Path 15

Path 15 is the name of a major north-south power transmission corridor in California. It forms a part of the Pacific AC Intertie and the California-Oregon Transmission Project. Path 15, along with the Pacific DC Intertie running far to the east, forms an important transmission interconnection with the hydroelectric plants to the north and the fossil fuel plants to the south. Most of the three AC 500 kV lines were built by Pacific Gas and Electric (PG&E) south of Tesla substation. There are only two connecting PG&E lines north of Tracy substation that connect Path 15 to Path 66 at the Round Mountain substation. The third line between Los Banos and Gates substation, south of Tracy, is operated by the Western Area Power Administration (WAPA), a division of the United States Department of Energy. This line was constructed away from the other two lines and it's often out of sight. Most of the time the lines are in California's Sierra foothills and the Central Valley, but there are some PG&E lines that come from power plants along the shores of the Pacific Ocean and cross the California Coast Ranges and connect with the intertie. The Diablo Canyon Nuclear Power Plant and the Moss Landing Power Plant are two examples.Route descriptions and tower designs are based on Google Earth images.] ] Near Antioch the line runs parallel with the two PG&E lines. All three lines cross both the Sacramento and San Joaquin Rivers on very large pylons. The WAPA line turns away from the PG&E lines and heads for another large substation near Tracy. South of Tracy Substation, it continues as a large, dual-circuit 500 kV line that connects with the PG&E lines as they leave Tesla Substation.

Other information

;Other power lines that follow Path 15From Tesla substation to Midway substation, a set of 230 kV wires follows the main 500 kV wires. The dual-circuit 230 kV power lines run to the east of the 500 kV wires. Most of these wires were built by PG&E.

;Power transmission capacityPath 15 can transmit 2,000-3,265 MW of electrical power from north to south.The capacity for south to north power transmission is 4,800-5,400 MW.

;Parallelism of Interstate 5 (South of Tesla substation)=In the section south of Tracy, the eastern two wires form an infrastructure corridor along with an aqueduct and Interstate 5 and provide some artificial scenery to look at, especially when they do not run in the hills west of Interstate 5. The eastern parallel PG&E lines cross Interstate 5 twice.

;Environmental impactsThe northern part of this electrical transmission corridor (including Path 66) is visible from space and Google Earth as lines of bare, treeless ground. This is because the power lines here run through forests of conifer trees which appear dark green-green from space. The utility companies here have logged and sometimes clear-cut the land to create a right-of-way for the power lines due to the fact that a wildfire could start when an electrical arc and/or discharge occurs between the wires and a tree if they come close enough to each other. [Cite web|title=Trees and Power Lines|url=http://www.wapa.gov/newsroom/pdf/treesandpowerlines.pdf|publisher=Western Area Power Administration|accessdate=2007-09-20]

Differences in tower design

Like Western Area Power Administration's 500 kV line, the tower design for the entire transmission system is not the same, although the difference is not as dramatic as on the WAPA line. For the PG&E line, the differences are subtle and from a casual, far away view, it looks like the towers are all the same for the entire power line. It seems to be south of the Table Mountain substation, the tower legs spread apart from the tower bridge (upper section of tower) down to the tower base and there are four guy wires for tower stability. In contrast, the towers to the north of Table Mountain have thinner legs and look like thin sticks from far away. The weaker tower legs have two additional guy wires for stability. As for the tower bridge, the towers south of Table Mountain have five X's in between the tower legs. The towers north of Table Mountain have only four X's. In addition, the tower arms on either side of the towers have smaller steel bars inside for added strength. In the northern towers, they are positioned like equilateral triangles, but south of Table Mountain, they are shaped like right triangles. See below for a visual comparison.;Visual reference

History

This entire project was built in the 1970's and 1980's in order to provide California and the Southwest with excess hydropower from the Pacific Northwest without actually having to construct any new power plants. Usually during the cold Pacific Northwest winters, power is sent north due to heater use. In the summer, that is the reverse, with hot, dry summers in California; many people will run air conditioners at these times. [Cite web|title=Pacic Intertie:The California Connection on the Electron Superhighway|url=http://www.nwcouncil.org/LIBRARY/2001/2001-11.pdf|publisher=Northwest Power Planning Concil|accessdate=2007-09-20] In order to do this the maximum south-to-north transmission capacity is 5,400 MW for most parts, but between Los Banos substation and Gates substation, there were only two 500 kV lines. The capacity at this electricity bottleneck was only 3,900 MW, and this was identified in the 1990s as a trouble spot, but no one acted upon it.Cite web|title=Path 15 Upgrade Project|url=http://www.wapa.gov/sn/ops/transmission/path15/factSheet.pdf|publisher=Western Area Power Administration|accessdate=2007-09-20] This was one of the leading causes of the California electricity crisis in 2000-01. To remedy this problem, WAPA along with several utilities built a third 500 kV line between these two substations to eliminate this transmission constraint and raise the maximum south-to-north transmission capacity to 5,400 MW. The project was completed under budget and on time in December 21,2004.Cite web|title=Administrator joins Gov. Schwarzenegger to commission Path 15|url=http://www.wapa.gov/newsroom/cct/2005/jan14/27no12.htm|publisher=Western Area Power Administration|accessdate=2007-09-20] California's governor, Arnold Schwarzenegger attended the commissioning ceremony at California-ISO's control center in Folsom.

Additional pictures

Maps

ee also

*California-Oregon Transmission Project
*Pacific AC Intertie

References

External links

* [http://www.westcoastroads.com/california/i-005ni_ca.html Interstate 5 Pictures of Path 15]
* More pictures of Path 15 from West Coast Roads [http://www.westcoastroads.com/california/images005/i-005_nb_exit_337_02.jpghere] , [http://www.westcoastroads.com/california/i-005sn_ca.html here] , and [http://www.westcoastroads.com/california/i-005sl_ca.html here] .
* [http://www.wapa.gov/sn/ops/transmission/path15/ Path 15 upgrade project at Wapa.gov]