Climate Change Reformulated Gasolines Reduce Mileage and Produce Negligible Emission Benefits

by Staff

The EPA has mandated gasoline reformulation for nine major metropolitan areas throughout the country to control volatile organic emissions, ground level ozone, carbon monoxide ‘CO’ and nitrogen oxide or ‘NOx’ compounds. Fuel formulations can vary significantly depending on where one lives. These regulations have been in effect since the passage of the 1991 Clean Air Act.

Carbon monoxide is credited with triggering ozone alerts and nitric oxide or ‘NOx’ compounds with acid rain so essential for proper nitrification of the soil. Today’s automobiles no longer contribute to the formation of smog removing ground level ozone, as in the past because of the automobile’s catalytic converter, which oxidizes carbon monoxide, i.e. ‘CO’ directly to carbon dioxide or ‘CO2’.

(1) CO + ½ O2 --> CO2

It should be noted that reaction (1) occurs in open atmosphere given sufficient time. However, on hot sunny days, ozone (2) forms to attack and degrade the carbon  monoxide much more readily.

(2) CO + O3 --> CO2 + O2

CO2 does not cause the formation of ground level ozone as carbon monoxide. So, what scientific justification might there be for the EPA to require the use of re-formulated gasoline's? Well, there’s still the issue of NOx compounds, the source of acid rain, so essential for soil fertilization.

Environmental groups have pressured the federal government to institute further restrictions on automobile emissions. What environmentalists try to get the public to believe is that the small quantity of fuel that escapes from the vehicles gas tank, i.e. about 0.1% escapes in automobiles of the past generating smog while they conveniently ignore the hydrocarbon emissions of conifer and deciduous trees which also causes smog. Remember, It was former President Ronald Reagan who first said trees pollute emitting substances known as mono-terpenes.  See Appendix 'G' at the bottom to see how to determine them.. When days contain 12 hours of sunlight or more, a tree produces about a gallon of tree aromatics per year.

1.0 gm/hr  x  10 hrs avg sunlight /tree-day  x 1 lbm/453.6 gm  x  365 days/ yr  x 1 gal tree Aromatics /7.187 lbm  = 1.12 gal aromatics/tree-yr                                                                                                                             

So How effective is ethanol in reducing auto emissions? To answer that question will require the use of a mathematical model and a simplified fuel formulation, which can easily be modified to develop the computations used in exhaust pollutant concentrations and gasoline mileage.

We will demonstrate the negligible environmental benefits of blended gasoline's and debunk the philosophy in which hides a vast network of suppliers and provocateurs anxious to get their hands on public money. We begin by choosing a test model, an older style vehicle without pollution controls to simply the calculations and tabulate the vehicle emissions. A simplified gasoline formulation, one in use a number of years ago, containing lead tetra-ethyl has been selected. The representative gasoline formulation was developed for testing in an EXCEL spread sheet simulator that conserves mass and energy. Each component listed includes its structural formula, weight, molecular weight, density and the number of component moles it adds to overall gasoline composition.

A series of simple alkane hydrocarbons was assumed and adding simple octane, without consideration of any of its18 isomers, to develop simulated engine mileage as close as practicable to actual results obtained by the vehicle manufacturer. An octane number is simply a standard measure of a fuel's ability to withstand compression in an internal combustion engine without detonating (knock). Our test vehicle has a compression ratio of just 6.3 to one so it is not critical to the simulation  Lead  tetraethyl was also added  to give our base formulation more realism. The gasoline performance has to be estimated from its assumed components which are found by trial and error calculations that compare mileage to three actual interval points of real engine data from the Buick manual( Fig. 1) until the best fit is obtained. 

Ethyl alcohol is the oxygenate to be tested as ETBE and MTBE are not taxpayer subsidized as is ethanol. 

Manufacturers have supplemented their reformulated gasoline's with fuel oxidants such as Ethyl Tertiary Butyl Ether, (ETBE) Methyl Tertiary Butyl Ether (MTBE) or ethyl (grain) alcohol to develop a cleaner burn with less overall pollutants.  Wikipedia states: "Methyl tert-butyl ether is a gasoline additive that replaced tetraethyllead. MTBE is an oxygenate and raises gasoline's octane number. Its use declined in the United States in response to environmental and health concerns." EtBEeliminates many o the problems with MTBE. According to Wikipedia: Ethyl tertiary-butyl ether, also known as ethyl tert-butyl ether, is commonly used as an oxygenate gasoline additive in the production of gasoline from crude oil. ETBE offers equal or greater air quality benefits than ethanol, while being technically and logistically less challenging.

So just how effective is ethanol? To answer that question, will require the use of a mathematical model in which to test our simplified fuel formulation, which is readily modifiable to develop the computations of exhaust pollutants and gasoline mileage.  Lead d tetraethyl was also added to give our formulation a more realistic flair.

Table 1 Simplified Gasoline Composition

The pseudo-fuel formulation is represented by four simple alkane chain hydrocarbons, C5 to C8 and lead tetraethyl, to avoid the complexity of some 300 compounds including aromatics, olefins and benzene as in real reformulated gasoline. The test formulation shows additions of ethanol in tests of 5 and 10 percent. Additional information on reformulated gasoline is available from EPA at http://www.epa.gov/otaq/rfgvehpf.htm.

