AirBattery energy storage system

Designed to enable total renewable integration. Providing grid-scale, ultra-long duration storage.

As the energy transition advance, dependence on intermittent renewable energy grows, leading to grid vulnerability during long periods of undersupply.

Traditionally, fossil fuel power plants provided backup during these times. Augwind's AirBattery offers a sustainable alternative, replacing fossil fuel generation with a cost-effective, eco-friendly energy storage asset.

In 2021, an AirBattery system was installed at pilot scale (250 kW, 1 MWh) in southern Israel, reaching a round-trip efficiency (RTE) of 21%. In early 2024 the system was re-commissioned with upgraded machinery and processing.

The current pilot capacity is 0.5MW/1MWh, with current a RTE greater than 47%.

The project is a small-scale viability demonstration of Augwind’s AirBattery energy storage technology. Augwind is now ready to further advance the AirBattery towards commercialization.

The experiments in Yahel validate the company’s roadmap targeting >60% for a fully commercial AirBattery system.

The program is a cooperative effort alongside the Israeli Ministry of energy and the communal settlement of Kibbutz Yahel.

Round-Trip Efficiency Roadmap

The AirBattery is a closed loop, bi-directional system, meaning that all elements run at one direction for charging, and work in reverse when discharging. At the core of the process is Augwind’s proprietary near-isothermal liquid piston, responsible for both charging and discharging procedures.

A liquid piston process describes compression of gas using fluids. In our case, we use water to compress air. To host this liquid piston process, Augwind developed the “AirX”- our patented, underground vessels. When coupled, two or more AirX vessels serve as a liquid piston, with a pump delivering water from one vessel to the other.

Liquid piston mechanism

The compression process begins with one AirX vessel that is full of water and one AirX vessel that is full of air.

Water is pumped from the water filled vessel into the air-filled vessel. As the water level rises in the air-filled vessel, it compresses the air like a piston. Once the air pressure is high enough, the air is sent for storage and the vessel that was initially full of air is now full of water.. On the other hand, the vessel that was originally full of water is now full of air. Now, the water can be pumped back into the first vessel for another compression cycle. The process is repeated as long as there is excess electricity and room in the storage reservoir.

During expansion, a bubble of stored compressed air is released into the water filled AirX vessel. The expanding air streams the water though the same set of reversible pumps (this time operated as turbines) to regenerate electricity. The streamed water is transferred from the pump into the other vessel. Once all of the water has been transferred, the other vessel is full of water and another expansion cycle can begin.

The AirBattery System

The AirBattery combines the strengths of Compressed Air Energy Storage (CAES) with those of Pumped Hydro Energy Storage (PHES) to offer grid-scale, multi-day energy storage. It utilizes cost effective geological compressed air storage, along with efficient hydroelectric turbomachinery.

The system uses a closed-loop liquid piston mechanism to compress and expand air in an underground, near-isothermal process. Once compressed, the compressed air is stored in underground salt caverns (which are prevalent in the natural gas industry throughout the world), waiting for discharge.

Key Advantages:

Cost Efficiency

The cost of increasing storage duration is only the cost of increasing the cavern volume. As opposed to other CAES technologies (such as A-CAES) there is no need for thermal storage (in the form of heat or fossil fuels). This enables the AirBattery to provide much lower capex per kWh installed at multiday/weekly duration.

Environmental Impact

AirBattery has minimal land footprint, does not require rare raw materials, does not consume water, and does not emit anything but fresh air- Contributing to a safer and cleaner energy supply.

Supply Chain

Onsite construction that is based on local materials (steel, concrete and polymers) and labor- The AirBattery contributes to local economies where it is deployed.

For further information on AirBattery multiday energy storage

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Energy Storage

AirBattery

Hydrogen Storage

Energy Efficiency

HydroAir

AirSmart

AirBattery energy storage system

Designed to enable total renewable integration. Providing grid-scale, ultra-long duration storage.

Round-Trip Efficiency Roadmap

Key Performance indicators

Parameter

Target (current)

AirBattery module design reffernce

Liquid piston mechanism

The AirBattery System

Key Advantages:

Cost Efficiency

Environmental Impact

Supply Chain

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