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Donald Bren School of Environmental Science & Management. Marine Hydrocarbon Seep Capture. Feasibility and Potential Impacts Santa Barbara, California. What are “Seeps?”. Seep Environment biogeochemistry & ecology. Seeps release between 80,000 to 200,000 m 3 of gas per day - PowerPoint PPT Presentation
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Marine Marine Hydrocarbon Hydrocarbon Seep CaptureSeep Capture
Feasibility and Potential Feasibility and Potential Impacts Santa Barbara, Impacts Santa Barbara,
CaliforniaCalifornia
Donald Bren School of Environmental Science & Management
What are “Seeps?”
Seep Environment biogeochemistry &
ecology
• Seeps release between 80,000 to 200,000 m3 of gas per day– Mostly methane with trace amounts
of toxics– Most toxics and hydrocarbons
disperse and/or biodegrade
• Bacteria metabolize seep hydrocarbons
Seep Environmentair quality
• Primary component is methane– Contributes to global warming
• Seep gas contains reactive organic gases (ROGs)
• Ozone (O3) is a serious health concern
ROG + NOX hv O3
Significance
1. Capturing natural seep hydrocarbons might reduce local air pollution
2. Recent CA energy crisis renewed interest in capturing this seepage as a potential “green” source of natural gas
Seep Tents?
Source: http://seeps.geol.ucsb.edu/
Research Approach
• Interdisciplinary approach to evaluate a potential seep tent project’s– Impacts on water quality and
marine ecology – Effects on air quality– Regulatory obstacles and
requirements– Economic costs and benefits
Seep Flux Varies in Space & Time
0 5 10 15 200
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5x 10
4
Number of Tents
Flu
x C
aptu
re (M
CF p
er y
ear)
Environmental Impact marine
impacts
• Impacts on soft bottom sediments– Recovery from disturbance is quick
• Tent installation– Short-term: One-time impacts to
seafloor communities– Long-term: Undetectable impacts
• Pipeline– Short/Long-term: Possible ecosystem
level impacts if piping is not placed sufficiently far from critical habitats (kelp beds)
• Magnitude of seep contribution to ozone formation varies depending on: – Climate
– Levels of ROGs & NOx
Environmental Impact ozone
production
ROG + NOX hv O3ROG + NOX hv O3
Relative amounts of ROGs and NOx:
NOx
NOx
Limited by:Ozone production
model output:
ROG
NOx
NOx ROG
ROG
ROG
ROG NOx NOx & ROG
100%
0
50%
Atmospheric Regime:
ROG-limited
NOx-limited
Co-limited
Environmental Impact ozone production
model
• Relates seep gas emissions to ozone formation (reactivity)
• Estimates the change in ozone associated with seep gas capture
Relative amounts of ROGs and NOx:
NOx
NOx
Limited by:Ozone production
model output:
ROG
NOx
NOx ROG
ROG
ROG
ROG NOx NOx & ROG
100%
0
50%
Atmospheric Regime:
ROG-limited
NOx-limited
Co-limited
Seep Gas Composition & Contribution to Ozone
Production
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
Rea
ctiv
ity (m
ol O
3/m
ol C
)
0102030405060708090100
Reactivity Volume
Vo
lum
e (%)
Environmental Impact ozone production
model
• Estimates the change in ozone associated with seep gas capture
• Results– Seeps account for 5.1% of SB ozone– 1st seep tent reduces 0.8 to 0.4% of
County ozone annually
Regulatory Requirements processing
facilityCurrent regulatory obstacles limit development
or use of onshore gas processing facility
– Measure A96 requires county voter approval of onshore infrastructure for offshore projects
– Coastal Act: new facilities not developed unless existing facilities used at maximum capacity
– Existing facility: Ellwood Oil and Gas Processing Facility currently under-utilized, but designated as non-conforming land use
Regulatory Requirements emission reduction
credits • Credit worth $4,000/ton ROGs
reduced
• Unlikely for 2 reasons: 1. Difficult to prove tents would
permanently reduce ROGs 2. Seeps are natural source of
ROGs– Credits for seep tents would be an
exception
Cost-Benefit Analysis approach
• Compare costs of seep tents to gas sales revenue and health benefits
