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A crane stores energy

How concrete cube towers can store green energy and supply it to the electricity sector in Israel when needed

Dr. Daniel Mader, Angle - news agency for science and the environment

Renewable energies produced from the radiation of the sun and the wind are currently the most viable solutions for producing energy for human needs. Their environmental impact - on climate change, air pollution, water pollution, use of resources, damage to ecosystems and damage to health - is minimal compared to the damage produced by fossil fuels such as natural gas, oil and coal. Also, in recent years the trend has reversed, and generating electricity from the sun and wind has become cheaper than fossil fuels.

However, the weak point of renewable energies is the fact that "they cannot be trusted". That is, they usually do not produce electricity at a fixed rate known in advance for a long period of time, for the simple reason that the sun does not shine throughout the hours of the day, nor does it shine with the same intensity during the day, when clouds or dust hide it. The strength of the wind also changes frequently and sometimes unpredictably. That is why there are limitations on the relative share of these energies from the entire electricity sector: it is necessary to invest in a special electricity infrastructure that can deal with this volatility, and it is necessary to keep a significant part of the electricity sector operating using fossil fuels, hydroelectric energy or nuclear reactors as a backup.

A solution to this central problem is energy storage: energy that is produced during hours when there is wind or sun is stored, and is used later, when there is no wind or sun. We know such small solutions from our daily lives, in the form of electric batteries and accumulators. However, to supply electricity to homes, buildings and cities, much more extensive solutions are needed. Therefore, there is currently a race to develop various means of storing energy on a large scale - and a new development by a Swiss start-up company, which makes smart use of technology that already exists today, is another step on the way to their application.

How can renewable energy be provided to the world in a reliable and continuous manner? Photo: NASA
How can renewable energy be provided to the world in a reliable and continuous manner? Photo: NASA

Generate electricity from water

In the technological race to find solutions for energy storage, sophisticated technological developments often make headlines, such as huge batteries based on metals or various organic materials, or batteries based on flywheels (rotating mechanical components used for energy storage). These solutions attract a lot of media attention and therefore also the most investments; However, these solutions are still under development, and most likely they will be very expensive, at least in the first period of their operation, due to their complex and long development. This phenomenon can be seen happening in the car market: hybrid and electric cars are still very expensive, which makes it difficult for them to penetrate massively into world markets.

On the other hand, less sophisticated solutions already exist today, such as heat or cold storage, and potential energy storage of weight at high altitude (more on that later). But these have not yet been used on a large scale. A solution of this type already exists today, even in Israel, and is known as pumped storage: water is pumped from a low reservoir upwards and stored in a high reservoir when there is an excess of electricity in the network. When there is a need for electricity in the system, electricity is produced from the water fall into the lower water reservoir through a turbine that generates electricity.

This system has an advantage due to the short start-up time that allows electricity to be generated within seconds of starting the system (unlike coal and other power plants, which require a much longer initial start-up time - long minutes and even hours) and its efficiency is relatively high and stands at 80 percent - that is, if a ton of water is pumped into the reservoir The top, when it is released down, receives 80 percent of the energy invested in raising it, while 20 percent of the energy is lost due to the friction between the parts of the system and due to loss of water in the form of evaporation or seepage. Other disadvantages of the process are the need for an extensive infrastructure of reservoirs and tunnels, which takes a long time to build and which harms nature - toxic substances may seep into the groundwater during tunnel mining, and water pumping during mining may damage the groundwater balance. In addition to this, in order to establish the system, areas with height differences of hundreds of meters between them are needed, such as a mountain near a valley, or a plain with a deep mine; In order for the entire Israeli electricity network to rely on renewable energies and pumped storage, tens of square kilometers of pumped storage reservoirs will be needed. Land is an expensive resource that is not sure if it will be possible to provide in the small and dense Israel, which is not surrounded by towering mountains.

