This study, one of the few I can find that investigates emissions of biofuels (which I suspect is causing the recently accelerating and widespread tree decline), is titled "Fuel Properties and Nitrogen Oxide Levels of Biodiesel Produced from Animal Fats". Published in 2005 and funded by the USDA, it compares the emissions of NOx from burning soy-based and various animal fat-based biofuels, concluding that animal fats have potential to release less NOx than vegetable-based biofuels. Why might this matter?
"Experimental data have shown that the addition of biodiesel to diesel fuel reduces particulate and carbon monoxide emissions but increases nitrogen oxide (NOx) emissions (7,8). Pure soy biodiesel (B100) increases NOx emissions by approximately 12% when compared with NOx emission data for petroleum diesel. At the more widely used 20% blend level of biodiesel in petrodiesel, however, the increase in NOx emissions is only on the order of 2–4%. With increasingly strict environmental regulations, even this relatively small increase in NOx can negatively impact the use of biodiesel. Therefore, it may be of beneﬁt to identify other feedstocks for producing a biodiesel that could improve NOx emissions when blended with petroleum diesel."
Note, that the two studies upon which that first statement is based were published in 1998 and 1994 - so our government has known - and ignored, while pushing for mandated use - for years that biofuels increase emissions of NOx. What does "negatively impact the use" mean? "even this relatively small increase in NOx can negatively impact the use of biodiesel."
I think it means, that biodiesel shouldn't be used because it increases NOx, and even a "relatively small increase" in NOx is enough reason NOT TO USE biodiesel! Just how bad is NOx?
One study, published in 2005 in the Journal of Geophysical Research by scientists from Harvard, uses satellite data to look at the ozone resulting from burning biomass, and states at the outset, in the introduction:
Nitrogen oxide radicals (NOx = �NO + NO2) originating from combustion, lightning, and soils largely control tropospheric ozone production [Kasibhatla et al., 1991; Penner et al., 1991; Murphy et al., 1993; Jacob et al., 1996]. Tropospheric ozone plays a key role in determining the oxidizing power of the atmosphere, is an important greenhouse gas, and is toxic to biota.
Oh my, toxic to biota?? All the collective living flora and fauna? So how come I got raked over the coals at Real Climate for saying ozone is toxic to life?
Even the biodiesel industry's own website admits that NOx admissions increase, which they then attempt to hedge with some completely hypothetical technological mitigations that aren't being employed:
"NOx emissions from biodiesel increase or decrease depending on the engine family and testing procedures. NOx emissions (a contributing factor in the localized formation of smog and
ozone) from pure (100%) biodiesel increase on average by 10 percent."
They base their estimates on an EPA document, a "Comprehensive Analysis of Biodiesel Impacts on Exhaust Emissions" which, while predicting a net loss in efficiency (how's that cleaner energy?), also includes the following chart red-lining NOx emissions - and, parenthetically, this comical caveat:
"We were not able to identify an unambiguous difference in exhaust CO2 emissions between biodiesel and conventional diesel. However, it should be noted that the CO2 benefits commonly attributed to biodiesel are the result of the renewability of the biodiesel itself, not the comparative exhaust CO2 emissions."
But getting back to reactive nitrogen, The Bangor Daily News reports that up in Maine, they already have what shellfish harvesters call "Dead Mud". Following is the article, which begins with CO2 acidification, and then moves on to NOx - that other, "biggest environmental disaster you've never heard of":
“There may be controversy surrounding global warming, but there’s no debate about the fact that the ocean is becoming more acidic,” said Paul Dobbins, former oyster farmer and co-founder of the Portland-based kelp grower Ocean Approved LLC. “It doesn’t receive all that much coverage, because it’s not controversial, but [the ocean's acidity is] what has all of us who are working with ocean organisms and shellfish worried.”
The double whammy
As usual, both of these videos conclude with a token happy "there is a solution" ending, which, whether wedge reductions or bioremediation, is entirely unfounded in reality (since emissions AND population are rising with no reduction in sight) and far out of scale with the scope of the problems they describe. One paper, newly released by two researchers from the University of Virginia, which assesses the sources and impacts of anthropogenic emissions leading to the global degradation of air, water and soil, calls the results, "Acidification of Earth". We are starting to understand.
Every now and then it's possible to find a more realistic assessment of how this will be resolved. Following is background commentary by the creators about their South Park episode "Smug Alert", the full hilarious episode of which can be seen by clicking at that link to South Park Studios.