• Integrated model:– Gas price forecast– Project cost estimates– Ozone reduction
Health benefit or emission reduction credits
Profit = Gas Sales Revenue - Costs + Credits Social Value = Gas Sales Revenue - Costs + Health Benefit Profit = Gas Sales Revenue - Costs + Credits Social Value = Gas Sales Revenue - Costs + Health Benefit
Cost-Benefit Analysis natural gas price
forecast • Predict natural gas prices to determine
project revenues– Best forecast is $2.45 per 1000 cubic feet (MCF)
Natural Gas Price Forecast (Average Annual)
0
2
4
6
8
10
12
1989 1994 1999 2004 2009 2014 2019 2024
Year
Gas
Pri
ce (
$/M
CF
) Historical City Gate PriceHigh ARIMAConservative ARIMAStructuralHotelling
Natural Gas Price Forecast (Average Annual)
0
2
4
6
8
10
12
1989 1994 1999 2004 2009 2014 2019 2024
Year
Gas
Pri
ce (
$/M
CF
) Historical City Gate PriceHigh ARIMAConservative ARIMAStructuralHotelling
Cost-Benefit Analysis project costs
Project costs: – Capital &
design– Piping– Maintenanc
e
Cost-Benefit Analysis health benefit
valuation • Monetary value of improved health
from ozone reduction• Benefits-transfer approach• Best estimate = $2.1 million • Large effect on project decision
– Uncertainty in ozone reduction amount, health improvement, valuation theory
Cost-Benefit Analysis Model most likely
scenario
Input Parameter Value Source
Gas Sales Scenario Conservative ($2.45/MCF) ARIMA Time Series Model
Health Benefit Scenario Intermediate Benefits-Transfer Approach
Air Regime (NOx or ROG limited) Co-limited (NOx-ROG) Ozone Production Model
Emission Reduction Credits No SBAPCD Judgment
Input Parameter Value Source
Gas Sales Scenario Conservative ($2.45/MCF) ARIMA Time Series Model
Health Benefit Scenario Intermediate Benefits-Transfer Approach
Air Regime (NOx or ROG limited) Co-limited (NOx-ROG) Ozone Production Model
Emission Reduction Credits No SBAPCD Judgment
Cost-Benefit Analysis Model most likely
scenario Most Likely Project Scenario
$40
$30
$20
$10
$0
$10
0 5 10 15 20
Number of Tents
Mill
ion
s o
f D
olla
rs
Total Project ValueProject ProfitHealth Benefits
Most Likely Project Scenario
$40
$30
$20
$10
$0
$10
0 5 10 15 20
Number of Tents
Mill
ion
s o
f D
olla
rs
Total Project ValueProject ProfitHealth Benefits
Cost-Benefit Analysis Model
scenarios Description Optimal Tents
Revenues - Costs
Credits Project Profit
Health Benefit
Social Value
High Gas Pricing
Private & Social
1 $0.1 $0 $0.1 $2.1 $2.2
Private 0 - - - - - High Health Benefits Social 2 -$7.5 $0 -$7.5 $20 $12.5
Private 3 -$9.8 $40 $30 $2.6 -$7.2 Emission Reduction
Credits Social 0 - - - - -
Profit = Gas Sales Revenue - Costs + Credits Social Value = Gas Sales Revenue - Costs + Health Benefit Profit = Gas Sales Revenue - Costs + Credits Social Value = Gas Sales Revenue - Costs + Health Benefit
Cost-Benefit Analysis Results
Under likely project conditions, installing new seep tents NOT
practical from social or entrepreneurial viewpoint
Recommendations further
research
• More precise and complete research into – Chemistry of the Santa Barbara airshed– Marine ecology of the seep field
• Use of Santa Barbara County hospital data to derive the exact relationship between illness and ozone
Recommendations policy
1.Verify precise amount of ozone reduced by seep tents
2.Revise permit and credit conditions
3.Institute a socially responsible value for credits
4.Compare cost effectiveness
Acknowledgements• Advisors: Christopher Costello and Natalie Advisors: Christopher Costello and Natalie
MahowaldMahowald
• Mel Willis Mel Willis (Ph.D. student advisor)(Ph.D. student advisor)
• Peter Cantle Peter Cantle (SBCAPCD)(SBCAPCD)
• Bruce Luyendyk, Jordan Clark, Libe Bruce Luyendyk, Jordan Clark, Libe Washburn, James BolesWashburn, James Boles (UCSB Hydrocarbon (UCSB Hydrocarbon Seeps Research Group)Seeps Research Group)
• Tom Murphy, Doug Allard, Patricia Tom Murphy, Doug Allard, Patricia Holden, Mike Edwards, Steve Sterner, Holden, Mike Edwards, Steve Sterner, Michelle Pasini, Jim Fredrickson, Sally Michelle Pasini, Jim Fredrickson, Sally HolbrookHolbrook