Basslink

Basslink is a high-voltage direct current (HVDC) cable link crossing Bass Strait, connecting the Loy Yang Power Station, Victoria on the Australian mainland to the George Town substation in northern Tasmania. It can supply some of the peak load capacity to the mainland of Australia and take some of the excess base load capacity off the coal-fired generators on the mainland to supply Tasmania, leading to reduced pollution. 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 the majority of Tasmania's electricity generation is hydroelectricity. However, "Basslink-related costs have been around $130 million ($ nominal) greater than the actual revenue benefits".^[1] This was due to drought conditions reducing hydro production

History

When the Board of Hydro Tasmania originally entered into a preliminary agreement to build Basslink in 2000, it was projected to cost $500 million.^[2] Efforts to prevent corrosion of pipelines and other factors ultimately meant it cost around A$800m to build.^[3]

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.^[4]

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.

The Basslink interconnector facility fee of approx. AU$70 million p.a. is paid by the Tasmanian electricity producer Hydro Tasmania for the transport of the electrical energy via the Basslink interconnector cable. Said facility fee is said to have a variable factor linked to the interest rate.^[5]

2015-2016 outage

See also 2016 Tasmanian energy crisis

On 21 December 2015 it was announced the Basslink was disconnected due to a faulty interconnector approximately 100 kilometres (62 mi) off the Tasmanian coast. Basslink originally announced the cable would be repaired and returned to service by 19 March 2016,^[6] however they then advised the date would not be met and as of 22 February 2016 there was no set time for completion of the task.^[7]

Due to the loss making situation of the link, and general prognosis, the demise of the company and the link have been speculated upon.^[8]

Reconnection and repair of the link was set back to June 2016 completion date.^[9]

By late April 2016, the first stage of the repair of the link was announced as successful.^[10]

However some reports suggest that repairs on the cable requires a window of time of 18 days of clear weather, longer than the usual weather patterns that occur in the Bass Strait in winter.^[11]

Restored

Power through the cable was restored on 13 June 2016, after nearly 6 months.^[12] A separate non-cable fault caused another failure of power flow on 22 June.^[13] After almost 36 hours power flow was again restored in the evening of 23 June.^[14]

Technical description

Basslink is a monopolar with metallic return^[15] HVDC operating at a nominal voltage of 400 kV DC. The nominal rating of the link is 500 MW (670,000 hp) although it is capable of transmitting 630 MW (840,000 hp) from George Town to Loy Yang for up to 4 hours.

It consists of:

• 290-kilometre (180 mi) long submarine power cable from McGaurans Beach near Giffard, Victoria to Four Mile Bluff above George Town in Tasmania. The cable weighs 60 kg/m.^[16] It is the second longest submarine power cable in the world. (see also NorNed)
• 60.8 kilometres (37.8 mi) overhead power line to the Victorian coast
• 6.6 kilometres (4.1 mi) underground cable in Victoria
• 11 kilometres (6.8 mi) overhead line section to the Tasmanian coast
• 1.7 kilometres (1.1 mi) underground cable in Tasmania.

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 upmost longer crossbar, while the electrode line is carried by the lower smaller crossbar, which shows in the opposite direction.^[17]

Communications cable

The Basslink cable also included a run of dark fibre. This is notable as it was the first non–Telstra operated fibre cable crossing Bass Strait. 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.^[18] The link was also to be used by the now defunct OPEL network.^[19]

The Basslink fibre between Loy Yang and Georgetown went into operational testing in April 2009^[20] and went live in July 2009.^[21]

Basslink Telecoms was officially launched on Thursday 16 July 2009 by the Tasmanian Premier David Bartlett, Federal Minister for Communications Stephen Conroy and Basslink CEO Malcolm Eccles.^[22]

Sites

• LoyYang Static Inverter Plant: 38°15′45″S 146°36′29″E / 38.26250°S 146.60806°E / -38.26250; 146.60806 (LoyYang Static Inverter Plant)
• Victorian Cable Terminal: 38°24′22″S 147°4′6″E / 38.40611°S 147.06833°E / -38.40611; 147.06833 (Victorian Cable Terminal)
• Tasmanian Cable Terminal: 41°2′32″S 146°52′07″E / 41.04222°S 146.86861°E / -41.04222; 146.86861 (Tasmanian Cable Terminal)
• Georgetown Static Inverter Plant: 41°6′53″S 146°53′31″E / 41.11472°S 146.89194°E / -41.11472; 146.89194 (Georgetown Static Inverter Plant)

References

External links

• Basslink Site
• http://www.engaust.com.au/magazines/en/pdf/ElectNewsNov.pdf
• http://www.nationalgrid.com.au/document.php?objectID=102
• Get the Basslink Fibre Going!
• Siemens article with photo of Loy Yang DC to AC converter
• Basslink Outage to be resolved by March 2016