Another study weighing in against biofuels, this time by Nobel Prize winning Paul Crutzen. Yes, I said that just to wind up Maribo - read his take. I've long been skeptical (septical?) of the biofuels stuff, especially corn-based ethanol, which looks more like pork for farmers than a sensible policy. On the conventional view, CBE is at best marginally useful in reducing CO2 emissions (but in which case the same money would be far better off spent elsewhere) or actually harmful. In a sense, this doesn't matter, because its driven by pork barrel politics not science, but I suppose we can hope to keep the science somewhere in the picture.
So the new argument is N2O release from agro-biofuel production negates global warming reduction by replacing fossil fuels and the argument is that "The relationship, on a global basis, between the amount of N fixed by chemical, biological or atmospheric processes entering the terrestrial biosphere, and the total emission of nitrous oxide (N2O), has been re-examined, using known global atmospheric removal rates and concentration growth of N2O as a proxy for overall emissions. The relationship, in both the pre-industrial period and in recent times, after taking into account the large-scale changes in synthetic N fertiliser production and deforestation, is consistent, showing an overall conversion factor of 3-5%. This factor is covered only in part by the ~1% of "direct" emissions from agricultural crop lands estimated by IPCC (2006), or the "indirect" emissions cited therein. This means that the extra N2O entering the atmosphere as a result of using N to produce crops for biofuels will also be correspondingly greater than that estimated just on the basis of IPCC (2006). When the extra N2O emission from biofuel production is calculated in "CO2-equivalent" global warming terms, and compared with the quasi-cooling effect of "saving" emissions of fossil fuel derived CO2, the outcome is that the production of commonly used biofuels, such as biodiesel from rapeseed and bioethanol from corn (maize), can contribute as much or more to global warming by N2O emissions than cooling by fossil fuel savings". So this means (if correct) that only by considering N2O you get a net warming, let alone all the CO2 emissions in producing them. The difference, as Maribo points out, is their using 3-5% rather than 1%. C et al. know they are doing this, and think they are justified (e.g. response here).
Quite who is right is not clear to me; but this is only the "under review" copy of the paper so it will be interesting to see what changes occur during the review process. At the moment it looks to me as though C et al. aren't giving any ground.
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I have to admit to having been terribly amused by recent research (only a newspaper report of it though) which showed that the NO2 emissions from worms in wormeries had the same CO2 -e effect as the methane from the same garden and kitchen wastes rotting in landfills.
Given that we now collect 85% of the methane and convert it to CO2, this makes wormeries worse than landfill on CO2 grounds.
I think my cynicism about much of what we are told to do to reduce global warming is becoming more and more justified over time. At the very least, could we be informed by proper cost benefit analysis?
Ethanol-from-corn is certainly a boondoggle. Biodiesel-from-rapeseed is far from the best method. There are plenty of good biofuel solutions to be found on Biopact:
http://biopact.com/
including the quite exciting new idea of electricity directly from a microbial fuel cell...
"I have to admit to having been terribly amused by recent research (only a newspaper report of it though) which showed that the NO2 emissions from worms in wormeries had the same CO2 -e effect as the methane from the same garden and kitchen wastes rotting in landfills."
Reference?
It would be interesting to see if that included the waste transport, landfill infrastructure, wormery construction & transport, transport & packing required for the compost & liquid feed produced by the wormery (at the site of use), and reduced commercial compost production (inc. any +/-ve effects of digging up and surface of many spreading tonnes of peat).
Obviously reducing the amount of stuff to be dumped into landfill is good for others reasons (space) anyway, but as you say, a proper comparison would useful than just one of the direct gases emitted.
Great post and timing is perfect with the massive ethanol bashing that is occuring in all medium, including the blogosphere. I have been documenting this trend at http://www.collectiveintellect.com/2007/10/ethanol_and_biofuel_bust.php
and thought you might find my collaboration interesting, especially since this post is part of it.
P.S. I also think Biopact has done a great job covering ethanol and biofuels.
Whilst not particularly interested in "biofuels",there are some salient aspects that are interesting with N and its oxides.
First the nitrogen/methane/carbon biogeochemical cycles, and the ozone cycle are intertwined in a state of self-organisation in an excitable media.
We can not separate one component(mitigation) from a dynamic system without causing changes in the other components viz a viz Le Chatelier.
(1) Indirect greenhouse gases (NOx, CO, NMHC, etc.) trigger a photochemical reactions when they are irradiated by ultraviolet light in the troposphere, thereby leading to the production of ozone and OH radicals.
(2) Since ozone is a potent greenhouse gas, reducing tropospheric ozone by controlling emissions is effective in curbing global warming. It is already known that the reduction of tropospheric ozone is most effectively achieved by controlling NOx concentrations. However since ozone has a short life cycle (1 to 2 weeks in summer, and approximately 2 months in winter), the abatement of global warming due to a decrease in NOx levels takes effect almost concurrently with the reduction of NOx in the short term.
(3) On the other hand, OH radicals react with another greenhouse gas, methane that has the effect of eliminating methane from the atmosphere. When NOx levels are lowered OH radicals also decrease, thereby raising methane concentrations in the atmosphere. Rather than mitigating the problem, global warming is advanced due to methane's greenhouse effect.
If we move from the simplistic numerical simulations of ''modelworld" for a second and examine reactions in the microbial biosphere we see that nitrogen-fixing enzyme nitrogenase is inhibited by UV-B even after a few minutes of in vivo exposure. A complete loss of activity was found within 35-55 min depending upon the species. The inactivation may possibly be due to the inhibition of ATP synthesis by UV-B. In contrast to the effect on nitrogenase, a stimulation of nitrate reductase by UV-B was found in all nitrogen-fixing cyanobacterial strains studied so far.(Hader et al)
One Taxa's temporary loss in dominance is another's gain so to speak.This more so evident with the competitive oscillations in wetland , permafrost and paddifields with the rise of methanogens in the absence (or limitations of sulphur oxidizers)
Of course we can observe intuitively why plants are green.
NO2 absorbs intensively solar radiation in green and blue part of spectrum the irradiance at the Earth's surface decreases.