Path 66
California Oregon Intertie (COI), identified as Path 66 by Western Electricity Coordinating Council (WECC), is a corridor of three roughly parallel 500 kV alternating current power lines connecting the electric grids of Oregon and California. Their combined power transmission capacity is 4800 MW.[1]
Two of the power lines run from
Route
Path 66 is composed of one segment of TANC, PG&E and PacifiCorp 500 kV lines. The TANC line route starts at Captain Jack Substation (42° 4' 38.06"N 121° 23' 25.47"W) close to Malin, close to the California-Oregon border, near the Malin Substation, where the other 500 kV lines start (owned by PacifiCorp and PG&E). These substations link to both the
- Path 66 - Captain Jack to Olinda
Path 66 consists of the northernmost segment of TANC's 346 mi (557 km) 500 kV line from Captain Jack substation to Tracy substation in California's
- Connecting wires to Path 15 - Olinda to Tracy
From Olinda Substation, the TANC 500 kV continues as a
The line crosses the two separated PG&E 500-kV lines, near Woodland and Rio Vista. Near Antioch the line turns and runs parallel with the two PG&E 500 kV lines. All three lines cross both the Sacramento and San Joaquin Rivers on very large pylons. The TANC line turns away from the PG&E lines and heads for another large substation near Tracy.[3]
- Connecting wires to Path 15 - Tracy to intersection with PG&E wire
From Tracy Substation, the line again to a rare, tall,
- Path 66 - Malin to Round Mountain
The other two 500 kV lines start in the Malin substation to the east of the Captain Jack substation. One circuit of a rare,[citation needed] tall BPA dual-circuit and one single-circuit 500 kV line connect Captain Jack substation with Malin substation. The PG&E and PacifiCorp 500 kV line both head south together across the Modoc Plateau, generally following the lone WAPA line at a distance. The parallel lines then turn southwestward climb to about 5,400 feet (1,645 m),[6] before descending and turning south once again. Both lines enter the Round Mountain substation. This is the terminus of the Path 66 portion of the parallel 500 kV wires.[3]
Substations
- Path 66
TANC line (North to South)
- Captain Jack
- Olinda
PG&E and PacifiCorp
- Malin
- Round Mountain
- Connecting power line
- Series capacitor station in Colusa County
- Tracy
Issues
- Power transmission capacity
Path 66 can transmit 4,800 MW of electrical power from north to south. From south to north, the system can transmit only 3,675 MW of power.[4]
- Environmental impacts
The northern part of this electrical transmission corridor (including Path 15) 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.[3] The land through here has been logged and sometimes clear-cut to create a right-of-way for the power lines because a wildfire could start when an electrical arc occurs between the wires and a tree if they come close enough to each other.[7]
Tower design and differences
This TANC 500 kV power line, unlike its PG&E counterparts, is triple-bundled, meaning that it has three wires per phase, whereas the PG&E lines are only double-bundled, or two wires per phase. In addition, the tower's design is strikingly different from the lighter and wider PG&E tower, and the design also changes significantly as one goes from north to south on WAPA's 346 mi (557 km) 500 kV line.[3]
The TANC line changes design at the Olinda substation from the delta pylon pictured at the Interstate 5 crossing[8][9] to the two-level pylon pictured above. This is because much of the segment between the Olinda and Tracy substations was constructed by upgrading an existing double-circuit 230 kV line.[3][10] The segment of TANC's 500 kV line from the Sacramento River crossing south to the Tracy Substation has delta pylons like those found on the Captain Jack-Olinda segment, although they are slightly different.[3] This is because south of the Sacramento River crossing, the original 230 kV line paralleled the two PG&E 500 kV lines almost all the way to Tracy Substation. In order to meet separation requirements, a new alignment for the 500 kV line had to be built some distance to the east, with the exception of the San Joaquin River crossing, which utilizes the former 230 kV facilities. This alignment can be seen from Highway 4 and the western part of the San Joaquin River portion of the Sacramento River Delta. A portion of the former 230-kV line south of the Sacramento River remains in service today as part of the 69 kV system that serves the pumping stations on the Contra Costa Canal.[3]
As for the pylons of the PG&E and PacifiCorp Round Mountain-Malin parallel lines, the PG&E line uses the same tower type as the PG&E Table Mountain-Round Mountain 500 kV segment does. The PacifiCorp 500 kV line uses a pylon that looks similar to the pylon used in WAPA's Olinda-Captain Jack segment.[3]
- Visual reference
-
WAPA Olinda-Tracy 500 kV transmission line outside ofInterstate 80.
-
PG&E wires near Tracy.
-
PG&E 500 kV Table Mountain-Vaca Dixon line spanning over the WAPA line (Olinda-Tracy segment).
Problems
Since TANC's Captain Jack-Olinda 500 kV wire rises to almost 6,000 feet (1,800 m) as the line crosses the rugged mountains near Grizzly Peak,[6] that section of 500 kV line is covered with large amounts of snow during the winter. Despite its location far from the Pacific Ocean, 20 feet (6 m) of snow can accumulate near Grizzly Peak's 6,250 feet (1,905 m)-summit.[10] The extreme snowfall there can cause ice and snow to accumulate on the insulators and the wires and sometimes lead to power outages when the wires snap in these extreme conditions.[11] This high-elevation segment of 500 kV line is also said to be problematic.[10]
Map
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Map of Path 66 located in the upper section, left of the other two 500 kV lines south of Round Mountain substation
See also
References
- ^ a b "COI Utilization Report" (PDF). Transmission Utilization Group. 2011-05-04. Archived from the original (PDF) on 2014-04-07. Retrieved 2014-03-30.
- ^ "California-Oregon Transmission Project". Transmission Agency of Northern California. Retrieved 2014-03-31.
- ^ a b c d e f g h i j k l Route descriptions and tower designs are based on Google Earth images.
- ^ a b Paths 61-70 (Report). Western Electricity Coordinating Council. 2006.
- ^ "California Transmission Lines" (PDF). Retrieved 2007-09-20.
- ^ a b c Google Earth elevation for GNIS coordinates.
- ^ "Trees and Power Lines" (PDF). Western Area Power Administration. Retrieved 2007-09-20.
- ^ "Picture of TANC's 500 kV line from Interstate 5". WestCoastRoads.com. Archived from the original on 2007-09-27. Retrieved 2007-09-20.
- ^ "Picture of WAPA's 500 kV line from Interstate 5". WestCoastRoads.com. Archived from the original on 2007-09-27. Retrieved 2007-09-20.
- ^ a b c "SN foreman outlines 3 decades of t-line ops". Western Area Power Administration. Archived from the original on 2007-09-27. Retrieved 2007-09-20.
- ^ "Calif. snow gets SN crew out to repair line". Western Area Power Administration. Archived from the original on 2012-12-14. Retrieved 2007-09-20.