SunCable - a very long extension lead and lots of solar

[GregLocock]

Basic plan is to build a very big solar farm in the Northern Territory of Australia, where land is cheap and sun is somewhat plentiful most of the year round, and then supply power to Darwin, and also to Singapore via a 4000 km long undersea cable.

Or

Basic plan is to get as much upfront taxpayer money from 3 governments into the developers pockets as possible

These two plans are not mutually exclusive.

Details

So, 1.75GW more or less to Singapore, 24/7, and 4 GW to Darwin (not necessarily 24/7). 20GW of panels, 40 GWh of storage. As you can see the numbers don't add up, 20 GW of panels might average 120 GWh of energy per day (i've got irradinace data for a few years from there, and I'll have a look in detail later on), but for days at a time there are monsoon related storms that kill the solar, and they've got less than a day's storage for Singapore never mind Darwin.

 

[GregLocock]

Data source for Tennant Creek Insolation https://nt-solar-resource.fulcrum3d.com/download I'll do more on this later but here's an illustration of multiday variability.

We aren't in the rainy season yet, even so some pretty lousy days. Incidentally the brief spikes are a fun phenomenon, on cloudy days when the sun appears through a gap in the clouds irradiance exceeds the expected value because the clouds reflect sunlight back down. Cute hey?

 

[GregLocock]

Yes well that was orrible. Learning to use LibreOffice is not especially pleasant. But, at long last I have managed to extract daily kWh/m^2 for the couple of years worth of data. Unfortunately there are missing samples, for days at a time. I'll add some logic to clean it up but here's a first look. As you can see the general trend is clear, as are the frequent failures to reach even 50% of what you were hoping for. Now this may be exaggerated due to data problems, but the data for the past year seems robust at least.

 

[GregLocock]

I'll be looking at what will happen on these 5 days.

 

[GregLocock]

I'm abandoning trying to analyse what they are up to. Here's the website https://www.suncable.energy/our-projects

Firstly Darwin's grid serves two towns, and averages 200 MW, half of which will be solar by 2030. So why build an 800 km transmission line with 4000 MW?

Secondly they are supplying Singapore 1.75 GW 24/7, that means 42 GWh per day, 2/3 of which is from batteries due to night. That means their 40 GWh batteries will be cycled by 70% of their capacity every day.

Thirdly, in order to charge those batteries from 20 GW of solar they need at least 2 hours of plate capacity energy per day, ie 20*2 GWh

This is the data for March this year, 3 days at least where the battery will be flat.

​	kWh/m^2/day​	20GW panels​
​	​	Gwh in​
15 Mar 24​	7.4​	147.9​
16 Mar 24​	7.4​	147.2​
17 Mar 24​	6.2​	124.9​
18 Mar 24​	5.9​	118.3​
19 Mar 24​	1.0​	19.5​
20 Mar 24​	1.2​	24.4​
21 Mar 24​	3.5​	69.8​
22 Mar 24​	3.2​	63.9​
23 Mar 24​	2.4​	47.8​
24 Mar 24​	1.3​	25.1​
25 Mar 24​	3.4​	68.2​
26 Mar 24​	3.3​	66.1​
27 Mar 24​	4.3​	86.8​
28 Mar 24​	5.9​	119.0​
29 Mar 24​	6.8​	136.4​