Hidden deep under a sprawling Toronto block of condo towers, offices, shops and six levels of underground parking is a giant battery — but not the kind you might be thinking of.

There’s no lead or lithium inside it. Instead, it’s full of water — enough to fill three Olympic-sized pools — and all the heat that water holds. 

It’s called “The Well,” and it supports the buildings’ low-carbon heating and cooling system. 

Wind and solar generate cheap, clean power. But it’s not always sunny or windy at the times we need it most, such as the hottest days of summer or the coldest nights of winter. That makes storing energy an important part of a low-carbon grid — and storing it as heat can be cheaper, safer and more convenient than storing it in traditional batteries.

Source: www.cbc.ca/news/science/thermal-storage-explainer