Energy Storage, the Golden Partner of Photovoltaics

Behind the global electricity supply shortages lies a critical shortfall in the power system that remains unresolved: energy storage technology.

Underdeveloped energy storage technology means that the electricity product lacks inventory as a buffer. Any significant fluctuations in supply and demand relationships can impact the power system. This shortfall becomes increasingly pronounced, especially as the global energy structure shifts from traditional to renewable sources.

Based on current global electricity consumption, a solar panel area of only 40,000 square kilometers would be sufficient to supply global electricity needs. While 40,000 square kilometers may sound daunting, it's actually only 1/40th of the area of Xinjiang Uygur Autonomous Region.

The reason why human electricity consumption cannot rely entirely on solar energy is mainly due to the lagging development of energy storage technology.

０1 The four technical directions of energy storage

Whether China can achieve carbon neutrality by 2060 hinges significantly on energy storage technology. Against the backdrop of new energy and carbon neutrality, energy storage technology emerges as a crucial area of focus.

In July 2022, China's National Development and Reform Commission issued the "Guidance on Accelerating the Development of New Energy Storage," clearly stating that by 2025, the installed capacity of new energy storage should exceed 30 million kilowatts, nearly ten times the current installed capacity. This represents a nine-fold increase in just four years.

In the future, energy storage technology may primarily focus on electrochemical energy storage. There are four main directions for energy storage technology: pumped hydro storage, compressed air energy storage, flywheel energy storage, and electrochemical energy storage.

Pumped hydro storage involves pumping water to a high elevation and generating hydroelectric power when needed. While this method offers large capacity and high cycle numbers, it requires specific terrain conditions, thus limiting its application scenarios.

Compressed air energy storage and flywheel energy storage, while possessing smaller energy and power capacities, have not yet entered commercial applications.

Electrochemical energy storage, represented by various battery technologies such as lithium-ion batteries, boasts widespread application scenarios. It is considered the mainstream of future energy storage technology, expected to account for over 90% of all energy storage.

The energy storage sector can be divided into two main categories:

• First, battery manufacturers;

  
  

• Second, integrators of battery systems, which combine battery packs, security and fire protection systems, inverter systems, energy management systems, and more.

  
  

• Currently, national standards for the energy storage industry are not yet fully established and mostly remain in the consultation phase.

In the future, a shared energy storage model may emerge.

According to regulations from the National Development and Reform Commission (NDRC), new energy generation projects must be accompanied by energy storage capacities of no less than 10% to ensure grid stability. However, if each new energy station must independently build 10% of its energy storage capacity, it could be cumbersome. Therefore, a possible future commercial model involves establishing shared energy storage stations, where various new energy stations in the area pay for their services to manage peak shaving and frequency regulation.

Whether in battery manufacturing or integration capabilities, China is quickly advancing to the forefront of the global energy storage industry.

What are energy storage stations used for? They can serve as backup power sources for cities, providing emergency power during grid failures for hospitals, emergency services, communication facilities, and rescue facilities.

Additionally, energy storage stations can serve as black start power sources. In the event of a grid failure, they can drive thermal power units in the grid to restore power supply.

０２ The types of batteries used in new energy storage

The current new energy battery race primarily involves three types of technology routes: lithium-ion batteries, sodium-ion batteries, and hydrogen fuel cells.

Recently, vanadium batteries have emerged, and since July, the capital market has been heating up, with vanadium battery concept stocks collectively rising.

In October 2022, the upcoming Dalian energy storage station will utilize a new technology called an all-vanadium redox flow battery, also known as a vanadium battery. Vanadium is a rare metal, and the principle of the all-vanadium redox flow battery involves different valence states of vanadium ions undergoing oxidation-reduction reactions in the electrolyte, thereby achieving charge and discharge. This Dalian energy storage station is currently the world's largest all-vanadium redox flow battery energy storage station.

Vanadium batteries were commercially applied in 1993, while lithium batteries were commercialized in 1991. Although they started almost simultaneously, subsequent battery application scenarios favored lithium batteries, while being unfavorable to vanadium batteries.

In the past 30 years, the largest application scenarios for battery technology have been electronic devices and electric vehicles, which demand smaller battery sizes, favoring lithium batteries but posing a fatal weakness for vanadium batteries.

The energy of lithium-ion batteries is mainly stored in solid electrode materials, while the energy of vanadium batteries is directly stored in tanked electrolytes. Liquids inherently take up more space than solids, and coupled with the additional structures of the electrolyte system—a pumping system and an electrochemical stack—required for charge and discharge, vanadium batteries have significantly larger sizes.

The solubility of vanadium ions is relatively low, and the electrolyte cannot reach the desired high concentration.

Currently, the energy density of lithium-ion batteries ranges from 80 to 300 watt-hours per kilogram, while the energy density of vanadium batteries is only 12 to 40 watt-hours per kilogram. To store the same amount of electricity, the volume of vanadium batteries needs to be five times that of lithium batteries.

With the advent of the energy storage era and the surge in demand for energy storage, energy storage stations are being constructed everywhere. For energy storage stations, space is available, so the large volume of vanadium batteries is not a problem.