Cycle News - Archive Issues - 1980's

Getting the lead out: Part 2 The delDise of leaded gasoline and the alcohol threat By Jim Wolcott By J a n u a ry 1,1986; the maximum lead con. tent of ga so lin e win be 0.1 gra m s-p er-ga llon (gpg) - about 1/10 w h at i t is to day - and there's a good chance tha t by 1988 th e u se of .. 34 lead as a gasoline additive will be completely outlawed. The obvious question is . .. why? At the 0.1 gpg level , the amount of a tmosp her ic pollution caused by leaded gasoline will be miniscule; in fact , the amount of lead pumped into the atmosphere will h ave been reduced n o less th an 99% from the peak usage year of 1970. Since new motor vehicles - motorcycles and ca rs - ar e now designed to run exclusively on unleaded fuel, whv is th e Environmental Protection Agen cy (EPA) co ncerned a bo u t th e small percentage o f vehicles that require lead ed fuel? The an swer is ca lled " m isfuel ing;" a term th e EPA ha s co ined for those motorists who use leaded gasoline in vehicles designed for unleaded fuel. Currently, leaded regular-grade gasoline is 'a n ywhere between five and 20 cents cheaper per gall on than unlead ed regular-grade gasoline. Worse, th e more expensive unleaded fue l has a lower octane rating than leaded gas, a n d consumers associate higher octane numbers with higher qua lity fuels. Add to this the widespread notion that leaded gasoline is somehow better for your car or motorcycle, and the predictable result is that legions of consumers began filling their unleaded-dedicated vehicles with leaded gasoline. When misfueling, the victim is the vehicle's ca talytic convertor. Lead deposits can quick ly coat the exhaust system, which in turn, coats the delicate platinum catalyst element within the convertor. Thus coated, the catalyst stops scrubbing the exhaust emissions, and the bui lding blocks of air pollution are free to waft from the tailpipe. Understandably, the EPA isa little upset about all this. Their solution? To permanently solve the prob lem of misfuel ing by banning leaded gaso• line. This misfueling problem is intensified in that. many. consumers are baffled by the cost difference of un leaded fuel. After all , it must cost less to make , since the refineries don 't have to add lead , right? Who knows? Maybe removing the lead from gasoline might even be a part of an EPA conspiracy to increase oil refinery profits? Wrong. Rem ember , tetraethyllead (T EL) was originally blended with ga sol in e to boost th e oc ta ne rating of inferi or-grade fuel. Without lead, gasoline ha s to be more potent to achieve the sa me oc ta ne rating. Th e bottom line is th at unl eaded gasoline is gen u in el y more expe n sive to m anufa cture th an leaded gasoline. T h is is part of th e EPA 's ta cti c with lowerin g th e maximum lead limit to 0.1 gpg: that leaded ga so line will f inally cos t more to produce than its unleaded co u n terp a rt . The EP A is co u nt ing on thi s price difference to pr event penn y-conscious co n su me rs from p oisoning th eir ca ta lytic co n vertors with lead ed fuel. Of co urse, if next J anuary's 0.1 gpg leaded gasoline doesn't cost more th an un lead ed gasoline a nd th e rnis fueling trend continues, th e EPA will be armed wi th more rea son to forever ban leaded fuel. A q uestion of octane As yo u might imagine, there's no free ride in th e refining process; the removal o f lead has forced chemical engineers to devise other ways to boost gaso line's octane rating. First of all, what is octane? Any time a gas (like air) is compressed, heat is generated; this is why a bicycle pump get s hot when inflating a tire. The sa me goes for the gasoline/air mixture within an engine: when the piston comes up on compression, the mixture is heated because it's compressed. If the engine compression is high enough, enough heat will be gen erated to detonate the mixture -a phenomena called pre-ignition, where the fuel ignites before fired by th e spark p lug, Th e octane rating refers to a gasoline's resistance to this compressionrelated detona tion: the h igher the octane, the more co m p ression it can .withstand without self -igniting. The higher the compression, the more power can be extracted from a given quantity of gasoline, Which is not to say that a higheroctane gasoline produces more power. A motorcycle designed for regulargrade gasoline will not make a n y more power if run on a higher-octane pr emium gasoline - un less thecylinder head is mi lled or different pistons are fitted to raise compression. Conversely , a high-compression motorcycle engine needs high octane ga sol ine. Detonation is a sm all -scale explosion within th e combustion ch a m ber. At best, detonation makes a n eng ine produce less power and run hotter. At worst, detonation will burn holes in the piston tops. With lead out of the picture, the refining industry must immediately use other wa ys to boost gasoline octane, Right now , this is being handled through the addition of hydrocarbon compounds called aromatics. Aromatics and air poUution First of all, a little backgro und in chemistry is in order. The term aromatics actually refers to a large family of volati le h ydro car bo n s, but for our purposes refer to three compounds: benzene. toluene and xylene - aromatics known in the refining biz as the BTX's. These three aromatics have numerous indus trial applications, and are removed from crude oil early in the refining process. But the BTX's also do a dandy job of boosting the octane ra ting of gasoline, so some of these aromatics a re blended back into gasoline to achieve the des ired octane rating. In fact , the BTX's (primarily tolu ene) do such a good job that they 're packaged and sold by various companies as "octane boosters," and form the active ingredients for products like PJ -I, Maxima and Morose octane boosters. However, th ese aromatics have a sinister sid e wh en it comes to the qu estion of a ir pollution . When ' b u rn ed in th e co m bustion chamber, th e BTX's represent a percentage of th e tot al hyd ro carbon exha ust emissio ns . Of co ur se, th e to ta l amount of hydrocarbon em issio ns is a lready con troll ed by th e EPA (and in the Golden Stat e, by th e Californ ia Air Resources Board ), so th e use o f aro ma tics to boost gas oline oc ta ne ca n ' t damage th e a tm osp he re, right? Well, not exactly. Though the total hydrocarbon ex ha ust em issio ns are str ictly co ntrolled , th e nature of those hydrocarbons is not. The question is th e reactivity of th e exhaust gasses, a nd th eir lik elihood of converting into various form s of sm og when released into the atmosphere. Adding a ro ma tics to gasoline to increase octane rating results in at least two types of air pollution threats not specific ally addressed by current emissions regulations: pollution from aldehydes. and the secondary effects of increased exha u st reactivity. Aldehydes are sometimes referred to as instant sm og, because they can contribute to the smog problem without going through photochemical rea ctions in the atmosphere. Whi le the addition of aromatics doesn't increase the total a ldehyde content of the exha ust ga sses, it does increase the aromatic aldehyde content - as much as 70%. Studies conducted by General Motors found that benzaldehyde, the major aromatic aldehyde in the exhaust, led to the formation of peroxybenzoyl nitrate (P BzN): the chemical species blamed for the major portion of eye irritation in Los Angeles, California smog. Exhaust reactivity refers to what happens to exhaust gasses when exposed to sun light, as well as other chemical pollution already present in the atmosphere. Aromatics are mem bers of the chemical families tha t rea ct most readily to form ozone, oxidants, and eye irritants - photochemica l smog. Catalytic convertors can help break these compounds down int o lessharmful oxides, but don't solve the problem ent irely. For vehicles without

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