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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

#181

Post by akvadrako »

_ph_ wrote: post #172
zaarn wrote: post #166

Earlier quoted context omitted.

The thing about a coal, gas or nuclear plant is that they can't switch off as fast as solar. Solar can switch off in the span of a microsecond without much of an issue. A coal/gas/nuclear plant might actually need the entire day to shut down operation to 0 kW output. And probably needs a day to get back to full operation. So in cases of negative prices, a solar energy producer can do the sensible thing and switch off…

Coal and nuclear plants are slow to switch off, but gas plants are usually reasonably fast.

Only the less efficient "peaker plants".

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

#182

Post by redblacktree »

_ph_ wrote: post #174
tremon wrote: post #167

Earlier quoted context omitted.

some supply simply cannot reduce quickly (e.g. nuclear) What is it about nuclear that makes it impossible to reduce as fast as gas or coal? From my layman's point of view, they all use comparable (steam) turbines to power the actual generators, so I would expect them to be equally capable of disengaging the generator from the turbine. Is this perhaps due to design decisions, or simply a size problem? A foolish questi…

The nuclear part of the reactor is slow to react to control input. Even when completely switched off it produces hundreds of megawatts of thermal energy. This is what doomed the Fukushima reactor. After the earthquake it was technically switched off, but required a lot of cooling as the nuclear reactions continue to go on even with the control rods completely extended. But with the failure of the power supply there w…

I don't think you answered the question. The way I read it was "Why can't the nuclear power plant simply vent the steam they create instead of turning turbines with it?" In order to switch off power generation, even if the reactor is still creating thermal energy.

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

#184

Post by _ph_ »

redblacktree wrote: post #182
_ph_ wrote: post #174

Earlier quoted context omitted.

The nuclear part of the reactor is slow to react to control input. Even when completely switched off it produces hundreds of megawatts of thermal energy. This is what doomed the Fukushima reactor. After the earthquake it was technically switched off, but required a lot of cooling as the nuclear reactions continue to go on even with the control rods completely extended. But with the failure of the power supply there w…

I don't think you answered the question. The way I read it was "Why can't the nuclear power plant simply vent the steam they create instead of turning turbines with it?" In order to switch off power generation, even if the reactor is still creating thermal energy.

That could possibly done, but then, no one had created such a design yet. It is also not trivial to cool in the gigawatt range. Actually, many power plants even run into cooling issues in some time of the year, as they often rely on local rives to provide the cooling and the water supply as well as maximum water temperatures (animal and plant live) limit their cooling capacity in normal operations.

In Belgium there were even streetlights being installed along all highways to use up nuclear energy when the grid was not consuming it.

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

#185

Post by mhandley »

jabl wrote: post #175
Dylan16807 wrote: post #164

Earlier quoted context omitted.

How much money does it cost to build this out to every house, compared to what it saves? And do people want their electricity prices to vary over the day? If you have a lower cost part of the day then you have to charge more the rest of the time, all else equal.

These spot price contracts for end users do exist in many places (don't know about SA specifically). They haven't been particularly popular; I guess most people are scared about the other side of the coin, will I accidentally drain my bank account if I do my laundry when prices are at the roof limit?

It probably works best when you only have some sockets in a home that are on spot price contracts. And on those sockets, you have plugged in a washer/freezer/AC that is smart enough to receive spot price information and turn on and off as prices rise or fall. We're not quite there with all the pieces of the puzzle, but it's all technically possible now and likely much cheaper than using batteries to load-shift.

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

#186

Post by hanniabu »

teraflop wrote: post #105
hanniabu wrote: post #89

Earlier quoted context omitted.

> Dumping that kind of power is... hard. Why not route it to a nearby neighborhood? It's free it doesn't matter if a lot is lost in transmission and you don't need to pay somebody to take it.

Because that nearby neighborhood already has enough power being generated to meet its demand. You can't just send the power somewhere without either increasing demand or reducing other suppliers.

> reducing other suppliers

This would be the case, what's wrong with this? It's better than paying people to take your electricity and isn't this how business works? I don't see why they shouldn't be able to increase supply (And hence reduce other suppliers) just because it would ruin the profit margins of others. Unless there's something I'm missing here or not following correctly.

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

#187

Post by ourlordcaffeine »

oxinabox wrote: post #163
ourlordcaffeine wrote: post #152

Earlier quoted context omitted.

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.

To be clear: this is literally what the US has. I suspect @ourlordcaffeine knows this, but for anyone else reading it.

UK as well

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

#188

Post by jillesvangurp »

ThrustVectoring wrote: post #117
jillesvangurp wrote: post #100

The solution is to deregulate the market and allow multiple companies to buy and sell electricity. The problem here is not an over supply but poorly regulated demand that causes energy to be priced higher than is justified; mainly to protect expensive sources of energy such as coal and gas plants. The basic issue is not that there is no demand but that it is unevenly spread. People turn on their ACs when they get hom…

Your analysis completely ignores the capital costs associated with building out a variable demand system. Every battery built will tie up a certain amount of money into fixing grid pricing variability, as well as depreciate in value and usefulness over time. If electric overproduction is an infrequent enough condition, it may well be cheaper to waste energy than to build a battery that just sits there 300+ days a yea…

Capital cost vs. captial gains is what normally dictates these things except we are talking about effective monpolies where the monopolist is protecting their prior investments and can choose to deny access to the market for everyone else. It's basically forcing consumers to help them turn a good ROI on already obsolete investments that should rightfully be killed ASAP otherwise.

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

#189

Post by donw »

flukus wrote: post #64
peteretep wrote: post #50

Earlier quoted context omitted.

> that's enough to boil an Olympic-sized swimming pool in about 25 minutes This is in a country that — as I understand it — could definitely do with more desalinated water. How capital intensive can putting a huge kettle element in the sea with something to catch the vapour be?

More desalinated water would be handy, but typically it's not needed anywhere near the salt water and where it is needed more electricity isn't.

But can't those plants just pull from the (now cheaper) power on the grid?

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

#190

Post by jillesvangurp »

ThrustVectoring wrote: post #117
jillesvangurp wrote: post #100

The solution is to deregulate the market and allow multiple companies to buy and sell electricity. The problem here is not an over supply but poorly regulated demand that causes energy to be priced higher than is justified; mainly to protect expensive sources of energy such as coal and gas plants. The basic issue is not that there is no demand but that it is unevenly spread. People turn on their ACs when they get hom…

Your analysis completely ignores the capital costs associated with building out a variable demand system. Every battery built will tie up a certain amount of money into fixing grid pricing variability, as well as depreciate in value and usefulness over time. If electric overproduction is an infrequent enough condition, it may well be cheaper to waste energy than to build a battery that just sits there 300+ days a yea…

It doesn't ignore it but the premise of capital cost is that it then gives you access to potential gains. That breaks down if you are dependent on selling to a monopolist that sets prices based on their own needs rather than the market needs. In this case, local energy providers get protective about their more costly infrastructure when faced with homeowners supplying cheaper energy to the point where they charge negatively.

Right now the power market is weird because people are deliberately installing less solar than they need/want because their local energy providers are simply refusing to buy the excess energy beyond a certain number of kwh. And since they are the only party you could feasibly sell to, a lot of homeowners simply install less capacity.

Think about it, you've got engineers on the roof to install solar panels, wires, inverters, etc. and the panel cost is only a small portion of the overall cost. Why would you cap your installation at 4kwh when your needs are closer to 10 kwh and you have room for 20 kwh? That's exactly what's happening in a lot of places.

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