In winter, the Pacific Northwest needs power for heat – and must import it from So Cal.
In summer, the Pacific Northwest has excess power – and exports it to So Cal.
“Paths” are the major transmission lines that form the “grid” – which connect geographic areas covered by utilities.
Of interest here are the “paths” that transmit power north and south in California. These path make the importing and exporting of power possible.
These paths were built in the 1970s and 1980s in order to provide California and the Southwest with excess hydropower from the Pacific Northwest without actually having to construct any new power plants.
During the cold Pacific Northwest winters, power is sent north due to heater use. This transfer reverses in the hot, dry summers, when many people in the South run air conditioners. 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. This bottleneck was one of the leading causes of the California electricity crisis in 2000-2001. 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 on December 21, 2004. California’s governor, Arnold Schwarzenegger attended the commissioning ceremony at California-ISO’s control center in Folsom.
Path 26 is three 500 kV lines with 3,700 MW capacity North to South and 3,000 MW capacity south to north. Itl inks PG&E (north) to SCE (south).
Path 26 forms Southern California Edison’s (SCE) intertie (link) with Pacific Gas & Electric (PG&E) to the north. Since PG&E’s power grid and SCE’s grid both have interconnections to elsewhere, in the Pacific Northwest (PG&E) and the Southwestern United States (SCE), Path 26 is a southern extension of Path 15 and Path 66, and a crucial link between the two regions’ grids.
The path consists of three transmission lines, Midway–Vincent No. 1, Midway–Vincent No. 2 and Midway–Whirlwind. Midway–Whirlwind was part of what was called Midway–Vincent No. 3 before Whirlwind was built, as part of the Tehachapi Renewable Transmission Project.
The three Path 26 500 kV lines can transmit 3,700 MW of electrical power north to south. The capacity for south to north power transmission is 3,000 MW.
Path 26 – Vincent to Midway
The Path, starting from the south, starts at the large Vincent substation close to State Route 14 and Soledad Pass near Acton east of the Santa Clarita Valley. The same Vincent substation is linked to Path 46 and Path 61 via two SCE 500 kV lines that head southeast to Lugo substation. As for these SCE 500 kV wires, like Path 15 to the north, the three 500 kV wires are never built together for the entire length of the route. Straight from the substation, all three lines head north-northwest. The westernmost SCE 500 kV line splits away and runs west of the other two SCE 500 kV lines.
After crossing State Route 14, two 500 kV wires built by Los Angeles Department of Water and Power (LADW&P) join the eastern two SCE 500 kV wires. Some point west of Palmdale, one line (SCE) continues northwest and the other three (one SCE, two LADW&P) head west. The lone SCE line continuing northwest (with 230 kV lines) runs close to the Antelope Valley California Poppy Reserve, famed for its California Poppy flowers. The one SCE line that ran west of the other two SCE lines (now separated) re-joins the single SCE 500 kV running west with the two LADW&P lines. The four 500 kV lines run together for some distance until, at some point in the mountains, the two SCE lines continue to head west and the two LADW&P lines turn southwest and head for Sylmar in the San Fernando Valley (close to the Sylmar Converter Station southern terminus of the Pacific Intertie HVDC line). The two SCE lines heading west meet up with Interstate 5 on the arid foothills of the Sierra Pelona Mountains to the east of Pyramid Lake. The lines parallel I-5 crossing Tejon Pass (running on the eastern foothills of Frazier Mountain) and run out of sight for a while as they cross the high woodlands of the northern San Emigdio Mountains at their highest point at around 5,350 ft (1,630 m).
As for the third line, north of Lancaster and State Route 138, it runs through a remote, roadless area of the Tehachapi Mountains with two 230 kV lines. Although it runs across sparse to dense oak woodlands at around 5,300 ft (1,615 m), it is not easy to spot it on Google Earth since its right of way is not as clear cut as Path 15 and Path 66 to the north. Due to this, the line is not readily seen again until it crosses State Route 184 as a PG&E power line. Somewhere to the east of State Route 184, in the mountains, the line changes from SCE towers to PG&E towers. By the time the all three lines are visible to Interstate 5, they roughly parallel each other until all three lines, two SCE and one PG&E, terminate at the massive Midway substation in Buttonwillow in the San Joaquin Valley. Two pairs of PG&E 500 kV lines heading north and southwest (separated), form Path 15.
Connecting wires to Path 46 – Vincent to Lugo
Adjacent to the Path 26 wires, two other SCE 500 kV also begin in Vincent substation. The two 500 kV power lines head northeast from Vincent to meet up with LADW&P’s two other 500 kV wires from Rinaldi and then all four lines head east in the Antelope Valley along the northern foothills of the San Gabriel Mountains. Another LADW&P line from Toluca joins the four-line transmission corridor, resulting in a large path of five power lines. However, one LADW&P splits off from the other four lines and heads southeast. Soon after, the SCE lines split away from the remaining two LADW&P lines and head southeast as well. They cross the lone LADW&P line that split away and Interstate 15 as they head to the Lugo substation northeast of Cajon Pass. The lines terminate at Lugo, where one SCE Path 61 500 kV line, two SCE Path 46 500 kV lines, and three other SCE 500 kV lines end.
Path 15 is an 84-mile (135 km) portion of the north-south power transmission corridor in California, U.S. 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.
Path 15 consists of three lines at 500 kV and four lines at 230 kV. The 500 kV lines connect Los Banos to Gates and Los Banos to Midway. All four 230 kV lines have Gates at one end with the other ends at Panoche, Gregg, and McCall.
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 is 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 Power Plant and the Moss Landing Power Plant are two examples.
The Vaca-Dixon substation (38°24′8.33″N 121°55′14.75″W) was the world’s largest substation at the time of its inauguration in 1922.