Introduction
Renewable energy is the answer to sustainable development. It is the hot topic of our generation and even though it is in its rudimentary stage, it is the best solution in maintaining the balance between environment and our energy needs. We all know that a lot of research is going on in this field, whether it is the oft talked about and used solar and wind energy, or the slightly less used ocean thermal energy.
But, what do you do after you produce this energy? What if it is in excess to your current need? You need to store it because… Frankly, it would be a waste of resources otherwise. And this is the need of the hour.
A lot of this storage is now being done on Lithium ion batteries but we’re still trying to find new ways to store it which is more efficient, environment friendly and cost effective as well. One of these methods is storing energy in molten salt.
What is the molten salt technology?
Basically, it stores energy in molten salts. Salt at the room temperature is brought to a higher temperature by heating and hence converting it into its molten state. The energy is stored as the latent heat of the salt. This energy being stored can be used as and when required.
Alphabet’s ‘Project Malta’ have used this concept to store energy from wind and solar. The set up consists of 4 large, insulated vats, 2 containing salt and the other 2 containing antifreeze. The electrical energy produced from these sources is used to create 2 separate streams of hot and cold air. These streams are used to respectively heat the salt and cool the antifreeze. When we need to use this energy, the 2 reservoirs can be used to produce hot and cold streams of air that leads to the formation of powerful gusts; this can then be used to run the turbine. The advantage of this method is that it is non-toxic and chemically inert.
Solar Reserve also uses the same basic concept. Here, we have a tank with a salt which is a mixture of sodium and potassium nitrate. The heat energy from the sources is used to heat up the salt and then it is maintained at a higher temperature of around 560˚C. To use this energy, it is sent to a heat exchanger which produces steam at high temperature and pressure. This is then used to run a turbine.
Apart from this, a lot of research is also going on in this field all over the world. The University of South Australia recently won the ANSTO Eureka Prize for Innovative Use of Technology for their ground-breaking work in this field.
