Mojave Desert Air Quality Management District
July 2, 2007
Page 15
July 2, 2007
Mojave Desert Air Quality Management District14306 Park Avenue
Victorville, CA 92392
Re: / Nursery Products LLC
Dear ______:
Thank you for the opportunity to participate in the preliminary consideration of the feasibility of regulating emissions from composting operations by the Mojave Desert Air Quality Management District (MDAQMD or District).
My understanding is that the MDAQMD is considering three types of measures that could apply to composting operations within the District: (1) measures requiring composting, chipping and grinding facilities to register with the MDAQMD and to provide throughput information; (2) measures designed to prevent inadvertent decomposition associated with stockpiling of green and/or food wastes by establishing holding or processing time requirements for chipping and grinding activities; and (3) measures requiring co-composting operations to reduce Volatile Organic Compounds (VOCs) and ammonia emissions by 80% by enclosing their activities or presenting an alternative method of compliance17.
Nursery Products has five years of experience with co-composting operations within the MDAQMD, and is committed to working collaboratively with the MADQMD to ensure that its composting operations are carried out in an environmentally responsible fashion. To that end, this letter provides information on (1) accurate measurement of VOC emissions associated with composting activities; (2) sources of VOCs in the District’s area; (3) the cost of reducing VOC emissions from composting and other sources; and (4) the overall impact of composting on climate change.
I. Accurate measurement of Volatile organic compound emissions from composting operations
Studies conducted by the South Coast Air Quality Management District (SCAQMD) and the California Integrated Waste Management Board (CIWMB) provide rough estimates of emission factors for composting operations. The SCAQMD study measured facility-wide emissions, including tipping piles, active composting piles, and finished product piles at two California composting facilities. The CIWMB study only tested active windrows.
The two studies found considerable variation in emissions, both within and among individual composting facilities. Emissions from a single composting facility can vary over time, depending on the carbon-to-nitrogen ratio of feedstocks, ambient temperature, humidity, and other variables. At the same time, differences in composting processes and practices (for example, the frequency of windrow turning) create significant variation between composting facilities.
Overall, the SCAQMD studies estimated higher VOC emission factors from composting operations than the CIWMB studies.[1] For that reason, the SCAQMD’s measured emissions factors—an average of 1.78 pounds of VOCs per wet ton of mix—is considered a reasonable worst-case estimate of VOC emissions from composting operations. This is the factor that was used in the Nursery Product Hawes Environmental Impact Report (EIR). Table 1 below shows the estimated emissions from the Hawes facility. As described above, we believe the 357 tons/year of VOC is an over estimate. Nonetheless that figure is used in the remainder of this letter. Also, as shown on Table 1, the Nursery Product Hawes Facility will result in a reduction of truck trips and an associated reduction in VOC emissions.
It is important to note, however, that responsible management practices can reduce VOC emissions from composting operations far below the level calculated using the SCAQMD’s average measured emissions factor. As noted above, VOC emissions vary significantly depending on factors such as the carbon-to-nitrogen ratio of feedstocks and the frequency of windrow turning. For example, the two facilities studied by the SCAQMD had very different VOC emissions factors: 3.1 pounds of VOCs per wet ton of mix at San Joaquin Composting and 0.53 pounds of VOCs per wet ton of mix at RECYC. This massive difference is partially attributable to the fact that San Joaquin Composting was primarily utilizing curb side green material during the emissions testing. This, in turn, led to a low carbon-to-nitrogen ratio, a high moisture content, and a decrease in oxygen levels. In addition, it appears that San Joaquin Composting was not using current Best Management Practices (BMPs) during the SCAQMD study.
Therefore, in order to accurately measure VOC emissions from composting operations, it is important to move beyond the SCAQMD’s average emissions factor. Although that factor may provide a useful worst-case scenario, we believe it does not account for significant variables that will affect emissions. To more accurately measure actual VOC emissions, we suggest that the MDAQMD account for factors such as carbon-to-nitrogen ratios, moisture content, oxygen levels, pH values, particle size/porosity, windrow structure, frequency of windrow turning and the type of green material feedstocks.
TABLE 1
Estimated Emissions from proposed Nursery Products Hawes Facility
Activity / CO (tons/year) / VOC (tons/year) / NOx (tons/year) / SOx (tons/year)Composting Emissions / 0 / 357.0* / 0 / 0
On-site Equipment Emissions / 2.92 / 0.64 / 10.35 / 1.12
Employee Commute Trips / 0.61 / 0.03 / 0.07 / 0.001
Transportation Emissions Savings / -3.7 / -25.1 / -83.8 / -1.5
Total Emissions / 0.1 / 332.6 / -72.6** / - 0.2**
* See discussion regarding realistic range of VOC emissions.
