Actually, I've always said, to shut down coal is dumb, also I think smurph agrees.
My personal view is to take a pragmatic approach.
If the whole world is going to move away from coal then pouring new investment into coal-fired generation in Australia would seem a high risk strategy.
On the other hand, we need reliable and economical power and I see no valid reason to close existing coal-fired plant and leave ourselves literally in the dark. That's just silly unless the world as a whole really is going to move away from coal far more quickly than seems likely.
So some balance is needed. If it were up to me then I'd be continuing to run existing coal-fired plant for the remainder of its useful life but I would't build new capacity unless it were the only option in a given circumstance. That still moves us away from coal, just in an orderly manner instead of the chaotic one we're pursuing at the moment.
So far as my view on specific energy options we have:
Nuclear - forget it. Too much expense and it will take too much time that we don't have. At best it would be a long term option but it's not a solution to our problems right now or within the next 20 years. Plus I do worry that we'd do it properly. If we can't get wind turbine protection settings right and we end up running coal plants into the ground then I do worry as to how safely we'd do nuclear in practice. "She'll be right" just won't cut it and nor will a focus on profit (noting that if we did have nuclear, then it would have lost money every single year for as long as we've had the National Electricity Market so unless the operator was an actual government department propped up by taxes they'd be under massive financial pressure and that's not a good thing when it comes to safety). I base that claim on the actual cost of nuclear in other developed countries, most notably recent projects in the UK.
Geothermal - closest thing to a "silver bullet" if we could get it working. We ought to put some serious $ in and prove it one way or the other just as we did decades ago when we too big risks with hydro and brown coal, the latter being something we didn't really have a clue about even after construction had started but we made it work.
Hydro - there's a massive resource in PNG being used for absolutely nothing. Origin did look at a 1200 MW (base load) project to supply Queensland but lost interest given all the political risk. Ultimately it could go to at least 4000 MW (base load) and that's enough to run two thirds of Qld (roughly) with 100% renewable and pretty reliable energy (hydro is vulnerable to drought yes, but its actual track record in most places is still better than coal, gas or nuclear). On a smaller scale there's still some undeveloped potential in Australia, outside high conservation value areas, that is worth looking at. It's by no means a total solution but could make a contribution with the key benefit being that it's firm, dispatchable power - works when we need it to work.
Gas - dumbest thing we've ever done as a country is sell practically the whole lot thus depriving ourselves of what would otherwise be a reasonably cheap (not much more costly than coal) and reasonably clean (60% lower emissions than coal for base load operation) energy source. Too late now unfortunately. I reluctantly agree with those opposed to coal seam gas development on farms etc. In theory I'm not opposed but there's just no point in taking even the slightest risk given that any increase in supply just means we'll give more of the stuff away to someone overseas, it won't do anything at all to help Australian industry or homes with energy supply.
SA - building a pumped hydro scheme would make an awful lot of sense given that the basic problem is one of meeting peak demand and that SA has already built a lot of intermittent generation, which at times exceeds the total load within the state, and remains a good place to build more of it. Yes there are plenty of sites in SA where pumped hydro could be built and no they don't involve flooding anything of particular note in terms of nature conservation etc so there's no real reason not to go down that track. It's the one thing that could fix the current problems without investing a cent into new fossil fuel generation that may be rendered obsolete depending on what really happens internationally with the CO2 issue. There are 3 such schemes presently in Australia, two in NSW and one in Qld, and another one planned for Qld but we need to put one in SA and do it ASAP. Also it removes the need for more interconnectors between SA and anywhere else so saves on that cost.
Solar - it was worth building some, which we did (mostly on roofs) as that reduced the summer afternoon peak. That opportunity is now fully exploited in most parts of the country however and building more solar will not greatly reduce the problem we have with meeting peak loads which have now been delayed until after 6pm and being driven by the sun getting lower and solar output falling off. Further development of solar only makes real sense if it is either (1) cheaper than the marginal operating cost of conventional power generation (2) has storage attached (eg solar thermal or the Qld solar + pumped storage project) or (3) we're going to build storage elsewhere in the grid (see point above about pumped hydro).
Wind - much the same as solar. Building more really only stacks up as a solution to the extent that it's either saving on operating costs (which generally it isn't) or if we build storage. Which brings me back to pumped hydro again....
Coal - makes sense to keep what we've got while it lasts but I personally wouldn't build more unless as a last resort option. My reasoning is simply that a new plant will be around for about 60 years from today, that's the time from deciding to build it until it closes, and is far too likely to be rendered obsolete in that time unless the internationally community decides to ignore the CO2 issue (or science finds it's not a problem). I'd get Northern (SA) and Anglesea (Vic) running again though if at all possible and I'd look very seriously to see if Hazelwood can be patched up for a reasonable and run for a few more years - my understanding is it could be done for about $140 million which isn't huge and that would keep it going for 10 - 15 years (after that it really is the end). Reason being to keep the lights on until we get something else built - otherwise we're in a very serious mess less than a year from now.
Biomass - burning it for power generation makes a lot more sense than dumping it in landfill or setting it on fire in the open but there's only a limited amount of it so it's a supplement to other power sources but not a replacement. I personally wouldn't want to see forests being logged for wood to fuel power stations for reasons of nature conservation and suffice to say I don't trust the forestry industry when it comes to that given the track record of woodchipping of "waste" timber which ended up being practically every log taken from the forest in the first place. So waste biomass yes, logging forests no.
Landfill gas - another supplement that can add a bit but nowhere near enough. Makes more sense to burn it in a generator than just letting it escape to the atmosphere though and I think it ought to be mandated at any landfill that has a power line reasonably close by unless there's a good reason to not do it at that specific site.
Wave, tidal etc - worthy of ongoing research and has a lot of potential given the predictability of the tides but it's not ready yet to replace coal etc.
Oil - simply too expensive, as is gas these days, for base load but has a limited useful role as peaking or backup power. Plus it's still the only real option in many remote areas. Given that we're a net importer for two thirds of the oil we use in Australia, from a supply security perspective it's really not a good option to be using it for power generation. Adding wind or solar to remote systems to save on fuel consumption generally does stack up economically so ought to be pursued more aggressively. No major infrastructure is required, just plonk the solar panels or a wind turbine or two somewhere in the the "grid" being supplied by those systems and that's it really.