According to the International   Hydropower Association, or IHA, a  facility with two reservoirs roughly   the size of two Olympic swimming pools, and  a 500-metre height difference between them,   would have an energy capacity of about three and  a half megawatt hours. And they last for decades,

in south australia we've got the hornsdale power reserve which is a 00:32:43 100 megawatt capacity this is one that elon musk very famously uh put in so this is what the european union is now using as the standard to talk about you know it's 00:32:56 been done in australia we can do it here so in the global system we would need 15 million 635 and 478 such stations across the planet 00:33:08 in the power grid system just for that four week buffer so and that is actually about 30 times capacity uh compared to the entire global

The steel tower is a giant mechanical energy storage system, designed by American-Swiss startup Energy Vault, that relies on gravity and 35-ton bricks to store and release energy.