Education

Learn more about the Southern Cross Transmission Project.

Click on the questions below to learn more about the Southern Cross Project.

Learn about the project

PROJECT INFORMATION:

  • The proposed Southern Cross Project is currently under development.
  • In 2014, the Southern Cross Project was granted both a 210 and 211 order from the Federal Energy Regulatory Commission which described the need for the project as being in the public interest and the benefits of the project as:
    • Encouraging the mobilization of energy and capital
    • Optimizing the use of facilities and resources
  • The Southern Cross Project proposes to construct the following facilities in Louisiana and Mississippi:
    • A high-voltage, direct current (HVDC) converter station to be located in Northwest Louisiana;
    • Approximately 400 miles of HVDC transmission lines to be constructed across Louisiana and Mississippi;
    • A HVDC Converter Station to be located in Northeast Mississippi.
  • The Project is planned to interconnect with the ERCOT portion of the electrical grid in Texas via the Rusk to Panola Transmission Line Project near the Western HVDC Converter Station and with the Southeast electrical grid near the Eastern HVDC Converter Station.
  • The Project will provide bi-directional power flow capability, which allows each region to either import or export power based on need or relative power price in the regions served.

Benefits of the proposed project

  • The FERC found in its FPA Sections 210/211 Order that the Southern Cross Project will allow the Southeast U.S. increased access to economical renewable energy from Texas wind generators within ERCOT
  • The FERC also found that the Project will improve competitive conditions throughout the ERCOT and Southeast regions by increasing the availability of transmission service and the supply of electricity
  • In addition, the FERC determined that the Project will allow for the increased utilization of the CREZ transmission build-out previously authorized by the Public Utility Commission of Texas
  • And because of the Project’s capability to move electricity bi-directionally, the FERC found that the Project will contribute to the more efficient utilization of generation within both ERCOT and the Southeast.
  • The FERC determined that, because the Project’s customers will pay transmission rates within ERCOT, even ERCOT customers not taking service over the Project will be benefitted by the Southern Cross Project
  • In addition, the Project will spur the development of new low-cost renewable energy resources within Texas
  • Increased access to renewable generation within Texas should reduce reliance on fossil fueled generation, with resulting long-term public health and environmental benefits
  • The Project will create new jobs, investment, tax base and economic development opportunities within Louisiana and Mississippi
  • The more efficient utilization of generation within both the ERCOT and Southeast regions created by the Project should improve reliability within both regions

Learn about Southern Cross Transmission LLC

Southern Cross Transmission LLC (Southern Cross) is a subsidiary of Pattern Energy Group LP (Pattern Development). Pattern Development strongly believes that the success of its projects is directly tied to the strength of the relationships that we build with local communities. As future stakeholders in the communities where we will work, and because the Southern Cross Project will have a long-term presence in these communities, we will work to establish trusting and meaningful land owner and community relationships that add value to the local communities for decades to come.

What is DC transmission?

High-voltage, direct current (HVDC) transmission is a unique type of transmission line that has a frequency of zero. HVDC is used for special purposes such as efficiently transmitting power over very long distances or where it is important to control the amount or direction of power being delivered across the line. Electricity is transmitted as a current and voltage that flows from generating stations over transmission lines, to substations, and then through distribution lines before it reaches our homes and offices. Since the U.S. electric system operates using AC almost exclusively, a HVDC system includes two converter stations, one at each end of the HVDC transmission line. The converter stations change AC power to HVDC at one end of the line, and HVDC power to AC at the other end of the line.

Learn about the difference between alternating current (AC) and direct current (DC) transmission

The primary difference between high-voltage, direct current (HVDC) and alternating current (AC) transmission is that HVDC flows constantly in only one direction, like a battery, whereas AC changes direction 60 times per second. Most people use a combination of AC and DC power every day. Some of the benefits of using HVDC over AC include:

  • A HVDC line offers the benefit of “scalability,” meaning the amount of power the line can transmit can be increased by adding equipment at each end of the line. This decreases the need to build more power lines in the area if demand for power increases.
  • HVDC lines are more efficient than AC. One 500 kV HVDC line can transmit a similar amount of power as four double circuit 230 kV AC lines or seven single circuit 230 kV AC lines
  • All power lines experience line losses—power that’s lost in the form of heat when a line is operating. HVDC transmission lines typically experience 30-50% less transmission losses compared to AC lines, meaning better energy efficiency and less power wasted.

What are electric and magnetic fields?

Electric and magnetic fields, also called EMF or "electromagnetic fields," are produced by any wiring or equipment that is energized and carrying electric current, whether AC or DC, including lights, appliances, electrical wiring, and power lines. The strength of both electric and magnetic fields decrease rapidly with increasing distance from the source. Please click here for more information.

How do electric and magnetic fields differ for AC versus DC transmission

Electric and magnetic fields differ between high-voltage, direct current (HVDC) and alternating current (AC) because of the difference in frequency, i.e. the alternation of the current. Because HVDC current doesn’t alternate as it does for an AC line, the fields are referred to as “static”, which is a frequency of zero. DC electric and magnetic fields are identical to those found in the natural environment.

Learn about the different structure types

To view PDFs of the structure types, click here