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Solar farm has to switch off every second day due to negative prices

reneweconomy.com.au

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Re: Solar farm has to switch off every second day due to negative prices

#151

Post by Reason077 »

ryan_j_naughton wrote: post #142
ZeroGravitas wrote: post #80

I'm not a fan of most reporting of these negative price events. First, they rarely explain why the price is negative. As the article explains, solar can switch itself off, so it's nothing physical about solar that can cause negative prices, as all solar can switch itself off before it goes negative it would bottom out at zero for those reasons. In most cases I've seen so far, contractual agreements with gas, coal or…

I agree. Negative prices make perfect sense in electricity markets, and journalism does a bad job at explaining it. Supply and demand must always be in equilibrium in real time with electricity (forgetting storage / batteries for a second). If there is more supply than demand or vice versa, then you have instability in the grid and can have blackouts. Those electrons have to go somewhere. This is in contrast to virtu…

> "combined cycle natural gas plants can turn on and off very quickly"

Response/ramp times for CCGTs are not particularly quick. Typically they need 15 minutes notice to initial grid synchronisation, a further 60-80 minutes to reach full power output from a "warm" start, and up to several hours from a "cold" start. That's much better than coal-fired plants which need many hours of notice, but still likely to be too slow to respond to unexpected grid imbalances without additional support.

Natural gas "peaker" plants typically use less-efficient but faster responding OCGTs for that reason.

Re: Solar farm has to switch off every second day due to negative prices

#152

Post by ourlordcaffeine »

brownbat wrote: post #4

Storage is definitely the wise answer here, as the article mentions. The fun answer here is giant crypto farm.

An answer that no-one seems to have thought of is a liberalized energy market where non physical traders are allowed, and allowed to deliberately take themselves to imbalance.

Re: Solar farm has to switch off every second day due to negative prices

#154

Post by Dylan16807 »

eecc wrote: post #72
steve19 wrote: post #15

Earlier quoted context omitted.

The grid has to finely balance supply and demand. You can't just dump power into the grid. If you did the grid frequency would increase out of spec and it could damage connected equipment and machinery. Water storage would only work if there is a steep mountain or big hill nearby. Another way to look at negitive pricing is the grid is paying industrial users to burn as much power as they can.

Hmm has anyone experimented with variable frequency transmission and solid state frequency synthesizing power transformers?

So you might be able to increase all the turbines from 50 to 70. That will absorb the excess power for a moment. Then you're maxed out and still need to shed just as much power as before.

So it doesn't help in any significant way, you have to set up a more complicated grid with very expensive transformers, and it requires you to design all your turbines to be twice as strong.

Re: Solar farm has to switch off every second day due to negative prices

#155

Post by nl »

cperciva wrote: post #59
nl wrote: post #46

Earlier quoted context omitted.

How? Or was that meant ironically? Desalination plants use a lot of power, but it's not obvious to me how to use it to store power.

The idea there isn't that you store power but rather that you only run the plant when power is cheap (and then keep a large enough fresh water reservoir to serve demand until the next cheap electricity arrives). Demand management rather than supply management, effectively.

Yeah, the problem is that it's not easy to store very large amounts of water (at least not near where the Adelaide Desalination plant is).

I believe they can pump the water up into the hill, so I guess it's not entirely out of the question.

Re: Solar farm has to switch off every second day due to negative prices

#156

Post by Reason077 »

Dylan16807 wrote: post #147
ZeroGravitas wrote: post #80

I'm not a fan of most reporting of these negative price events. First, they rarely explain why the price is negative. As the article explains, solar can switch itself off, so it's nothing physical about solar that can cause negative prices, as all solar can switch itself off before it goes negative it would bottom out at zero for those reasons. In most cases I've seen so far, contractual agreements with gas, coal or…

> In most cases I've seen so far, contractual agreements with gas, coal or nuclear (who struggle to switch themselves off quickly without hurting themselves) have been the reasons for negative pricing and the grid wasn't actually at 100% renewable at the time of the curtailment. In other words, solar switches itself off, while other, dirtier plants get fined (negative price!) for demanding that they be allowed to sti…

> "No contracts or fines are necessary. The plant is making the power ... So they pay for it to be disposed of."

They only pay if they are selling into the market at the market rate. Often, large operators will have some or all of their output contracted to buyers at a fixed contractual rate, so they are not affected by negative prices.

Re: Solar farm has to switch off every second day due to negative prices

#157

Post by Dylan16807 »

perilunar wrote: post #93
synchro77 wrote: post #77

Earlier quoted context omitted.

I'm not sure I understand, in what system would this not happen? You can say that the goverment should store the extra electricity but that's not as easy as it sounds. Most things need very specific geographical or technical conditions for pumped hydro, compressed air energy storage, boreholes, hydrogen, molten salts. So in what system wouldn't this happen?

> in what system wouldn't this happen? In any system designed by half-competent engineers, instead of by politicians who hate renewable energy for ideological reasons.

Be specific. How would it work differently? (Assume the designer of the system is trying to deliver reliable power without wasting a lot of money.)

Re: Solar farm has to switch off every second day due to negative prices

#158

Post by iguy »

Iv wrote: post #132
iguy wrote: post #114

Earlier quoted context omitted.

No, it's not always valuable. If you get free electricity for an hour, some days of the week, then your giant biofuel plant spends a lot of time sitting idle. It's not obvious that your mostly-idle plant is a better business than a much smaller one which runs all the time. The costs of building and maintaining the thing are real too. (Not to mention needing to design the plant to ramp up to full production in minutes…

> It's not obvious that your mostly-idle plant is a better business than a much smaller one which runs all the time. This process is usually not profitable because of the energy cost it requires. This is why I am proposing it as a way to absorb energy surplus. But I am only talking about what would happen if you got electricity at zero cost. At negative costs, even crazier things would happen. The reality, is that, t…

"dissipate heat in well ventilated radiators": you've just invented a https://en.wikipedia.org/wiki/Cooling_tower , often the largest building at a power plant.

Re: Solar farm has to switch off every second day due to negative prices

#159

Post by 7thaccount »

Reason077 wrote: post #156
Dylan16807 wrote: post #147

Earlier quoted context omitted.

> In most cases I've seen so far, contractual agreements with gas, coal or nuclear (who struggle to switch themselves off quickly without hurting themselves) have been the reasons for negative pricing and the grid wasn't actually at 100% renewable at the time of the curtailment. In other words, solar switches itself off, while other, dirtier plants get fined (negative price!) for demanding that they be allowed to sti…

> "No contracts or fines are necessary. The plant is making the power ... So they pay for it to be disposed of." They only pay if they are selling into the market at the market rate. Often, large operators will have some or all of their output contracted to buyers at a fixed contractual rate, so they are not affected by negative prices.

Also, they're hedged with the day ahead price.

Re: Solar farm has to switch off every second day due to negative prices

#160

Post by 7thaccount »

ZeroGravitas wrote: post #80

I'm not a fan of most reporting of these negative price events. First, they rarely explain why the price is negative. As the article explains, solar can switch itself off, so it's nothing physical about solar that can cause negative prices, as all solar can switch itself off before it goes negative it would bottom out at zero for those reasons. In most cases I've seen so far, contractual agreements with gas, coal or…

So as awesome as the wind production tax credits are in creating many GW of wind power (in the US at least), it did result in many wind farms being able to submit offers that are artificially low. That lowers price signals for everyone else too and causes market distortion.
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