The world’s largest advanced compressed air energy storage is ready for commercial operation

It's located in Zhangjiakou, a city in north China’s Hebei Province.
Loukia Papadopoulos

The largest and most efficient advanced compressed air energy storage (CAES) national demonstration project has been successfully connected to the power generation grid and is ready for commercial operation in Zhangjiakou, a city in north China’s Hebei Province, announced in a press release the Chinese Academy of Sciences lat week. The project is the world’s first 100-MW CAES power plant.

Powering 40,000-60,000 households

The plant was developed by the Institute of Engineering Thermophysics (IET) of the Chinese Academy of Sciences and can generate more than 132 million kWh of electricity annually. This will see 40,000-60,000 households equipped with power during peak electricity consumption. From an environmental perspective, it also offers promising results, saving 42,000 tons of standard coal and reducing carbon dioxide emissions by 109,000 tons annually, stated IET.

What is CAES?

CAES is a type of battery that uses off-peak or surplus electricity from the grid to produce energy. It does this by using that extra electricity to run a compressor which in turn generates heated compressed air. This air is stored inside a purpose-built underground cavity, where hydrostatic pressure pushes it back to the surface.

There, it is re-heated by the thermal store and directed through a turbine which generates electricity. CAES systems are increasingly growing in popularity, because compared to conventional batteries, they can store energy for longer periods of time and have less upkeep.

Most CAES developments use renewable electricity in valleys of electricity demand to compress and store air in large storage caverns. During hours of peak electricity demand, high-pressure air is set free from the storage caverns and combined with fuel to drive turbines resulting in power generation.

These systems provide large storage capacity, low capital cost, a long lifetime, safety, and environmental friendliness. They are often touted as one of the most promising technologies for large-scale energy storage.

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However, the technology has long been restricted and burdened by its dependence on fossil fuels, its large storage caverns, and its low system efficiency.

Solutions implemented

The Zhangjiakou 100-MW advanced CAES project researcher and development team has been working on finding solutions to these issues since 2004. It took them 14 years to come up with their new system that was launched in 2018. This modified and optimized CAES uses artificial air storage vessels to improve energy storage density and reduce dependence on large gas storage caverns.

It does this by recycling compression heat, a process that solves the problem of dependence on fossil fuels. In addition to these measures, the team has also adopted supercritical thermal storage, supercritical heat exchange, high-load compression and expansion, and system optimization and integration technologies in order to improve system efficiency.

This is not the first such system to come to market, In May of 2021, Canadian firm Hydrostor, a long-duration energy storage solution provider, revealed that it was going to develop a CAES in California. The Hydrostor facilities were said to use an updated version of the CAES technology called Advanced Compressed Air Energy Storage (A-CAES) that incorporates components from existing energy systems to produce an advanced, emissions-free storage system. Not only is the system low-impact and cost-effective, but it can also be placed anywhere the grid needs it.

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