Rooftop Solar on the Australian Grid

wattmatters

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Today a new record was set on the Australian national grid; renewables hit 57.6% of total supply on a weekday. The single largest supplier of energy was rooftop solar PV with 32.4% of supply at 12:30pm AEST - nearly 8GW of rooftop solar PV supply.

This national grid represents most of the country's electricity supply except for the far north and the state of Western Australia, and anything off-grid of course.

As a nation our grid is still heavily reliant on coal but it's changing fast.

In WA the other day they hit over 55% of the state's grid supply coming from rooftop solar PV at 12:30pm Perth time - 1.2GW of rooftop PV.

Screen Shot 2021-09-09 at 3.14.12 pm.png

These records are going to keep tumbling as we head deeper into Spring and into the years ahead as solar PV is being installed at an amazing rate. It won't be long before 40% of all Australian homes have a grid-tied solar PV system on their roof.

The transition might get a bit bumpy at times.
 

mrzed001

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We had problems with that ... too much is as bad as too few.
Here are almost no battery systems. Not in user level and not in utility level.

Here the nuclear is the base power plant (deep blue). That plant goes in constant mode. Always producing the same amount, and not easy to change that. Even worst to shut down completely ... it would need a long time to be able to start it again.
The red is the brown coal.
Blue is gas.
Yellow is solar
Green is wind.
Paks_solar_turndown2.png

And in one day the solar + wind production was so high that even the nuclear power plant needed to throttle down.

In Australia you burn a bunch of coal. That is easier to control but would not call it green.
Germany has similar problems since closed the nuclear plants.
At night (and even days in winter) ... the sun does not shine, wind does not blow.

TLDR: a lot of sun/wind power is good if you have a way to store it
 

wattmatters

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There are a variety of grid scale storage projects underway here. Many very large battery projects are starting (heading towards 1GW capacity with storage capacity ~4 hours) and one very large pumped hydro scheme as well (2GW / 35GWh). Some smaller pumped hydro as well.

My understanding is our current trajectory is fine until we hit ~65% renewables of total supply (not just peak daytime numbers). After that it gets harder but is certainly doable.

Coal is going to exit here over the next decade or so, the coal power companies have mostly announced anticipated closure dates (mainly because they are losing money). Our Federal govt are coal loving luddites (big coal donors help keep those people in power) but the State govts are and have been far more progressive with energy policy (and have considerable influence on what actually happens since the laws governing energy delivery are mostly state laws).
 

mrzed001

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Elon Musk with Hornsdale created a whole new ... industry.
And this industry is rapidly expanding. GW scale capacity big batteries are under construction.
But even then continuously working base power pants are needed: nuclear, water, coal.
They give momentum to the power with big, heavy and fast rotating parts. Only with them is the grid capable of handling the big inrushes that happen all the time.

The other big problem with renewable is that they are unreliable.
For every GW of renewable you need an another GW of fast reaction coal or gas based power plant. Even big batteries are not enough to get through a stormy week. They are short term solutions and go empty in some hours.

Pumped water and hydrogen (and gravity) plants seems to be the real long term power storage solutions.

I would love to see someone make a cheap solar + hydrogen based (off-grid) residential solution. An almost closed system.
Where you make a lot of power when sun shines, split H2O to H2 + O2, store H2 long term in containers/tanks, and when needed with fuel cells create AC power from it (or DC and store it in battery and from that AC).
I know the round trip efficiency is below 50% with hydrogen and near 90% with pumped water. But pumped water can be done only in big scale while hydrogen can be made and stored everywhere.

I just saw a video where electric race cars where charged in the racetrack with a hydrogen fuel cell generator.
How cool is that :)
 

wattmatters

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The other big problem with renewable is that they are unreliable.
Renewables are not unreliable, just variable. Firming renewable supply requires some storage, but much less storage than many think. Indeed getting to 60% renewables requires very little storage.

Our ageing fleet of coal stations are not exactly reliable, even the "newer" stations suffer problems. Failures are happening more regularly and they are becoming less economically viable every day so maintenance costs are problematic. On average our coal and gas power plants experience a breakdown every 3 days.

This is one of our youngest coal power stations a few months ago:

38e195b7473e06ac230b747201af1b40.jpeg

In recent times it's been renewables and batteries which have kept the grid going when coal plant supply has failed.
 

Hedges

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I don't recommend people make those at home either.

How about diesel?!

Being serious for a moment - I strongly recommend people do NOT play with generating hydrogen at home! It is incredibly dangerous.

Would it be OK if used immediately, like bubbled through vegetable oil to make Crisco?

