With the advent of the COVID-19 era, many office spaces have become empty and skyscrapers in the business centers of cities are now idle. Researchers at the International Institute for Applied Systems Analysis in Vienna have proposed converting them into gravity-type energy storage devices with flexible working hours. Most importantly, the modernization will require minimal effort, and the building can continue to be used in the same way.
The idea is based on the fact that modern elevator systems are equipped with energy recovery systems and have intelligent control. Elevators with a permanent magnet synchronous gearmotor can operate with an efficiency of about 92%. In fact, these are already ready-made energy generators built into buildings, you just need to modify them a little. The system will take into account the needs of people and be used for the accumulation and release of energy in their spare time.
It is proposed to use many small containers with wet sand as cargo. They will be transported by compact robots, which, depending on the task, will load and unload an arbitrary number of containers on any floor. This will allow you to store the load in empty rooms, in the corridors, and if the inhabitants of the skyscraper do not mind, move a few containers in the elevator along with people.
Such a system will not be able to accumulate a significant amount of energy and quickly transfer it to the network, but it is quite suitable as a backup option. Calculations show that with proper organization, the cost of such a battery will be three times lower than a lithium battery of the same capacity. And if all the skyscrapers of the world are equipped with gravitational storage devices, they will be able to accumulate up to 300 gigawatt-hours, which is enough for such a metropolis as New York for a whole month.