I'll be extremely cautious in what I say for various reasons but let's just say the inevitable has happened.
Most political movements tend to split into factions. Labor has its Left and Right factions, the Liberals have their Moderate, Center-Right and Right factions and so on.
It seems that the broad environmental movement, not specifically referring to The Greens but the overall conservation and movement, has finally gone the same way.
One one side are those who'll be protesting something, anything, until the day they die. It's an all or nothing approach which rejects the notion of "better" and seeks perfection at all costs.
On the other side are those who've had enough of that and are seeking ways forward. That is, they consider that actual solutions, even imperfect ones, to the various problems are far better than forever marching down the street waving placards and reliving the only real success that approach had which is 40 years ago now.
Now to the transmission line, from a technical point it addresses the problem of insufficient capacity between NW Victoria and the rest of Victoria, in doing so bringing benefits for SA and NSW as well. Because at present, we have the rather unfortunate situation of forced flow, via a single circuit DC link, from NW Vic into SA on a routine basis.
Opposing the line are (1) farmers not generally opposed in principle but concerned about practical impacts which come down to the specific location of the line (2) farmers who in truth are worried about it impacting their ability to subdivide their farm for residential building land and (3) hardline protestors and activists.
In favour of the line are (1) renewable energy advocates (2) AEMO, engineers, governments and anyone else simply wanting to keep the lights on (3) what I'll term the pragmatic faction of the environmental movement that sees big electrical projects as perhaps not ideal, but a lot less bad than climate change.
From a technical perspective quite simply no, there is not a single circuit transmission line being built from Tasmania to Townsville as Professor Mountain claims. Individual lines are built as single or dual circuit yes, and a group of lines is commonly shown on a map as a single line for simplicity, but the bulk transmission routes are 2+ circuits in the context of running between states.
Qld - NSW is 2 x 330kV AC lines and there's the DC line as well.
NSW - Vic there's 3 x 330kV, 1 x 220kV and also via Hume power station there's a connection that's 66kV on the Victorian side and 132kV on the NSW side.
SA - Vic there's 2 x 275KV, which connects to 2 x 500kV lines not far into Victoria, plus there's the separate DC line as well.
Tas - Vic is the exception, that is a single circuit DC line. Hence the proposal to build a second and ultimately third cable across Bass Strait.
Within the states it gets more complicated but bottom line is the bulk transmission system generally comprises 2+ circuits from A to B. though not always following the same physical route. Some exceptions do exist, for example the line from Mildura to Broken Hill is single circuit and likewise the smaller hydro, gas turbine and wind / solar generators are often connected via a single circuit line simply because there's no real need to do otherwise.
Those single circuits don't threaten the entire system, worst case if they fail then a mine or low population area loses power or they take a small power station offline but they don't threaten the system overall. Larger stations are all on multiple circuits for reliability.
Vic - Tas being the exception but even that won't matter most of the time. There are circumstances where it would, it could cause some blackouts in Vic during periods of extreme demand and it could require more gas to be used for generation in Tas, but ultimately society won't crash and burn. Bearing in mind that Tas was a completely isolated system, not connected to any other state, until late-2005 anyway.
So I really don't know what he's on about there but it's simply not a correct statement.
Transmission maps as below.
Note there's nothing further west in SA so I've cut that off. Map source = AEMO and noting this is all freely available to anyone who wants it, there's nothing hidden or confidential about any of this stuff.
Voltages:
Yellow = 500kV
Orange = 330kV
Pink = 275kV
Blue = 220kV
Red = 110 and 132kV
Brown 66kV and lower
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