Or maybe stored as a metal hydride, e.g. in platinum?
 

wattmatters

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How about diesel?!
Done well, making biodiesel is reasonably safe and can be done at home from used cooking oil. While there are risks with any such substance, the much higher flash point of diesel does help reduce risks somewhat.
 

wattmatters

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Would it be OK if used immediately, like bubbled through vegetable oil to make Crisco?
I don't know the answer to that.
Or maybe stored as a metal hydride, e.g. in platinum?
Well we are not talking the production of the gas in the same form anymore.

May as well buy a metal hydride battery system:

But watch for the eye watering price...
 

mrzed001

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Hydrogen Generators, Definitions are little flux at this point, they can make hydrogen or burn hydrogen, Much like Solar Generators trigger some

You can buy the ones that make hydrogen on Amazon, question is how long before someone DIYs a home power station :p


To separate H2 and O2 you only need two plates in a water. That is the easy part. The power can be made by PV.
But after that ... you need to compress the hydrogen (closed system so no contact with air ... because that would be bad).
After that you need a container to store it
After that you need a fuel cell that generates power from H2
And everywhere with sealing available to restrain the world smallest element

Not a bad DIY project ;)
 

mrzed001

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Renewables are not unreliable, just variable. Firming renewable supply requires some storage, but much less storage than many think. Indeed getting to 60% renewables requires very little storage.
I know in Australia the sun shines a lot ... but other parts in the world there are sometimes weeks without direct sunshine.
A storm comes in the middle of the day and 70% of the solar production is gone.
So yes, the solar is unreliable. Wind also.
And in the perspective of the grid organizer you have to have enough reserve to make up for the missing solar power.


Our ageing fleet of coal stations are not exactly reliable, even the "newer" stations suffer problems. Failures are happening more regularly and they are becoming less economically viable every day so maintenance costs are problematic. On average our coal and gas power plants experience a breakdown every 3 days.
Even they are old and break down, they are way more reliable as solar :)
And ... scalable ! That is a very important point.

This is one of our youngest coal power stations a few months ago:

View attachment 64009

In recent times it's been renewables and batteries which have kept the grid going when coal plant supply has failed.
Because you do not have big nuclear or water (or ...) based base plants.
And it seems there is too few fast reacting gas plant to stabilize the grid. This one can be replaced by batteries (a good short term solution).
That pumped storage plant you wrote before will be a huge extra to your grid system.
 

toms

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The world’s largest energy corporations have the technology to extract hydrogen from seawater and combine it with CO2 to make a synthetic gas with similar properties to methane.

Easy to store, negative carbon emissions, and slightly energy negative. Once there is enough excess PV they will be profitable.
 

wattmatters

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So yes, the solar is unreliable. Wind also.
Unreliable means it doesn't work as it should.

That's not the same as being a variable source of energy. Variability of output from solar PV and wind is expected. Indeed it can be pretty reliably forecasted.
Even they are old and break down, they are way more reliable as solar :)
And ... scalable ! That is a very important point.
They are uneconomic and are causing more harm than good. Coal stations are not nearly as scalable as solar PV and wind are.

And it seems there is too few fast reacting gas plant to stabilize the grid. This one can be replaced by batteries (a good short term solution).
QLD has a new big 100MW battery started up today, and much more is coming on line over the next year of so. It was commissioned in late May and went live on the grid today. Try that sort of ramp up with coal. The Hornsdale battery (Tesla/Musk) went live in under 100 days from the contract signing. It's not actually Tesla's batteries though, they were sourced from elsewhere.

Australia now has 1GW of big batteries on the grid. That is growing rapidly. QLD also has a large pumped hydro system which also stabilises the grid.

The outages from the Callide explosion are still being investigated but it would seem some stuff went awry in other fossil plants that was not supposed to happen.

That pumped storage plant you wrote before will be a huge extra to your grid system.
It will.
 

mrzed001

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Unreliable means it doesn't work as it should.
Unreliable means that the organizer of the grid must make a plan for a day when what big loads will start, rush-hour, when to start and stop specified fast reaction and backup plants, or communicate/control base plants to when throttle them up or down.
The grid built on balance. You can not generate nor less nor more power that is actually needed.
More power generated will bring the grid frequency up, less will bring it down. There is a Hz deviation limit when substations will automatically disconnect from grid to protect customer's equipments.
It is a delicate balance ... like a rope walker between two skyscraper ... and solar is the joker jerking the cable on one end.

I am all about green energy but we must see that it is connected to the grid so it must work as part of the grid ... not against the grid.

