skip to main content
DOE PAGES title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Modeling magnetic fields from a DC power cable buried beneath San Francisco Bay based on empirical measurements

Abstract

Here, the Trans Bay Cable (TBC) is a ±200-kilovolt (kV), 400 MW 85-km long High Voltage Direct Current (DC) buried transmission line linking Pittsburg, CA with San Francisco, CA (SF) beneath the San Francisco Estuary. The TBC runs parallel to the migratory route of various marine species, including green sturgeon, Chinook salmon, and steelhead trout. In July and August 2014, an extensive series of magnetic field measurements were taken using a pair of submerged Geometrics magnetometers towed behind a survey vessel in four locations in the San Francisco estuary along profiles that cross the cable’s path; these included the San Francisco-Oakland Bay Bridge (BB), the Richmond-San Rafael Bridge (RSR), the Benicia- Martinez Bridge (Ben) and an area in San Pablo Bay (SP) in which a bridge is not present. In this paper, we apply basic formulas that ideally describe the magnetic field from a DC cable summed vectorially with the background geomagnetic field (in the absence of other sources that would perturb the ambient field) to derive characteristics of the cable that are otherwise not immediately observable. Magnetic field profiles from measurements taken along 170 survey lines were inspected visually for evidence of a distinct pattern representing the presence ofmore » the cable. Many profiles were dominated by field distortions unrelated to the cable caused by bridge structures or other submerged objects, and the cable’s contribution to the field was not detectable. BB, with 40 of the survey lines, did not yield usable data for these reasons. The unrelated anomalies could be up to 100 times greater than those from the cable. In total, discernible magnetic field profiles measured from 76 survey lines were regressed against the equations, representing eight days of measurement. The modeled field anomalies due to the cable (the difference between the maximum and minimum field along the survey line at the cable crossing) were virtually identical to the measured values. The modeling yielded a pooled cable depth below the bay floor of 2.06 m (±1.46 std dev), and estimated the angle to the horizontal of the imaginary line connecting the crosssectional center of the cable’s two conductors (0.1143 m apart) as 178.9° ±61.9° (std dev) for Ben, 78.6°±37.0° (std dev) for RSR, and 139.9°±27.4° (std dev) for SP. The mean of the eight daily average currents derived from the regressions was 986 ±185 amperes (A) (std dev), as compared to 722 ±95 A (std dev) provided by Trans Bay Cable LLC. Overall, the regressions based on fundamental principles (Biot Savart law) and the vectorial summation of cable and geomagnetic fields provide estimates of cable characteristics consistent with plausible expectations.« less

Authors:
 [1];  [2];  [2];  [3]
  1. Electrical Power Research Institute, Palo Alto, CA (United States)
  2. Univ. of California, Davis, CA (United States)
  3. Univ. Miguel, Hernandez de Elche (Spain)
Publication Date:
Research Org.:
Electric Power Research Institute, Palo Alto, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1252958
Grant/Contract Number:  
EE0006382
Resource Type:
Accepted Manuscript
Journal Name:
PLoS ONE
Additional Journal Information:
Journal Volume: 11; Journal Issue: 2; Journal ID: ISSN 1932-6203
Publisher:
Public Library of Science
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; 59 BASIC BIOLOGICAL SCIENCES; magnetic fields; magnetometers; surveys; geomagnetism; animal migration; marine fish; sturgeons; trout

