What is energy storage?

Created on 07.28

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Energy storage refers to the technology of storing energy in some form and releasing it for use when needed. Its core function is to address the mismatch between energy supply and demand in terms of time or space, improve energy utilization efficiency, and ensure the stable operation of the power system.

1. Why is energy storage needed?

Balancing supply and demand: New energy sources (such as wind power and photovoltaics) have intermittency (dependent on weather), and energy storage can "peak shaving and valley filling," storing electricity when generation is high and discharging when generation is low.

Improve grid stability: reduce power fluctuations, avoid power outages or voltage instability.

Reduce electricity costs: Charge during off-peak hours at low rates and discharge during peak hours to save on electricity bills.

Support for electric vehicles and off-grid applications: such as home energy storage, mobile device power supply, etc.

What are the main technical classifications of energy storage?

Energy storage technology can be divided into physical energy storage, electrochemical energy storage, electromagnetic energy storage, thermal energy storage, etc.:

(1) Physical Energy Storage

🔹Pumped Hydro

Principle: Use electricity to pump water from a lower place to a higher reservoir, and release water for power generation when needed.

Features: large scale, mature technology, but dependent on geographical conditions.

Application: Grid peak shaving (accounting for over 90% of global energy storage installed capacity).

🔹Compressed Air Energy Storage (CAES)

Principle: Use electrical energy to compress and store air, which drives a turbine to generate electricity when released.

Features: Suitable for large-scale energy storage, but with lower efficiency (about 50-70%).

🔹Flywheel Energy Storage

Principle: Use a high-speed rotating flywheel to store kinetic energy and convert it back to electrical energy when needed.

Features: Fast response, long lifespan, but short energy storage time (minute level).

(2) Electrochemical Energy Storage (Batteries)

🔹Lithium-ion battery

Features: High energy density, long cycle life, widely used in electric vehicles, mobile phones, and home energy storage.

Challenge: High costs, risk of thermal runaway (e.g., fire).

🔹Lead-acid battery

Features: low cost, mature technology, but short lifespan, high pollution, gradually being eliminated.

🔹Sodium-ion battery

Features: Rich in raw materials (sodium is cheaper than lithium), but with lower energy density, suitable for energy storage power stations.

🔹Flow battery (such as vanadium battery)

Features: Long lifespan, high safety, suitable for large-scale energy storage, but relatively high cost.

(3) Electromagnetic Energy Storage

🔹Supercapacitor

Features: Fast charging and discharging, long lifespan, but low energy storage, suitable for short-term high power scenarios (such as electric vehicle acceleration).

(4) Thermal Energy Storage

🔹Molten Salt Energy Storage (Concentrated Solar Power)

Principle: Use solar energy to heat molten salt, store heat, and generate electricity when needed.

Application: Solar thermal power station (such as the Dunhuang 100MW solar thermal project in China).

3. What are the application scenarios of energy storage?

Application Fields	Typical Technology	Function
Power grid peak shaving	Pumped storage, lithium battery, flow battery	Balance power supply and demand, reduce wind and solar curtailment
New Energy Supporting Facilities	Photovoltaic + Energy Storage, Wind Power + Energy Storage	Smooth power generation fluctuations and improve grid stability
Home Energy Storage	Lithium-ion battery, lead-acid battery	Self-use, reduce electricity bills, cope with power outages
Electric Vehicle	Lithium-ion battery	Provide power, support fast charging and energy recovery
Industrial/Data Center	Flywheel, supercapacitor	Provide backup power to prevent instant power outages.

What are the future development trends of energy storage?

Cost reduction: The price of lithium batteries has dropped by over 80% in 10 years, and in the future, cheaper technologies such as sodium batteries will become widespread.

Long-term energy storage: Develop hydrogen storage, compressed air, etc., to meet multi-day or even seasonal energy storage needs.

Policy support: China, Europe and the United States have introduced energy storage subsidies and mandated energy storage for new energy sources (such as China's requirement for photovoltaic power stations to have 10%-20% energy storage).

Intelligent Management: AI optimizes energy storage scheduling, enhancing grid flexibility.

Summary:

Energy storage is the "power bank" of the new energy era, solving the problem of instability in wind and solar power generation, and improving energy utilization efficiency. With technological advancements, energy storage will play a greater role in power systems, transportation, households, and other fields, promoting the global energy transition.