Harnessing Vertical Cities for Sustainable Energy Solutions
The sun doesn’t always shine and the wind doesn’t always blow. What do we do if there is no renewable energy when we need to turn on the lights? Typically, cities rely on lithium batteries or pumped hydroelectric plants . However, cities that build vertically, such as Benidorm , have another untapped option.
In short, a comprehensive University of Waterloo study has unveiled a groundbreaking concept: using the height of buildings to create a gravity energy storage system . This innovative idea transforms vertically-oriented cities into enormous devices capable of storing and releasing energy on demand.
<img alt="They are not lakes, they are batteries: China is transforming its reservoirs into the largest pumping stations in the world" width="375" height="142" src="https://i.blogs.es/cc3361/china-embalses/375_142.jpeg"/>Mechanical batteries. The concept is straightforward yet revolutionary. It features a heavy mass—often made of concrete or steel blocks—and incorporates a system of pulleys and cables akin to an elevator. Additionally, a motor serves as both a motor and generator.
Here’s how it works: When there is a surplus of energy—such as at midday when a building’s solar panels operate at full capacity—the motor utilizes that electricity to lift the heavy mass along a vertical shaft. In this process, electrical energy is converted into potential energy .
When electricity is needed, such as at night or during calm weather when renewables are not producing, the mass is released in a controlled manner. The force of gravity takes over: the descending weight then drives the generator, converting potential energy back into usable electricity.
Tested successfully. Researchers propose this innovative system as the core of a hybrid energy ecosystem integrated within the building itself. This ecosystem can include photovoltaic panels on the façades, small wind turbines on rooftops, and supportive lithium-ion batteries .
As highlighted by PV Magazine, companies like Gravitricity in Scotland have already proven the viability of this technology through functional prototypes and are advancing full-scale commercial projects ranging from 4 to 8 MW. This system generates energy from both solar and wind sources while employing gravity as the principal battery for daily energy storage . This arrangement allows for the management of extensive charge and discharge cycles.
Is it viable? To evaluate whether their concept was merely an intriguing theory, the University of Waterloo team conducted a large-scale simulation. They analyzed 625 different building designs, altering various parameters such as height, floor plan shape (more square or elongated), and overall energy efficiency.
The results generated by this study are highly promising. The system (which includes facade solar panels, small wind power, gravity storage, and battery support) achieved a levelized cost of electricity ranging between $0.051 and $0.111 per kWh. This cost is incredibly competitive and even outperforms other renewable energy systems integrated into buildings located in areas with moderate solar or wind resources.
Taller buildings, particularly those with larger floor plans, benefit the most from this innovative system, making cities like Benidorm exceptionally well-suited for such technologies. The results underline the possibility of utilizing urban density for sustainable energy solutions.
Image | Diego Delso (CC BY-SA 3.0)
In Xataka | Finland has discovered an affordable way to store energy for the entire winter: it involves a tower made of 2,000 tons of sand.
This development presents a promising avenue for energy resilience in urban environments. By integrating gravity-based energy storage within high-rise structures, cities could significantly reduce their dependency on traditional electricity sources. In the face of environmental challenges and the unpredictability of renewable resources, this innovative approach offers hope for a sustainable and efficient energy future.