Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

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

reneweconomy.com.au

Post reply on HN
Print view View original

81–90 of 191 posts

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

#81

Post by Udik »

viraptor wrote: post #27
JMTQp8lwXL wrote: post #22

Earlier quoted context omitted.

Why do they have to pay someone to take the electricity? I could take a dollar bill and rip it in half (perhaps not legally, but besides the point). I understand there's costs to shutting down a system. So, they might keep it running. But what I don't get: the electricity producer has to pay someone to take the excess electricity off their hands? The producer can't route the excess to, well... nowhere?

Not at that levels of output. With large enough machines it's "we're going to spend X to spin everything down, do maintenance checks, spin back up" vs "we're going to pay you X/2 so you take the output and we can keep going". The X may be spent on extra workers, on extra maintenance, on replacement for posts that wear out faster, etc. It's the cost of unusual operation. And once you're generating there's no great way…

This makes me wonder how do you stop generating with a solar farm that is made of PV panels. They're entirely passive, right? The light hits them and they output electricity. How do you stop them?

I guess the process is somehow invertible, and once reached a certain static charge each panel stops absorbing energy?

In which case you're sort of already dumping the (non)produced energy in the environment- as heat, on each single panel?

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

#82

Post by [deleted] »

donw wrote: post #31
JMTQp8lwXL wrote: post #22

Earlier quoted context omitted.

Why do they have to pay someone to take the electricity? I could take a dollar bill and rip it in half (perhaps not legally, but besides the point). I understand there's costs to shutting down a system. So, they might keep it running. But what I don't get: the electricity producer has to pay someone to take the excess electricity off their hands? The producer can't route the excess to, well... nowhere?

I'm going to hazard a guess. If we assume the numbers for a sort of medium-size nuclear plant, we've got a total power generation of 500MW. Dumping that kind of power is... hard. If I haven't missed an order of magnitude, that's enough to boil an Olympic-sized swimming pool in about 25 minutes (500MW to boil 2.5ML of water, assuming STP). So you'd either need to build and maintain the infrastructure to burn that kind…

[deleted]

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

#83

Post by Terretta »

JMTQp8lwXL wrote: post #6

An explanation of the mechanics of how I'd have to pay somebody else to take my electricity (e.g., a negative rate) would be helpful. As prices approaches 0, I could take the excess electricity and say, mine cryptocurrency. Is nobody considering the arbitrage opportunities here? Take the 0-cost electricity, move water up a hill, and convert it back to electric when it's needed, etc.

> convert it back to electric when it's needed

FTA: "Tailem Bend is also considering a battery storage..." and links to https://reneweconomy.com.au/tailem-bend-solar-farm-officiall... which adds "Vena Energy also has plans for a Tailem Bend Battery Energy Storage Project."

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

#84

Post by iknowalot »

solotronics wrote: post #58
apendleton wrote: post #17

Earlier quoted context omitted.

Anything you could do it with it would have capital costs. Maybe it's transient enough that that money would be better invested elsewhere. Like, if you only run your cryptocurrency mining when the price is negative, your capital is stuck in an idle asset most of the time, and if you run it all the time, it's the average price you want to consider, not the minimum price (even if the minimum price is negative), and my…

There are older bitcoin ASIC miners that aren't nearly as efficient but if you are getting totally free electricity... definately an opportunity here.

Yea shutting off anything that is producing free electricity to keep a market price stable is moronic....

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

#85

Post by Gibbon1 »

Aperocky wrote: post #10
rosege wrote: post #7

Earlier quoted context omitted.

Yeah I had thought surely they can find a use for free electricity rather than just turning it off

Free electricity that turns off half the time and run basically randomly for the other half? Without a battery it’s useless, and you have to pay for that battery. Treating the electric grid as a battery shouldn’t be free. It’s just in this case they found the cost of battery to be greater than the value of the electricity they’re creating.

I keep coming back to electrowinning iron. When I search for papers it looks like people have started working on it again in the last ten years. I think it's not particularly high tech. Intermittent tolerant and scalable.

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

#86

Post by nabla9 »

JMTQp8lwXL wrote: post #6

An explanation of the mechanics of how I'd have to pay somebody else to take my electricity (e.g., a negative rate) would be helpful. As prices approaches 0, I could take the excess electricity and say, mine cryptocurrency. Is nobody considering the arbitrage opportunities here? Take the 0-cost electricity, move water up a hill, and convert it back to electric when it's needed, etc.

It happens when high inflexible power generation meets low demand. Some power sources can’t be shut down and restarted in a quickly and cost-efficiently. If the cost of stopping and restarting their plant is higher than the costs of selling energy at a negative price for some time, prices go negative.

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

#87

Post by perilunar »

stOneskull wrote: post #40
nl wrote: post #20

Earlier quoted context omitted.

In SA there are some pump-hydro storage projects in the pipeline which should smooth out some of these variations.

Good stuff. I was wondering if maybe a desalination plant could work..

Adelaide has a desal plant. It was even in the news today: https://www.abc.net.au/news/2019-11-07/how-will-the-sa-desal...

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

#88

Post by zwaps »

Iv wrote: post #74
JMTQp8lwXL wrote: post #6

An explanation of the mechanics of how I'd have to pay somebody else to take my electricity (e.g., a negative rate) would be helpful. As prices approaches 0, I could take the excess electricity and say, mine cryptocurrency. Is nobody considering the arbitrage opportunities here? Take the 0-cost electricity, move water up a hill, and convert it back to electric when it's needed, etc.

tl;dr: the Australian grid is working on a faulty system because of politics. This is not a technical limitation there.

There are economic involved. Long term, it pays to have many variable load generation in the grid, because they are cheap and environment friendly.

But a net needs to be handled exactly to match supply to cost, and demand has a large random component that no-one foresee perfectly.

Hence, negative prices are a normal feature of balancing demand and supply, which is a technical necessity not to have black-outs and brown-outs or, in this case, damage expensive base-load powerplants during emergency shut-downs.

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

#89

Post by hanniabu »

donw wrote: post #31
JMTQp8lwXL wrote: post #22

Earlier quoted context omitted.

Why do they have to pay someone to take the electricity? I could take a dollar bill and rip it in half (perhaps not legally, but besides the point). I understand there's costs to shutting down a system. So, they might keep it running. But what I don't get: the electricity producer has to pay someone to take the excess electricity off their hands? The producer can't route the excess to, well... nowhere?

I'm going to hazard a guess. If we assume the numbers for a sort of medium-size nuclear plant, we've got a total power generation of 500MW. Dumping that kind of power is... hard. If I haven't missed an order of magnitude, that's enough to boil an Olympic-sized swimming pool in about 25 minutes (500MW to boil 2.5ML of water, assuming STP). So you'd either need to build and maintain the infrastructure to burn that kind…

> 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.

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

#90

Post by qtplatypus »

mcv wrote: post #79
flukus wrote: post #64

Earlier quoted context omitted.

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.

So use the energy to pump the water to where it is needed. Use it to generate hydrogen or methane or something to sell as fuel. Mine bitcoin even. It seems weird and wasteful to just shut off free energy.

One of the projects is to build an interconnect to the snowy mountains. When this happens the power can be used to pump water up hill to fill the hydro electric dams.
Post reply on HN