Grid expansion for more renewables

In this piece, I wrote that South Australia was already at 57.5% renewables, that by the end of 2018 it would prolly reach 65%, and by 2020/21 it could be 80%.  That was before the announcement of the Aurora CSP plant near Port Augusta which will take renewables penetration to 90%.  In fact South Australia is in the vanguard of transition to a carbon-free economy:

• SA went coal free on 9 May, 2016

• If it were a country, SA would have the highest combined wind and solar penetration in the world — reaching 59% in July

• while Australia has the highest rooftop solar uptake in the world, the average crow-eater [South Australian] owns twice as much solar as their NSW and Victorian counterparts

• SA hosts the western end of the world’s longest underground High Voltage Direct Current (HVDC) transmission network

• by summer, SA will host the world’s largest lithium battery

• by 2020 it will host Aurora, the world’s largest single-tower concentrated solar tower and molten salt storage facility.

• British billionaire Sanjay Gupta has bought a majority stake in Adelaide-based Zen Energy and will harness the local expertise for his ambitious plan to use renewable energy for a significant portion of the energy required to run the Whyalla steelworks.

• This week EnergyAustralia published the first-stage feasibility report for yet another world leading project — the Cultana Pumped Hydro Energy Storage Project.  The proposed 225 MW seawater pumped hydro energy storage (PHES) project would be sited on the Spencer Gulf, not far from former coal town Port Augusta, and will have a capacity of 1770 MWh, holding almost 14 times more than Elon Musk’s ‘megabattery’.

•  Sundrop Farms, the innovative solar thermal ‘farm of the future’ where 23,000 mirrors and a 115m-tall tower desalinate seawater and power a farm that hydroponically grows 100 million truss tomatoes annually for Coles supermarkets.

[Read more here]

Australia's HV transmission lines
Source of original image: Wikipedia Commons.  Edited.

But South Australia, being right on the edge of a huge desert, can get very hot in summer, and peaking gas plants which the state uses to ensure enough electricity is available to run all those aircon units needed when temperatures hit 40 or 45 C have a habit of failing in the heat.  Originally all Australian states had separate electricity grids, but over the last 20 years two smallish interconnectors have been built linking SA to Victoria.  Yet when a massive storm hit South Australia a year ago, causing wind farms to go off line, the demand on the interconnectors caused it to trip.  So what about another interconnector, to the NSW grid?

Broken Hill, just over the New South Wales border, has ironically developed into a bit on a renewable energy hub: the wind blows most of the time, though perhaps not as strongly as it does at the coast, and the sun shines most of the time.  I say "ironically" because Broken Hill was once a rough mining town, and that was where BHP--or Broken Hill Proprietary, the world's largest mining house--was founded.  The distance between Port Augusta in South Australia and Broken Hill is just 412 km.  There is a 300 km long high voltage line from Broken Hill to Buronga in the south of the state, where it connects to the Victorian grid and the NSW grid.  I was unable to find the capacity of the Broken Hill-Buronga line, but I suspect it's less than 500 MW.

What would an interconnector between the South Australian grid at Port Augusta and the NSW/Victorian grid at Broken Hill cost?  As an example, the new Plains and Eastern Clean HVDC line will be 1150 kms long, with a capacity of 4000 MW, and will cost US$2.5 billion (A$3.3 billion).  Let's assume that costs are comparable in Australia to the US in A$, and that a HVDC line of 400 km with 800 MW capacity is built.  It would likely cost something in the order of A$230 million.  Of course, it isn't that simple.  For example, you still need a transformer at the beginning and the end however long the line is.  And the capacity of the Broken Hill/Buronga high voltage connector may have to be increased.  Say A$400 million total.

This seems a small price for South Australia to pay for additional energy security.  With the pumped hydro, the Aurora plant,Tesla's big battery, and the additional interconnector, South Australia would be able to go to 100% renewables without the risk that the lights will go out.  And it would be useful to Victoria and NSW too, because the wind and sunshine in South Australia isn't highly correlated with wind and sun in Victoria or NSW.  When SA has surplus power, the other states could use it.