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