Morocco has the goal of generating 52 percent of its electricity from renewable sources by 2030. One of the major renewable electricity projects the country has commissioned is the Ouarzazate Project, which is divided into several phases. Another one is the solar hybrid project at Midelt which generates 800 MW. Both power projects have something in common – molten salt energy storage system.
What is molten storage energy system? How does the technology work? This article answers these questions and much more.
What Is Molten Salt Energy Storage System?
Renewable energy sources are good for the environment. However, they have a key disadvantage; they are not always available.
For example, the sun doesn‘t shine at night, and the wind doesn‘t always blow when needed. Moreover, renewable electricity can not be easily ratcheted up to meet peak demand or “ramping“.
Even when not accounting for fluctuation, ramping requirements may introduce complexities when designing renewable energy systems.
This is where energy storage comes in. Engineers use different methods or technologies to absorb excess energy during off-peak periods and use it balanced increased demands.
One of the methods used to store surplus energy and release it when needed is molten salt energy storage.
Molten salt energy storage system is a thermal method of storing energy using heat in its “sensible“ or “latent“ state.
The salt is heated and stored in an insulated container during off-peak hours which is then funneled into a steam producer that heats water.
The steam is then used to drive a turbine which generates electricity. There are several options for converting the thermal energy to electricity and they include the Rankine, Brayton, and Air Brayton cycles.
Salt is chosen because, in its molten form, it possesses a high boiling point, low viscosity, low vapor pressure, and high volumetric heat capacities.
The heat from the discharge can continue to produce power for 10 hours after sunset.
Why Use Molten Salt Energy Storage System?
Molten salt energy storage system has advantages over other options. For example, the German Energy Storage Association, BVES, discovered that molten salt is 33 times cheaper than using lithium-ion batteries. This is partly why it is the most common method of storing heat in large CSP plants.
Also, molten salt energy storage systems use dry cooling, which helps to reduce water usage, especially in countries where water is closely regulated.
In addition, unlike the hydropumping method, molten salt does not depend on geographical location. Hydropumping works where water is sufficient, which is unlikely to happen in areas like desserts where solar plants are more ideal.
Molten Salt Energy Storage System In Morocco
As Morocco continues to pursue its renewable energy policy, it has been commission solar projects in different parts of the country.
For example, the Noor-Ouarzazate Solar Complex project has the NOOR I CSP molten salt installation acting as capacity firming.
It has a 160,000 kW energy storage capacity and was completed in 2016. It was developed by a consortium formed by ACWA Power International, Aries Clean Energy, SENER Grupo de Ingenieria, and TSK Group.
ACWA Power International and SENER Ingenieria y Sistemas developed NOOR III another molten salt energy storage installation with a capacity of 150,000 kW, located in Ouarzazate, Draa-Tafilalet.
The Midelt renewable electricity installation is special because it puts Morocco on the map as the first solar project in the world to combine PV thermal storage and CSP. Excess power from the PV is stored using molten salt.
Outside Morocco, solar projects are thriving. For example, the state of California in the US hosts a molten salt energy storage system in Rocketdyne.
The Kalkaar Molten Salt Thermal Energy Storage System is another 150,000 kW energy storage project situated in Free State, South Africa.
The Future Of Molten Salt Energy Storage
Countries promoting electric vehicles can incorporate molten state energy storage systems into their energy mix to provide electricity for owners that can only charge after sunset.
Moreover, more nations are waking up to the harmful realities of hydrocarbon-based power generation. As such, renewable energy projects are springing up in different parts of the world.
This means there will be more need for technologies like molten salt energy storage to smoothen out fluctuations. It is safe to say the technology is here to stay, and research will continue how to make it more efficient.