2009 VW Jetta TDI Emissions Results In!

That's exactly why I tried to convert all of the metrics to g/mi.

The 2-day/3-day diurnal test is in "g/test". Actually, the 3-day diurnal is the FTP and the 2-day diurnal is the "supplemental" FTP (SFTP). The diurnal tests are conducted to determine VOC emissions while the car is "sitting" (i.e., not being driven). The methodology of determining diural emissions is given in Electronic Code of Federal Regulations: , § 86.1233-96, Diurnal emission test. (a)(1). The conversion to g/mi (approximately) is given by CARB...

Conversion - 3-day diurnal emissions (g/test) to g/mi = 3-day (g/test) ÷ 53.73 (36 ÷ 0.67) http://www.arb.ca.gov/msprog/macs/mac0503/mac0503.pdf (page 12)

The "running loss" is given in g/mi.

ORVR (on-board refueling vapor recovery) is the test to determine evap emissions during refueling. It's given in g/gal, so it's a function of fuel mileage.

Then there are the "indirect" or "upstream" VOC emissions from the distribution of the fuel to gas stations, etc. It's also in g/gal.

I'll admit this is somewhat convoluted, but here is an explanation of how I came up with the evap emissions in g/mi...

Based on EPA’s AP-42 (http://www.epa.gov/ttn/chief/ap42/ch07/final/c07s01.pdf - Table 7.1-2 on page 7.1-63), diesel fuel is no more than 0.44% as volatile as gasoline (using the lowest reid vapor pressure of gasoline; it could be as low as 0.2% as volatile @ the highest reid vapor pressure of gasoline listed in Table 7.1-2) on a mass-equivalent basis @ 80 degrees F (i.e., for every pound of diesel fuel that evaporates, at least 226.7 pounds of gasoline would evaporate under the same ambient conditions).

Based on EPA data from the Federal Register, January 10, 2008, page 1930 (http://www.epa.gov/ttn/atw/area/fr10ja08.pdf) , approximately 372,000 tons of VOCs will be emitted per year from the distribution of gasoline (AFTER full implementation of the Final Rule). This does not include "spillage" during refueling (§ 63.11112 (a))

Based on data from EIA, the U.S. uses 385 million gallons of gasoline every day (EIA Energy Kids - Energy Kids: Energy Information Administration) (385,000,000 X 365 = 140.5 billion gallon/year).

370,000 tons/year x 2000 lbm/ton = 740,000,000 lbm/year ÷ 140,500,000,000 gal/year = 0.005267 lbm/gal X 453.6 g/lbm = 2.389 grams/gallon. 0.7 lbm/1000 gal (spillage during refueling) X 453.6 grams/lbm = 0.318 grams/gallon.

Calculation of evaporatve emissions at various points in the fuel distribution chain...

VOC Source....................................Gasoline*.............................Diesel*

Bulk Storage ...................................0.037 g/gal.........................0.00016 g/gal (from "Example 11" page 7.1-120 of Chapter 7)
Loading.......................................... 0.272 g/gal........................ 0.016 g/gal (no control) (from LL calculations page 5.2-7)
Transit ............................................0.027 g/gal .......................0.0001 g/gal (Table 5.2-5, page 5.2-12)
Gas station tank filling (lowest) ...........0.151 g/gal...................... 0.00066 g/gal (Table 5.2-7, page 5.2-15)
UST breathing and emptying ...............0.454 g/gal ......................0.002 g/gal (Table 5.2-7, page 5.2-15)
Spillage...........................................0.318 g/gal ......................0.01 g/gal (Table 5.2-7, page 5.2-15; OEPA**)
Total VOC........................................1.26 g/gal........................ 0.029 g/gal

http://www.epa.gov/ttn/chief/ap42/ch05/final/c05s02.pdf

*Vapor pressure generally based on Table 7.1-2 of chapter 7 of AP-42 (http://www.epa.gov/ttn/chief/ap42/ch07/final/c07s01.pdf - page 63) (assumed LOWEST RVP for gasoline @ 80*F)

**Diesel fuel spillage emission factor calculated from http://www.epa.state.oh.us (OEPA)

Using the same ratio...(0.019/0.941) x 3 g/gal (calculated from FR NESHAPs Rule @ current emission rate of 475,000 tons/year) = 0.06 g/gal for diesel in distribution chain (excluding "spillage")

Calculated emissions factors for evap emissions - 2.389 g/gal + 0.318 g/gal ("spillage") = 2.7 g/gal gasoline; 0.06 g/gal + 0.01 g/gal ("spillage") = 0.07 g/gal diesel


Therefore, the total emission factor for this activity is 2.7 grams per gallon for gasoline and 0.07 grams per gallon for diesel fuel (calculated from AP-42).

