I'll keep out of the "religious" aspect of the debate but one thing I'll point out is that the relative cost of the various options is by no means static and is influenced by a number of factors.
Scale is one. Some technologies benefit from economies of scale far more than do others. Coal in particular is economically problematic at anything other than a very large scale. Alinta found that out in SA the hard way and it's no secret that coal is struggling financially in WA despite having already shut the higher cost operations and the private stations having been built as cheaply as could possibly be done. In contrast some of the coal stations in the eastern states are hugely profitable, such is the benefit of their massive scale.
Cost of finance / returns to investors is another since the capital employed per unit of output varies hugely depending on the technology. Even within the same resource type, well it's more costly to build for low grade coal than to build for high grade coal and it's more costly to build high efficiency gas than to build low efficiency gas. Etc.
Location also has an effect and for more than one reason. Construction costs, access to natural resources (wind, sun, water, fossil fuels), existing electricity transmission infrastructure, value of the land itself, climate will affect the efficiency and output capacity of gas turbines, etc.
Plant capacity factor is another key since if it's not running then there's a saving on fuel costs but little saving on some other costs and no saving at all on the original cost of construction. Since electricity demand itself varies, it's simply not possible to run all plant constantly and if we take SA as the more extreme example, well average demand is only about 46% of peak demand so that means plant is idle more than it's running. Victoria's not a lot better, average demand being about 51% of peak. It's higher in the other states, Queensland and Tasmania in particular at about 75% and 70% respectively, but still can't run flat out constantly.
Looking at some specific data for real power stations, annual capacity factors as follows:
Torrens Island A (480 MW) and B (800 MW) combined data. Plant location is SA, fuel is gas (steam turbines), owner is AGL (an ASX listed company).
2005-06 = 22%
2006-07 = 26%
2007-08 = 29%
2008-09 = 21%
2009-10 = 20%
2010-11 = 21%
2011-12 = 22%
2012-13 = 19%
2013-14 = 15%
2014-15 = 16%
2015-16 = 24%
2016-17 = 25%
2017-18 = 25%
2018-19 = 23%
The low figures aren't because it's broken or otherwise unable to operate, technically it could achieve 80%+ easily, but because there simply isn't a constant market for its full output.
Now for another one, Newport D. This is a gas-fired plant (steam turbine) in Victoria owned by Energy Australia (not listed).
2005-06 = 10%
2006-07 = 31%
2007-08 = 40%
2008-09 = 24%
2009-10 = 12%
2010-11 = 6%
2011-12 = 10%
2012-13 = 3%
2013-14 = 6%
2014-15 = 2%
2015-16 = 8%
2016-17 = 10%
2017-18 = 20%
2018-19 = 19%
Reason for the above is simply the market, from a technical perspective the plant could achieve around 90%.
Now another one, Tamar Valley Combined Cycle which is gas-fired CCGT plant in Tasmania. Owner is AETV, the parent company of which is Hydro Tasmania (state government owned). The plant has been in service since 2009.
2009-10 = 63%
2010-11 = 81%
2011-12 = 85%
2012-13 = 85%
2013-14 = 47%
2014-15 = Zero production
2015-16 = 30%
2016-17 = 40%
2017-18 = 41%
2018-19 = 18%
2019-20 to date = zero production, plant has not operated since April 2019
The above is again due to the market which is itself driven by hydro system inflows, wind speeds, temperature (heating / cooling load), gas prices, electricity prices in other states especially Victoria, etc. There was nothing precluding this station operating in 2014-15 or in recent months, just no technical need to run it and no financial incentive to do so in lieu of something else. If it needs to run to keep the lights on in Tasmania, or there's money to be made by running it and sending the output to Victoria, then it'll be back in action.
Finally, monthly data for Barker Inlet which is brand new, completed just before Christmas last year, and located in SA. Fuel is gas with diesel pilot (internal combustion plant) and the owner is AGL. Plant capacity is 210 MW and AGL have publicly disclosed the construction budget as $295 million.
January (first full month of normal operations) = 23%
February = 11%
March = 18%
April = 16%
May = 25%
June to date = 28%
First production from the above was on 17 October 2019 however progressive commissioning and plant testing involved some periods of uneconomic running, indeed at times it was run with negative prices, which was needed to get the work done but obviously not how it'll normally be running given that it's capable of going from shut down to full output in a matter of minutes thus has no need to stay running when doing so is unprofitable.
On a day to day basis there's also a lot of variation. Eg Barker Inlet ran with a 65% capacity factor on 17 June but there are certainly days when it's literally zero.
Now in looking at that data, they're all ultimately responding to the market. It's no coincidence that AGL (a listed company), Energy Australia (not listed) and AETV / Hydro Tas (government) all backed off production from gas around 2014 - 15. They're all ultimately feeding the same grid, they're all experiencing similar conditions and all responding similarly to them. Ownership may influence the detail but they're all ultimately reaching very similar conclusions.
I have deliberately chosen examples of the same resource (gas) being used by very different companies (listed, unlisted, government) to illustrate the point that all are acting similarly which is unsurprising given it's one big interconnected market.
I've posted this for the information of those interested either because they're invested in companies or this sector or for other reasons. I'll steer well clear of any "religious" type debates as I said.
On the gas side of it all, well as an example of the sort of company that might be in a good position with all this going on is Cooper Energy. The Sole gas field offshore Victoria has 241 PJ of reserves and once they get it working properly (currently in commissioning with some minor difficulties according to their recent update) the gas processing plant can process 68 TJ / day.
That makes them a minor player in volume terms, it's only about 12% Victoria's annual gas use if they run it flat out or about 6% of peak day consumption, but the resource will sustain that rate for almost a decade in a market short on supply and it seems that the company is selling much or all of it into the spot market.
That's for information only - do your own research before investing into Cooper Energy or anyone else, I'm just pointing out the opportunity and market background.
The above information could, if you really wanted to, all be sourced via AEMO and the ASX. Not in an easy form for much of it but ultimately the data's in the public domain - I've chosen specific examples with that in mind.