I don't argue that the NEM market operation as it stands now is...

I don't argue that the NEM market operation as it stands now is floored... just look at the way that gas, diesel and hydro manipulated the market to the point where AEMO had to intervene.

BESS units certainly are used for FCAS services, but they also do arbitrage... Hornsdales RoI is phenomenal partly because of FCAS
https://www.linkedin.com/pulse/hornsdale-power-reserve-earns-record-revenue-2019-marija-petkovic/
but it does still participate in arbitrage... even OpenNem shows BESS & hydro usage where charging is occurring at roughly half of the price that the output is occurring at. Currently FCAS is a primary source of income for BESS - but as more BESS comes online, there will be less need for FCAS services and that will increase the capacity available for arbitrage.

GNX modelling for its Bauldercombe BESS has a few videos on YouTube - well worth finding and watching for their discussion of profits available for a BESS on days where a peak price events (such as Calide generator explosion) occurred.

But your point about coal should also be considered over time... since 2003 - where its output peaked at Jul 2008 at 16,000 Gwh, it is now approaching a 1/3 less than that... and it will continue falling as a proportion of the total mix.

I never insisted that renewables were used for storage, my statement is that the surplus is coming as a result of renewables:
firstly - new renewable capacity is being built, there isn't any new coal (Calide replaced their generator that blew up - but there isn't any new generators being added to the supply side) - most gas & diesel plants operate relevant to market price points (don't operate when not profitable to do so), therefore, its not illogical to conclude that surplus is coming from renewables.
Secondly, coal is also inflexible in its operation - each generator has a minimum capacity factor to which it can operate at (~60%) and its ability to ramp up or down its output is slow (minimum 15 minutes). Yesterday its supply varied between 11000gwh and 15000gwh - the only way coal could have lowered output further would have been if they shut down a generator unit - but that is both costly, time intensive and hard on components. At the time of lowest coal output - the NEM price was 40 per Mw... that would be less than the cost of coal (~0.5 tonne needed for a Mw... current spot price is ~604Aud per tonne) Yes, I know AGL have contracted coal prices... but that was for illustration point. AGL has been on record previously stating that their cost of production from coal is ~120 mwh. AFAIK even solar wouldn't be making much at that price level - Telstra did a PPA for solar back in 2017 (from memory) for $55/mw - so there must still be some profit there for the right asset.

Show me one point where I quoted that coal output was zero... just one.

Your point about not needing to review wind capacity factors because " I worked on the Victorian wind atlas project" & " I don't need to review the wind capacity the company I worked for used to laugh at how figures were being manipulated to be favorable."... do a bit a research... you might learn something.

The other factor to consider is that most renewable output is pre-purchased via PPA's - Snowy Hydro uses PPAs to recharge its reservoirs, but in essence, you are correct that some (or most) BESS & PH will be recharged by coal (or whatever electricity is supplying the market at the time that it is cheapest).

bald hills was constructed in 2015 (was that the one your company worked on?) and you might have gone fishing for one of the worst performing wind farms (BTW you should have picked AGLs Macarthur Farm built 2012 26.29% (average 2012-2020)... come a bit closer to now

These are the best three performing wind farms for 2021 by capacity factor
Badgingarra wind farm 44% completed 2019
Kiata wind farm 43% completed 2017
Granville Harbour wind farm 41.6% completed 2020

David Dixon has compiled the best performers for June 2022 here:
That is 14 wind farms with wind capacity factors greater than 45%... the third infographic on his post is very telling about coals contribution since January 2022
https://www.linkedin.com/posts/david-dixon-50365b25_top-assets-in-june-activity-6949886106674810880-_Hsh/

The following quote is from 2015:
"Australian wind farms produce on average capacity factors of 30–35%, making wind an attractive option. South Australia’s large share (along with nearby Victoria) means most of Australia’s wind power occurs around the same time"
https://www.asiawind.org/research-data/market-overview/australia/#:~:text=Australian%20wind%20farms%20produce%20on,occurs%20around%20the%20same%20time.

We have digressed a long way from your claims that I called you out on...

BUT your argument that we need more renewables BEFORE we worry about storage ignores one key factor... if we overbuild generation capacity while existing coal assets are in operation, the price of electricity will drop excessively without any demand to use it - meaning that those new assets will be told by AEMO to constrain their supply until demand exists... no generation means no income... no income isn't a very feasible business case for building an asset with a cost of ~$1m/Mw (solar) or ~$1.6-2m/Mw (wind) - as a nation - we need GW's of new generation (some of that is already in development)

Having storage will storage will soak up the cheapest energy and then sell it at the most expensive times, and having higher lowest prices help support the investment in new generation assets... storage assets may be net consumers... but they facilitate the increasing of renewable capacity by making it more financially feasible to do so.

The cheapest generator will recharge BESS & PH (depending on the weather - that may be coal) - but an asset that has the least variable input costs will be the cheapest over time... and that is wind and solar.