I used the "combined" fuel mileage per fueleconomy.gov for the g/gal to g/mi conversion.

Apparently, the OBD in the Jetta TDI does not meet all of the CARB requirements and thus is considered "deficient". Don't know for sure how it's deficient however.

 

Ok, let's once again take a clear, concise, and dispassionate look at the data. We find the Jetta diesels have relative to the 2010 Prius:

NMOG CERT - 2.4 times higher
CO CERT - 10 times higher
NOx CERT - 16 times higher
Hwy NOx - 15 times higher
​

Both vehicles meet their respective, minimum standards but not obvious in the data, they have different thresholds:

	NMOG CERT (g/mi)	CO CERT (g/mi)	NOx CERT (g/mi)	Hwy NOx (g/mi)	model
1	no STD	1.0	0.02	0.03	2010 Prius
2	no STD	4.2	0.07	0.03	Jetta UL
3	no STD	3.4	0.05	0.07	Jetta 50K

.
So the Jetta is allowed 4.2x CO, 3.5x NOx but identical highway NOx in the UL test protocol.

The source data:

	NMOG CERT (g/mi)	CO CERT (g/mi)	NOx CERT (g/mi)	Hwy NOx (g/mi)	EVAP 2-D	model
1	0.005	0.04	0.003	0.002	0.28	2010 Prius **
2	0.009	0.10	0.010	0.010	0.14	2007 Prius **
3	0.012	0.40	0.050	0.030	***	2009 Jetta TDI **
4	0.007	0.20	0.040	0.020	***	2009 Jetta TDI*

* - used the @50k data
** - used the @UL data
*** - untested, non-gasoline vehicle, we don't know

All data from California Air Resources Board executive orders:

• A-014-0657 - Toyota 2010 Prius
• A-014-0560 - Toyota 2007 Prius
• A-007-0271 - Volkswagen Jetta, Jetta Sportwagen diesel

No need, here are the 2010 Prius and Jetta TDI evaporative test results:


The Prius was tested so we have certified, offical results, Annette Herbert, Chief Mobile Source Operations Division, signed both forms:

• 0.20 - three day
• 0.28 - two day
• 0.00 - running
• 0.01 - ORVR(?)

Jetta evaporations were not tested. The absence of a test does not mean an absence of evaporative emissions. It simply means no one attempted to take a measurement. If you measure something and get a value of "0", it is data. But the absence of a measurement is not a "0" value. It is unknown.

As for the units, it comes from the California Air Resources Board documents describing the testing protocols.

Bob Wilson

 

Bob - I don't disagree. But you're not suggesting that the evaporative emissions from diesel vehicles are in the same ball park as gasoline vehicles, are you?

Also, I don't completely follow your last post, because you're the one that insisted on using the same units for each metric. I proposed a methodology for converting the fugitive VOC emissions to g/mi. If you have another methodology, please let me know.

If you're really set on using the g/test units for the 3-day diurnal test, I propose using the non-PZEV (ULEV) version of the gas Jetta (cert available at http://www.arb.ca.gov/msprog/onroad/cert/pcldtmdv/2009/volkswagen_pc_a0070274_2d5_u2.pdf ) and correcting those values using the relative evaporation rate of diesel:gasoline (based on AP-42, 5.4 psi vapor pressure for gasoline; 0.012 psi vapor pressure for diesel fuel at 80 F).

At any rate, evaporative VOC emissions cannot be legitimately dismissed from the emissions discussion in my opinion. VOCs are every bit as "bad" for air quality as the HC emissions from the tailpipe.

 

ORVR: Onboard Refueling Vapor Recovery. This is used at source of dispensing for volatile fuels, mandated on all new gasoline fueled vehicles >1998 model year

So, what is your point? These rare earth metals are used to make high strength steels. The issue of the battery alone is a red herring at best

By the time those with simple minds talk about the "benefit" of a Hummer vs a Prius, they have totally failed to understand that the TOTAL CUMULATIVE nickel content of the Hummer is far more than the Prius, BATTERIES INCLUDED

So what in particular is it about the battery?

