# New Source Review: Modeling and Offsets

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New Source Review: Modeling and Offsets
November 2, 2005 Judy B. Yorke Yorke Engineering, LLC x25

NSR Modeling Requirement
A demonstration that the new/modified source will not “cause a violation, or make significantly worse an existing violation…” of the NAAQS. Exemptions are identified in Rule 1304, for example: Replacements; Emergency Equipment; and Air Pollution Control

NSR Modeling Demonstration
SCAQMD Rule 1303 Appendix A Screening Analysis If hourly emissions are less than the values in Table A-1, the modeling requirement is satisfied If source does not pass screening analysis, detailed modeling is required

Table A-1: Allowable Emissions
Heat Input Capacity (million BTUs/hr) NOx (lbs/hr) CO (lbs/hr) PM10 (lbs/hr) Noncombustion Source 0.068 3.7 0.41 < 2 0.20 11.0 1.2 >2 < 5 0.31 17.1 1.9 >5 < 10 0.47 25.9 2.8 >10 < 20 0.86 47.3 5.2 >20 < 30 1.26 69.3 7.6 >30 <40 1.31 72.1 7.9

Detailed Air Quality Modeling
Create dispersion model using SCREEN3 or ISCST3 Calculate highest pollutant concentration for receptors outside facility boundary 1-hour average Annual average Determine ambient pollutant concentration by taking highest value from most recent 3 years data Add new concentration to ambient concentration Modeling satisfied if sum does not exceed values in Table A-2.

TABLE A-2: Most Stringent AAQS
Air Contaminant Averaging Time Most Stringent Air Quality Standard Nitrogen Dioxide 1-hour Annual 25 pphm* 5.3 pphm 500 ug/m3 100 ug/m3 Carbon Monoxide 1-hour 8-hour 20 ppm 9.0 ppm 23 mg/m3 10 mg/m3 Suspended Particulate Matter -<10um (PM10) 24-hour Annual Geometric Mean 50 ug/m3 30 ug/m3` Sulfate 24-hour 25 ug/m3 * pphm = parts per hundred million

NSR-Offsets Goal of Offsets
Use emission reductions from existing sources to offset emission increases Reductions more than compensate for increases and result in a net air quality benefit

Offset Ratio Generally, offsets are required at a 1.2-to-1 ratio
Some variations, e.g.,: Priority Reserve Offset Budget RECLAIM NOx/SOx

Offset Exemptions Exemptions are identified in Rule 1304, for example:
Qualifying Replacements; Emergency Equipment; Air Pollution Controls; Relocations; Facilities with a PTE below thresholds

NSR-Offset Exemption Thresholds
Offsets are required if facility exceeds:

Cost of Offsets The cost of offsets vary with the demand…
Examples of market prices, current bids/offers*: ·         Non-RECLAIM Emission Reduction Credits - o       PM10 ~ \$65,000/lb o       ROG ~ \$1,500/lb o       CO ~ \$7,800/lb ·         RECLAIM Trading Credits - o       NOx ~ \$ /lb o       SOx ~ \$1.35-\$3.5/lb * From Christine Grandstaff of Cantor Fitzgerald ( )

Generating ERCs Rule 1309 defines requirements to obtain ERCs
Rule 1306 the emission decrease which may be considered Requirements are very stringent

To Obtain ERCs 2 years of records demonstrating actual emissions must be provided Actual emissions are discounted to current BACT emission rate Discounted emissions are further cut by usage factor if operated less than 180 days/year.

Summary Review carefully BACT determination
Review offset and modeling applicability and requirements Check permit conditions carefully Get help when you need help!

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