You could generate hydrogen. Install a few hundred MW's worth of hydrolyzers around the continent and direct all excess there. If there is no excess, they simply don't produce.

I feel that this basically has to happen sooner or later when the political obstacles to producing your own energy are removed. Electricity in several regions fluctuates between negative to 30-40 cents per kwh, having a storage mechanism like this to extract the differences as profit has to be a money-fountain, and it's not even expensive or difficult to build.