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Compost Air Emissions
Association of Compost Producers
Dec. 2, 2010
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This Presentation
1. CalRecycle commitment to composting
2. Past CalRecycle emissions studies3. Current CalRecycle emissions studies4. Compost and climate change5. Title 1, Title 5 and fugitive emissions
The HierarchyCA Public Resources Code Section
40051State and local government SHALL
promote the following waste management practices in order of priority:
(1)Source reduction. (2)Recycling and composting.(3)Environmentally safe transformation and
environmentally safe land disposal…
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Massive investment
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Public
PrivatePrivate
CIWMB Strategic Directive 6.1
Reduce organics sent to the landfill by 50% by 2020
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Compostable organics
Everything else
Materialsstill going to California landfills
CalRecycle proactive efforts
• 20 years of support for composting
• Fund basic research on compost use and compost emissions
• Work with stakeholders to determine reasonable best management practices
• Work with other regulators to foster efficient, effective rulemaking
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Studying Compost Emissions
2002 CIWMB StudyTierra Verde Industries, Irvine, CA
High C:N windrow (67:1) emitted 63% less VOC than low C:N ratio windrow (22:1)
Turned windrows emitted more VOC than static windrows, but matured faster
Ammonia not a concern in green waste compost operations
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2006 CIWMB StudyCity of Modesto Compost Facility
Measure life-cycle (60 days) VOC emissions for greenwaste and food waste windrows
Test efficacy of two potential emissions-reducing practices (BMPs)– Additives: one feeds microbes; other forms
crust on windrow (Cost: $1.50 per ton)– Pseudo-biofilter: Cover “active” windrows with
a layer of finished compost (60 cents per ton)
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Putting on the “pseudo-biofilter” compost cap
Windrows as seen from above
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Modesto study conclusions 70-80% of VOCs emitted during first two weeks of
composting 70-85% of VOC emissions vent through top of windrows as
opposed to middle or sides “Pseudo-biofilter” compost cap reduced VOC emissions up
to 75% for first two weeks. Additives reduced VOC emissions 42% for first week; 14%
for first two weeks. Greenwaste emissions factor @ 1 lb/ton 15% food waste roughly doubled emissions
Wide range ofgreenwaste emissions
factors
12 Pounds of VOC per ton feedstock
Food waste likely toincrease emissions?
13 Pounds of VOC per ton feedstock
2009-10 CalRecycle-led study
4 Locations in the San Joaquin Valley Not all VOCs make ozone; reactivity
strongly impacts ozone formation Focus on types of VOC and ozone
formation, instead of how much total VOC Compost emissions mostly alcohols, very
weak ozone formation in all samples 3-week old windrows slightly more
potent than young windrows Compost cap made of “overs” reduces
ozone formation14
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Overall reactivity very low
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Comparative reactivity of different VOC sources
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Compost & Climate change Organics in landfills release methane Methane (CH4): GHG Factor 21 Synthetic N fertilizers used in farming
made from fossil fuels, release N2O Compost piles also release methane
and probably release N2O Nitrous oxide (N20): GHG Factor 296 ARB analysis shows very slight GHG
benefit for composting
CalRecycle GHG Study
$450,000 contract with UC Davis Study plan finalized November,
2010 Will study CH4 & N2O from piles Are there ways to reduce GHG
emissions? Will study impacts of compost use
in ag lands, both alone and in conjunction with synthetic N use
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Increasing compost use…
…may decrease use of less sustainable methods.
The BackstoryVery low thresholds in bad-air basins
for federal “major source” polluter status
San Joaquin Valley APCD saying all new compost facilities will go through Title 1 New Source Review
Will composters be subject to Title 5 permitting too?
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What is Title I? Authorized by federal Clean Air Act Known as “New Source Review” Applies to new or modified facility with an
increase in 2 lbs. per day of pollutants Requires facility to adopt “best available
control technology” (BACT) Even after BACT, facilities must purchase
offsets for all emissions over threshold VOC offsets run up to $40,000 per ton in
SJV; many owned by oil companies
What is Title V? Federal permit program, authorized
by Clean Air Act, implemented by local air pollution control districts
Monitoring, record-keeping and reporting requirements
Fees to apply for, review & revise permit, and also for annual renewal
USEPA can inspect, issue fines Opportunities for public input
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Title V Permits are the same permits used for oil refineries, chemical factories, etc.
Fugitive emissions? Fugitive emissions cannot
“reasonably” be passed through a “stack, chimney, vent or functionally equivalent opening”
Fugitive emissions generally do NOT count toward a facility’sTitle I or Title V emissions threshold
USEPA guidance, but no case law CalRecycle position: compost pile
emissions ARE fugitive.26
