There was an interesting article in The Financial Review about the extreme cost an inefficiency of the proposed pumped storage hydro in the Snowy Mountains. Basically the extreme expense of actually building the thing is a massive problem. Malcolm has given a very conservative estimate of $4 billion but apparently the real figure once land acquisition and supporting infrastructure is taken into account is around $8-12 billion. And we already have pumped hydro storage in this country but it isn't used because its too expensive:

Pumped hydro is an inefficient storage technology. Australia already has significant pumped hydro capacity – 900 megawatts (MW) at Tumut 3 in Snowy and 500 MW at Wivenhoe in Queensland. Both are rarely used because they are inefficient...

Not only that but it will be extremely energy intensive and they will have to put approximately double the amount of energy into running it as they'll get back:

At $4bil or $2/Watt for 2000MW of pseudo generation it's pretty pricy.  

Qualitatively, I've read this is because it includes a large transmission network to connect SA, western Vic, Sydney and Melbourne with the scheme.  In particular it seems to incorporate a transmission network to Broken Hill and other areas where large scale wind and solar projects have been proposed or even approved but aren't viable for the lack of a transmission network.  Perhaps the transmission network upgrade to facilitate new RE generation is worthwhile on it's own, but I doubt it, and there si no way to tell from the published feasibility study.

But for me, there are three really big red fags:

Red Flag 1:

67% round trip efficiency is too low.  AFAIK pumped hydro should be 80-90%.  AFAIK it's the length of the tunnels that are the issue.

Red Flag 2 (&3):

Red Flag 3:

Malcolm Turnbull - the father of the Australian republic - the good shepard of the ETS - the saviour of the NBN - has his paws all over it.  His track record on any major nation building exercises, or picking winners, is appalling.  

There are a few other minor things too - like the 200MB Complete Feasibility Study is unreadable in either of my PDF viewers.  If they were proud of the study, and *wanted* people to read it, this little bug would have been tested for, found and fixed.  Rather it smells like there is a lot of arse covering buried in squillions of words over multiple hard to search documents.

But prima face, while the concept is inspiring, there are issues with this project that if the feasibility study did answer, they were deemed not suitable for public consumption by people with a track record of being full of sh*t .