How Do Sand Batteries Store Renewable Energy

By: Emily Newton

As world events have drastically driven the prices of fossil fuels and gasoline up, the search for renewable energy resources is more critical than ever. World governments are investing more in renewable energy research and development than ever before.

While innovators continue to research the more well-known sources of renewables such as solar, wind and hydroelectric power, they must find ways to store the excess energy these technologies create effectively. One of these is sand battery energy storage.

What Is a Sand Battery?

Sand batteries use sand’s ability to store heat as a thermal energy storage method during the winter. Devices powered by solar or wind energy generate heat into the sand battery through resistive heating. The heat then circulates through the sand using a heat exchanger and is absorbed by the sand, storing it for future use.

Sand battery energy storage is a large silo-like structure filled with low-quality sand. Surprisingly, sand can be a good heat conductor — it can store heat up to 500° Celsius for several months if properly insulated.

Sand Batteries and Renewable Energy

One of the most significant challenges of using renewable energy is how to use it year-round. While solar and wind energy are currently the cleanest forms of renewables, outside factors such as weather can significantly reduce their efficiency. It’s this factor that keeps solar and wind from being reliable energy sources.

Thermal energy storage technologies are constantly innovating to meet this problem, along with reducing the prices of equipment, construction and training. Sand batteries are also one such technology.

Sand batteries can store much energy generated from renewable resources as heat. While most of the energy from solar panels or wind turbines powers buildings, a portion of it can store in sand batteries. This can ensure the energy generated from renewable sources can continue to be useful, even if conditions are not ideal for them to continue running. Currently, sand batteries heat hot water that can be used for various purposes.

The First Commercial Sand Battery

Finnish startup Polar Night Energy recently completed the first fully operational sand battery facility alongside Vatajankoski, a Western-Finland-based energy utility company. While sand battery energy storage has always been an experimental technology, the one in Finland is the first functional and commercially available one.

Polar Night Energy’s sand battery can store an estimated 100 kW of heating power, which functions once the battery reaches 600° C or more, depending on the client’s needs. While it might not seem like much, the ability to provide extra heat to residential homes is a great boon for many towns in Finland.

The country gets most of its fossil fuels from Russia. However, because the nation decided to join NATO amid the conflict in Ukraine, Russia halted fuel and electricity supplies to the country. With the threat of the cold season, Finland has turned to renewable energy to help citizens with little or no power survive the severe frost. In this way, thermal energy storage units like Polar Night Energy and Vatajankoski’s can make a huge difference.

Applications of Sand Battery Technology

Other countries are following in Finland’s footsteps and developing sand battery energy storage technology to respond to the increasing shortage of fossil fuel and electricity resources. Energy companies Enel X and Magaldi Group have begun constructing their thermal energy storage facility in Salerno, Italy. However, instead of using heat to warm residential buildings using hot water, the Magaldi Green Thermal Energy Storage unit will use sand battery energy storage technology to boil water into steam.

The Magaldi Green Thermal Energy Storage uses patented technology to store 13 MWh of thermal energy. It can release this heat to boil water between 120° and 400° C, turning it into steam. This steam can power turbines that generate mass amounts of electricity directly.

This can have an enormous impact on the renewable energy sector worldwide. Sand battery energy storage can store enough power from renewable energy resources to generate electricity, making renewable resources more reliable. Being able to store and use clean energy more often will drastically curb the world’s dependence on fossil fuels, reducing harmful emissions across the globe.

Can Sand Batteries Replace Lithium Batteries?

Interest in sand battery energy storage has prompted researchers to look into the possibility that it could replace lithium batteries as an alternative storage unit. While lithium batteries are not harmful to the environment, mining and refining them destroys ecosystems and creates toxic emissions.

In addition, rapid advancements in technology and global events have increased the demand for lithium batteries, causing a worldwide shortage of the mineral. Currently, green and renewable energy technologies rely heavily on lithium batteries for storage.

Sand battery energy storage technology can relieve some of this dependence. Not only is sand much cheaper than lithium, but it’s also easier to find and use. While lithium batteries are best as smaller energy storage units, sand can hold much more energy than lithium, making it ideal for large-scale energy storage.

Unlike lithium, sand doesn’t require that much refinement and functions as a thermal energy storage device. In addition, sand can be more reliable than lithium. Because it does not need to be refined and there are not many complex moving parts in a sand battery, they are less likely to break down and last much longer without maintenance.

Sand battery energy storage facilities are also resistant to power surges because of sand’s insular nature. This can mean fewer potential accidents in the event of a large-scale disaster.

Sand Battery Technology Is the Future of Renewables

Sand battery energy storage units developed alongside new renewable energy technologies can significantly reduce the world’s dependence on fossil fuels and other harmful energy sources. Thermal energy storage units can help solve the reliability problem in solar and wind energy by making that power more readily available.

In addition, sand battery technology has numerous applications, from heating residential homes to powering electric power plants. As renewable energy technologies advance, scientists will find even more innovative uses for sand batteries.

Emily Newton is Editor-in-Chief at Revolutionized