Skyscrapers would be energy storage device with new breakthrough method

Taking away a chunk of capital expenditure associated with energy storage.
Ameya Paleja
Looking down at an open plan elevator shaft and exterior windowImageGap/iStock

Researchers at the International Institute of Applied Systems Analysis (IIASA) in Vienna, Austria, have suggested a nifty idea of converting skyscrapers into storage units for energy generated through renewable sources, New Atlas reported. This can be done for existing skyscrapers as well as those that will be built in the future. 

Renewable energy is a promising source that can be used to meet our energy demands in a carbon-free way. One of the significant hurdles in relying on this source is the intermittent nature of how energy is generated using this method.

Amongst the currently available methods, setting up large-scale battery storage facilities is a solution to tide over the uncertainties of power generation. However, this involves a lot of capital expenditure upfront. Therefore, researchers at IIASA have suggested utilizing elevator systems in the skyscrapers as vehicles of energy storage. 

How does the system work? 

Called the Lift Energy Storage System (LEST), the system will use the downtime of the elevator systems in tall buildings to move heavy items such as containers of wet sand from the bottom floors to the top floors when renewable energy is available in excess. 

When there is a need to use the energy, these weights can be moved back down through the elevators. Regenerative braking systems in the elevators can be used as mini generators of power that can be supplied to the grid. While most new elevators use these systems, even older ones can be retrofitted at a fraction of the cost needed to set up a battery grid. 

The IIASA team also suggests that autonomous robots could be tasked to do all the heavy lifting in these buildings. If the elevators are busy, the bots could simply be programmed to hop off the lift if it is nearing its load limits, and algorithms would be able to determine which time slots would be appropriate to move up the weights. 

The weights to be carried could be stored in corridors or even empty office or residential spaces in the building. Depending on the energy demands, the researchers estimate that the weights could be moved back as late as winter after being moved up in the summer months.

But is it practically feasible? 

The researchers argue that new state-of-the-art elevators currently work with efficiencies of 92 percent and could serve as excellent means of storage. More importantly, these structures are located in urban areas, close to where power demands are high and could be quickly implemented. 

The expenditure for installing these systems would include autonomous robots, some easily transportable weights, and little changes to the elevator systems. These would still be comparatively smaller than setting up battery storage for the grid. 

While capital expenditure would be less, the issue that sticks out is the operational expenditure. The researchers note that skyscrapers are notorious for their rents, especially the top floors and the parking lots, the two places needed to maximize the storage potential of such a system. 

Since buildings are not built in a singular design or simultaneously, one could need to analyze a structure on a case-by-case basis to determine how much weight can be stored on the top floors without risking the system's structural integrity. 

Nevertheless, the researchers estimate that the energy storage cost for such a system would vary between US$21-128, which is still cheaper than the $345 per kWh that is needed for battery systems, New Atlas reported. 

All we now need is an entrepreneur willing to make this thought experiment a reality on the ground.  

The study was published in the journal Energy.

Abstract

The world is undergoing a rapid energy transformation dominated by growing capacities of renewable energy sources, such as wind and solar power. The intrinsic variable nature of such renewable energy sources calls for affordable energy storage solutions. This paper proposes using lifts and empty apartments in tall buildings to store energy. Lift Energy Storage Technology (LEST) is a gravitational-based storage solution. Energy is stored by lifting wet sand containers or other high-density materials, transported remotely in and out of the lift with autonomous trailer devices. The system requires empty spaces on the top and bottom of the building. An existing lift can be used to transport the containers from the lower apartments to the upper apartments to store energy and from the upper apartments to the lower apartments to generate electricity. The installed storage capacity cost is estimated at 21 to 128 USD/kWh, depending on the height of the building. LEST is particularly interesting for providing decentralized ancillary and energy storage services with daily to weekly energy storage cycles. The global potential for the technology is focused on large cities with high-rise buildings and is estimated to be around 30 to 300 GWh.

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