Hi Ken and all >On Sep 28, 2007, at 6:15 AM, Joe Street wrote: > > > > > And what if good organic and biodynamic tecniques are used and the > > health of the soil and microorganisms is considered so that > > nitrogen is > > fixed through natural processes? Is this not a nitrogen sink rather > > than a source? > > >I think "nitrogen fixing" typically takes molecular nitrogen (N2) out of >the air -- not sure if nitrogen oxides can be fixed in the same way. >If NOx is really a bad GHG, and if it can't be utilized by nitrogen- >fixing bacteria, then methods must be employed to reduce its >emissions from biodiesel burning.... > >-K
This report, like so many others, fails to distinguish between biofuels and Agrofuels, and fails to take the full life-cycle approach, which is the only one that tells any truths. Some things probably have to be offset against other things. Agrofuels won't ever be carbon-neutral, but biofuels (small-scale, local) can be carbon-neutral, and in such a context any extra NOx that comes with biodiesel is probably a worthwhile tradeoff compared with fossil-diesel. Gasoline motors are still cleaner-burning than diesels, but diesels use much less fuel, and when they use local biodiesel the carbon reduction makes any extra NOx an even smaller issue. Klaus Elsbett told me this four years ago, in a comment on Tokyo's buffoon of a mayor's ridiculous "DieselNo!" campaign: "One has to distinguish between local pollution and global pollution: "The use of renewable energy is of greatest importance to reduce global pollution, especially that of greenhouse gases. But it cannot solve the problem of overpollution in overpopulated and overmotorised areas such as Greater Tokyo, Los Angeles, Mexico City and the like. While in city traffic and stop-and-go driving condition the diesel (i.e. compression ignition) system is by far the most fuel-efficient engine system, the exhaust gas emissions (whether with diesel or with veggie oil) in terms of nitrogen oxid, hydrocarbons and blacksmoke are less good than those of lpg or gasoline (i.e. spark ignition) engines. That is due to the fact that the exhaust gas aftertreatment and -aftercleaning of spark ignition engines is much more advanced, even though that costs you double the fuel consumption. "So in my opinion the DieselNo! campaign falls short as it is just trying to solve the problem of local pollution at the cost of higher global pollution. That is quite typical for local populistic politicians. In my opinion, the real solution was to ban every vehicle with a combustion engine and replace it with a perfect public transportation system and goods distribution logistic at least in those urban areas." Quite so. One reason exhaust gas treatment of spark ignition engines is more advanced than with diesels is the old high-sulphur petrodiesel fuel, because the sulphur poisons the catalyst in catalytic converters. But biodiesel contains no sulphur, so diesels using 100% biodiesel can use catalytic converters. So can diesels using the newer ULSD (Ultra-Low Sulphur Diesel) fuels, but the problem with that is that it's only the newer, more advanced diesel engines that can use those fuels, because it's the sulphur content of the fuel that provides the required engine lubricity. But biodiesel has very high lubricity even without sulphur, and when biodiesel is used as a lubricity additive to ULSD (2%), older diesels can burn the new fuel without a major retrofit and can also use after-treatment technologies. That's important because diesel motors last such a long time, and replacing them before their use-by date only for emissions reasons comes with very high eco-manufacturing costs (including extra emissions). If you visit DieselNet you'll find a lot of progress being made on improving diesel emissions, on all fronts. There are also fuel additives that reduce NOx emissions well below petro-diesel levels. A report like this that doesn't take all this into account is both biased and ignorant, IMHO. Real junk science. Ken, I don't know if N-fixing bacteria can deal with NOx or not, but I think it'd be asking rather a lot of them to handle this problem for us. A bit like asking cows not to fart so we can all go on guzzling gas like there's no tomorrow (actually they don't fart methane, they belch it). I think we can handle it ourselves. Publish-or-perish scientists don't help much though. All best Keith _______________________________________________ Biofuel mailing list Biofuel@sustainablelists.org http://sustainablelists.org/mailman/listinfo/sustainablelorgbiofuel Biofuel at Journey to Forever: http://journeytoforever.org/biofuel.html Search the combined Biofuel and Biofuels-biz list archives (70,000 messages): http://www.mail-archive.com/biofuel@sustainablelists.org/
