The Basslink electricity interconnector is a high-voltage direct current cable linking the electricity grids of the states of Victoria and Tasmania in Australia, crossing Bass Strait, connecting the Loy Yang Power Station, Victoria on the Australian mainland to the George Town substation in northern Tasmania. Basslink is bidirectional and enables Hydro Tasmania to supply some of the peak load capacity to the Australian mainland and take some of the excess base load capacity off the coal-fired generators on the mainland to supply Tasmania. Financial benefits from the Basslink investment included reduced or deferred need to invest in further base load generation facilities, and potential to profit from selling peak load power into a market in which prices are generally higher, and because the cable was also used to supply power to Tasmania in times of drought, as most of Tasmania's electricity generation is hydroelectricity. A government review of Basslink in 2011 found, "Basslink-related costs have been around $130 million greater than the actual revenue benefits... Taking both direct and indirect sources of value together, Hydro Tasmania concludes that over the period 2006-07 to 2010-11 the average net benefit of Basslink to its business is in excess of $40 million per annum". However economist John Lawrence estimated that the 2015-2016 Basslink outage cost Hydro "between $140 and $180 million." Basslink is owned by the Keppel Infrastructure Trust, which is listed on the Singapore Stock Exchange, of which one third is held by Temasek, the $350 billion sovereign wealth fund of the Singapore government, and two thirds by the public.
History
When the Board of Hydro Tasmania originally entered into a preliminary agreement to build Basslink in 2000, it was projected to cost A$500 million. Efforts to prevent corrosion of pipelines and other factors ultimately meant it cost around A$800m to build. The interconnector was constructed between 2003 and 2005 as an asset of National Grid Australia Pty Ltd, which itself was owned by UK company National Grid plc. On 1 December 2005, electrical power flowed across Basslink for the first time, as part of the testing procedure. At midnight on the morning of Saturday, 29 April 2006, the link was officially enabled for commercial trading of energy on the National Electricity Market. On 31 August 2007, CitySpring Infrastructure Trust, a wholly owned subsidiary of Temasek, completed the acquisition of Basslink Pty. Ltd. group, i.e. a conglomerate of 10 commercial subjects owning the Basslink cable infrastructure, with a total enterprise value of AU$1.175 billion. Since then, CitySpring Infrastructure Trust has morphed into the Keppel Infrastructure Trust, which is listed on the Singapore Stock Exchange, two thirds owned by the public and one third by Temasek, the $350 billion sovereign wealth fund of the Singapore government. Basslink derives most of its cashflow from a 25-year term Basslink Services Agreement with Hydro Tasmania, the electricity producer owned by Tasmania, which commenced on 28 April 2006. Hydro Tasmania pays a Basslink interconnector facility fee for the transport of the electrical energy of about AU$70 million p.a. This facility fee is said to have a variable factor linked to the interest rate.
2015-2016 outage
On 21 December 2015, Basslink was disconnected due to a faulty interconnector approximately 100 kilometres off the Tasmanian coast. It was originally expected that Basslink would be repaired and returned to service by 19 March 2016, but the link was not restored until 13 June 2016. A separate non-cable fault caused another failure on 22 June. Power was restored in the evening of 23 June, after almost 36 hours.
Technical description
Basslink is a monopolar with metallic return HVDC operating at a nominal voltage of 400 kV DC. The nominal rating of the link is although it is capable of transmitting from George Town to Loy Yang for up to 4 hours. It consists of:
The pylons of Basslink are of an unusual type. They have two asymmetric crossbars with different lengths. The high voltage line is mounted on the uppermost longer crossbar, while the electrode line is carried by the lower smaller crossbar, which projects in the opposite direction.
Basslink Telecoms
The Basslink cable also includes a 12-core fibre optic telecommunications cable, the first non–Telstra operated fibre cable crossing Bass Strait. Basslink Telecoms commenced commercial operation on 3 July 2009 and was officially launched on 16 July. The Tasmanian Government uses it, as well as the TasGovNet fibre backbone, as part of the Connect Tasmania Core infrastructure, to facilitate a more competitive telecommunications industry within the state. The link was also to be used by the now defunct OPEL network.
