What is HVDC Transmission?
High-voltage direct current (HVDC) is a technology that is able to transmit power over long distances. HVDC is steady-state, which means that it is extremely stable, and the combination of high voltage and direct current transfers energy more efficiently than in the common alternating current (AC) energy transmission lines. Unlike the common AC transmission, HVDC uses constant direct currents, which do not produce controversial electromagnetic fields.
What is the environmental impact of this transmission line?
The safe and reliable HVDC technology ensures that this energy transmission line has minimal impact on the surrounding environment – both during and after installation. The cables constant direct currents (which do not produce controversial electromagnetic fields) and because they are primarily buried they will not modify natural views.
Could the water become electrified if the line is damaged? How safe is it to put electric cables in water?
The water will not become electrified. HVDC protection reduces the current and voltage to zero in a fraction of a second if the cable is cut or broken. There is no possibility of damage to animals, the environment, people, or any nearby infrastructure. Underwater electric cables are safe and they are used all over the world.
How do you make sure that the cable is not damaged once it is buried under water? Can anchors or other equipment catch onto the cables?
The solid and compact cables will be buried underneath the waterbody’s sediment to keep it out of reach of fishing equipment and anchors. If any boat were to snag the cable, a situation that is highly unlikely, the weight and sturdiness of the cable will ensure that the boat knows that it is caught on something under the water. The insulation and protection along the cable will ensure the cable is protected against external damage and that the system knows of any physical change to the cable. If damaged, the system will shut down within fractions of a second. In this unlikely event, current and voltage are reduced to zero in the cable and safety equipment at the converter stations ensure that there is no damage to people, the environment, or existing infrastructure.
Is this transmission project safe?
Yes, this transmission line is a very safe project. The HVDC technology used for these cables is safe and reliable. The solid cables are well insulated, do not contain liquids or gels and are made from non-flammable materials. The HVDC converter stations are solid state which means that the conversion process is extremely stable. Unlike thermal generation stations, these converter stations contain no flammable fuel. If damaged, the electrical protection systems within the HVDC converter stations will shut down the system within fractions of a second. In this unlikely event, current and voltage are reduced to zero in the cable. The safety equipment at the converter stations ensure that there is no damage to people, the environment, or existing infrastructure.
Will the costs of this transmission project change my utility bill?
None of the costs for the installation of this project will be passed to the end consumer through your utility bill. oneGRID’s projects are merchant projects, which means that we are responsible for making this project an economic success. oneGRID as the developer will be responsible for cost overruns, not the ratepayer. Once this transmission line is in service, the new low-cost energy transmitted by the HVDC cable is expected to reduce energy costs to customers.
Are there any other transmission lines similar to this one?
All over the world, similar underwater HVDC cables are in use. For example, the Cross Sound project transfers energy between Shoreham, Long Island and New Haven, Connecticut is a transmission line using underwater HVDC cables. Burying transmission cables along natural waterways is an established and safe way to move energy.
How long will this transmission cable be in service?
There are many examples of these projects that have been in operation for more than 50 years. The equipment in the converter stations will have maintenance done to keep them running smoothly. Transmitting energy through the cables does not wear them down. The HVDC cables are constantly monitored and the only maintenance needed would be due to external damage.
How much upkeep needs to be done on the transmission system to keep it working properly?
The equipment in the converter stations will have maintenance done to keep them running smoothly. Transmitting energy through the cables does not wear them down. The HVDC cables are constantly monitored, and the only maintenance needed would be due to external damage.