Complex Solid Waste Air Permitting Issues

Transcription

1 Complex Solid Waste Air Permitting Issues A Threat to Landfill Gas as an Alternative Fuel Source Heather H. Little Sanborn, Head and Associates, Inc. John Gay, E.I. Casella Waste Systems, Inc.

2 NEWSVT Landfill Coventry, VT

3 Landfill Gas (LFG) Formed through the decomposition of organic matter in landfills Contains ~50% Methane (CH 4 ) Global Warming Potential = 25 Therefore, LFG is captured and combusted to help reduce odors and emissions through installation of a gas collection and control system (GCCS).

4 NEWSVT LFGTE Facility Enclosed Flare -Siloxane Removal System Five Caterpillar G3520C Engines Two Open Flares

5 The Beginning Title V Operating Permit Renewal (one facility, one permit) Increase Cat3520C Engine CO limits Evaluate PM limits Allow for voluntary installation of siloxane removal system prior to LFG combustion in engines

6 Typical Air Quality Concerns Combustion by-products Carbon Monoxide (CO) Nitrous Oxides (NO x ) Sulfur Dioxide (SO 2 ) Particulate Matter Hazardous Air Pollutants or Contaminants (HACs)

7 Project Specific Air Quality Concerns 1. 1-hr NAAQS: SO 2, NO 2 2. CO emissions increases resulting from siloxane fouling of LFG-to-energy engines: MSER required 3. PM significance threshold 4. HACs: Formaldehyde and Silica 5. VOC offsets

8 Air Quality Concern # hr NAAQS: SO 2, NO 2 Air dispersion modeling demonstrated potential exceedances Resulted in requirement to raise engine stack heights by 5 ft. Need to keep stacks out of fly zone (property abutter is airport) raising stacks requires FAA involvement

9 Air Quality Concern #2 2. CO emissions increases Bay Area Air Quality Management District White Paper, February 26, 2009

10 Air Quality Concern #2 (cont ) 2. CO emissions increases Need for tiered CO emissions limits from engines: 2.75 g/bhp-hr every 6 years 3.1 g/bhp-hr annually 3.5 g/bhp-hr at all times Oxidation catalyts on engines may be required upon 5-yr Title V Renewal.

11 Engine Cylinder Wear

12 What Are Siloxanes? Volatile Organic Compounds (VOCs) that contain silicon (Si) Not regulated by USEPA Non toxic - Not known as a health hazard Oxidized during combustion to form silicon dioxide (SiO2) a.k.a. silica or sand (particulate matter and a HAC!!)

13 Where Do Siloxanes Come From? Household products, cosmetics create overall smoothing/softening effect Plastics, adhesives, lubrications Synthetic food products chips, salad dressing Volatilize through evaporation warm temperatures and negative pressure differential in landfill

14 Manufacturer Siloxane Limits Manufacturer Warranty Limit for Siloxanes (mg /m 3 ) Caterpillar 28 Jenbacher 10 Waukesha 25 Deutz 5

15 Siloxane Treatment Cost Example 3,000 scfm LFG with 10 ppmv siloxanes Direct Capital Costs: $1.1 MM Total Capital Investment: $1.7 MM Total Annual Cost: $0.5 MM Payback: ~3 years

16 Air Quality Concern #3 3. PM significance threshold of 10 tpy PM emissions increase > 10 tpy would require MSER analysis. MSER = siloxane treatment. Owner wants siloxane treatment to be voluntary Therefore, accept PM emissions increase <10 tpy

17 Air Quality Concern #4 4. HACs: Formaldehyde and Silica (SiO 2 ) Formaldehyde = Product of incomplete combustion of hydrocarbons in IC engines SiO 2 (PM) Emissions from Siloxane Removal System = Product of oxidation of siloxanes during combustion.

18 Formaldehyde Ubiquitous in outdoor and indoor air Atmospheric sources include: Fuel combustion Building materials Chemical formation

19 Formaldehyde and Siloxanes Emissions can be reduced by good combustion and post-combustion catalytic oxidation Siloxanes can increase formaldehyde emissions due to SiO 2 deposits that: Coat engine cylinders and reduce combustion efficiency Render post-combustion catalysts ineffective

20 Air Quality Concern #4 (cont ) 4. HACs: Formaldehyde and Silica (SiO 2 ) Both HACs > 8-hr Action Level HMSER for formaldehyde = MSER for CO HMSER for SiO 2 established as facility wide PM emission limit. Costly HMSER Alternatives (e.g. oxidation catalysts on engines and controls on exhaust from SRS) may be required upon 5-yr Title V renewal!

21 Air Quality Concern #5 5. VOC offsets Formaldehyde = a VOC (not just a HAC!) Facility-wide VOC limit (50 tpy) imposed to avoid the requirement for VOC offsets

22 Permit Process Results 2 year process Source Control 1 permit versus 2 permits Two Permits Issued Title V Operating Permit to Landfill Owner Title V Operating Permit to LFGTE Owner

23 Permit Process Results Additional stack testing required Additional sampling required Separate Startup, Shutdown, and Malfunction (SSM) plans Compliance reporting under 2 separate permits Higher annual emission fees (~$30,000/yr additional)

24 Conclusions Air regulatory costs to generate electricity from LFG are increasing: Permitting Compliance Operations For some smaller LFGTE projects, the costs are prohibitive, and sites continue to flare the collected LFG.

25 Conclusions Increasing Costs $ Air Permitting $ Capital investments for controls $ Annual Air Emissions Fees $ Operations $ Compliance (monitoring, reporting, stack testing, LFG sampling) Regulatory climate may limit the beneficial use of LFG as alternative fuel source

26 Thank you! Contact Information Heather H. Little Sanborn, Head and Associates, Inc John Gay, E.I. Casella Waste Systems, Inc

27 What Are Siloxanes? Decamethylcyclopentasiloxane, or D5, a cyclic siloxane Hexamethyldisiloxane, or L2, a linear siloxane.

28 Siloxane Treatment Technologies Refrigeration condense out siloxanes Low removal efficiency < 50% Higher efficiencies may be possible with advanced refrigeration

29 Siloxane Treatment Technologies Activated Carbon adsorbs siloxanes Large vessels, not feasible to regenerate on site, frequent media change-out and disposal Image from:

30 Siloxane Treatment Technologies Regenerative Adsorption >95% removal efficiency, smaller vessels, low change-out frequency Image from:

31 Example of a Regenerative Adsorption System Coalescing pre-filtration Remove liquid aerosols and solid particulate from the raw LFG Regenerative siloxane adsorption Typically two or more vessels with non-carbon adsorptive media in the form of loose beads Particulate after filtration Removal of dry particulate via filtration

32 Temperature Swing Adsorption Media is regenerated using heated ambient air provided by blower with electric heater LFG stream is directed through one vessel while the other is isolated and regenerated Collected siloxanes are exhausted to a flare