50 percent cheaper than any other technology

A new development by the Swiss start-up company Energy Vault may be able to provide a cheaper and greener alternative to the pumped storage method. The company recently developed an automatic crane, which by creating piles of concrete blocks - just like Lego - manages to store potential energy, and turn it into electrical energy when needed, which can be fed back into the electricity grid.

How It Works? very simple. The crane creates piles of concrete blocks while using excess electricity that exists in the general electricity grid (for example during the afternoon when the production power of solar energy is at its peak). An electric motor lifts the cubes up and places them up the stack. When additional electricity is needed for the grid, the crane grabs the cubes from the top of the stack and releases them towards the ground (when they are connected to a cable that is connected to the generator, turns it and produces electricity), in an action that converts the potential energy (height difference) into electrical energy - similar to the pumped storage system mentioned earlier.

How It Works? The crane of the company Energy Vault
How It Works? The crane of the company Energy Vault

How It Works? The crane of the company Energy Vault

Each crane can operate automatically when it receives a command to store or release energy. The automatic system remembers where it placed each cube, and where it should place the next cube in the most efficient way. The system is modular and can be built in several sizes. Each crane is able to store energy in the amount of 10-35 megawatt-hours (MWh) and more, and supply energy with a power of 2-5 megawatts. This system size is excellent for modular installation in many sites, without occupying a large area (in contrast to pumped storage that needs extensive and "special" areas such as mountains next to valleys). In this system, energy can be stored for an unlimited time, without energy loss, but while maintaining a quick response time of tens of seconds when it is necessary to inject electricity into the grid.

A disadvantage of the new development is that it is not possible to build very large systems from it, similar to a single pumped storage reservoir. However, tens or even hundreds of such automatic cranes can be controlled by one person in another control room. Therefore, the operating expenses of this system are extremely low, and each system has a lifetime of 30 years or more, with 90 percent efficiency.

Since this is an incredibly simple system, and since all the parts of the system have been in human use for decades and are stable and reliable (concrete, steel, cranes), the main development is creating the appropriate software for automating and optimizing the system. According to the company, the price of this system is currently at least 50 percent cheaper than any other storage technology on the market. Building the system is relatively simple and fast. The concrete blocks can be produced on the construction site itself, or transported to it. The energy storage material (the concrete) does not disappear from the system over time, so it does not need to be renewed, unlike pumped storage, where the water evaporates and seeps out of the system. It is convenient to set up the system in any industrial area or in an urban area with high construction (installation in an urban area with low construction or in open areas will cause landscape damage).

At the end of the system's life, all its parts can be easily reused. You can even use heavy waste to create the cubes, instead of landfilling. For example, to use a mixture of coal ash, construction waste, crushed asphalt and more. The system is safe to use, without the risk of leaking dangerous substances and without the need to use high temperatures. Theoretically, these facilities can even be built underground. Although their maintenance and construction will be more complicated and expensive, this way it will be possible not to waste space on them that could be used for other alternatives, and they will even be immune to combat incidents.

to change the rules of the game of the electricity grid

Israel currently relies on an electricity network with a capacity of about 15 gigawatts ~15 GW, which consumes about 65 terawatt-hours ~65 TWh of electricity per year. If Israel's entire electricity production system is based on renewable energies (mainly solar), which, as I remember, do not operate at a fixed and known rate in advance and therefore must be stored, 5,000-10,000 such cranes will be able to store and supply all of Israel's electricity consumption for over 24 hours, without any other power source. Such a distributed system could even save the construction and maintenance of an expensive electricity transmission system that covers the entire country.

Today, the electricity sector in Israel is centralized and vulnerable. A localized damage to the Rabin power plant in Hadera, for example, whether as a result of war, an earthquake or a tsunami, can disable about 20 percent of the total scope of electricity production in Israel. A point damage to a gas supply rig or a main transmission pipe can paralyze the gas supply to 60-70 percent of the power plants and many factories. If Israel switches to generating most of its electricity from the sun on buildings, every city will be able to generate and store its own electricity. But even if not, it will be possible to store electricity from the main grid for every city. In the event of a shutdown of the national electricity system, each city can have a backup and can continue to function.

