Elevators in Skyscrapers Can Serve as Energy Storage Devices
(Credit: Thyssenkrupp)
Sustainability Technology

Elevators in Skyscrapers Can Serve as Energy Storage Devices

Solar and wind power (renewable energy) are becoming more affordable, which has resulted in an increasing demand for energy storage solutions to keep electricity supply and demand in balance. Installing large-scale battery storage facilities is one available approach for coping with the uncertainties of clean electricity generation.

This, however, necessitates a significant infusion of money up front and the unsustainable practice of mining for minerals. That’s why a team of researchers in Vienna, Austria, came up with a new idea: tall buildings could be used as batteries to improve electricity quality in metropolitan areas.

By 2026, worldwide renewable electricity capacity is predicted to increase by more than 60% from 2020 levels. Current worldwide fossil fuel and nuclear power capacity are equal to this. The International Energy Agency estimates that by 2026, renewables will account for about 95% of the increase in worldwide electricity capacity, with solar PV accounting for more than half of that increase. However, new approaches to energy storage and use are needed to achieve a low- or zero-carbon civilization.

Skyscrapers Can Store Renewable Energy

Since renewable energy generation is inconsistent, energy storage and release will be crucial in the following decades. Thus, researchers at the International Institute of Applied Systems Analysis (IIASA) have devised an ingenious idea: using skyscrapers as enormous gravity batteries to store renewable energy at a surprisingly low price. Existing towers can be retrofitted with this technology, and new ones can incorporate it from the start.

The researchers examined the height and position of buildings and detected a plentiful supply of pre-built energy storage waiting to be exploited. The idea they got was that we could store extra renewable energy as potential energy by using it to move something heavy (an elevator) to a higher point. Then, gravity can be used to power a generator to release that energy.

The IIASA researchers offer a novel gravitational-based storage method that uses lifts and empty apartments in tall buildings to store energy. This innovative elevator energy storage concept, which the authors dubbed Lift Energy Storage Technology (LEST), stores energy by lifting high-density materials like wet sand containers, which are moved remotely in and out of a lift with autonomous trailer devices.

Energy Storage Using Established Infrastructure

LEST is a fascinating option because elevators are already present in high-rise buildings, so there is no need for more investment or space occupancy. Instead, all we have to do is utilize what is already there in a novel way to create added value for the power grid and the building owner.

Elevators in Skyscrapers Can Serve as Energy Storage Devices
(Credit: IIASA)

Researcher Julian Hunt of the IIASA Sustainable Service Systems Research Group and lead author of the study said:

“I have always been fascinated with topics involving potential energy, in other words, generating energy with changes in altitude, such as hydropower, pumped storage, buoyancy, and gravity energy storage. The concept of gravity energy storage has also recently received significant attention in the scientific community and start-ups. The concept of LEST came to me after having spent a considerable amount of time going up and down in a lift since recently moving into an apartment on the 14th floor.”

According to the authors, the cost of the power capacity is the biggest obstacle to commercializing a gravity energy storage system. That’s LEST’s most significant advantage. Elevators equipped with regenerative braking systems already have the power capacity needed for LEST. There are over 18 million lifts in use worldwide, and many of them spend a significant amount of time idling. Instead, these elevators could be utilized to store or generate electricity when not transporting passengers.

Researcher Behnam Zakeri of the IIASA Integrated Assessment and Climate Change Research Group and co-author of the study added:

“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.”

When the elevators are wholly loaded and set to descend at the best place for generating energy, they can function with an efficiency of 92% (if they are state-of-the-art permanent-magnet synchronous gear-motor smart elevators). It is possible to decrease the efficiency of the lifts to make them descend faster when large amounts of energy are required quickly. This system could be even more efficient when coupled with a cable-free, Willy Wonka-style magnetic elevator system like the Thysenkrupp multi-elevator.

Elevators in Skyscrapers Can Serve as Energy Storage Devices
(Credit: Thyssenkrupp)

A Cost-Effective Energy Storage Solution

LEST has specific distinct attributes that could get it a place at the table with other grid-level energy storage technologies in development. Since all you have to do to get up and running is introduce some robots and weights into the lobby and mess with elevator programming, this system can operate right in the center of the cities it serves, saving a significant amount of money on construction costs.

In addition, it might be a great way to address some of the shortcomings of extensive battery systems, such as the fact that they’ll likely be less effective for longer-term seasonal energy generation fluctuations and multi-day blackout scenarios. However, it won’t be able to respond to demand spikes as quickly or reliably as a giant battery project.

Still, it’s a clever use of lateral thinking, and if the team’s estimates hold up, it’s a surprisingly low-cost choice. Depending on the building’s height, the installed cost of the LEST’s energy storage capacity ranges from US$21 to $128 per kWh. While the National Renewable Energy Laboratory predicted that four-hour battery systems would cost $345 per kWh in 2020, even under the most optimistic of assumptions, the installed capacity cost of these systems is expected to remain above $100 for decades.

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