Thread: Grid can go 75% renewable

We briefly hit 57% renewable energy at the weekend, which is significant, but there is still a long way to go.

Solar power in Australia outstrips coal-fired electricity for first time | Energy | The Guardian

So tell me how the solar generators make money by "being more nimble" when prices turn negative.
That means they make a loss.

Regards PhilipA

That’s like saying I ran at 80km/h. For the first 15mm

My PV array does some great output during edge effect cloud. It’s not sustained very often

Because solar and wind are cheaper when the sun is shining and the wind is blowing. Coal can't compete on price at those times without selling power at a loss.
As for nimble, you can't just switch a coal generator on or off.
'Baseloard power' is not the minimum grid demand. Baseload power actually means the minimum level coal generators can operate at. Below that, they have to shut down for long periods.
So, that means when solar and wind are cheaper, coal generators still have to keep operating at their minimum baseload level, even though their electricity is too expensive and they are losing money. So they are not nimble.

Originally Posted by PhilipA

So tell me how the solar generators make money by "being more nimble" when prices turn negative.
That means they make a loss.

Regards PhilipA

Because solar and wind are cheaper when the sun is shining and the wind is blowing. Coal can't compete on price at those times without selling power at a loss.

You have not answered the question.

The problem is the "duck curve" where most solar is generated when nobody wants it ,so the power has to be sold by the solar generators at a loss or even pay others to accept their power..

It is some of this excess that the government wants to harness to produce Hydrogen.

BUT the simple question still is how do they make money when selling at a loss.

We all know that Coal power stations are slow to spool up , but they supply power at night which has now been recognised by the Government in their latest proposed rule change.

The more solar the bigger the problem, and that is why California is now building some new gas plants, even when they can buy power from other states.
Regards PhilipA
BTW AFAIK you cannot turn solar off when there is too much generation unless you have a bloke with a lot of blankets, so how is it "nimble"

Originally Posted by PhilipA

...........
BUT the simple question still is how do they make money when selling at a loss.

We all know that Coal power stations are slow to spool up , but they supply power at night which has now been recognised by the Government in their latest proposed rule change.
......

I think you are missing the point - a solar power station is not "losing" when it cannot supply to the grid; the output is simply switched off - it does not have to 'go' anywhere. Almost all the cost of "running" a solar power plant is capital cost, which is still being incurred even if the station is not supplying power, so the cost of capital when shut down is spread over the power produced when it is supplying. This calculation is taken into account in designing the business model of the plant.

Fossil fuel plants also have capital cost, but in addition have as their major cost, the cost of fuel, and the cost of this per kwh sold can easily exceed the market price when there is plenty of supply or when they have to operate at low outputs resulting in lower thermal efficiency. And if they shut down to avoid this cost, a lot of fuel is expended during shutdown and restart. You cannot simply switch off the output of a fossil fuel plant - it will almost certainly cause catastrophic damage (less likely with a gas turbine, but these are not particularly efficient at best). The business model of fossil fuel plants generally only envisages shutdowns for the minimum necessary for maintenance. If you tried to design a business model for a fossil fuel plant that is only used part of the time, you are looking at a "peaking" facility, usually gas turbine, and intended only to be used when the price is abnormally high.

I think you are missing the point - a solar power station is not "losing" when it cannot supply to the grid; the output is simply switched off -

No, i am not missing any point.

If what you say is true , how come solar prices go negative?

You must understand that these are competing companies and nobody wants to "blink" first. They all want to keep producing until an oversupply and negative prices happen, then one or several may blink.

So if it is a liability for coal stations to have to buy fuel, lets see the solar producers supply at night.

The only way is with batteries or maybe pumped storage.

Everything I have seen is that such batteries would cost hundreds of Billions, making coal input prices trivial in comparison. Pumped storage is very inefficient and costly also.

You must understand this in the context of this thread. 75% renewable is a dream by demented greenies who do not care how much electricity costs or the economic outcomes as long as their purity is unsullied.
Regards PhilipA

What John said.

In the national energy market, generators bid to supply specified amounts every 30 minutes.
If a solar or wind company's bid is not accepted, it simply does not supply. The fuel cost is nil.
If a fossil fuel company's bid is not successful, it has to either continue operating at a loss, consuming fuel, or shut down, at considerable cost.
Keep in mind also that many generators also have long-term contracts with companies and other big consumers including governments to supply at a fixed price, which is obviously profitable for the generator or it wouldn't sign up.
Also, re batteries, the SA Tesla battery is making healthy profits and can supply cheaper than fossil fuel generators at any time, day or night, which is why many other batteries are happening.
The situation is changing and new ways of thinking are needed.