Finnish City Inaugurates 1 MW/100 MWh Sand Battery

I think with enough renewable in the grid, there will always be times when the costs are 0 or negative, so you can help stabilize the grid by consuming.

Are there downsides to "just" sending all of the extra energy to ground? I've often wondered why overpowering the grid has been talked about as this huge unsolvable problem.

I understand it's wasteful, of course, but waste in a ecosystem of vast abundance seems like a feature, not a bug.

As I understand it, you need to limit the current flow to ground to not create a fault that burns out the whole setup. The most practical way to do that is with a bank of resistors. At that point, the resistors are doing the work and you're just using the ground as a return path, which isn't necessary.

Solar and wind can be trivially turned down when not required. They are much, much better at it than traditional sources.

So easy that one of the actual problems we face is that by default grids will generally prefer to turn off the clean renewables and let the difficult to modulate fossil fuels run.

This is why negative prices are a good thing, financially incentivizing fossil producers to plan for flexibility and fining them when they fail to do so.

> but waste in a ecosystem of vast abundance seems like a feature, not a bug.

The problem is that it's not a ecosystem of vast abundance, just occasional abundance. Literally no-one in the world right now is sitting on a constant supply of TWs of excess electrical power and saying "golly gee what are we going to do with all this". Perhaps France got closest in history and their prices still aren't "too cheap to meter".

You can "waste" the power (either by actually "burning" it to heat and dumping it, or just disconnecting the solar panels), but then you'll be short of power later and need to fall back on something expensive or with high externalities. It's also bad in terms of the capex for the solar panels (assuming solar), as you can't use your expensive plant as much as you want. If you can you'd rather use "$10" of energy that you can't sell to store and sell it later, even as heat, at any price than just lose it all.

Even if you massively, massively overbuilt solar and wind so that you were in a "vast abundance" scenario on average, you still have to store some of it for night and/or winter.

To clarify, the current flow never goes to ground; it goes back to where it started, which is why we call it a "circuit". When you do it without routing it through a load like a bank of resistors, it's called a "short circuit". Electromechanical generators will generally tend to catch on fire if you short-circuit them.

Solar panels have no problem with being short circuited; the amount of heat they produce in that state is the same as any other black object in sunlight.

Windmills are like any other electromechanical generator in this sense. You have to stop them with a brake. But that is totally a thing you can do, and quickly, and every mainstream windmill does it regularly (if only to handle overspeed winds safely), although, when this system fails, you get spectacular viral video content.

In the usual case where it works, though, you don't need a load bank either.

Load banks come into play when conventional inflexible baseload generators can't ramp down fast enough or when perverse market incentives pay renewables operators to pump power into the grid when it's not being demanded.

> Solar panels have no problem with being short circuited; the amount of heat they produce in that state is the same as any other black object in sunlight.

Internet akchually: a small amount of the heat will be dropped in the wiring that forms the short circuit rather than in the internal resistance. So the panel will be slightly cooler than you'd expect for an object of that colour even in short circuit. They're the same temperature in open circuit, though. When operating normally, they can be quite a lot cooler and in fact you can detect non-functional panels by looking for hot ones with thermal cameras.

Yes, agreed, especially if you're "short-circuiting" them with MOSFETs or TRIACs or something instead of relays.

I did know that normally-operating panels were significantly cooler (23% efficiency means 23% less heat than a regular black body) but I had no idea that people used this feature to detect broken panels with thermal cameras. I'd only seen people forward-biasing the panels from an external source to stimulate NIR light emission and using NIR cameras.