That's not the same as being a variable source of energy. Variability of output from solar PV and wind is expected. Indeed it can be pretty reliably forecasted.
A forecast only means that it will produce 60% (for an hour) then 20% (for 3 hours) then 40% (for 2 hours) ....
The problem is that you will need right now 70% ... or you have a lot and need only 20%.
You can not control it. You have no control over it.
Before solar maintaining the grid was much easier. There was a stable hourly plan. Nowadays they need to plan in 15 minutes intervals (with a lot of backup).

They are uneconomic and are causing more harm than good. Coal stations are not nearly as scalable as solar PV and wind are.
But its production is :)

QLD has a new big 100MW battery started up today, and much more is coming on line over the next year of so. It was commissioned in late May and went live on the grid today. Try that sort of ramp up with coal. The Hornsdale battery (Tesla/Musk) went live in under 100 days from the contract signing. It's not actually Tesla's batteries though, they were sourced from elsewhere.
Hornsdale was a huge step for mankind. Big battery (industry) can mostly replace the expensive gas turbine plants and stabilize more the grid.
But to replace the base plants ... not enough.
We made calculations about replacing our 2GW nuclear power plant with solar and big battery.
It would cost more than 4 times the nuclear plant and would need a big chunk of soil to be covered with solar panels.
And even then in the dark winter months could be power shortage.
 

houseofancients

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Elon Musk with Hornsdale created a whole new ... industry.
And this industry is rapidly expanding. GW scale capacity big batteries are under construction.
But even then continuously working base power pants are needed: nuclear, water, coal.
They give momentum to the power with big, heavy and fast rotating parts. Only with them is the grid capable of handling the big inrushes that happen all the time.

The other big problem with renewable is that they are unreliable.
For every GW of renewable you need an another GW of fast reaction coal or gas based power plant. Even big batteries are not enough to get through a stormy week. They are short term solutions and go empty in some hours.

Pumped water and hydrogen (and gravity) plants seems to be the real long term power storage solutions.

I would love to see someone make a cheap solar + hydrogen based (off-grid) residential solution. An almost closed system.
Where you make a lot of power when sun shines, split H2O to H2 + O2, store H2 long term in containers/tanks, and when needed with fuel cells create AC power from it (or DC and store it in battery and from that AC).
I know the round trip efficiency is below 50% with hydrogen and near 90% with pumped water. But pumped water can be done only in big scale while hydrogen can be made and stored everywhere.

I just saw a video where electric race cars where charged in the racetrack with a hydrogen fuel cell generator.
How cool is that :)
you are from poland correct ?

then you of all people should know what happens when nuclear ( for what ever reason) goes south ( chernobyl ? ) , that is not even mentioning storing the waste material..

while "clean" in co2 , not so clean in other ways.
need i remind you a part of robbert oppenheimers speach " now i have become death, the destroyer of worlds" ?

 

wattmatters

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But its production is
Coal production is relatively slow to ramp up/down. Some are better than others.

Meanwhile renewables can be curtailed or brought back online pretty darn quickly (that's the thing with having more renewable capacity than is needed at any time - something you can do when it's so bloody cheap and fast to build), while batteries are responding within milliseconds with their FCAS activity. Gas peaker plants have lost a significant amount of earnings to batteries and can no longer extract exorbitant fees for rapid response any more. The batteries are doing it better, faster, more reliably and for much lower cost.

And grid management isn't just about supply, there is smart demand management as well. e.g. in NSW the Tomago aluminium smelter (which currently draws ~ 850MW) is moving away from steady state coal supply to entirely renewable electricity supply as they rework their plant to produce based on when the energy is available. No longer will it be "baseload demand". That alone is one massive customer at 10-15% of the state's total electricity demand.

South Australia's grid is now at 61% renewables over a full year. There is zero hydro and zero coal. Battery discharging (including Hornsdale) only represented 0.6% of grid supply. Yes they have their contingency gas (and the odd diesel) plants in place if/when needed but it's affordable because the cost of renewables is so good now. Natural gas is their fill in fuel but it's contribution to their grid is dropping like a stone. Amazingly the amount of firming storage capacity required to get to 60% renewables has been bugger all. Their only real reliability problem was caused when major transmission infrastructure got taken out by storms. Much more storage is coming as gas's contribution will continue to decline.
 
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wattmatters

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Here's a chart showing the transformation going on in South Australia over the past couple of decades:

Screen Shot 2021-09-10 at 9.28.32 pm.png

The teal is renewables, dark grey is fossil fuel and the purple is import/export from neighbouring states.

Note also the average wholesale price of that energy.
Renewables @ 2.7c/kWh (US2.0c/kWh)
Fossil supply @ 7.7c/kWh (US5.7c/kWh)
 
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