Gravity energy storage is a kind of mechanical energy storage, which is divided into liquid medium energy storage system and solid medium energy storage system according to different media. The solid medium energy storage system realizes the charging and discharging process of the energy storage system by lifting and lowering the energy storage medium based on the height drop.
New gravity energy storageThere are various types of gravity energy storage, and different types of gravity energy storage have different application scenarios. According to the medium and height difference of gravity energy storage, there are mainly the following four types of energy storage: new type of pumped storage, gravity energy storage based on height difference of structures, gravity energy storage based on mountain drop, and gravity energy storage based on underground shafts.
Development status of gravity energy storage
Gravity energy storage belongs to mechanical energy storage, and its energy storage medium is mainly solid matter and water. The basic principle of gravity energy storage is to lift and lower the energy storage medium based on the height difference, so as to complete the charging and discharging process of the energy storage system.
When water is used as the gravity energy storage medium, the energy storage system can use pipes, shafts and other structures with better sealing performance. The biggest limitation of water medium is that its flexibility and energy storage capacity will be greatly limited by water source and terrain. When solid material is used as the medium, the solid heavy material needs to choose a material with higher density, such as metal, cement, stone sand, etc. to achieve a relatively high energy density. The new gravity energy storage will be realized through a variety of paths.
Various types of new gravity energy storage
There are various types of gravity energy storage, and different types of gravity energy storage have different application scenarios. According to the medium and height difference of gravity energy storage, there are mainly the following four types of energy storage: new type of pumped storage, gravity energy storage based on height difference of structures, gravity energy storage based on mountain drop, and gravity energy storage based on underground shafts.
Undersea energy storage system:
- Use seawater static pressure difference to store and release energy through water pump-turbine;
- Make reasonable use of ocean space, suitable for large-scale coastal energy storage. Most of the electricity load in my country is in coastal areas. The construction of offshore wind farms is accelerating, and the demand for energy storage in coastal areas may usher in an outbreak period. The difficulty of this kind of energy storage lies in the manufacture of hollow spheres, the reinforcement of subsea systems, and the erection of cables and pipelines for communication on the sea surface.
Piston water pump energy storage system:
- Use the gravitational potential energy of the piston to form water pressure in a well-sealed channel to store and release energy;
- According to the change of the quality of the piston and the height of the lift, its energy storage capacity can be changed, thereby realize long-term energy storage at grid level. The capacity of the energy storage system is adjustable, the water demand is small, and it can be flexibly applied to urban medium and small power energy storage and large-scale energy storage.
The new gravity energy storage has outstanding advantages
The new gravity energy storage has a wide range of downstream application scenarios, and the energy storage tower has outstanding performance.
Compared with lithium battery energy storage:
- In terms of cost, the kWh cost of gravity energy storage is relatively low.
- In terms of energy storage duration, the energy storage duration is longer, which is relatively more able to meet the energy storage needs of customers, such as long-term peak shaving on the grid side, industrial and commercial arbitrage through energy storage, etc.
- In terms of efficiency, the efficiency span of gravity energy storage is larger than that of lithium battery energy storage, but the efficiency gap between energy storage tower projects and lithium battery energy storage is smaller. Lithium batteries are greatly affected by temperature. When the temperature is too low, the energy storage capacity of lithium batteries will decrease accordingly. In comparison, the efficiency of gravity energy storage at the temperature level is more stable than that of lithium batteries.
- In terms of safety, lithium battery energy storage belongs to chemical energy storage, which has a low safety factor and is prone to spontaneous combustion or explosion. Because gravity energy storage is mechanical energy storage, there are no safety hazards such as spontaneous combustion and explosion. Compared with pumped hydro, the new gravity energy storage is easier to site. Pumped hydro storage has high requirements on water source and terrain, and the variety of new gravity energy storage is not completely dependent on water source and terrain.
The upstream and downstream industrial chain of gravity energy storage
Midstream energy storage system integrators may become the protagonists of the gravity energy storage industry chain. The upstream of the industrial chain is mainly based on construction raw materials (cement, metal, steel, etc.) and equipment, the midstream is the energy storage system integrator, and the downstream applications are distributed on the power generation side, the grid side and the user side.
Upstream raw material prices are stableThe upstream of gravity energy storage is infrastructure raw materials and mechanical equipment. Gravity energy storage needs to use materials with high energy density such as metal and cement as heavy objects, so the selected materials and equipment belong to the infrastructure category. The prices of bulk raw materials for infrastructure are mostly fluctuating within the range, and there are few cases of sharp rises.
Midstream gravity energy storage system becomes the protagonist
The midstream of the industry chain is the focus of the gravity energy storage industry chain, mainly composed of energy storage system installers and operation and maintenance providers. The installation of gravity energy storage system: gravity energy storage has high control requirements, and there are certain technical requirements for the installation of energy storage systems.
The operation and maintenance of the gravity energy storage system: the operation and maintenance of the gravity energy storage system improves the charging and discharging efficiency of the energy storage project.
The downstream of gravity energy storage is the full application scenario of energy storage
The downstream application of gravity energy storage can be opened in all directions around the power generation side, the grid side, and the power consumption side.
- Power generation side: The proportion of new energy power generation such as wind power plants and photovoltaic power plants has increased, and the demand for distribution and storage on the power generation side is strong.
- Grid side: The power supply and demand do not match, and the superimposed new energy power generation cannot supply stable power. On the grid side, in order to cope with the peaks and valleys of power consumption and ensure that the power supply demand of the grid is relatively stable, the demand for energy storage explodes.
- Electricity side: The widening of the peak-to-valley price difference has led to the gradual opening of the arbitrage space on the electricity end, and the awareness of industrial, commercial and household energy storage has increased.
Gravity energy storage opens up energy storage market space
The overall space of the industry has grown substantiallyThe installed capacity of new energy has maintained a relatively high growth rate, and energy storage can solve the adverse impact of new energy on the power system to a certain extent. In terms of characteristics, new energy power generation has the characteristics of intermittent and unstable. When the power fluctuation of new energy power generation is relatively large, direct access to the Internet will have an impact on the power grid.
The new type of gravity energy storage has great potential
The new gravity energy storage has outstanding performance. In terms of efficiency, electrochemical energy storage in current energy storage technologies has relatively low requirements for geographical location, but electrochemical energy storage is seriously affected by temperature.
On the one hand, the safety of electrochemical energy storage is relatively low due to unstable factors in battery charging and discharging. In recent years, safety incidents related to electrochemical energy storage have occurred frequently.
On the other hand, since chemical energy storage needs to increase fire protection costs, it will increase the overall energy storage cost. In contrast, the new type of gravity energy storage as mechanical energy storage is relatively high in safety and low in safety cost.