While there are benefits to HVDC undersea cable projects, there are also downsides, as these projects are more expensive than it would be to put cables up over an equivalent distance above ground, according to Paul Kraske, partner, energy and infrastructure projects, with Skadden, Arps, Slate, Meagher & Flom.
Other challenges involve insurance issues and environmental restrictions, he said Feb. 29 at Infocast’s Transmission Summit 2012, held in Washington, D.C.
He said his firm has represented several undersea cable projects, including the 7-mile, 345-kV Hudson Transmission Project proposed by Hudson Transmission Partners that ends in New York; the 53-mile, 200-kV Trans Bay Transmission Project sponsored by Trans Bay Cable that ends in San Francisco, Calif.; and the 65-mile, 500-kV Neptune Transmission Project sponsored by Neptune Regional Transmission System that ends in New York.
Kraske noted that it is a small, specialized market of insurance for undersea cables and it is subject to fluctuation. If insurance is not available, he said, “you can’t build your project – you certainly can’t finance it.”
He also said there are limited suppliers for HVDC technology.
“[I]f you’re going to get your project financed in the United States, you’re going to have to pick a technology, really, between Siemens and ABB, and even for undersea cable installation, it’s a pretty limited universe of people that can help you,” he said.
There are also long lead times in the regulatory process, Kraske said, noting that projects are likely to need federal approvals from the U.S. Army Corps of Engineers, as well as state approvals from state environmental departments. A related issue is possibly having to choose a technology early to get the appropriate approval, as the chosen technology may affect the project’s footprint of converter stations, for instance.
There are benefits to doing undersea cables, however, he said, as obtaining rights of way for undersea routes will not galvanize the resistance that terrestrial transmission projects do. “Fish don’t vote,” he said, citing a client.
Speaking to TransmissionHub on the sidelines, Kraske said there is another side of that coin, which is that some of the undersea cable projects have been held up for fish-related reasons. Neptune, for instance, he said, had an issue involving flounder that have a particular season during which they should not be disturbed.
Developers work with the environmental community, as “there are fish/wildlife-related concerns about some of these projects that have delayed or made them more expensive or required you to fix [them].”
Other benefits he discussed during his presentation include controllability if the project has a HVDC connection. “This is important, both for insulating different transmission regions – if you got a project that’s connecting two different grids, so that if you have failures, you can isolate those problems and it does not spill over into the grid to which you’re connecting,” he said.
HVDC technology also enables regulation of power flow across the transmission line, offering a way to manage transmission that AC connections don’t offer, he said. Furthermore, projects are not vulnerable to storms and tree growth that may affect a terrestrial transmission line, he said.
Key factors to consider include a limited selection of contractors, Kraske said, adding that the provision of reliable engineering data is important.
“[W]hen you’re signing a contract for the installation of a submarine cable, contractors are going to want to know with a great deal of specificity what is on the bottom of the ocean in the route that you have picked,” he said.
Coordination with construction of the cable and the testing of converter stations should also be considered, as well as specific issues associated with the burial of the cable, he said.
Another important consideration involves vessel availability, he said, noting that cable company Prsymian has one ship that “goes all over the world,” and if it were to get delayed in the Middle East, for instance, “your project in the United States is going to be delayed accordingly.”
Financing issues, unanticipated weather and unanticipated obstacles, such as finding a subway car on the bottom of New York harbor, should also be considered, he said.
Among other things, he said there are more HVDC undersea cable projects on the way, citing efforts to connect the Hawaiian islands with undersea cables, the 330-mile, 320-kV Champlain to Hudson Power Express Project that ends in New York City planned by Transmission Developers Inc., and the Atlantic Wind Connection (AWC) led by Trans-Elect Development Company and involving Google, Good Energies and Marubeni Corporation. The AWC project will be able to connect up to 7,000 MW of offshore wind when complete.
Speaking to TransmissionHub, Kraske said offshore wind is going to encounter all of the issues he mentioned during his presentation. “I don’t think the offshore wind [developers] have really gotten to the point of scoping all of these things out,” he said. “That’s coming and I think when it does, they’re going to have to reach out to Prysmian or to ABB to sort out connectivity with undersea transmission.”