Solar farm has to switch off every second day due to negative prices • Hacker News Board

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

#121

Post by Scarblac » Thu, Nov 07, 2019, 8:22 AM UTC

JMTQp8lwXL wrote: post #22

manicdee wrote: post #18

Earlier quoted context omitted.

Executive Summary (drastically oversimplified): In a wholesale electricity market we have a market operator who estimates the demand for the near term future and opens the market up to bids for supply. Suppliers bid a certain capacity for each period, with the operator typically accepting firm supply offers, contingency supply offers, and ancillary service offers in advance. Since some suppliers are “baseload” (ie: u…

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?

No, electricity can't be routed to nowhere, that's not how the grid works. The amount produced and the amount used have to stay in balance.

There is a bit of leeway in that turbine power stations will run a little bit slower or faster depending on exact use (resulting in a grid frequency a little bit faster or slower than 50Hz) but the difference has to be made up quickly.

(not an expert, this is badly remembered from Internet articles so probably hurts to read for real experts, I'm sorry. But I hope I got the gist sort of right.)

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

#122

Post by Scarblac » Thu, Nov 07, 2019, 8:25 AM UTC

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.

Those are really capital intensive solutions to a problem that occurs only now and then and might stop entirely if the situation changes a bit. In the meantime, to give people a reason to implement them, there is this market mechanism.

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

#123

Post by jussij » Thu, Nov 07, 2019, 8:26 AM UTC

_AzMoo wrote: post #94

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…

> and my guess is that Australian electricity isn't cheaper on average South Australian electricity is actually some of the most expensive in the world due to incredibly high transmission costs.

Historically South Australia has generally had the most expensive electricity in Australia.

The Australian Energy Minister, Mr Frydenberg has even placed some of that blame on the SA Government's and it's "self-inflicted wounds" on deciding to transition away from coal to clean energy.

However, in the article above has there is a link to this page:

https://reneweconomy.com.au/south-australia-had-lowest-cost-...

which states:

The renewable energy state of South Australia recorded the lowest prices in Australia’s main grid in October, a month when it sourced well over half of its it's electricity supply from wind and solar.

That would suggests that transition to clean energy is working out just fine.

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

#124

Post by Scarblac » Thu, Nov 07, 2019, 8:26 AM UTC

hanniabu wrote: post #89

donw wrote: post #31

Earlier quoted context omitted.

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.

What, how? Increase the voltage and damage people's electronics?

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

#125

Post by ZeroGravitas » Thu, Nov 07, 2019, 8:27 AM UTC

cperciva wrote: post #57

Felz wrote: post #47

Earlier quoted context omitted.

I'm not sure how South Australia works, but I think in general you pay for the cost of electricity generated (here going to zero) AND for the infrastructure required to get it to your house. In part that's why rooftop solar is hazardous for a grid in high amounts- you don't pay the infrastructure price half the time, but the infrastructure still has to be there for you.

Indeed -- so called "net metering" ignores the fact that the costs are driven by both consumption and capacity . Providing a 400A supply to a house is expensive even if you never draw any power, because the utility has to be ready to provide the power.

The reason for net metering (other than it being a cheap hack to take advantage of just rewinding a standard power meter) is that the energy from the houses is valuable to the grid in lots of ways (e.g. in reducing peak generation and transmission demand).

It doesn't ignore those costs you mention, it just also doesn't ignore the benefits. In some jurisdictions the benefit exceed the money the householders are being paid (it varies depending on how dirty the grid is, when peak load happens etc.).

For whatever reason, like negative prices, this attack on net metering appears to resonate well with people who don't like renewables, but it's just a talking point from utilities who see the ability to increase their own profit by taking but not paying for that benefit via political shenanigans.

Apparently the idea that electricity can be differently valuable at different times of the day or year is something that ordinary people are insulated from, so paying an average seems normal, but getting paid an average seems crazy. But it's not something being argued against from a wider economic standpoint of efficiency, as it is literally a good thing, that's why people proposed it in the first place and continue to support it.

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

#126

Post by Udik » Thu, Nov 07, 2019, 8:33 AM UTC

beachy wrote: post #115

Udik wrote: post #102

Earlier quoted context omitted.

When I stop a turbine I'm not simply breaking the circuit- I stop converting some fuel into energy, and keep it for later. If I break the circuit on a solar panel, the "fuel" keeps hitting the panel anyway. I guess the panel just reaches a different thermal equilibrium. Which is the same as dumping the energy in the ground, only more distributed.

According to this https://physics.stackexchange.com/a/71445 : > Electric power is the product of voltage and current. If there is no external circuit, there can be no current and thus no electric power can be delivered by the panel, i.e., the "electricity" is never developed and thus, there is no need to consider "where it goes". There's also an interesting discussion in the linked post in more depth about electron h…

Thanks for the find! The second comment to the first answer says:

"The equilibrium temperature of the connected panel should be slightly lower than the disconnected panel, because those hole recombinations introduce heat. But the efficiency is only something like 12% to begin with. So the temperature difference isn't like the difference between a white and black surface. More like the difference between a dark and slightly darker surface"

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

#127

Post by james_s_tayler » Thu, Nov 07, 2019, 8:34 AM UTC

JMTQp8lwXL wrote: post #22

manicdee wrote: post #18

Earlier quoted context omitted.

Executive Summary (drastically oversimplified): In a wholesale electricity market we have a market operator who estimates the demand for the near term future and opens the market up to bids for supply. Suppliers bid a certain capacity for each period, with the operator typically accepting firm supply offers, contingency supply offers, and ancillary service offers in advance. Since some suppliers are “baseload” (ie: u…

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?

If I remember correctly there are rules that the estimated demand and actual generation have to match pretty closely and the overage can only be within a few percent tolerance. You're not allowed to just generate electricity that there isn't demand for.

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

#128

Post by Scarblac » Thu, Nov 07, 2019, 8:35 AM UTC

thaumasiotes wrote: post #52

duckymcduckface wrote: post #38

Earlier quoted context omitted.

The ground is a poor load and also there's a finite amount of energy you can dump into it because every watt that goes in gets turned into heat, you'd liquify the ground very quickly at the multi MW scale.

We routinely dump lightning bolts right into the ground and they go well beyond multiple megawatts. They're very brief, but if lightning took ten seconds to strike, it would still provide several dozen megawatts of power. How quickly would we be melting the ground at the multi-MW scale? How many lightning bolts would it take before the ground around my house melted and flowed downhill?

Lightning bolts do in fact melt the ground (see fulgurite), and they take at most about 0.2 seconds.

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

#129

Post by [deleted] » Thu, Nov 07, 2019, 8:39 AM UTC

Iv wrote: post #103

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?

If you suppose a well-designed grid, I really doubt that free electricity is something that clients would refuse. Electricity is valuable, at any time of the day. There is no reason for it to go below zero. Sure, storing energy is hard but spending it is easy. Hell, give me free electricity and I will be running a pyrolysis rig, making biofuel for free.

[deleted]

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

#130

Post by s1artibartfast » Thu, Nov 07, 2019, 8:39 AM UTC

g82918 wrote: post #2

It seems almost silly that we can generate more energy than we can use some, but not all of, the time.

Inconsistency has been the known challenge of renewable for decades.

You also need to duplicate the entire energy production infrastructure so that we can operate on 100% fossil fuels if the wind isnt blowing and the sun isnt shining.