It's long been known that pumped-hydro storage could help wind and solar to take a greater share of the energy market. By pumping water uphill when the wind is blowing and the sun is shining, we can save it for later use when demand is up but production is down.
Where the geography is right, it's an approach that has a lot of promise.
Ontario has looked into a 400MW pumped-hydro energy storage scheme. And Norway's recently announced wind power expansion is particularly enticing because it can use the country's vast hydropower resources as a gigantic battery.
Now the BBC reports that Scottish Power is planning a huge expansion of its Cruachan pumped hydro storage plant. Originally opened in the 1960s to provide back up if a nuclear power plant went offline, the plant's current 440MW nameplate capacity could be almost doubled, says the Scottish energy company, if they were to add a second dam in front of the existing one. The company is currently trying to secure a guaranteed floor price for the electricity produced, a measure it says it needs to justify the £300-£400m it would take to build the extension.
Maybe Scotland can build even more wind farms to annoy Donald Trump?
Whether or not the plan moves forward, it's a timely reminder that there's more to energy storage and grid stability than space-age battery packs. Sometimes old-school engineering solutions are just as valuable. As is turning the lights off. (Or on, for that matter.)