For anyone thinking negative prices is a good thing: It's not. It's a panic signal because there are no takers for an oversupply of energy, making the grid unstable.
The grid is not unstable and it was also not unstable the last view days when prices were negative. Germany has one of the most stable grids in the world. Negative prices are good when you need to buy electricity and they are bad when you are selling, but of course generally in a functioning market there shouldn't really be too many days with negative prices. It does mean that there isn't enough storage currently on the grid.
Sure, and negative prices will send a strong signal to the market to hurry up with adding storage. So, this will probably be more of a temporary situation and in the future there will be very few days with negative prices, however there will then also be fewer days with very high prices.
Now what we need is a cheap grid interconnect for home users running solar panels that automatically starts charging a battery when grid prices go negative, to absorb that extra power.
Yeah, the curtailment is a simple way to deal with instability. I wonder who chooses which power plants should curtail their output. The Bundesnetzagentur?
The plants that are willing to give supply for the most negative price are the ones that will not be curtailed. So market forces. Basically at such points power plants are paying for the privilege to be allowed to supply power. This is dominated by restart costs and as such is often paid by classic "baseload" plants such as nuclear ones. i.e. they will accept losing money during one part of the day/week so that they can make money during a different part of the day/week.
Yes, and no, maybe ;) the economic incentives are designed to always provide enough power and no more at the cheapest possible point for that time slot. The market (if free enough) searches for that point over time. One possible solution may be peaker plants (this was financially so in the burn fuel age) another maybe overbuilding (e.g. your home backup or off-site generator power that are sized at peak load/demand, not the actual demand). All constrained by what is physically possible on a grid.
Peaker plants gamble that there are going to be peaks (sure financially plan for but they are not guaranteed to make their profits).
In the peaker plant categories the storage options are different from the spin options because the incentives are slightly different. Specifically battery storage is not just a peak plant exercise it is a grid connection optimization exercise. Grid connections limit how much power one can sell from a generator. A battery system can be placed on the grid or between the grid and the generator. In the case of between grid and generator, it allows a generator to run at it's optimal speeds more often than not, and sell more because one can guarantee a wider range of output for a longer amount of time.
Some of the first battery storage systems were sold to gas peaker plants because it allowed them more time to react. i.e. idle at a more efficient level their gas turbines or even shut them off and start them on demand.
The grid is not unstable, Germany has a gigantic amount of batteries, flywheels, and giant resistors that can soak up the power, and is able to order wind farms and solar producers to curtail production if its still too much for the grid. Contrary to what a lot of folklore about Germany's grid suggests, these investments in stability are actually the primary reason Germany's electricity is so expensive compared to a lot of other countries
This is all actually beneficial. It creates real economic pressure for just about everyone to build and install more batteries everywhere to profit from the price swings.
Most importantly, it motivates the wind and solar producers to buy up batteries and install them on site, so that they can shift the times where they sell power to the grid to times of day where its more profitable.
For anyone interested, the dynamics are something like:
1) Commercial entities generally try to sell their products for a profit (positive price).
2) Negative prices make this quite hard.
3) To get back into positive profit, they're going to need to charge a higher price later on.
There are 3 ways the overall market can go if prices are negative - either prices go positive at some other time to make up for the losses the power providers are making, someone figures out a use for the free power and the price stops going negative or power providers go out of business. Typically what this seems to result in for renewable-heavy grids is occasional (even regular) negative wholesale prices and some impressively high retail prices. Free electricity turns out to be very expensive; it shows the grid isn't coping.
Yes, and that is in fact done. However, there it is still a bad deal with negative electricity prices.
> Isn't cheaper electeicity a good thing for the manufacuring industry?
It technically is, but its not as simple as that. Industrial manufacturing is a relatively steady load, which means the consumption is constant. The lowest prices do not matter all that much, the average price does. And that average price is relatively high here, even for industrial consumers.
Negative prices generally indicate that the transmission connections are already saturated: as much energy as possible (or financially/technically acceptable to the third parties) is already being exported.
Transmission capacity and interconnectors are usually the bottlenecks.
> Heck you could build some large bodies of water and boil them from time to time.
Some suppliers already do that. When a power plant also supplies the city heating, it makes sense for them to put the power surplus into pre-heated water which they can store and later distribute to the buyers of the heat.
Obviously this needs some huge and well insulated tanks.