Interesting article on the Northern Territories problems.
New CLP government scraps Labor’s 50 pct renewables target, but its focus on gas may leave it exposed to the blackouts it warns from the switch to solar.
I have in mind a much more elaborate solution......
This would be partly an electricity project, partly in the category of giving Aboriginal people from the area meaningful work during construction and longer term opportunity via formal qualifications of national value.
To be built in stages as follows.
Stage 1 is to build a single circuit 132kV transmission line between the existing East Kimberley Power System (EKPS) in WA and the NT's Darwin Katherine Power System (DKPS).
With reference to the map, this requires a new transmission line between the EKPS, physically connecting somewhere between Kununurra and the shore of Lake Argyle to the south where the existing hydro station is located, running to at the other end the existing gas turbine power station and 132kV substation at Katherine in the NT.
Red = existing 132kV transmission. Brown = existing 66kV transmission.
Operationally this enables the existing hydro to be repurposed. In short it'd be turned off during daytime, and run heavily overnight to supply about 20% of the overall system demand. Daytime power would be from solar, located anywhere on the system (eg could be anywhere from Darwin to Kununurra itself) noting this does not require batteries, it's just direct and thus cheap use of the solar.
Physically this line would be built as a single circuit 132kV line between the EKPS and Victoria River (the river roughly half way between Kununurra and Katherine). Between Victoria River and Katherine would be built on towers designed for 2 x 220kV circuits, initially strung with one circuit only and operated at 132kV.
Stage 2 being to construct a dam and hydro power station on the Victoria River. This being a large storage scheme, it'll hold 4.5 years' worth of river flow so it's effectively drought proof. Generating capacity will initially be 30MW, installed as a single reversible pump turbine though initially without any use of the pumping function.
Combined with stage 1, this raises the hydro contribution to 40% of system overnight load.
Stage 3 is to construct a second dam lower on the Victoria River with transmission back to the upper dam site. Installed at this location will be a 35MW conventional (no pumping) hydro turbine. Note that this lower reservoir holds just over 3 years' of river flow by itself, not including water held in the upper reservoir discharging into it, so would be reliable.
Stages 1, 2 and 3 combined will provide over 60% of overnight system load.
Stage 4 is to duplicate the generating capacity at the stage 2 power station. Noting that with the lower reservoir this is now a pumped storage scheme, being pumped during daytime when otherwise surplus solar power is available.
Since it provides a daytime pumping load, it substantially increases the ability to install solar economically, that is with full utilisation, and by doing so results in solar still supplying a very high portion of daytime load on higher than average demand and/or overcast days. Noting that with the transmission network in place, the solar would be located at whatever is the best site in terms of weather patterns.
So this arrangement gives full solar during daytime and 80%+ hydro overnight. The remaining 20% supplied from existing thermal plant located in Darwin which will provide spinning reserve to mitigate the risk of a transmission fault on the single Darwin - Katherine line.
Existing thermal plant will also continue to provide peak power (eg evenings) when required as well as backup for transmission outages.
Stage 5 is to duplicate Darwin - Katherine transmission (new towers built for 220kV), further increase generating capacity at the upper power station, and do away with thermal generation at Darwin. Timing to suit either future load growth or end of life of existing plant.
Stage 5 could be split into sub-stages to suit the considerably differing ages and remaining life of existing plant. Eg put the line in, add another hydro turbine, in due course add a 4th, 5th etc turbine when required.
Energy storage capacity of the pumped scheme is nominally 569GWh so that's more than adequate to facilitate any realistic level of generating plant being installed. It's long term fit for purpose infrastructure capable of expansion simply by installing additional pump turbine generators, hence the future proofing by building the transmission towers to suit 220kV use in order to facilitate that higher capacity.
The economics wouldn't be all that great but if we consider the broader national development aspects, it may also facilitate some irrigated agriculture for example, and the Indigenous training and opportunity aspects, as well as the gas saving, then it could plausibly stack up overall. Bearing in mind the hydro and transmission are inherently very long lived assets, they're good for a century at least.
The staged construction is intentional firstly to get maximum life out of existing assets but it also enables construction with a local workforce over time rather than a "boom, bust" approach of doing it all at once.
For the avoidance of doubt, this is by no means a "dam the lot" approach. There's quite a bit more hydro potential in the NT but it's really not necessary to develop it since the above combined with solar can do the job in full. This is after all really quite small stuff compared to the eastern states or south-west WA.