Wind Turbines Power Liquid-Air Energy Storage

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Photo: Keuka Energy

One startup energy company is looking to reinvent not only wind energy, but also energy storage.

Keuka Energy recently launched a 125-kilowatt prototype vessel that uses its novel floating wind turbine design paired with liquid-air energy storage to create a steady source of electricity.

Unlike traditional wind turbines, which have three blades and a central gearbox, Keuka’s turbine is a pinwheel of aluminum blades that sits atop a floating V-shape platform containing liquid air.

The Florida-based company claims that its wind turbine design allows for larger turbines that could produce far more electricity. The world’s largest single offshore wind turbine is currently about 6 megawatts; Keuka says its full-size turbines could produce at least double that amount.

Liquid-air energy storage, also sometimes called cryogenic energy storage, is a long-term energy storage method: electricity liquefies air to nearly -200°C and then stores it at low pressure. When the energy is needed, the liquid air is pumped to a high level of pressure and heated to a gas state. The gas then drives a turbine.

Although it is an attractive energy-storage technology because of its long duration, liquid-air energy storage requires a significant amount of electricity to make the liquid air, limiting its usage by utilities. Keuka claims that because its design substantially reduced the cost by supplying the power directly from the turbines to the liquefaction equipment.

The company also says its wind turbine design is more cost effective, thanks to elimination of the gear box and the use of light-weight aluminum blades that cost less than 10 percent the price of traditional composite blades. Even if the technology is effective and can come in at lower costs, Keuka will likely face a long road to acceptance by the notoriously risk averse utility industry.

Keuka is not the only startup looking to advance liquid-air energy storage. In 2014, General Electric signed an exclusive global licensing deal with Highview Power Storage, a U.K. startup that makes utility-scale liquid-air energy storage systems.

Another similar technology that has gained more traction is compressed-air energy storage, which does not have the energy density of liquid air, but so far has proven more cost effective. Compressed air, while a cheap form of energy storage once built, is still expensive to build and geographically limited; underground caverns are needed to store the air.

Other startups are also looking offshore for cheap energy storage. Bright Energy is developing a system that would use offshore renewable energy to store compressed air in vessels in the ocean. Canadian startup Hydrostor also has a design to store compressed air underwater. 

If Keuka’s 125-kilowatt prototype is successful, it plans to launch a larger 25 MW demonstration project in early 2017.

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