Yes, I had no choice but to off myself after reading this entire thread. Now I've turned into the Living Undead. Actually has advantages

 

I always laugh when someone uses wikipedia as acceptable data. Its funny because most colleges in the state of WI and MN wont accept wiki as source on any paper at a college level. The biggest reason is the edit button at the top of the page

 

not that wiki is wrong in this instance ... it's just fun to make light of the source ... though the facts of the unreliable source ... in this instance are valid. poo poohing the source in this instance neither invalidates nor obfuscates the fact of the matter.

.

 

Holy CARP! Have you read the material safety data sheet for:

• NiMH batteries
• lead-acid batteries

Just Google "material safety data <product>" and any products that are shipped will have a sheet somewhere. But I did not realize that sulfuric acid is:

I knew the lead plates included antimony but the data sheet was eye opening. In contrast, the NiMH batteries are relatively benign.

Bob Wilson

 

H2SO4 is nasty stuff. It also has industrial uses, eg in the production of fertilizers and in petrochemical production (Enhances octane of gasoline)

Hard to believe at one time, old batteries were just upended on the ground to let the H2SO4 dribble out. Folks make a big deal of the alkaline electrolyte gel in NiMH batteries, but liquid H2SO4 is scary

 

Diesel particulate filter traps soot from the exhaust. How often do you need to change it?

Can you recycle particulate filter or do they just got dumped in the garbage?

 

My understanding is some of them have an 'enrichment' mode where they 'burn out' the particulates.

Bob Wilson

 

Wxman's assertion that smog should be viewed as a NMOG problem has *some* validity, inasmuch as both NMOG and Nox are required ingredients in ozone smog, and industrialisation has dumped both into the atmosphere. However, the little reading I have gotten under my belt thus far tells me that normal earth chemistry includes baseline NMOG emissions that on a molar basis far exceeds NOx. So from the get go, the Earth is a Nox sink, but I do not know how much this amounts to.

This article from 1975 in Los Angeles broke down the sources of air HC and came up with about automotive exhaust 47%; gasoline, 31%; commercial natural gas, 8%; and geogenic natural gas, 14%. Old data, only presented to say that the topic is complicated.

Anyway, I'll learn more, and links are appreciated. At a certain level though, this discussion could be changed from Prius vs TDI, to the following: we know that petrol and diesel are going to be used, so lets ask if the Prius is the smartest way to burn petrol, and whether the TDI is the smartest way to burn diesel. A parallel question that comes to my mind is if it makes enviromental sense to crack diesel into petrol in order to set up a NOx poor(er), NMOG rich(er) atmosphere.

 

That's true, but unfortunately, it's vastly more complicated than that.

NOx and HC are required for ground-level ozone (“smogâ€) to form and accumulate. However, ambient conditions determine how to effectively control ozone from a regulatory perspective, and it’s the regs with which I have an issue.

It has been noted for decades that ambient ozone levels have often increased on weekends in Southern California despite significant reductions in ozone precursor emissions, primarily from a decrease in traffic volume, which is obviously counterintuitive. This has been dubbed “the weekend ozone effectâ€.

Studies in the late 1990s and early 2000s noted that in areas where ozone increased on weekends, both ambient NOx levels and ambient ozone levels decreased, but NOx levels decreased relatively more than HC levels. The Air and Waste Management Association devoted almost an entire issue of its publication (JAWMA) in July 2003 to this issue. A good overview of this issue is available at http://www.altfuels.us/pdf/lawson[1].pdf .

These studies have concluded that greater relative reductions in NOx than HC in areas with ambient conditions that are “VOC limited†are actually counterproductive in reducing ozone levels. Actually, from an areal perspective, most locations are “NOx limited†in which greater reductions in ambient NOx levels than HC levels would tend to decrease ozone levels. Unfortunately, the areas that are “VOC limited†with respect to ozone formation are common in large metropolitan areas which are where most of the nonattainment with the ozone NAAQS (National Ambient Air Quality Standards) occurs and where a lot of people live. I would also suggest taking a look at Journal Abstract even though the article has to be purchased (the abstract is available however).

