>Renewables are still mostly more costly than coal,
This is not even generally true anymore. Here in South Africa we have two big coal plants being built (both now several years late and way over budget), and the government is trying hard to get a 15-Billion rand nuclear deal passed (because the president's son owns the biggest local uranium mine - and that's just the start of the corruption). If it goes ahead- that will be 15 years minimum to get any power from, and likely far more overbudget (nuclear always is).
There was a study done here - which compared the cost per kw/h of those plants with wind and solar (our climate is among the best for solar with well over 300 sunny days a year and lots of coastal wind too). At the original quoted prices - with the expected costs of coal/uranium factored in the coal plants came in at around R1.20 per kw/h over their lifetime. Nuclear at about R1.90 - Solar - 75c, wind slightly worse at 95c. Oh and a solar plant with the same capacity as those coal plants can be up in 2 years, to match the nuclear you only need to add another 3 months - and they are usually under-budget.
We don't have much hydro possibility and we're already using what we can (mostly imported from our neighbours), the area is completely geologically dead (so no geothermal) and our tides are tiny (so tidal isn't practical) but we should be investing in what we can do.
But let's assume that solar and wind wouldn't be reliable enough to supply our industrial needs without excessive investment in additional storage tech (and the nicest one - hydro-pumps aren't an option). That still leaves the obvious answer which I wish government would take: give people serious incentives for home solar. Lets get every house off the grid, we distribute the cost (and it's been shown that solar is so economical here that if you BORROW the money to do solar you will still profit because the savings exceed the the interest rates, you can pay back the loan with the savings and have money left over - and that's assuming a worst case scenario where the batteries have to be replaced in just 5 years and the panels in 7 - they've both been way beyond that for some time). If we get all the residential demand off-grid, then the grid ONLY has to worry about supplying industry - which means we no longer need to have shortfalls (coal which provides nearly all our power at the moment can't keep up. We have one active nuclear plant but that only supplies one city). And by distributing the cost so widely the price per taxpayer is hugely reduced and you can optimise the process to build high-demand first.
Then your need for the grid-plants is lower, so you can get rid of half of them and use the savings to upgrade and maintain the other half.
The idea that solar and wind is more expensive is simply not true. Now it may be MORE true in Europe and the USA where, presumably, the climate mandates a greater investment in storage - but it isn't true globally. The real market where they lose is the market for bribing politicians. Big Russian government-owned nuclear companies (whose track record includes the worst nuclear disaster of all time) can afford much bigger bribes than solar companies can.