What is a 'concrete battery' that can be realized at a lower cost than hydraulic power generation?

Electric energy is sent to each household by distribution equipment such as electric wires, but there is a risk that electric power can not be supplied if electric power demand increases. Therefore, in many countries such as Japan, a reservoir (dam) is made at a high place and a low place with pumped hydraulic power generation , and electricity is generated by flowing water from a high place to a low place when the electric power demand is high, and the demand is low We are pulling up water from a low place to a high place at the timing, and we are storing energy in preparation for high electricity demand. However, in order to realize pumped hydropower generation there is a limitation due to the topography, and the construction cost also becomes high. Swiss startup Energy Vault has developed " Concrete Battery " to avoid such restrictions.

Swiss startup Energy Vault is stacking concrete blocks to store energy - Quartz
https://qz.com/1355672/stacking-concrete-blocks-is-a-surprisingly-efficient-way-to-store-energy/

Energy Vault 's concrete battery system uses concrete blocks and cranes instead of using water and dams. Concrete batteries stack concrete blocks at a high place instead of pumping up water that was done with pumped hydropower, and lower the concrete blocks stacked when the electricity demand exceeds a certain level to the ground in order by a crane I will. The drop energy generated in the cable will be supplied as electric power when this block is lowered to the ground.

Energy Vault's concrete battery is characterized by high power efficiency. Lithium ion batteries are listed as the representative of those with high energy efficiency as of 2018, and its efficiency is said to be capable of generating 90% of the charged capacity. Concrete batteries have approximately 85% of the electric power generated when lowering the concrete battery to the ground against the electric power required to lift the block, which has almost the same energy efficiency as lithium ion batteries.

At the time of writing, the concrete battery that Energy Vault built for demo is 20 m high and 1 crane which lifts the concrete block, it is a very small facility and can not produce too much electric power. However, according to the concept of Energy Vault, the height of the concrete battery to be actually constructed is 120 m, and the number of cranes which lift the block is 6, which means that a very large facility is planned. In addition, when realizing this large facility, the maximum electric energy that can be generated is 20 megawatts hour, and it is possible to supply enough electric power to cover the electricity of 2000 Swiss general households one day ... apparently ...

Also, the concrete battery is also characterized by the very low cost of electricity supply. As of 2018, lithium-ion batteries used for power generation use is 280 dollars per kilowatt-hour (about 31,000 yen) to 350 dollars (about 39,000 yen), but for concrete batteries it costs about $ 150 It is calculated as 17,000 yen).

Energy Vault says that concrete is much cheaper to obtain than lithium-ion batteries, which is also advantageous in terms of facility construction costs. If you use unnecessary items from construction work etc. as concrete to be used in the block, it is possible to make material cost even cheaper.

Concrete battery technology has nothing new in terms of hardware, but it is devised in terms of software. Actually lifting the concrete block with the crane, it is considered that wasteful power is consumed for stacking the block because the block shakes with the grazing due to the influence of the wind. Therefore, Energy Vault implements a mechanism that minimizes the influence of the wind in the crane control program, and devises are not devised so as not to hinder the stacking of blocks even if it receives some wind.

Although it is a concrete battery of Energy Vault which seems to be a perfect facility, there are tasks as well. As of 2018 the electricity supply cost is a very low price, but lithium-ion batteries are expected to fall to the cost of 10 dollars per kilowatt-hour (about 1100 yen) in the future. For this reason, it is pointed out that it is necessary to further reduce the cost of electricity supply, etc., in order for Energy Vault to be top in energy storage field.

About the Energy Vault concrete battery, it is also explained easily in the following movies.

Storing energy in concrete blocks - YouTube