Solar radiation is clean and an unlimited source of energy. However, its major problem is its lack of energy production during night time. Other renewable energy technologies such as wind or wave generation also suffer intermittent supply in energy production due to environmental conditions.
Donald Sadoway, a professor from Massachusetts Institute of Technology, is one of the inventors of a new liquid battery which has the potential to be a large electricity storage device and can overcome the challenge of intermittent energy production from renewable sources. The prototype of the battery is made from all-liquid active materials.
The battery is very different from any other existing type. Its electrodes are made from molten metals, and the electrolyte that fills the space between them is a molten salt. Such a novel construction ensures very quick electricity absorption in large amounts. Electrodes of this battery can apparently work properly with current levels tens of times higher than in any other battery.
One of the battery electrodes is made from antimony and the other from magnesium. The electrolyte between them is sodium sulphide. These raw materials are in a molten state, and placed in insulated containers. Both electrodes and electrolyte have different densities, which makes each of them remain in distinct layers. Such a solution makes manufacturing of the device easier.
When electric current flows into the battery, the charging process begins. During this time, magnesium ions from the electrolyte take electrons and the creation of magnesium metal is possible. This formed metal becomes a part of the magnesium electrode. The same situation appears in the opposite electrode, but this time metal is formed due to giving up of the antimony ions by the electrode. While metal is created, the amount of electrolyte decreases and the electrodes increase their volume. The discharge mode is a reverse of the above process during which metal atoms become ions again.
The first liquid battery system will probably be used for peak hours shifting, whereby electricity will be stored during off-peak hours and used during peak hours. Such a solution will contribute to avoiding building new power plants and transmission lines necessary to satisfy peak hour demands. Sadoway and his research team have a vision of the huge liquid battery system that will be able to satisfy peak hour demands of 13 GW in New York City. Such a system will occupy around 60 000 square metres.
Frost & Sullivan believes that liquid batteries have the potential to become a cheap and scalable large-scale storage system with many advantages in comparison to existing large-scale storage techniques, such as pumping water uphill and releasing it to spin a turbine. Liquid batteries are expected to be three times cheaper than the best batteries currently available on the market. The next step in the development of the battery will be the replacement of currently used raw materials by other liquid metals, which will allow for creating more scalable prototypes. The research team believes that the battery will be ready for commercialisation in five years.
For more information contact Patrick Cairns, Frost & Sullivan, +27 (0)18 464 2402, patrick.cairns@frost.com, www.frost.com
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