feed that wouldn’t be produced by switchgrass/miscanthus..
The usual caveats of these types of modeling studies apply, mostly there are alot of assumptions and averaging of results over large areas which may not be realistic. Additionally the logistics and policy that would enable this are not discussed but would be pretty complex, especially because we aren’t very good at turning cellulosic material into ethanol in an economically profitable manner, and certainly don’t have existing capacity to handle it. And how would we convince the farmers to move from an annual crop that they can switch next year depending on prices, to a perennial, that they are basically “stuck” with for a while.
Not to say these issues can’t be overcome. And as a society we have to weigh the costs and benefits of intensively managed corn based on more variables than simply yield. But that is for economists and policy makers – I’m just a biologist 🙂
PS: I had no idea you can cite your own article, within your own article, but they did! (multiple times)
Here is the reference:
Davis, S., Parton, W., Del Grosso, S., Keough, C., Marx, E., Adler, P., & DeLucia, E. (2011). Impact of second-generation biofuel agriculture on greenhouse-gas emissions in the corn-growing regions of the US Frontiers in Ecology and the Environment DOI: 10.1890/110003