When we talk about renewable energy, what usually comes to mind are solar panels or wind turbines working throughout the day. But what happens when the sun is not shining or the wind is not blowing? This is where energy storage technologies become essential. One of the most promising solutions today is solar energy storage using molten salts.<\/p>\n
In this guide, we explain how this system works, its main applications, and its advantages and disadvantages.<\/p>\n
The basic principle is simple: store heat and release it when needed. Molten salts, typically a mixture of sodium and potassium nitrates, are heated to temperatures between 290\u00b0C and 565\u00b0C and stored in large steel tanks. The process works as follows:<\/p>\n
This system allows electricity to be stored indirectly by converting solar radiation into heat and releasing it when needed.<\/p>\n
Molten salt energy storage is not limited to solar power plants. Several applications are already demonstrating its effectiveness and potential.<\/p>\n
This is the most common application. Molten salts are widely used not only in Spain but also in countries such as the United States. They have become a standard solution to ensure continuous electricity production, even after sunset.<\/p>\n
A well known example is the Gemasolar plant in southern Spain, a global pioneer capable of providing more than 15 hours of energy storage thanks to its molten salt system.<\/p>\n
Molten salts are also highly useful in industrial processes that require constant heat, such as cement production, metal smelting, or food processing. These industries consume large amounts of thermal energy, and molten salts provide an efficient way to stabilise costs and reduce dependence on fossil fuels.<\/p>\n
Another important application is integration into hybrid systems that combine solar, wind, or even biomass energy. Molten salts help stabilise the electricity grid by smoothing demand peaks and preventing drops in production. This results in a more balanced, reliable, and sustainable energy mix.<\/p>\n
Many countries are investing in this technology for several good reasons:<\/p>\n
Like any technology, molten salt storage also has some limitations that should be considered:<\/p>\n
To better understand the strengths and weaknesses of molten salt storage, here is a comparison with other energy storage solutions:<\/p>\n
| Technology<\/th>\n | Storage capacity<\/th>\n | Lifespan<\/th>\n | Cost<\/th>\n | Main application<\/th>\n<\/tr>\n |
|---|---|---|---|---|
| Molten salts<\/td>\n | High (hours to days)<\/td>\n | More than 30 years<\/td>\n | Medium<\/td>\n | CSP plants and industry<\/td>\n<\/tr>\n |
| Phase change materials (PCM)<\/td>\n | Medium<\/td>\n | 15 to 20 years<\/td>\n | Medium to high<\/td>\n | Climate control and thermal processes<\/td>\n<\/tr>\n |
| Lithium ion batteries<\/td>\n | Medium to low<\/td>\n | 8 to 12 years<\/td>\n | High<\/td>\n | Electronics and self consumption<\/td>\n<\/tr>\n |
| Hydraulic storage systems<\/td>\n | Very high (days to weeks)<\/td>\n | More than 40 years<\/td>\n | Medium to high<\/td>\n | Large power grids<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\nHow Is Energy Stored Using Molten Salt?<\/h2>\nThe process begins by heating the salt to a temperature between 500\u00b0C and 600\u00b0C until it becomes liquid. The molten salt is then pumped into a thermally insulated storage tank, where it can retain heat for days if necessary.<\/p>\n To recover the stored energy, the hot salt is pumped through a steam generator, which produces steam to drive a turbine and generate electricity. The heat can also be used directly for industrial processes. Step by step, the process is as follows:<\/p>\n
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