Skidmore, Owings & Merrill (SOM), the designer of the world's tallest building, Dubai's Burj Khalifa, has joined forces with Energy Vault Holdings to investigate the possibility of creating something even taller: huge 1-km [3,280-ft]-tall skyscrapers that would also function as gigantic gravity based energy storage systems.

The proposal features two particularly notable ideas. The first brings to mind research from the likes of Gravitricity and IISA, and would use excess energy – whether from renewable sources like solar or from a standard power grid – to raise a weight up to the top of a very tall skyscraper. When required, the weight is then released, allowing it to descend to the bottom of the building, harnessing the force of gravity to drive a generator.