I'm thinking that'd be a stretch. Anything that would sink enough power would have high capital costs, and negative prices (in my experience in US power market

I'm thinking that'd be a stretch. Anything that would sink enough power would have high capital costs, and negative prices (in my experience in US power markets) don't occur all that often. If you tried this as your primary business model, you'd wind up with a lot of money sunk in assets that may or may not pay off (and if they do pay off, will happen indeterminately in the future).