Cleaner Energy Storage Using Liquid Air
Solar energy costs may be on a steady decline, and wind energy projects may be moving forward progressively, but the problem of energy storage is still at large. There are quite a number of proposed and developed alternatives though, with most staying away from the traditional battery concept, such as this new idea of storing generated energy using “liquid air”.
Highview Power Storage is a British energy storage systems company that has recently proposed the idea of storing electricity using cooled “liquid air”. Basically they would use excess energy to chill air up to the point that it liquefies, storing it, to be later reused to drive a turbine and generate energy. The system is intended to be used as a backup energy source, and they have already received at least $18 million to fund a research project that would test and prove its feasibility.
The storage and energy reuse process follows several systematic, but easy to apply steps. First, air is extracted from the environment. The air is then filtered to remove elements that become solid at low temperatures, such as carbon dioxide and water vapor. After that, the remaining extracted air is cooled and liquefied down to -190C (-310F), then stored in tightly sealed vacuum tanks.
To reuse energy stored within these chilled containers, the air is simply exposed to warmer air. As the cool air warms up, it expands, driving a turbine that would generate energy. The source report describes the process as both simple and inexpensive, and can potentially be well suited to serve the long term storage needs of any renewable energy source.
According to the report, the storage and reuse process of the proposed system has an estimated efficiency rate of about 50-60%, which is in stark contrast to the typical 90% efficiency rate of battery-type energy storage systems. Despite the considerably lowered efficiency rate, there are other perceived benefits of using such storage systems. The most notable one is its capability to store energy almost indefinitely, with only the actual durability (as years pass) of the storage containers to be taken into account. Also, simply storing air is definitely a whole lot safer for the environment than using, let’s say, an array of lead-acid batteries for a local small-scale solar or wind energy system.
As it is currently known, battery-type energy storage system holds the inherent disadvantage of high long-term investment costs. Though convenient to install and use, batteries tend to wear out after a few years of use either due to charge cycle limits, or due to the usage issues related to a battery type’s self-discharge rate. Moreover, some of the more “powerful” and efficient battery types are quite expensive to use.
The liquid air energy storage concept may also have its own practicality issues, but at least it provides an alternative solution, one that could even be potentially improved so that it might one day be more efficient, and more reliable, to use than current energy storage systems.
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