that is why lowering of battery storage costs to less than $100k/whr should be the turning point in economic analayis of renewable energy/ back up vs other options.
Agreed and all of these things should be seen as fluid in terms of relative costs.
Different materials, different countries where things are produced, different land requirements, different labour requirements and so on. Change any one input cost and it doesn't simply change the cost as such but it also changes relativities between the options.
Even using a very similar fuel that can be the case. For example, a comparison of Bayswater (NSW) with Loy Yang A (Victoria). Both are coal-fired plants brought into operation during the mid-1980's under government ownership and both are currently owned by AGL.
Bayswater has a capacity of 2640 MW versus 2210 MW at Loy Yang A. So not identical but very similar. Both stations comprise 4 generating units.
Bayswater burns black coal which has an export value and as such is worth the commodity price of the coal plus the cost of transporting it to the power station.
Loy Yang A uses low grade coal from a mine right next to the power station. The coal is well below export grade specifications, indeed it's about 58% water "as mined", and has zero value as a commodity as there's simply no market for coal like that. The cost of the coal is that of mining it plus royalties to the Victorian state government. Transport cost is trivial - it goes on a conveyor belt in the mine and that belt runs straight to the power station, no trains or trucks required.
Due to the coal moisture content, boilers at Loy Yang are physically more than twice the size of those at Bayswater per unit of output. So that's more steel used in construction, more labour, more cranes and so on to build it, etc. It's also more to maintain and, noting that all coal contains ash, clean.
The lower energy density of coal at Loy Yang also means everything else is scaled up simply to handle the greater volume of material. So larger conveyors, larger mills (which crush the coal) and so on. More materials to build all that stuff, more materials and labour to maintain it, even a warehouse storing spare parts needs to be larger.
So everything costs more at Loy Yang except that the coal is worthless, that's the one thing massively in its favour which offsets the other costs of more materials, labour, maintenance etc.
Change any one input cost there, so labour or steel or the commodity price of black coal and it changes not only the total cost but it also changes the relativity between the two stations. Two stations with a very similar output, built at the same time and with the same owner.
Now throw gas, hydro, wind and so on into the mix and it becomes far more complex. Change the cost of steel for example and there's a different amount of steel per unit of output in a gas turbine versus a wind farm.
Also cost changes may result in design changes. For example there's quite a few ways a dam can be built including methods which use practically no concrete. If cement becomes expensive, or the cost to transport it is expensive, then that of itself may prompt a radically different approach to design of the dam so as to enable the use of some cheaper material.
Even just using gas or oil as the fuel there's more than one way to go about it and different cost inputs for open cycle turbines, combined cycle or reciprocating engines. How the plant is intended to be used (base load versus peak) and the cost of those inputs (fuel, labour, equipment etc) will influence the decision as to the most economical plant type.
So it's all variable and with that in mind I'm cautious as to what's about to happen given the pandemic and overall circumstances. It wouldn't seem out of the question that we see significant shifts in exchange rates, material costs, equipment costs and labour in the aftermath of it all.
As one example, solar panels (largely imported from China) versus the locally sourced labour to install them or indeed anything. Given tensions with China, and mass unemployment, it wouldn't seem out of the question that there's a shift in the relative costs there and that then influences the non-solar options also.