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

131–140 of 191 posts

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

#131

Post by Scarblac »

GhostVII wrote: post #33
robjan wrote: post #19

Earlier quoted context omitted.

If the grid were smarter it could schedule demand for the excessive production times. It could be used, for example, in render farms or other non-time-critical high load batch operations.

Some places have flexible pricing, where electricity costs more at certain times, which allows users of electricity to do this. I don't think it should be the grids responsability to do that kind of scheduling. It would be nice if everywhere we had some kind of hourly pricing adjustment that would fluxuate within some predefined price range, then you could hook into the grids api to determine when to run your applian…

That's exactly what this is, but at the wholesale level. The price is so flexible that it sometimes goes negative.

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

#132

Post by Iv »

iguy wrote: post #114
Iv wrote: post #103

Earlier quoted context omitted.

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.

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, to my knowledge, the Australian grid does not "sell" electricity for negative prices, it only "buys" it. If it were to pay clients to absorb electricity, I would just dissipate heat in well ventilated radiators, make a ton of steam, and make a show of giant tesla coils. Radiators can be made out of scrap metal, it really is a small investment that can lie dormant at no cost if negative electricity prices only happen 5% of the time.

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

#133

Post by emirp »

lazyjones wrote: post #120

Buy some Tesla Megapacks, install some DC fast chargers on-site and sell electricity for 0.2$/KWh or so all day long.

https://www.abc.net.au/news/2018-04-06/tesla-battery-outperf...

"The world's biggest lithium-ion battery — built by tech billionaire Elon Musk's company Tesla last year — has survived its first summer in South Australia's mid-north."

"And according to a new report by the Australian Energy Market Operator (AEMO), it's outperforming coal and gas generators on some key measures."

"AEMO says the Hornsdale Power Reserve is capable of charging at a rate of 80 megawatts and discharging at 100 megawatts."

"It has a storage capacity of 129 megawatt hours."

"That means it could operate for about 75 minutes at full capacity."

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

#135

Post by steve_gh »

manicdee wrote: post #18
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.

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…

And what happens when a solar farm goes bankrupt? Its major operating overhead is servicing the loans for the initial capital cost. So all that will happen is that the bank will take possession of the solar farm. It will still be producing cheap power, and it will now be owned by an organisation with very deep pockets!

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

#136

Post by emirp »

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…

What you're describing is known as a smart grid in the industry (https://en.wikipedia.org/wiki/Smart_grid).

I can't speak for other countries but Australia has quite a few initiatives for progressing toward a smart grid but it simply takes time.

Here is some info:

https://arena.gov.au/projects/?project-value-start=0&project...

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

#137

Post by taneq »

iguy wrote: post #110
taneq wrote: post #39

Earlier quoted context omitted.

1. Energy can neither be created nor destroyed. In practical terms the energy has to go somewhere. Maybe they could build massive dump resistors to burn off the energy that way but doing so would only increase load on everything (shortening component lives) for no gain.

Those giant cooling towers that are most people's image of a power station are almost exactly this. They are a giant system for dumping heat into the air, usually (but not always) by evaporating water. (The heat being dumped is usually low-temperature waste heat, not final output.)

Those giant cooling towers are pretty expensive and the water to run them can cause significant damage to the local ecosystem if it raises the temperature of whatever water body they draw from. It's a lot easier to just turn off the energy sources (such as solar) that can be turned off without ill effect.

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

#139

Post by zAy0LfpBZLC8mAC »

coin wrote: post #54
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.

How does excess electricity impact the frequency?

It's not really excess electricity, but excess energy, and it's an artefact of how traditional power generation works: You generate electricity by creating rotation and using that rotation to drive a generator. Now, it's basic physics (conservation of energy) that if you add energy into a rotating system, it will spin faster and faster with every bit of energy you add, because the energy is transformed into kinetic energy of the rotation. The only way to prevent that speeding up of the rotation is to take energy out of the system--which, in the case of an electric generator you would usually do by connecting it to an electric load, i.e., the grid. But if demand is too low, you are removing energy from the rotation at a lower rate than it is added back from the mechanical drive side, so the net energy in the rotation increases and thus the speed of the rotation increases and thus the frequency of the electricity output increases.

Essentially, electric load is what brakes electric generators, if you take off the brakes but keep the motor running, they'll speed up.

Post reply on HN