The transition to renewables really isn't that complicated. It just needs time, money and a cohesive policy response from government.
1) Over-build renewable generation capacity with a diversified sources of generation (hydro, solar, onshore wind, offshore wind) with as much geographic spread as possible to minimise demand for energy storage. It will be generally some sunny or windy somewhere. If you have installed capacity equal to 500% peak demand, then you only to be operating at 20% capacity or less to meet demand.
2) Invest in electricity storage (e.g. Battery and Pumped Hydro) to meet demand 99% of the time (aiming for 100% would be economically and environmentally inefficient).
3) Maintain emergency gas-powered generators to cover any supply shortfalls. These would only be operated as a last resort and would be funded using an availability payment system.
All that's kind of true.
1: A wind turbine has power proportional to the cube of the wind speed. That means if your wind turbine will work well in a 40km/h wind, when its a 10km/h wind you only get 1/10 of the output. So 20% is too conservative. The scientific term for how much overcapacity you need is "s**t loads". Similarly you need to have a lot of surplus capacity for your solar, because some days there is bugger all.
2: 99% will also be economically inefficient. People are already complaining about costs at the snowy II, a scheme that already has convenient dams in place.
3: Yes they will need to have enough capacity to supply a LOT of the grid. Economically you need to pay for 100% capacity of gas power stations , to sit in mothballs, as well as a huge overcapacity of renewables.
The geographic spread has issues as well.
Under the old SEC the government did a deal to provide cheap electricity to Portland for the Aluminium smelter. It was a shocker of the deal, because it didn't allow for the transmission costs. One of the reasons the S.A. transmission link was made, was so that it didn't appear obvious that millions were spent on a transmission line to Portland. Then when the SEC was privatised, a shell company was retained so it could buy electricity and sell it to the Aluminium company at a loss.
DC transmission may be of interest though. An AC transmission has around 7% per 1000km losses. DC can be around half of that.
Solar Arrays actually generate DC electricity, so in principle you could have a DC link in outback NSW supplying electricity to Melbourne.
The overcapacity of renewables principle is fine in a Government owned system.
But what happens when you have a huge surplus of renewable electricity on a sunny windy day, and the solar and wind installations are all owned by competing companies. Who is going to build the surplus , when the investment returns decrease with every added installation?
Your statement that it is generally sunny or windy somewhere has been proven incorrect by the Europeans who are well advanced in their wind power.
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Right now , the wind power in Germany is around your 21% capacity. Check it out from time to time, it gets a lot less.
Looks like the UK are close to 40%. Ireland doing great at around 70%. Spain 40% Of those countries , only Ireland isn't using significant gas.
Of course the Euro's can never really get into trouble, there are enough neighbouring countries that they can always buy their way out if they get in trouble.
Night time in California right now , so their 15Gw of Solar is doing nothing. Wind is at 12% capacity. They are burning gas in Green California.
Wanting to be green and pretending its all simple doesn't really help.