Originally Posted by
JDNSW
Drought and lack of wind do not necessarily go together - I suspect you are extrapolating from North America, which is topographically and climatically very different from Eastern Australia, where most electricity in Australia is required.
And Australia does not and never will be in a position to use hydro as a major energy source - there is simply not enough water or variation in elevation, whether we are in drought or not.
Similarly, yes, solar efficiency does decrease with increase in temperature, but the effect is relatively minor, and more than compensated for by the longer periods of sunlight which accompany hot weahter and droughts.
It is absolutely clear that there is no good reason why Australia can not stop using coal in the relatively near future, even if it requires some use of gas in the interim as the solar and wind capability is increased, if only to provide enough generator capability that can react instantly to power demand (which is the main reason for needing battery/hydro).
Australia stopping thermal coal exports* (or for that matter gas exports) is a completely different kettle of fish - it is not a technical problem, it is an economic one. Not only does the coal industry support a lot of Australians directly and indirectly, but it is a major factor in supporting the $A exchange rate and hence the Australian standard of living**. And in addition, royalties and taxes both directly and indirectly from coal and gas exports are a major revenue source for the Commonwealth, NSW, Qld, and WA governments, and to a lesser extent NT.
*Currently there is no real substitute for metallurgical coal. In theory hydrogen can be used instead, but putting this into practice requires replacing almost the entire steelmaking infrastructure at enormous expense. And coal is a lot cheaper than hydrogen, even hydrogen from natural gas, which is a lot cheaper than hydrogen from electrolysis using green power.
** If coal exports cease, the $A will decline in value, meaning that everything imported gets more expensive. OK, you say, make it here! Right, but the only reason it becomes practical to do this is because it can be sold for a higher price. So it still raises the cost of living. This is not to say that there is no reason to support stopping coal exports, but don't pretend it is a costless exercise!