ABB has completed the delivery and energisation of the world’s first cross-linked polyethylene (XLPE) insulated 345 kV AC submarine cable system. Extruded in a single continuous length without factory joints, the new cable system brings 512 MW of power generation capacity to the critical wholesale power market in New York City. The power will come from a new natural-gas fired plant in Bayonne, New Jersey, that will generate up to 512 MWe for transfer to a Con Edison substation in Gowanus, Brooklyn. It is scheduled to start production in the spring of 2012.
The EHV cable system is part of the Bayonne Energy Centre (BEC) power generation and transmission project, a new facility that ABB says will provide cleaner, more reliable power for Manhattan and the New York City power transmission network. The cable system links the power plant to the substation across New York Harbour. The system includes three single-core XLPE submarine cables, each 6.5 miles (10.4 km) in length, and two XLPE underground cable segments that connect the submarine cables to the power plant in Bayonne and the substation in Brooklyn respectively.
The 6.5 mile submarine cables are the longest extruded extra-high voltage submarine AC power cables ever manufactured. Most extruded submarine AC cables have so far been at the 145 kV level or lower, including the world’s longest submarine AC cable, which ABB is supplying for the Goliat floating oil and gas platform in the Barents Sea (the Goliat cable is 105 km in length and has a voltage rating of 123 kV).
The cable installation is also entering the record books for two other reasons. In accordance with BEC’s requirements, ABB manufactured each of the three 6.5 mile extruded cables in a single continuous length. Such a long extruded extra-high voltage AC cable without factory joints had never been attempted before. It requires exceptional levels of expertise at the cable factory, with no margin for error in the extrusion process which, for a cable of this length, takes more than 10 days.
Secondly, New York is a busy international sea port with freighters, cruise ships, ferries and tourist boats anchoring or operating in the harbour. To mitigate concerns about possible future dredging in the harbour and the risk of anchor damage, ABB was required to bury the cables at a depth of up to 15 feet (4.6 m), which is significantly deeper than the 3-6 feet burial required for most other submarine power cables. The water depth along the cable route in the harbour is on average 20 m.
ABB was responsible for delivering a turnkey cable system including design, engineering, manufacture, field construction at the landfall sites, laying and installation, and commissioning.
The work at the landfall sites included construction of in-water cofferdams and horizontal directional drilling (HDD) in Brooklyn. The construction work at the landing sites and the laying of the cables were performed by a local New Jersey based firm (Caldwell Marine International) under a subcontract with ABB.
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