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Originally Posted by SinepMan
I read that bio has more NOx than regular fuel. Is there any truth to this? Overall, which is better for the environment?
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Yep. Out of the 20 or so measured EPA emissions, NOx is the only one that is slightly higher than in petroleum fuels.
Nitrogen oxides are grouping gases with a varied amount of nitrogen and oxygen. NOx forms when fuel is burned at high temperatures. The primary sources of NOx are ALL internal combustion engines, electric utilities, and other industrial, commercial, and residential sources that burn fuels. Here in the US, the EPA's weighting system is different than in Europe. Who is right and who is wrong?
I'll leave you with a little contraversial information that seems to indicated that we don't really understand the difference between Nitrogen oxides.
NOx and volatile organic compounds (VOCs) are involved in complex photochemical reactions to form ground-level ozone. Recent U.S. Department of Energy-supported studies have strongly suggested that the strict control of NOx emissions may have the unintended consequence of making ambient ground-level ozone worse. The California Air Resources Board (CARB) has put increasingly strict emission limits on NOx emissions in an attempt to reduce ground-level ozone (ozone is an inhalation health concern), for which Southern California is notorious. However, many previous studies have shown that ozone levels are actually higher on weekends (WE) than on weekday (WD) (WD/WE effect) when diesel truck traffic decreases relatively much more than automobile traffic (which mostly are powered by gasoline engines). The DOE studies have confirmed that NOx is reduced significantly more than VOC (HC) and as a result ozone levels increase. It has been discovered that most large urban areas in the U.S. have similar conditions in which ambient ozone levels rise with decreasing ambient NOx levels and that NOx controls in Southern California (and other urban U.S. locations) are generally counterproductive for reducing ambient ozone, they actually increase ambient ozone levels. Were it not for large concurrent HC emission reductions on weekends, weekend ozone would be even higher than it is, and the weekend/weekday ozone difference would be even larger. DOE concludes that gasoline exhaust and gasoline vapor account for ~80 percent of ambient NMHC (VOCs) in on-road samples and at regional air monitoring locations suggesting that gasoline emissions are responsible for the majority of ozone found in the SoCAB. Whether these recent findings change CARB's (or even EPA's) ozone control strategy remain to be seen.
Re: biodiesel
my garage shop R&D department has not calculated any real possiblities as far as automotive use. The stirling engine much better at providing modest amounts of power from heat and can be linked to generation equipment and will run smoothly as constant RPMs for long periods of time. I've often thought that with most EV cars, they have plenty of charge to run short periods without having the stirling generating any power until the heat would be built up. (think of a steam engine without the water, etc.) Efficiencies are gained by use of different internal gasses and utilizing the stirling generator setup with a home plug unit would give a nice balance between gas/diesel hybrids and straight electric powered vehicles like the Toyota Rav4 EV. I think that a proper vehicle equiped with appropriate battery systems could run for extended periods of time and be charged by a rather small stirling engine/generator.
