Researchers have proposed a new gravitational energy storage system, dubbed Lift Energy Storage Technology (LEST), which seeks to use the already-installed lifts in high-rise buildings to generate off-the-grid electricity. “LEST is particularly interesting for providing decentralized ancillary and energy storage services with daily to weekly energy storage cycles,” wrote the researchers in the paper. “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 [300 billion watt hours].”
Uplifting Idea
Breaking down the research, he said LEST proposes to store the energy not in a battery, but in the form of gravitational potential energy that’s accumulated in a heavy mass hauled up a tall building against the effects of gravity. When that mass is allowed to drop back to earth, the energy is captured by the lift motor acting as a generator. “At a time when there are pressures on the supply chains for many critical materials used in energy storage applications, a novel solution that looks at making innovative use of existing infrastructure and low-value materials is an interesting proposition,” Gavin Harper, Critical Materials Research Fellow, Birmingham Centre for Strategic Elements & Critical Materials, at the University of Birmingham, told Lifewire in email. Several others, such as Energy Vault, have proposed such gravity batteries that use Artificial Intelligence (AI)-controlled cranes and concrete masses, instead of lifts. From a broader perspective, the gravity battery is just one of the renewable energy storage technologies studied at the National Renewable Energy Laboratory (NREL) as part of the NREL Storage Futures Study. In an email discussion with Lifewire, Nate Blair, Group Manager, Distributed Energy Systems and Energy Storage Analysis within the Strategic Energy Analysis Center at NREL, pointed out that as per their modeling, there’s a significant need across the grid for additional energy storage at many scales. “This skyscraper model of gravity storage could be a viable option with more study and is definitely an intriguing thought-experiment on how to use existing infrastructure,” said Blair. “Urban energy issues are subject to space limitations as well as transmission limitations, and so urban storage is a uniquely difficult situation.”
Long Way to the Top
Harper opined that the researchers have put forth a unique use of existing infrastructure, especially since it helps generate energy right in the middle of the city, close to the point of use. He cautioned that while LEST’s flexibility seems good on paper, its implementation in the real world may prove challenging. For starters, Harper said loading densities of heavy masses at the top of slender buildings raises all kinds of civil engineering questions that would need to be carefully considered. “Also, lifts are designed for long and reliable storage life, but they are not designed for use in this way as energy storage,” pointed out Harper. Further, he argued that using lifts to generate energy will possibly result in accelerated wear on lift components, which would impact the service availability in the building. And if the lifts are frequently taken out of action for repairs, that would have a major impact on the commercial viability of this scheme. The researchers have proposed using robots to haul the weights to the top of the buildings, though Harper isn’t sure if that’s a good idea. “It would seem a poor allocation of resources to have utility robots trundling through carpeted, furnished spaces awaiting new tenants,” said Harper. He said that while the researchers have proposed using the vacant space in the buildings, a better option would perhaps be to use old, abandoned structures that can be stripped back to their shells and then refitted as energy storage devices. “In the race to net-zero, we need innovative thinking, and it is commendable to look at creative ways that make use of existing infrastructure and potentially low-value materials,” said Harper, “but we need to think through all of the implications.”