The model simulates the operational characteristics of a real motor including rpm, horsepower, curb weight, gearing, fuel consumption and emission quantities in conjunction with reaction stiochiometry to achieve comparable rpm, fuel consumption and speed of the real engine.


Note that the model rpm diverges from the actual engine but is closest at 30 miles per hour. Emission calculations will be based on this 30 miles per hour driving speed.

Table 2 shows how well our model compares to real engine specifications.

  

Ethanol composition results are tabulated on a mole percent basis. Two curves were plotted, one for 5% and another for 10% ethanol demonstrating that ethanol addition decreases mileage at the reference speed.  Figure 2 shows the model and the vehicle’s actual Rpm which matches most closely at 30 mph, so this was selected as the reference speed for modifications to the emissions estimates. This velocity correlates well with the speed limits established by many city municipalities including Overland Park, Kansas, who has noted in their Spring 2005 Overview magazine, that "The average driver spends 443 hours behind the wheel." This corresponds to 15,500 miles per year at 35 mph.

This is the starting point for evaluation of grain (ethyl) alcohol additions to gasoline NO MTBE or ETBE are considered in the ethanol trials.

Figure 3 conducted at 35 mpg suggests a pollutant CO level of 1.207 tons per year: 1.34 times greater than at 30 mph with just a five mile per hour increase. 

Note that water vapor is missing from Figure 3 because it is NOT considered a green house gas. Figure 5 shows how significant water vapor's contribution to atmospheric heating really is.

Assuming that the oxygenates are consumed in a manner consistent with their intended purpose, i.e. organic compounds containing NOx agents, such as peroxyacetyl nitrate (PAN), are not formed in or around the catalytic converter.  But, occur outside the vehicle under dissimilar conditions, then a stoichiometric analysis can evaluate the effectiveness of any oxygenate, in our case ethyl alcohol.

Figure 4 shows the effect of ethanol in the mix. In order to calculate the cost of using this oxygenate, we begin by eliminating the difference in mileage at the crossover point between the actual and simulated mileage curves which occurs at about 40 miles per hour. The mileage obtained for comparison is then 17.5 miles per gallon.

At 10% C2H5OH: the loss of mileage is 17.5 - 15.22 = 2.28 gallons.

If the speed were increased to 50 miles per hour the loss in fuel economy would be significantly greater.

The vehicle range from a standard 16 gallon tank:

15.22 miles/gal x 16 gal = 243.2 miles/tank

Driving 15,500 miles at 243.2 miles/tank will consume 63.7 tanks/year compared to just 51 tanks with standard gasoline.

Environmentalists conveniently ignore H20 because it is a far more virulent green house gas. Note that water vapor lies significantly ABOVE carbon dioxide in the thermodynamic chart through all temperature ranges, more than double that of carbon dioxide.  Convective heat transfer is governed by the relationship H = m Cp dt where 'H' is enthalpy measured in Btu/lb and 'm' is the mass involved, 'Cp' is the Heat capacity shown in Figure 5 stated as Btu/Lb-F and 'dt' is the temperature. So water vapor both absorbs and transmits heat far more effectively than carbon dioxide.

Figure 5 - Heat Capacity of CO2 vs Water vapor  (Appendix F)

Note carbon dioxide in 0.26 Btu/lbm-F at the chart's maximum temperature.

One of the inescapable conclusions of this study is that federally mandated gasoline formulations are not intended to meet air quality standards of the Clean Air Act. The notion that 3 to 6% reductions in a non-accumulative pollutant will affect climate change or anything else is simply ludicrous. Federal requirements on fuel formulations unnecessarily burden consumers with the threat of localized fuel shortages and higher gasoline taxes to support the special interests that grow corn and manufacture the alcohol, which neither reduces pollution nor improves fuel economy.  But are more in tune with creating the basis for a global energy and per mile use tax.

A 0.04 ton reduction in Carbon dioxide is not much savings in comparison to the cost of buying an extra 11.7 tanks of gasoline. Regulating water is not as conducive to controlling with emission credits as is carbon since you will never get the public to accept the green house gas characteristics of water.

TABLE 3 - Tons per Year of  Vehicular emissions at 30 miles/hr

                    Old Leaded Gas         5% Ethanol    10% ethanol

CO:                     0.903                         0.893              0.884

NOx:                   0.373                          0.359            0.346 

H2O                    0.907                          0.909            0. 912
Total                    2.18                            2.16              2.14 


Table 3 demonstrates an emission reduction in both CO and NOx from addition of ethanol to the fuel. But also note the corresponding INCREASE of water vapor out the vehicle tail pipe which is never observed except on cold days before the exhaust mixture climbs above the dew point.  Now we see the true reason why water vapor is omitted from Figure 3.

EPA requirements permanently alter the supply and demand curves without public benefit and these regulations are just another means for the federal government to increase control over private industry and property. It is no longer the public that chooses a product but a socialist government that dictates what is or is not acceptable to the consumer with no more than the ‘junk’ science of environmentalism to justify it.





 

References   


Appendix  F - Heat Capacities of liquid and vapors at one atmosphere
                 Himmelblau, Basic Principles and Calculations in Chemical Engineering, Second Edition, Prentice Hall, 1967, P- 448

 

Appendix G - Diffusivity of Tree Organics.