** The Nursery Products Hawes Facility will reduce NOx and SOx significantly while nearly eliminating all the CO that is currently generated by composting the material in Kern County and Arizona.
II. SOURCES OF Volatile Organic Compounds within the mojave desert air quality management district
In order to evaluate the potential for cost effective emission reductions from composting operations within the MDAQMD, it is important to look at the larger picture of VOCs and other ozone precursors—particularly NOx—within the District. Ultimately, the MDAQMD must determine the feasibility and practicability of any proposed reduction in emissions, and that necessarily entails review of all source categories, and the costs and benefits associated with imposing new regulations on each of them.
The MDAQMD 2004 ozone attainment plan states that “[t]he MDAQMD is downwind of the Los Angeles basin, and to a lesser extent, is downwind of the San Joaquin Valley. Prevailing winds transport ozone and ozone precursors from both regions into and through the Mojave Desert Air Basin during the summer ozone season. These transport couplings have been officially recognized by CARB. Local MDAQMD emissions contribute to exceedances of both the NAAQS and CAAQS for ozone, but the Mojave Desert Air Basin would be in attainment of BOTH standards without the influence of the transported air pollution from upwind regions.”18
Despite the continuing influx of ozone precursors from sources outside the MDAQMD, the District is currently on track to meet its federal ozone targets. Indeed, the MDAQMD 2004 ozone attainment plan notes that “the portion of the MDAQMD designated as a Federal ozone non-attainment area will be in attainment of the NAAQS for ozone by the required year, 2007. The entire MDAQMD will show significant progress towards attainment of the ozone CAAQS by that year.” [insert citation here]
The MDAQMD may not be able to effectively regulate sources of ozone precursors from outside the District. However, there are many sources of VOCs and NOx within the MDAQMD area. Table 2 provides a summary of estimated annual emissions of VOCs and NOx for selected sources within the District.
TABLE 2
Estimated Annual Average Emissions in District
VOC (tons/year) / NOX(tons/year) / Total Emissions of VOC & NOx
(tons/year) / Total Emission of VOC & NOx
%
MDAQMD Total* / 13,615 / 57,853 / 71,468 / 100%
Nursery Products / 332.6 (25.1 ton trucking savings) / -72.6 (83.8 ton trucking savings) / 260 / 0.4%
Victorville Composting Facility / 490.56 / Negligible / 490.56 / 0.7%
High Desert Dairies / 128.0 / Negligible / 128.0 / 0.2%
Cement Manufacturing in MDAQMD / 157.8 / 11,813.8 / 11971.6 / 16.8%
Mitsubishi Cement in MDAQMD / 17.1 / 2,2244.8 / 2261.9 / 3.2%
TXI Riverside Cement in MDAQMD / 77.4 / 4,186.0 / 4263.4 / 6.0%
PG&E in Hinkley / 70.1 / 578.7 / 648.8 / 0.9%
*Based on 2004 annual average emissions reported by MDAQMD and contained in the EIR
As shown in Table 2, the projected NOx, PM10 and SOx emissions from, Nursery Products Hawes facility fall near the bottom of the list of sources in the Mojave Desert area. The Hawes facility will actually reduce NOx in the District. Also, as shown in Table 2, the composting industry as a whole is a minor source of ozone precursor gases. For 2002, the NOx emissions in the MDAQMD for the cement manufacturing industry was 11,813.8 tons/year, electric generation industry was 1049.7 tons/year, natural gas industry was 863.4 tons/year (PG&E in Hinkley emits 70.1 tons VOC/year and 578.7 tons NOx/year), glass manufacturing industry was 578.5 tons/year, aerospace industry was 177.4 tons/year, and batch plant industry was 200.4 tons/year.
Nursery Products is not the only facility that generates VOC and other PM precursor gas emissions from composting operations in the Mojave Desert area. The SCAQMD calculated that green material composting has an emissions factor for VOC of 3.84 lb/wet ton of mix14. There is a large green material composting facility currently operating in Victorville, and we have calculated that the facility generates more VOC than the proposed Nursery Products Facility. See Table 3 for a comparison of the Victorville facility to the proposed Hawes facility.
Even in the Hinkley area, farms and associated manure probably generate greater VOC emissions than the Hawes facility will generate. While we have not performed the calculation, it is estimated that each 1,000 cattle generate 6.4 tons of VOC per year.
TABLE 3
Composting Emissions Comparison14
Permitted Tons of Mix per year / Emission Factor (lb VOC/ton mix) / VOC (tons/year)Proposed Nursery Products Facility / 400,000 / 1.78* / 357
Victorville Composting Facility / 255,500 / 3.84 / 490.56
* See discussion.