I’m not suggesting that anthropogenic NOx emissions shouldn’t be reduced and eventually eliminated. However, the approach has to be carefully considered based on the implications of the weekend ozone effect studies. The Tier 2 regs impose a greater regulatory reduction in NOx emissions (from 0.6/1.25 g/mi Tier 1 to 0.07 g/mi Tier 2) than HC emissions (NMHC/NMOG – from 0.31 g/mi Tier 1 to 0.09 g/mi Tier 2 (Bin 5)) exactly what the weekend effect studies suggest shouldn’t be done. There has been no documentation of increased ozone levels from decreasing HC levels relatively more than NOx levels in “NOx limited†locations, but there has been considerable documentation of ozone levels increasing from decreasing NOx levels relatively more than HC levels in “VOC limited†locations. Thus a policy of greater focus on HC emission reductions than NOx emission reductions would not potentially put any population at risk of poorer air quality as a result of the regulatory action, unlike the current regulatory approach.

Since based on the weekend ozone effect studies the Tier 2 regs are flawed, by extension, the “green vehicle scores†based on the Bin a vehicle hits has very little utility in my opinion.

 

So where there are measurements for three vehicles with the same units, we have the following:

	2009 Jetta	2010 Golf	2010 Prius	measured both vehicles
1	40.0 MPG (27 vehicles)	40.9 (1 vehicle)	50.3 MPG (64 vehicles)	user measured mileage
2	91 ft {3}	94 ft {3}	94 ft {3}	passenger volume
3	16 ft {3}	15 ft {3}	22 ft {3}	luggage volume
4	$24510	$24639	$24150	Kelly Blue Book MSRP Prius III *
5	0.090 (g/mi)	0.090 (g/mi)	0.010 (g/mi)	NMOG or NMHC STD UL test
6	0.400 (g/mi)	0.400 (g/mi)	0.040 (g/mi)	CO UL test **
7	0.050 (g/mi)	0.050 (g/mi)	0.003 (g/mi)	NOx UL test **
8	0.030 (g/mi)	0.030 (g/mi)	0.002 (g/mi)	Hwy NOx UL test **
9	$50 each	$50 each	$0 each	CARB fine per vehicle ***

* The 2010 Prius III is the middle of five trim levels. The 2010 Jetta TDI is listed as a single trim. The 2010 Golf TDI is the four door, automatic, just like the other vehicles.
** All vehicles meet these CARB standards but the diesel standard allows more emissions.
*** CARB has issued a fine of $50 for a problem with vehicle diagnostic system.

Sources:

• A-014-0657 - Toyota 2010 Prius executive order
• A-007-0271 - Volkswagen Jetta, Jetta Sportwagen diesel, Golf executive order
• www.fueleconomy.gov
• Kelly Blue Book

I noticed the mileage numbers for the 2010 Jetta TDI are different from the 2009 model. However, I would recommend the Jetta TDI advocates read the 2010 numbers, A-007-0285, before bringing them up for discussion.

I did not try to quantify the tax credits because there are state and local incentives and the federal tax credit is subject to the minimum alternative tax 'catch.' Many Prius buyers were disappointed that the minimum alternative tax eviscerated the tax credit.

Bob Wilson

ps. I will not be posting this summary in the TDIclub forums. However, I did share it with the "Green Humans" who went out of their way, 8,000 miles, to stage a cross country drive with a Prius. Apparently "clean" does not include head-to-head comparison of emissions per mile.

 

I've said this before and will repeat it: Someone considering a Prius and TDI should probably consider the Golf. Like the Prius, it's a hatchback and offers many of the usual hatchback advantages. It is a much newer design than the ~6 year old design of the Jetta, and has more interior volume as well. Unfortunately, it often gets overlooked simply because it's not a sedan, even though it is better in many regards.

Bob, the diesels qualify for a $1300 tax credit ($1700 for the Golf automatic). You may want that in your price comparison. Speaking of the Golf automatic, the DSG TDIs do get better EPA numbers than the manuals, but if anyone is driving the vehicle for fuel economy, the manual seems to be the way to go. It's also much cheaper to purchase and maintain, making it my recommendation for most people considering a TDI. That will knock about $1100 off the Jetta MSRP listed above.

About the 2010 vs 2009 EPA numbers, I don't know of any significant differences between the vehicles so I think it comes down to test parameters. I don't expect the 2010 to be any more efficient in the real world than the 2009.