Citation Formats

Kavet, Robert, Wyman, Megan T., Klimley, A. Peter, and Carretero, Luis. Modeling magnetic fields from a DC power cable buried beneath San Francisco Bay based on empirical measurements. United States: N. p., 2016. Web. doi:10.1371/journal.pone.0148543.
Kavet, Robert, Wyman, Megan T., Klimley, A. Peter, & Carretero, Luis. Modeling magnetic fields from a DC power cable buried beneath San Francisco Bay based on empirical measurements. United States. doi:10.1371/journal.pone.0148543.
Kavet, Robert, Wyman, Megan T., Klimley, A. Peter, and Carretero, Luis. Thu . "Modeling magnetic fields from a DC power cable buried beneath San Francisco Bay based on empirical measurements". United States. doi:10.1371/journal.pone.0148543. https://www.osti.gov/servlets/purl/1252958.
@article{osti_1252958,
title = {Modeling magnetic fields from a DC power cable buried beneath San Francisco Bay based on empirical measurements},
author = {Kavet, Robert and Wyman, Megan T. and Klimley, A. Peter and Carretero, Luis},
abstractNote = {Here, the Trans Bay Cable (TBC) is a ±200-kilovolt (kV), 400 MW 85-km long High Voltage Direct Current (DC) buried transmission line linking Pittsburg, CA with San Francisco, CA (SF) beneath the San Francisco Estuary. The TBC runs parallel to the migratory route of various marine species, including green sturgeon, Chinook salmon, and steelhead trout. In July and August 2014, an extensive series of magnetic field measurements were taken using a pair of submerged Geometrics magnetometers towed behind a survey vessel in four locations in the San Francisco estuary along profiles that cross the cable’s path; these included the San Francisco-Oakland Bay Bridge (BB), the Richmond-San Rafael Bridge (RSR), the Benicia- Martinez Bridge (Ben) and an area in San Pablo Bay (SP) in which a bridge is not present. In this paper, we apply basic formulas that ideally describe the magnetic field from a DC cable summed vectorially with the background geomagnetic field (in the absence of other sources that would perturb the ambient field) to derive characteristics of the cable that are otherwise not immediately observable. Magnetic field profiles from measurements taken along 170 survey lines were inspected visually for evidence of a distinct pattern representing the presence of the cable. Many profiles were dominated by field distortions unrelated to the cable caused by bridge structures or other submerged objects, and the cable’s contribution to the field was not detectable. BB, with 40 of the survey lines, did not yield usable data for these reasons. The unrelated anomalies could be up to 100 times greater than those from the cable. In total, discernible magnetic field profiles measured from 76 survey lines were regressed against the equations, representing eight days of measurement. The modeled field anomalies due to the cable (the difference between the maximum and minimum field along the survey line at the cable crossing) were virtually identical to the measured values. The modeling yielded a pooled cable depth below the bay floor of 2.06 m (±1.46 std dev), and estimated the angle to the horizontal of the imaginary line connecting the crosssectional center of the cable’s two conductors (0.1143 m apart) as 178.9° ±61.9° (std dev) for Ben, 78.6°±37.0° (std dev) for RSR, and 139.9°±27.4° (std dev) for SP. The mean of the eight daily average currents derived from the regressions was 986 ±185 amperes (A) (std dev), as compared to 722 ±95 A (std dev) provided by Trans Bay Cable LLC. Overall, the regressions based on fundamental principles (Biot Savart law) and the vectorial summation of cable and geomagnetic fields provide estimates of cable characteristics consistent with plausible expectations.},
doi = {10.1371/journal.pone.0148543},
journal = {PLoS ONE},
number = 2,
volume = 11,
place = {United States},
year = {2016},
month = {2}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record

Citation Metrics:
Cited by: 1 work
Citation information provided by
Web of Science

Save / Share:

Works referenced in this record:

Migration of green sturgeon, Acipenser medirostris, in the Sacramento River
journal, November 2008

  • Heublein, Joseph C.; Kelly, John T.; Crocker, Carlos E.
  • Environmental Biology of Fishes, Vol. 84, Issue 3
  • DOI: 10.1007/s10641-008-9432-9

Stranding of Spawning Run Green Sturgeon in the Sacramento River: Post-Rescue Movements and Potential Population-Level Effects
journal, April 2013

  • Thomas, Michael J.; Peterson, Matthew L.; Friedenberg, Nick
  • North American Journal of Fisheries Management, Vol. 33, Issue 2
  • DOI: 10.1080/02755947.2012.758201

Movements of out-migrating late-fall run Chinook salmon (Oncorhynchus tshawytscha) smolts through the San Francisco Bay Estuary
journal, October 2013

  • Hearn, Alex R.; Chapman, Eric D.; Singer, Gabriel P.
  • Environmental Biology of Fishes, Vol. 97, Issue 8
  • DOI: 10.1007/s10641-013-0184-9

The effects of environmental factors on the migratory movement patterns of Sacramento River yearling late-fall run Chinook salmon (Oncorhynchus tshawytscha)
journal, April 2012

  • Michel, Cyril J.; Ammann, Arnold J.; Chapman, Eric D.
  • Environmental Biology of Fishes, Vol. 96, Issue 2-3
  • DOI: 10.1007/s10641-012-9990-8

Diel movements of out-migrating Chinook salmon (Oncorhynchus tshawytscha) and steelhead trout (Oncorhynchus mykiss) smolts in the Sacramento/San Joaquin watershed
journal, March 2012

  • Chapman, Eric D.; Hearn, Alex R.; Michel, Cyril J.
  • Environmental Biology of Fishes, Vol. 96, Issue 2-3
  • DOI: 10.1007/s10641-012-0001-x

Magnetic Discrimination Learning in Rainbow Trout ( Oncorhynchus mykiss )
journal, January 1998


The use of celestial and magnetic cues by orienting sockeye salmon smolts
journal, January 1982

  • Quinn, Thomas P.; Brannon, Ernest L.
  • Journal of Comparative Physiology ? A, Vol. 147, Issue 4
  • DOI: 10.1007/BF00612020

Orientation of Chum Salmon ( Oncorhynchus keta ) After Internal and External Magnetic Field Alteration
journal, October 1983

  • Quinn, T. P.; Groot, C.
  • Canadian Journal of Fisheries and Aquatic Sciences, Vol. 40, Issue 10
  • DOI: 10.1139/f83-185

Ampullary electroreceptors in the sturgeonScaphirhynchus platorynchus (rafinesque)
journal, January 1980

  • Teeter, J. H.; Szamier, R. B.; Bennett, M. V. L.
  • Journal of Comparative Physiology ? A, Vol. 138, Issue 3
  • DOI: 10.1007/BF00657039