Switching biofuels could do a double-whammy on climate change

[Sgent]

Source: ars technica / Proceedings of the Natl Acad. of Science

Biofuel crops have the potential to offset the world's reliance on fossil fuels, increasing energy security and decreasing the risk of climate change. However, the choice of crops and target fuel can radically change their impact, as issues like fertilization and ease of processing come into play. But, as a paper released by PNAS points out, these aren't the only things that change when you shift the crop. The paper suggests that switching from corn to a perennial grass can alter the water cycle and sunlight absorption so dramatically that it will have a larger impact than the carbon emissions that biofuels avoid.

The researchers involved take advantage of some recent field work—literally, in a field—in which corn was planted side-by-side with a perennial grass that has been suggested as a potential biofuel stock, miscanthus. The results led them to model the switch to a perennial crop very simply: take the default values in an existing model (they used the Weather Research and Forecasting Model), and expand them by a month at each end. In other words, miscanthus (or another perennial grass, like switchgrass) would turn green earlier in the year, and last a bit later into the autumn.

At this point, their modeling gets a bit unrealistic. Instead of assuming a mix of crops, they simply convert all the cropland of the central US, a total of over 800,000 square kilometers, into miscanthus. Clearly, this is never going to happen, given that areas like Iowa and Illinois will need to keep providing the US with significant food. Still, it's an interesting thought experiment, and provides us with a sense of the trends we might see with a smaller-scale conversion of cropland.

One of the things that changes dramatically is the albedo, a measure of the amount of sunlight that's reflected back into space by the area in question. Since this is sunlight that doesn't heat the earth, a higher albedo can offset some degree of greenhouse-driven warming. And that's precisely what the authors see; each hectare converted to miscanthus reduces the Earth's energy budget to about the same extent that avoiding a significant amount of carbon emissions would. In fact, the effect is six times larger than the amount of carbon offset by harvesting the plant and converting it to biofuels.

Read more: http://arstechnica.com/science/news/2011/03/switching-biofuels-could-do-a-double-whammy-on-climate-change.ars?comments=1#comments-bar

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Grass good... corn bad :)

Link to Academic Article: http://www.pnas.org/content/early/2011/02/16/1008779108.full.pdf+html

[apnu]

1. Corn is great, just not a good fit for biofuels

As with everything in agriculture, balance is key. Sadly, human beings aren't very good at balance.

[M155Y_A1CH]

2. Growing grass is great

Mowing, distilling and burning it,
not so much.
Biofuel is just a new way to pollute.