Dettaglio di una gru

The energy tower

The World Changing Ideas Awards have honoured Swiss start-up Energy Vault for its innovative electricity storage system.

by Alessandra Pierro
7 min read
by Alessandra Pierro
7 min read

The continuous journey towards new destinations

Every idea, however small, helps us move forward in a new direction. According to pioneer of sustainable architecture Richard Buckminster Fuller, that is, and this is the same philosophy that inspires the World Changing Ideas Awards, promoted by Fast Company to encourage ideas that help keep us on the road to fairer and more sustainable scenarios. The winning projects were selected on the basis of feasibility and impact in 17 categories, from the application of artificial intelligence systems to advertising, consumer products to transport to projects in the fields of creativity, school education and social justice.

Electricity and storage

Great emphasis was placed on the energy sector, with Swiss start-up Energy Vault picking up an award for its innovative electricity storage system. The search for more effective and less costly energy conservation solutions is a central issue on which the future of renewables depends, regardless of the production context.
In a scenario that aims to decarbonize the energy system, energy produced from renewable sources is unlikely to present a real alternative to energy produced from fossil fuels due to the intermittence and unpredictability of natural factors such as the sun and the wind. Whilst the problem initially related to how this type of energy could be captured, it is important now, given the increasing demand and the obligation to reduce emissions, to also find new technologies to achieve sustainable systems that can store energy and ensure a regular flow at peak times even when renewable sources are unavailable.

Accumulating energy: a long-standing issue

This is a problem that has been around for some time and one to which pumped hydropower has provided a solution, currently accounting for around 99% of all electrical storage capacity at plants and proving to be the most competitive system for managing surplus energy in the most efficient way possible, with water flowing from upstream to downstream and producing electricity during the day, when demand is at its peak, and excess electricity being used to pump water to the upper basin, which is then returned ready for the next cycle, during the night, when the demand for energy is lower. The limitations of such a storage system are, however, starting to become clear; indeed, apart from the fact that it can only be used in areas with specific hydrogeological and morphological requirements, with access to water reserves at different altitudes, most importantly, there is the fact that water is about to become an increasingly scarce resource.

A ‘crane’ as a potential alternative

The Energy Vault plant, which, like hydroelectric pumping, is based on the force of gravity to conserve electricity produced from renewable sources, could present a valuable alternative. In this case, however, instead of using water and dams, the excess energy is stored and recovered through the vertical movement of cylindrical concrete blocks by means of a computer-operated crane. This means that when there is an excess of electricity produced by wind and solar farms available, the six-arm crane locates the blocks (using a camera connected to the arm) and proceeds to lift them off the ground and stack them; the system is fully charged once the crane is surrounded by a tower of blocks. When the time then comes to recover the stored energy, the crane is operated to reposition the blocks on the ground one by one, regulating the movements as required. At this stage, therefore, the crane’s electric motors, powered by the mechanical energy produced by the downward movement of the blocks, generate kilowatt-hours.

A more efficient system

In practice, as the system is loaded, the current (electrical energy) triggers a motor that raises (mechanical energy) the block, lifting it up (potential energy). When the system is then discharged to produce energy, the latter is generated by lowering the concrete block, operating the crane motor like a dynamo and transforming the potential energy stored in the descending block into mechanical energy and eventually, thanks to the motor, into electrical energy.
This means that it offers all the advantages of the pumped hydropower system but with a more efficient loading and discharge cycle. A concrete block can, in fact, be three times denser than water for the same volume and store three times more energy than a water tank of the same size. A tower of 35-tonne blocks can store up to 20 megawatt-hours of energy - enough to supply 2,000 homes for a day. It seems logical, therefore, that the system could easily guarantee a continuous and wide-ranging supply of electricity, particularly in countries with emerging markets such as Africa and Asia (it is no coincidence that the first plant will be established in India).

A very advantageous ‘crane’

This eco-friendly megabattery is part of a whole series of innovative energy storage systems and one that is also beneficial in terms of significantly reducing costs in relation to other storage systems, such as the electrochemical system using lithium batteries, for example. As well as providing a rapid installation system that requires minimal maintenance (the expected autonomous operating period being 30 years), the system also offers an interesting solution where materials are concerned. Although cement is much cheaper than a lithium battery, producing hundreds of 35-tonne blocks would require huge amounts of the material, and a machine has been designed to produce a low-cost material by combining gravel and building waste that would normally be discarded at considerable cost with concrete in order to overcome this issue. The blocks can therefore be produced on site as required.

The move towards self-sufficient homes

Until we see what the future holds for these concrete towers, the challenge of designing a system that, despite its unsophisticated technology, proves to be an extremely innovative and affordable solution for dealing with one of the most pressing problems facing the energy sector remains a very valid one. Research in the field has been revolutionary in that it has looked beyond the environmental approach and anticipates a new economic model whereby the production and storage of energy could even be managed by individual homes.
Projects like this show that it is still possible to come up with solutions for containing a crisis that is growing on several fronts, and whilst businesses can make a difference through forward-looking policies and investments, consumers also seem to be increasingly prepared to reward those taking steps in this direction.


The author: Alessandra Pierro

Graduated in philosophy, copyeditor and content curator.