OAR Box 1781 

Prepped by Ollie Stewart 

Document Number: 

18)11-1-9 

Docket Number: 

A-90-37 

Printed 10/29/2008 10:46:18 AM Sheet 18 of 142 

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POLLUTION REDUCTION IN AUTOMOTIVE PAINTING 

NSR MODIFICATION BASELINE EXAMPLE 

Auto assembly plant "X", a major source of volatile organic compound (VOC) 

emissions located in a moderate ozone nonattainment area, paints the vehicles it 

makes with a modern "basecoat/clearcoat" process. In this process, a base layer 

of color is applied, followed by a thicker layer of protective clearcoat before baking. 

The colored basecoats and the clearcoat contain multiple hydrocarbon solvents -

all VOCs that can react in ambient air to form ozone on hot, sunny days. 

With reasonably good economic conditions, the plant makes 900 to 1000 

cars per day on two production shifts. At maximum overtime it can build 1200 

vehicles per day for 280 days per year - 336,000 vehicles per year at peak 

capacity. However, with a weak economy for several years, strong foreign 

competition in its market segment and an aging design, customer demand for plant 

"X" products has been declining. In recent years the plant has worked no 

overtime, has reduced daily output to 800 vehicles at most, and has had 

occasional "down" weeks during the year and extended model changeover periods 

in the summer. Annual production has ranged between 50 and 60 percent of peak 

capacity, compared to 75 to 85 percent before the Gulf War. 

For the coming model year, along with a minor "facelift" in body styling, the 

plant wants to paint exterior body surfaces with waterborne basecoats. On the 

average, for the same quantity of film-forming solids, they contain only half as 

much VOC as the present basecoats, and can be applied in thinner coats. The 

waterborne basecoats include several newly popular colors to enhance customer 

appeal and boost market demand. No change is needed or proposed to the 

clearcoat. The VOC emission reduction from this integrated, multi-coat process 

would average one pound per vehicle, or 16.7 percent. 

The company requests the state agency to revise its air permit to allow the 

physical changes needed in the current topcoat system to use waterborne 

basecoats. The agency must determine whether the proposed changes would 

cause baseline emissions to increase by 40 or more tons per year and thus trigger 

New Source Review (NSR). Calculations made according to existing NSR rules 

and policies show the following baseline and post-change annual emissions: 

NSR BASELINE: solventborne basecoat; recent average actual emissions 

6.0#VOC/vehicle x 185,000 avg. vehicles/year x ton/2000# = 555 ton/yr VOC 
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POST-CHANGE: waterborne baseqqat;.maximum potential emissions 

5.0#VOC/vehicle x 336,000 max. vehicles/year x ton/2000# = 840 ton/yr VOC 

The "actual-to-potential" calculation-indicates a 285 ton/yr "increase", due 

entirely to the recent "underutilization" of the plant. At any consistent operating 

level, the change would clearly reduce VOC emissions. For instance, at the 

depressed operating level required, in the baseline calculation, the change would 

save over 90 ton/yr. In a stronger market, the change would save more emissions, 

likely in the 120-150 ton/yr range, and at peak capacity, 168. However, because 

the "actual-to-potential" difference exceeds the 40 ton/yr NSR "trigger" for 

increased VOC emissions, the project is subject to Lowest Achievable Emission 

Rate (LAER) control technology and emission offset requirements. 

To meet these requirements, the plant would have to retrofit the kind of VOC 

controls expected on a totally new topcoat system and either buy emission credits 

(if available) or reduce emissions from other sources to create the offsets. To 

avoid these requirements, future production could be restricted by permit condition 

so that the "increase" would never equal or exceed 40 ton/yr. This means limiting 

annual production to 238,000 cars, less than typical output before the Gulf War, 

and a sacrifice of 30 percent of present capacity, nearly 100,000 vehicles per year. 

Plant 'X' could not respond to strong market demand, and its competitors would 

get the additional business. The company cannot accept this. 

Alternatively, if topcoat emissions predicted at peak capacity could be 

reduced by at least 245 ton/yr, they would never exceed the NSR trigger. 

However, these emissions are diffused in a large volumes of exhaust air. To duct 

enough of this air to a carbon adsorber or incinerator to reduce 245 ton/yr would 

require a multi-million increase in capital investment and add to annual operating 

costs. This raises the total project cost to a point that makes it uneconomic; 

management does not approve it. It will not be considered again, at least until a 

major model change at plant "X", which is not planned for several more years. 

The plant withdraws its permit application, continues to use solventbome 

basecoats, and waits for a new advertising campaign and pricing strategy to boost 

market demand and production. Emissions will rise proportionally over recent 

annual levels. The opportunity to achieve substantial day-to-day reductions via this 

project is lost. 

dma.100593 

004665