Could Cryogenic Energy Storage Solve Renewable Energy’s Biggest Problem?

One of the biggest challenges facing renewable energy as it becomes cheaper and more ubiquitous is energy storage. A British energy storage company wants to scale up usage of cryogenic energy storage using liquid air.

Cyrogenic energy storage (CES) utilizes low-temperature (cyrogenic) liquids as energy storage, typically liquid air or liquid nitrogen. Scientists believe that cryogenic energy storage and supply might help improve the usability of renewable energies.

Highview Power Storage, a company that designs and develops large-scale energy storage for power systems, plans to construct the largest cryogenic energy storage plant in the world. The plant will be built at a location close to Manchester, England, and will use LAES or liquid air energy storage.

 

How Cryogenic Energy Storage Works

Cryogenic energy systems are broken down into three components: a charging system, an energy store, and a discharging (or energy recovery) system. 

Highview's plant will be fed electricity from land lines where the liquefaction plant will use the electrical energy to draw in air from the surrounding environment. Once the air is drawn in, liquid air (or, in some systems, liquid nitrogen) is generated through extremely low-temperature refrigeration. The heat lost in this process is captured and stored until the discharging stage. Meanwhile, the liquid air is pumped to insulated storage tanks where it is kept at low pressure. The liquid air can be stored in these tanks for long-term storage in large amounts as it takes up 1/700th the amount of space as ambient-temperature air.

To discharge the stored energy, the liquid air is taken from the insulated storage tanks and transported to a much higher-pressure area. Through the increase of pressure in the liquid, energy is created.

Once pressurized, heat (or a higher temperature waste) is applied to the liquid air through heat exchangers. The resulting high-pressure gas is then fed through a turbine to provide electrical energy to the required source.

Below is an illustration of this process:

 

Image courtesy of Highview Power Storage

 

The Role of CES in Renewable Energy

The incredible thing about this process is its efficiency. Highview's Gigafactory, for example, will theoretically use LAES to deliver 5MW/15MWh and up to 200MW/1.2GWh .

Solar and wind renewable energy sources cannot produce when there is no sunshine or airflow, respectively. Similarly, CES isn't restrained geographically like hydropower is in order to move water uphill. Cryogenic energy storage helps renewable energy sources to sidestep the problem of environmental factors by allowing intermittent (and sometimes unreliable) energy to be stored.

Gareth Brett, CEO of Highview Power Storage told BBC Science: "Anywhere that needs large-scale long-duration storage—that might be to help integrate an offshore wind farm—a system like ours can help achieve that."

Thus far, other forms of renewable storage, such as used for solar, can get costly as the size of the plant increases due to batteries. With LAES, this is not the case, giving it an advantage among renewable energy storage systems. CES also doesn't require any harmful or toxic metals that are so often associated with large-scale battery systems.

Below is a rendering of the proposed gigaplant that is projected to produce 200MW/1.2GWh:

 

Rendering of the proposed gigaplant. Image courtesy of Highview Power Storage

 

Another advantage to this LAES system is that it is able to use its own excess waste heat (and cold, as well) as from other systems. The proposed power plant will be located next to the Pilsworth landfill gas generation site. The Pilsworth plant puts out methane gas as it decomposes trash, which is used to generate electrical energy. The LAES plant will collect this waste heat from the methane and boost the efficiency of the cryogenic process.

As renewable energy becomes cheaper, it will need better infrastructure to store and discharge the power it harvests. LAES could be pivotal in helping renewable energy sources truly claim their place in the energy industry. 

 

Featured image used courtesy of Highview Power Storage.