Moreover, about 11 percent of all electricity produced today is "thrown away", because the electricity grid always produces more electricity than the amount of consumption at the same time, in order to deal with sudden increases in consumption. The excess electricity is grounded to the ground, and energy storage will be able to store these excesses, making it possible to produce less electricity each day.

The technology of the concrete towers (or those similar to it) is expected to change the rules of the game of the global power grids. From centralized networks that rely on expensive and polluting fossil fuels controlled by corporations and states, to decentralized networks that rely on clean energy and energy storage for an unlimited time.

10 תגובות

  1. Please only answers from electrical engineers or materials engineers -
    Why not store energy by mechanical means? (springs for example)

  2. Not a completely unnecessary technology, but... if they concentrated on utilizing the roof space in Israel for solar panels and saving electricity, it would be possible, in my opinion, to forego all the extras. The peak of the load is during the hot days when the solar panels are also at their peak and the problem of surpluses would have been solved automatically, because both consumption and production would have naturally decreased in the evening hours.

  3. light
    Not everywhere has water. The big advantage of this method is that it is scaleable. That is - it can be adjusted to the amount of energy that needs to be stored.

    In my opinion, this is one of the best ideas for solving the problem of balancing electricity generation from uneven sources.

  4. Idan.
    Nuclear fusion really sounds like a wonderful thing.
    (When you talk about energy from nuclear fusion, I hope you mean "controlled nuclear fusion" and not "cold fusion". Because we will be able to do cold fusion only after we find enough pink unicorns)
    Nuclear fusion sounds like a magic solution, infinite energy and free of the common matter in the universe.
    But that's not exactly the picture.
    The process itself is already being carried out. The problem is that probably in order to achieve energy efficiency we will need a huge facility. In the coming years (two or three years) the construction of such a facility is going to be completed, which is expected to achieve energy efficiency for the first time. That is to produce more electricity than the electricity required for its operation. But before you celebrate, it will still be light years away from economic efficiency.
    Even if the technology improves in the future, facilities for "controlled fusion" will cost a huge fortune and not only in construction but also in maintenance. This is a super complex, huge facility that works with a fairly low energy efficiency.
    One day I believe that such facilities will be built in the world but it will not be a comprehensive magic solution to the energy problems and we will not be able to stop worrying about saving electricity and it certainly won't be free.
    It could be part of a solution that would include the use of solar, hydraulic, and wind energy. Along with energy efficiency wherever possible. (gray water that "Mishu" mentioned for example)

  5. If at all, if you decide to invest in technology, there is a much simpler and cheaper option: storage pumped under pressure. Instead of the water rising and falling, it is pumped into a sealed container against air pressure. Without computers, many engines and while saving space. To save pressure in the tank, the water will accumulate (for the purpose of the example) in one large tank and the air pressure in the tanks in other tanks and only when the drain is opened will air pressure enter the water tank. By the way, if you want to save energy instead of producing more and more of it, you should encourage the use of gray water at the end points. In the current situation, water is pumped from a well or poured and then sent far away - and then returned from afar (in the case of differences in height from low to high there is no energy investment back, but much more is invested in transportation). Thus, a lot of energy is paid both for transporting the water back and forth and for desalination/pumping from the wells of water lost through leaks on the way back and forth. When water is used at the end points, the transport back and the addition (compensation) for the leaks on the way back are saved.

  6. First, it is not stated what the efficiency of the proposed system is - that is, how many percent of the energy spent can be recovered.

    Second, if you want to create energy reserves, then instead of using cubes made of heavy material, you can use batteries. Of course, there is a certain logistical complication of when to charge them and how to connect them (up the tower or down) to use the energy stored in them, but it is possible to store much more energy this way, and get another type of availability.

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