Historically, the vast majority of the world’s power has been consumed as quickly as it is made, or it’s wasted. But climate change has made governments interested in renewable energy, and renewable energy is variable—it can’t be dispatched on demand. Or can it? As research into utility-sized batteries receives more attention, the economics of adding storage to a grid or wind farm are starting to make more sense.
But grid-tied energy storage is not new; it has just always been limited to whatever resources a local power producer had at the time. Much like electricity production itself, storage schemes differ regionally. Power companies will invest in batteries that make sense on a local level, whether it is pumped storage, compressed air, or lithium-ion cells.
Looking at the kinds of storage that already exist is instructive in helping us see where storage is going to go, too. Lots of the latest battery projects merely build on engineering that has been in service for decades. To better see our way forward, we collected a number of images and diagrams of the world’s biggest energy storage schemes.
Pumped storage
Pumped storage is possibly one of the oldest forms of modern grid-tied energy storage, and it certainly packs the most punch as far as megawatt-hours delivered.
The way it traditionally works is simple: the system has a bottom reservoir of water to draw from and a top reservoir that’s topographically higher than the bottom reservoir. When there’s not a lot of demand for electricity, you use that power to “charge” the battery by pumping water up to the top reservoir. When demand for electricity is high, that reservoir can be drained via a hydroelectric generator, back down to the bottom reservoir.
In the future, Germany is looking at using old coal mines for pumped storage, and some German researchers have been working on building giant concrete spheres that can function as pumped storage containers after they’re placed on the ocean floor.
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