With regard to "* Expanded Electricity Grids - A National Electricity Grid For Australia" and two of the comments:

How much would an interconnect to NZ cost (using the Basslink cost as an indicator) ?

Why link to NZ?

Au$2bn (2004 dollars) plus end-of-line connections.

According to this PDF, Basslink was costed at Au$216m for Cable and installation. The length of the cable is roughly 350km, which gives a cost of Au$617,000/KM.

Brisbane-> Auckland (as the crow flies) is 1417km, which means the cable + installation costs would be Au$876m. Multiply by two to account for depth and inevitable cost overruns, and you are looking at Au$1752m. Call it Au$2bn to be safe.

End-of-cable connections are independent of cable length. If using HVDC, line losses for a cable of this length should be only 4% - 7%.

During the day, we route excess power to NZ which is used for both local needs and pumped storage. At night, NZ draw down the Pumped storage, and send us power (if we haven't already solved that problem). NZ gets a dual advantage of reliable, distributed power supply, as well as drought-proofing.

Consider that Sydney -> Wellington and Hobart -> Invercargill are both of similar (but shorter, particularly Hob-Inv) distances. Triple redundant links for between Au$3bn and Au$6bn (and NZ would probably pay for at least a third of that). We just [expletive deleted by Steven Conroy MP] away Au$10bn to keep the shops humming over Christmas.