Using high-rise buildings as gravity batteries

The world is undergoing a rapid energy transformation, with increasing capacities of renewable energy sources such as wind and solar power dominating. With the rapid decrease in the cost of renewable energy generation, there is an increasing need for energy storage technologies to ensure that electricity supply and demand are properly balanced.

Researchers at IIASA have developed a new energy storage concept that could convert high-rise buildings into batteries to improve power quality in urban areas. Lift Energy Storage Technology (LEST) is a novel gravitational-based energy storage solution that stores energy in lifts and empty apartments in tall buildings.

It stores energy by lifting wet sand containers or other high-density materials that are transported in and out of the lift remotely using autonomous trailer devices. The system would also make use of the building’s top and bottom empty spaces.

Lift Energy Storage Technology (LEST) (a) system components, (b) not changed and (c) fully charged the building, (d) operating on energy storage, (e) electricity generation, or (f) ancillary services mode

Because lifts are already installed in high-rise buildings, LEST is an appealing option. This means that there is no need for additional investment or space occupancy, but rather a different way of using what is already there to create additional value for the power grid and the building owner. The power capacity is already installed in lifts with regenerative braking systems that can harvest energy as the lift descends, making them effectively pre-installed power generators.

An existing lift can be used to transport containers from the lower apartments to the upper apartments for energy storage and from the upper apartments to the lower apartments for electricity generation. When the lifts are not in use to transport people, they can be used to store or generate electricity.

There are a few details that need to be worked out before the system can be deployed. This includes finding space to store the system’s weights at the top of the building when it is fully charged and at the bottom of the building when it is discharged. Another factor to consider is the ceiling bearing capacity of the existing buildings where the system will be installed.

the tallest buildings in the world

“Environmentally friendly and flexible storage technologies like LEST are set to become more and more valuable to society in a future where a large share of its electricity comes from renewables. Therefore, policymakers and power system regulators need to adopt strategies to incentivize end-users, in this case, high-rise buildings, to share their distributed storage resources, such as LEST, with the central grid. The coordinated utilization of such distributed resources alleviates the need for investment in large-scale central storage systems.”

study co-author Behnam Zakeri, a researcher in the IIASA Integrated Assessment and Climate Change Research Group

The ability to store energy where it is most needed, such as in cities, will greatly benefit the energy grid. Furthermore, researchers believe that LEST can provide affordable and decentralized ancillary services, which could improve power quality in urban areas.

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The installed storage capacity of the LEST is estimated to cost between 21 and 128 USD/kWh, depending on the building’s height. The global potential for the technology is estimated to be between 30 and 300 GWh, with a focus on large cities with high-rise buildings.

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