More than EnviroStats!

For a lot of you, like me, you’re looking probably at that statistic for the first time and asking what the heck?

As it turns out, microorganisms turn 3-5% of the nitrates in fertilizer used in growing these crops into small amounts of nitrous oxide, N2O, which should not be confused with nitrogen dioxides (NO2) released by industry or other nitrogen oxides (NOx) from similar sources. Unfortunately, N2O has a global warming potential (GWP) 296 times that of CO2 (US Dept of Energy)*, meaning 1kg of N2O has the same global warming impact as 296kg of CO2. Taking this into consideration, for a biofuel to be sustainable, the CO2 saved by using it instead of fossil fuel has to be greater than the N2O GWP generated. For example, why would you save 200L of CO2 per unit of biofuel when the N2O emitted in small quantities might do the damage of 300kg of CO2? You might as well use fossil fuels and not grow the extra crop for biofuels that would do extra damage equivalent to 100kg of CO2 to the atmosphere. You’re contributing more to global warming than using fossil fuels rather than preventing it. It’s not a complete argument, of course, for using biofuels or not, but we can’t be going around picking biofuels that cause more damage in one of the key areas for which we want to use them.

The N2O factor is not newly discovered, but the problem was that it had been so little that it was difficult to measure and accurately estimate it on a global scale. New research, though, shows the previous estimate of 1% conversion of nitrates in fertilizer was wrong by 3-5 folds. Compounded with that GWP of 296, the 3-5% volume makes a difference between net saving and net gain CO2 emissions.

The N2O factor is small by volume generated, and it isn’t rocket science, but it took a Nobel prize winning chemist to put it on the map. Paul Crutzen, best known for his work on the ozone layer, recently made this announcement on N2O that should put a good punch in the guts of the current first generation of biofuel investments before it gets out of hand and do more damage than it was trying to prevent. The variety in the N2O factors given is because lab tests cannot account for the variations in crop growing and harvesting situations, nor their biodiversity within the species. Even with the ranges given, though, it is clear that even if global warming beneficial, current biofuels’ impact is marginal compared to fossil fuels, at best.

No mention was made of the hot new biofuel alternative from India called jatropha mentioned in Stat 0335.

I can’t say for sure if the current first generation biofuel movement is still gaining momentum but it still is going strong. I’ve always maintained corn and rapeseed wasn’t sustainable, just on resources required alone, never mind this. However, now that the credible science is out that is overwhelming the debate, it’s time to start reconsidering, at least for rapeseed and corn. Keep the sugar cane, but start looking into jatropha and other alternatives.

* The US Environmental Protection Agency puts the GWP of N2O at 310, as per Stat 0117, but it’s in the same range as 296 and devastating  in GWP value either way.

All analysis commentary done by Envirostats author.

- Paul Crutzen via the Royal Society of Chemistry’s magazine, Chemistry World, via Alpha Galileo, Sep 21 2007

- Excellent article with link to academic paper on Science & Development Network, Oct 5 2007