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Marine Hydrocarbon Seep Capture

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

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Marine Hydrocarbon Seep Capture

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  1. Donald Bren School of Environmental Science & Management Marine Hydrocarbon Seep Capture Feasibility and Potential Impacts Santa Barbara, California

  2. What are “Seeps?”

  3. Seep Environmentbiogeochemistry & 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

  4. 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 + NOXhv O3

  5. Significance • Capturing natural seep hydrocarbons might reduce local air pollution • Recent CA energy crisis renewed interest in capturing this seepage as a potential “green” source of natural gas

  6. Seep Tents? Source: http://seeps.geol.ucsb.edu/

  7. 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

  8. Seep Flux Varies in Space & Time

  9. 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)

  10. Environmental Impact ozone production • Magnitude of seep contribution to ozone formation varies depending on: • Climate • Levels of ROGs & NOx

  11. Environmental Impact ozone production model • Relates seep gas emissions to ozone formation (reactivity) • Estimates the change in ozone associated with seep gas capture

  12. Seep Gas Composition & Contribution to Ozone Production Volume (%)

  13. 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

  14. Regulatory Requirements processing facility Current 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

  15. Regulatory Requirements emission reduction credits • Credit worth $4,000/ton ROGs reduced • Unlikely for 2 reasons: • Difficult to prove tents would permanently reduce ROGs • Seeps are natural source of ROGs • Credits for seep tents would be an exception

  16. 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

  17. 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)

  18. Cost-Benefit Analysis project costs Project costs: • Capital & design • Piping • Maintenance

  19. 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

  20. Cost-Benefit Analysis Model most likely scenario

  21. Cost-Benefit Analysis Model most likely scenario

  22. Cost-Benefit Analysis Model scenarios Profit =Gas Sales Revenue- Costs+ Credits Social Value = Gas Sales Revenue - Costs + Health Benefit

  23. Cost-Benefit Analysis Results Under likely project conditions, installing new seep tents NOT practical from social or entrepreneurial viewpoint

  24. 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

  25. Recommendations policy • Verify precise amount of ozone reduced by seep tents • Revise permit and credit conditions • Institute a socially responsible value for credits • Compare cost effectiveness

  26. Acknowledgements • Advisors: Christopher Costello and Natalie Mahowald • Mel Willis (Ph.D. student advisor) • Peter Cantle (SBCAPCD) • Bruce Luyendyk, Jordan Clark, Libe Washburn, James Boles(UCSB Hydrocarbon Seeps Research Group) • Tom Murphy, Doug Allard, Patricia Holden, Mike Edwards, Steve Sterner, Michelle Pasini, Jim Fredrickson, Sally Holbrook

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