Since winds and sunlight - two of the most popular sources of renewable energy - are unpredictable forces of nature, various energy storage technologies have been developed to store power for later use. One new approach is taken by MIT professor Donald Sadoway - he has developed the first ever pure liquid battery.
To keep the battery in liquid form, it's kept under constant high temperature of around 700 degrees Celsius. It's composed of three different liquid layers; two made of liquid metal alloys and one made of salt. These metal alloys are cheap and widely-available, thereby presenting the option of a cheaper storage technology. Energy from the renewable energy source is stored in the metal alloys, and when the battery needs to supply energy, ions from one of the alloys travel through the salt electrolyte, out of the battery. When the battery is being charged, energy is stored at the other metal alloy end for storage.
In the laboratory, energy input is needed for the battery to maintain its liquid form. But upon large scale use for power plants, the electricity coursing through the battery from the renewable energy source is enough to keep it liquid.
The technology has attracted the interest of various entities such as ARPA-E (Advanced Research Projects Agency, Energy), that gave the developers a $7 million grant within the next 5 years. Oil company Total has also invested $4 million in a joint venture with MIT for the development of a battery for homes and buildings using the same technology. Further studies and tests are needed before the researchers are able to build a large-scale model for practical use and at competitive cost.