Finnish City Inaugurates 1 MW/100 MWh Sand Battery

I like these technologies. They may not be as energy efficient as using more exotic materials, but what they do use is simple, cheap and often sourced locally. Such economic factors are often as important to the ROI as the purely scientific ones.

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.

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.