An elevator energy storage system would turn skyscrapers into giant gravitational batteries. It would work even better if combined with next-generation cordless magnetic lifts, such as the Thyssenkrupp Multi-elevator. This solution was proposed by researchers at the International Institute for Applied Systems Analysis (IIASA) in Vienna, Austria, who said that skyscraper elevators form an extremely cheap renewable energy storage.
The concept is quite simple: energy can be stored as potential energy by lifting something heavy to a certain height. This potential energy can then be released by the force of gravity to drive a generator.
Researchers from IIASA looked at the height and location of skyscrapers and saw a huge number of pre-built energy storage devices waiting to be used.
The LEST Energy Storage System (LEST) will use existing elevator systems in high-rise buildings. Many of them have already been developed with recuperative brake systems that can store energy during the elevator descent, so they can be effectively considered as pre-installed energy generators.
LEST will also use free space throughout the building, ideally close to the top and bottom. Thus, modernizing a building can be extremely cheap compared to creating a special gravity battery system anywhere else.
Basically, LEST would take advantage of a simple elevator by moving heavy objects, such as large containers of wet sand from the bottom of the building up when there is excess energy. It would move the load from top to bottom when you need to use the stored energy.
The IIASA team proposed to create a series of autonomous trailer robots to work with lifting loads and towing them in lifts, where appropriate. They can be stored either along corridors, or in empty apartments or offices, or possibly in separate rooms, if the building is planned with this system in mind.
The scales should not be bulky enough for people to not be able to sit in the elevator, and the robots can be programmed to jump if passengers enter the elevator and exceed the maximum allowable weight.
Algorithms can determine the best time to lift loads, as well as when to collect stored energy without turning the elevator system into a nightmare for users.
In a study published in the journal Energy, researchers claim that modern intelligent elevators with permanent magnet synchronous gear motors can operate at an efficiency of about 92 percent when the elevators are fully loaded and tuned for optimal descent.
If you need a lot of energy quickly, the elevators can be adjusted to a faster descent due to a certain efficiency.
There are many other energy storage technologies at the grid level that are under development, but LEST has some unique features that can give it a boost. First of all, it will be located right in the center of the cities it serves, which significantly reduces capital expenditures.
The cost of the installed capacity of the LEST energy storage is estimated at 21-128 US dollars per kWh. It largely depends on the height of the building. By comparison, the National Renewable Energy Laboratory has estimated the installed capacity of four-hour battery systems at $ 345 per kWh in 2020, and that figure is projected not to fall below $ 100 per kWh by the end of the 2040s. under the most rosy assumptions.
The IIASA team estimates that the world’s current high-rise crop could be converted into anywhere from 30 to 300 gigawatt-hours of energy storage.