A high-voltage, direct current (HVDC) electric power transmission system (also called a power super highway or an electrical super highway) uses direct current for the bulk transmission of electrical power, in contrast with the more common alternating current (AC) systems. For long-distance transmission, HVDC systems can be less expensive and have lower electrical losses.
Since a HVDC link is controllable, it can help stabilize a network against disturbances due to rapid changes in power.
Designed for Minimal Impact
With hundreds of underwater HVDC cables already in operation globally, the process for laying cable has been expertly refined to make it more accurate and efficient while minimizing environmental disruption.
- The cable is fed underwater from a vessel specially designed for this purpose.
- A small camera robot sends a video stream back to the ship to provide details of the river bed
- The vessel is specially designed to maintain course even in significant currents.
- State-of-the-art navigation employs GPS, sonar and video to follow the permitted route precisely. This also creates a detailed record of the installation.
- Once the cable is on the riverbed, the cable burying system is deployed.
- Using an innovative, low-impact system of water jets, the cable burying system follows the cable path digging a temporary trench only a few inches wider than the six-inch diameter cable and a few feet deep (according to permit specifications).
- This process creates very little impact to the riverbed or canalway. Within a few days the trench site is imperceptible on the riverbed.
Terrestrial cable routes are subject to a route selection based on:
- Environmental studies
- Technical feasibility
- Stakeholder consultation
- Low environmental impact
- Existing utilities
Using areas that are already designated as utility rights-of-way reduces disturbance to the environment. Because the cable will be buried, there is no visual impact and continued transportation, recreation and agricultural usage of the overlying land will be unchanged.