Can someone explain why you would ever pay someone to take surplus power? Is it because they don't want it To go to waste? Otherwise can't they just get rid of it somehow?
It's not a steady supply over power, it fluctuates with your supply and demand for it, so it takes work for another grid to take that power from you. If you send them power they have to scale their plants down to prevent the problem you're having. Then when your supply goes down and you no longer have an excess of power to send they have to scale their systems back up to make up for the power you're no longer sending. They can't store it or get rid of it easily. It's one of the reasons people don't like wind and solar power, it works great when the wind is blowing and the sun is out, but it fluctuates too much and causes heavy swings in power generation that have to be dealt with somehow.
They are not paying for someone to take the power - that's poor journalism.
It works like this: Every energy producer bids a price for their power, the lower your price the higher you are on the order book.
Then energy consumers will meet the demand by buying from the producers in the order of their price.
Once they have filled their power demand they pay everyone the price of the last price they needed to fill their needs.
So by setting a negative price they ensure they are always on top of the order book - but they don't actually have to pay for their power since other power sources have positive prices, and that's the price that is actually paid.
I suppose it is cheaper for them to pay another country to take the power and maintain the rates they are charging for energy than to have to pay the people back when it goes negative. They are trying to get their investment back.
That's a good question and they've mentioned one solution being transferring the energy to Sweden or Norway and they'll dial back the hydros and store more water in their dams. Of course I wonder if they could just selectively put a windmill in neutral to solve the same problem.
If you are a nuclear power plant, you have very little operational flexibility. If there is too much electricity, it's less expensive to pay someone to take it than it is to reduce the output of your inflexible generating asset.
