Lift (Elevator) Energy Storage Technology – Urban Energy Storage
Lift Energy Storage Technology (LEST) uses gravity and building elevators to safely and efficiently store energy right where it is used – in the city.
By elevating autonomously loaded modular weights from the lower floors to the upper floors, using an existing lift in the building, electrical energy can be stored as potential energy. When the weights are lowered from the upper to the lower levels, a generator in the system generates electricity and dispatches it to the grid.
Using dedicated software, the system detects the weight location and optimizes storage capacity between upper and lower storage sites. Depending on the discharge requirements, the elevators can run at different speeds. Gear reduction on the generation units allows them to generate more energy at very slow speeds – making them more efficient.
Building owners can choose to operate the elevators only during periods of low elevator demand to minimize the impact on building occupants. During periods of higher demand, the units still generate electricity but do it in conjunction with the standard operation of the lift.
The building’s height and weight-bearing capacity will determine the maximum weight loaded and, thus, the economic viability of the system; the ability to lift more weights a farther distance stores more energy and dispatches it for a longer duration. Automated weight carts containing sand or concrete would easily add weight to the system to reach its full potential as needed.
If a lift already has regenerative barking installed, the only costs are the carts, the material chosen to increase the mass of the carts, and the system to load them into the elevators.
LEST’s installed capacity energy storage cost is $21–128 USD/kWh considering an average height difference of 100 meters between the upper and lower reservoirs. A greater height difference between the lower and upper storage sites reduces the project cost per kWh. Depending on use, the system will have a technical lifetime between 20 and 30 years.
Because of its simple design, the process requires no rare earth metals compared to battery energy storage, and no toxic chemicals or waste disposal need to be disposed of at the end of life.
Using the same basic principles, gravitational energy storage technology is also being deployed in mine shafts and custom-designed structures at a very large scale to support large renewable energy projects like solar and wind.
Lift energy storage technology is currently seeing much research. It is simple, cheap and available everywhere lifts and elevators are located. Considering cities have them by the thousands in existing densely populated areas, they are an ideal solution for decentralized urban energy storage and one more piece in a decarbonized future.