S.E.C.

Fuel System Grading Policy

             

Let us introduce SEC, the System Emissions Calculator.  The purpose of SEC is to score different fuel systems based on the emissions generated during their life cycles.  The stages in these system life cycles include:  feedstock; fuel rendering; vehicle construction; vehicle transport; and the system use.  With the values for emission production supplied by the GREET model, the SEC generates a score for the system which can then be implemented to compare the emissions between systems.  It is important to note that the results of SEC reflect the system's emissions only, and not the overall conclusion of this project.  SEC can be applied to any of the other fuel systems that are being used today, as well as any systems which might be created in the future. 

Table 1 - This table represents the relative hierarchy of severity for the most prevalent emissions produced by the different fuel system processes.

Primary Emissions Hierarchy – Chemical Characteristics
Emission Compound	IDLH	Environ	Flamm/React	Total
Sulfur Oxides (SOx)	10	8	9	27
Nitrogen Oxide (NOx)	10	7	9	26
Carbon Monoxide (CO)	8	5	9	22
Volatile Organic Compounds (VOC)	4	5	5	14
Methane (CH4)	3	6	4	13
Particulate 2.5 – 10 micrometers (PM10)	5	3	5	13
Particulate under 2.5 micrometers (PM2.5)	5	3	5	13
Nitrous Oxide (N2O)	1	8	3	12
Greenhouse Gases (GHGs)	2	5	5	12
Carbon Dioxide (CO2)	1	6	1	8
Water (H2O)	1	1	1	3

The reason that we developed SEC was to address a flaw with the straight comparison of the total emissions that each system creates.  The only accurate way of comparing the emissions was to look at each compound individually, and decide the “winner” for each, between the systems.  The problem with this is that we are treating all of the compounds as equal to one another, when really they are wildly different.  For SEC, we decided to weigh the compounds more heavily based on how harmful they are.  To do this, we considered their IDLH values, environmental impact, and the flammability or reactivity based on the Severity Scale in Table 2.  A compound's IDLH value is the concentration, in one million air particles, that would prove to be Immediately Dangerous to Life or Health.  For example, if there were 1,200 ppm of CO in the air, a human would be at risk of serious injury or death the moment they entered that environment.  By comparison, it would take close to 40,000 ppm of CO2 to be as dangerous.  


Looking at Table 1, we can see the primary emission compounds that are given by the GREET model for most of the life cycle stages.  The values listed for the rating categories show the values that each compound was assigned based on the Severity Scale in Table 2.  These values are then totaled to give the Severity Multiple of each compound, which are used in SEC.  Figure 1 shows how the Severity Multiple is used in a model of the gasoline analysis of SEC.  The final comparison between systems will take place once a similar analysis has been completed for each of the fuel systems.

Table 2 - Severity Scale:  This scale is meant to describe the relative potency of the various compounds generated and released  by an automotive fuel system.

Comp Severity	Interpretation
10	IDLH:  0 – 500 ppm Environment: Immediate and devastating loss of life Reactivity/flammability: over 75 point explosive range, explosively reactive, caustic, carcinogenic, or strong oxidizer
9	IDLH: 500 – 1000 ppm Environment: Irreversible long term damage/death Reactivity/flammability: 60-75 point explosive range, highly reactive, caustic, or oxidizer
8	IDLH: 1000 – 1500 ppm Environment: Delayed long term damage Reactivity/flammability: 50-60 point explosive range or reactive
7	IDLH: 1500 – 2000 ppm Environment: Immediate short term damage/death Reactivity/flammability: 40-50 point explosive range or reactive
6	IDLH: 2000 – 5000 ppm Environment: Delayed short term damage Reactivity/flammability: 30-40 point explosive range or semi-reactive
5	IDLH: 5000 – 8000 ppm Long term exposure issues Environment: Delayed dispersal, disruption of ecosystem Reactivity/flammability: 20-30 point explosive range or semi-reactive
4	IDLH: 8000 – 12000 ppm Short term exposure issues Environment: Temporary disruption of ecosystem Reactivity/flammability: 10-20 point explosive range
3	IDLH: 12000 – 20000 ppm Environment: Quick dispersal, little impact Reactivity/flammability: 0-10 point explosive range
2	IDLH: 20000 – 40000 ppm Environment: Quick dispersal Reactivity/flammability: Non-explosive
1	IDLH: Over 40000 ppm Environment: No impact on environment Reactivity/flammability: Non-explosive, non-flammable, non-reactive

Figure 1 - SEC: This is an incomplete image of the analysis of gasoline's emission score

 
The results from the SEC analysis will begin to illustrate the distance that the automotive industry is from a perfect system.  It is our hope that the data will not merely put a title on each system, but also encourage the world to try and decrease these scores.  As a solution for the consumer market, SEC provides a better formed opinion on the impact of a given vehicle.  As opposed to a mpg rating that only considers the efficiency of the vehicle, SEC delves into the emissions which take place in the background, well hidden from the typical consumer scales.  SEC has the potential to redefine the way we shop, build, and operate our vehicles.