III. THE COST-effectiveness of Volatile Organic Compound EMISSION REDUCTIONS
Nursery Products supports the District’s efforts to ensure that the Mojave Desert Air Basin attains applicable ozone standards. It is important to recognize, however, that those standards can be met in a variety of different ways, some more costly than others. Therefore, in considering whether and how to restrict VOC emissions from composting operations, the District must consider both the impact and the cost of proposed regulations.
The MDAQMD’s List and Implementation Schedule for District Measures to Reduce Particulate Material, the item now being evaluated as we understand it, describes a proposed measure that would require co-composting operations to reduce VOC and ammonia emissions by 80% by either (1) enclosing their activities or (2) presenting an alternative method of compliance. We believe enclosure is unwarranted because it cannot produce cost-effective VOC emissions reductions, and it only reduces emission by about 25 percent. An alternative method of compliance can achieve 20 percent emission reductions at a percentage of the cost.
One of the biggest fallacies currently being discussed is that enclosing a composting facility eliminates 100% of VOCs. The idea can easily be dismissed by examining the impact of a San Joaquin Valley Air Pollution Control District (SJVAPCD) Rule similar to the issues now under consideration by the MDAQMD. SJVAPCD Rule 4565 requires a VOC control efficiency of at least 80% for enclosed facilities that compost over 100,000 tons per year. It also requires a VOC capture efficiency of 33%. Therefore, overall VOC reduction is only 26.4% (33% times 80%).16 Put simply, enclosure does not mean elimination of VOCs, it merely reduces them by about 26 percent.
SJVAPCD Rule 4565 also demonstrates that enclosure is not a cost-effective way to reduce VOC emissions from composting operations. Rule 4565 contains a set of Best Management Practices (BMPs), each of which is designed to reduce VOC emissions by 5%. Examples include maintaining a proper carbon to nitrogen ratio and covering compost piles with finished compost after turning. The BMPs provide an effective and economical means of reducing VOC emissions. Table 4 compares the per ton cost of emissions reductions under Rule 4565’s enclosure requirement with the per ton cost of emission reductions under Rule 4565’s BMP provisions. As shown in Table 4 the cost of VOC reductions by enclosure is about $1 million/ton whereas the cost of VOC reductions by BMP is about $42,000/ton.
Table 4
Cost of Illustrative VOC Reductions
VOCs Eliminated / New Total of VOCs/year (originally 357) / Cost toImplement / Cost Per Ton VOC Reduced
Enclosed Compost Facility per SJVAPCD Rule 4565 / 26.4% / 263 / $83 million and
$12.5 million per year for operations7 / $1,01,600.00
Open Facility with Four Best Management Practices Per Rule 4565 / 20.0% / 286 / $3 million per year for operations / $42,250.00
Table 5 demonstrates the practicability of VOC emission reduction, based upon the costs of regulating composting operations in the other air quality management districts that have reviewed composting. The SJVAPD and SCAQMD, both in areas with much worse air quality than the MDAQMD area, contain many more large composting facilities. The information in Table 5 can be found on each of the websites for the SJVAPCD and the SCAQMD. The cost per ton of VOC reduced in each air quality management district to implement their respective composting rules is shown below. The MDAQMD has traditionally considered per ton costs at these levels to be excessive and disproportionate to the emission reductions.
TABLE 5
Cost Comparison per ton of VOC Reduced
Air District / No. of co-composting Facilities > 100,000 tons per year / Low End Estimates Cost / High End Estimates CostSCAQMD / 9* / $23,798/ton VOC reduced / $27,287/ton VOC reduced
SJVAPCD / 8* / $9,796/ton VOC reduced / $41,301/ton VOC reduced
*Excludes green material composting facilities.
The cost effectiveness calculations in the SJVAPCD rule stated that a capital cost of $7,775,000 and an annual operations cost of $124,305 was necessary to meet the requirements of Rule 4565. Synagro has recently built a co-composting facility in the SJVAPCD area and it cost approximately $35,000,000 or 5 times more than what was stated in the SJVAPCD economic analysis. The Inland Empire Utilities Agency has also recently built a co-composting facility in the SCAQMD and it cost approximately $83,000,000 with $12,500,000 per year in operations costs.
In addition, the SCAQMD implemented Rule 1127 to reduce VOC and other emissions from livestock waste. The same emissions as studied by SCAQMD are emitted throughout the Mojave Desert area, including from the five dairies in Hinkley. Page 26 of the Final Staff Report of the proposed Rule 1127 shows that the cost of emission reductions associated with livestock was $6,770 per ton of VOC reduced. This demonstrates that it would be cheaper to regulate dairies to reduce VOCs than biosolid composting.