American Chemists report a new neat biofueled engine with low PM.

[NNadir]

Biodiesel1,2 is defined as the mono-alkyl esters of vegetable oils or animal fats. It can also be derived from used frying oils. Biodiesel is produced by transesterifying the parent oil or fat to achieve a viscosity close to that of petrodiesel. Biodiesel standards have been developed in the United States, Europe,and elsewhere around the world. Advantages of biodiesel include domestic origin, reducing the dependency on imported petroleum, biodegradability, high flash point, and inherent lubricity in the neat form.1,2 Improvement of the oxidative stability and low-temperature properties remain technicalchallenges. Most regulated exhaust emissions (particulate matter ) PM, hydrocarbons ) HC, carbon monoxide ) CO) with the exception of nitrogen oxides (NOx) are reduced through the use of biodiesel.3-5 Thus, the reduction of NOx exhaust emissions is another technical challenge facing biodiesel, especially in light of the increasingly stringent exhaust emissions regulations affecting diesel engines and becoming effective in the next few years (Table 1). This development is connected with the introduction of ultralow sulfur diesel fuel (ULSD; for example, less than 15 ppm sulfur in the United States). Several engine or aftertreatment technologies, such as selective catalytic reduction (SCR), exhaust gas recirculation (EGR), diesel oxidation catalysts

Summary and Conclusions
The exhaust emissions of commercial biodiesel and petrodiesel, three components of biodiesel fuels, methyl laurate, methyl palmitate, and methyl oleate (technical grade), and two components of petrodiesel, dodecane and hexadecane, were studied in a 2003 model year heavy-duty 14 L six-cylinder diesel engine with EGR. The commercial biodiesel fuel, as well as the fatty compounds, significantly reduced PM exhaust emissions (75-83%) compared to the petrodiesel base fuel, while the two hydrocarbons found in petrodiesel achieved reductions of only 45-50%. However, NOx exhaust emissions were slightly increased with commercial biodiesel and technical grade methyl oleate, while methyl laurate and methyl palmitate as well asdodecane and hexadecane led to a slight decrease of NOx compared to the base fuel. The chain length of the compounds had little effect on NOx and PM exhaust emissions, while the influence was greater on HC and CO, the latter being reduced with decreasing chain length. Unsaturation in the fatty compounds causes an increase in NOx exhaust emissions. The present results differ from previous literature data showing the effect of newer engine technology on exhaust emissions. The low levels of PM observed with the ester fuels may influence emissions reduction technologies when using biodiesel.

From Energy and Fuels Abstract here: http://pubs.acs.org/cgi-bin/abstract.cgi/enfuem/asap/abs/ef0502711.html

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[Dead_Parrot]

1. Whaa?

Can someone boil this down into English? I get the bit about the low Particulate Matter, but the rest might as well be in Chinese. Hey, my degree's in astrophysics, I dunt no dis stuf.

Sounds good, though. :)

[NNadir]

2. It's chemist talk.

These gentlemen are attempting to isolate the pollution characteristics of biodiesel be examining the components of the fuel.

Commercial biodiesel is a mixture of compounds, all of which have similar but not identical characteristics. Almost all of the compounds have the following properties: The are long straight chains of carbon atoms (generally straight chains running in length between 14 and 22 carbon atoms). They all have a carboxylic acid group one end, wherein there is one double bonded oxygen and one single bonded oxygen and the single bonded oxygen is typically bonded to another carbon with three hydrogens (methyl) and somewhat more rarely a carbon group attached to yet another carbon (ethyl).

The pollution characteristics of biodiesel are pretty well known now. It gives lower particulate matter than petroleum diesel, almost no sulfur dioxide pollution, but higher nitrogen oxide pollution under general circumstances. The particulate pollution - even at a reduced level - can complicate the ability of catalysts to treat the higher nitrogen oxide pollutants.

The chemists in this paper purified and isolated the various constituents of biodiesel (a "neat" compound or element is a liquid that is essentially chemically pure) to try to understand which compounds cause the (generally lower) particulates associated with biodiesel and which compounds participate in the formation of nitrogen oxides. This may suggest which of those species of plants that form biodiesel biologically are likely to give superior fuels for preventing the formation of pollutants.

Also the paper examined how engine design can effect the use of biodiesel. This has been an important area of pollution research.

Biodiesel is a useful tool in the attempt to arrest the global climate change crisis which is now underway. It's no magic bullet, and it's potential is limited, but saying this is not the same as saying that biodiesel industry is a useless enterprise.

Lead to consideration of biodiesel fuels by other DUer's, I have become a strong supporter of this industry, although I was initally quite skeptical. However, if I were the Secretary of Energy, I would recommend that biodiesel be promoted as an engine lubricant for diesel engines fueled (mostly) by dimethyl ether. Dimethyl ether, DME, is basically a pollution free fuel - it gives zero particulates, lacking carbon carbon bonds - in the case where it is made directly from carbon dioxide (and not from fossil sources.) Dimethyl ether has only one major drawback, it's lubricity, something that dollops of biodiesel might serve to address. Such an approach could generalize the ability of biodiesel to participate in a broad solution to the very difficult question of motor fuels, should humanity survive global climate change.

[Dead_Parrot]

3. Thanks!

Think I got it on the third read. I'm not touching that article with a barge-pole, though. :)

I'll do some homework on DME instead.