Following Russia’s invasion of Ukraine, which led to gas and oil exports being halted to Europe, many citizens faced the prospect of inadequate heating during winter and insufficient air conditioning in summer.

However, the Russo-Ukrainian War has unintentionally spurred a crucial aspect of the clean energy transition – the development of batteries made from inexpensive and abundant natural materials that store heat.

The concept of using elements like sand, salt, heat, and air as energy storage dates back centuries.

Ancient Egyptians used their homes to capture solar heat during the day, which was then released to provide warmth during cooler desert nights. Indigenous peoples in the Americas valued adobe, a mixture of earth, water, and organic materials such as straw or dung, for its ability to serve the same purpose.

For modern societies heavily reliant on fossil fuels for industrial growth, these materials offer a groundbreaking prospect: the absence of combustion.

The purpose of these natural batteries is to enable countries to harness the abundant energy from wind turbines and solar panels even when the sun isn’t shining or the wind isn’t blowing. While the cost of renewables is already lower than that of fossil fuels, long-term and cost-effective storage remains a significant challenge for the green energy revolution.

At Polar Night Energy’s facilities in Tampere and Kankaanpää, Finland, large steel containers hold piles of sand, heated to approximately 1,000 degrees Fahrenheit. This stored energy assists in stabilizing power grid fluctuations and providing backup for district heating networks, ensuring that homes, offices, saunas, and swimming pools remain warm.

The Science Behind Natural Batteries

The operation of natural batteries is quite fascinating. While the sensors and valves used to monitor their performance are considered high-tech, the design of the battery itself is actually quite simple.

To start, sand is brought in from various sources, such as demolished buildings or sand dunes. Since sand is so abundant, it costs energy companies almost nothing to buy it. 500 kilograms of sand can be purchased for less than 50 cents.

The sand is then dumped into a large container, referred to as the “battery.” The battery is consistently kept at a high temperature, or “charged.”

Renewable energy from sources like solar panels and wind turbines is converted into heat by a resistance heater. This heated air is then circulated through the sand by a fan, ensuring a continuous flow of warmth.

The sand retains its heat even after sunset, thanks to insulation from the container. In fact, the temperature of the sand remains above 200 degrees Fahrenheit even when the battery is partially charged. The temperature can reach over 1,000 degrees when it is fully charged.

The sand is capable of storing power for weeks or even months. This gives sand batteries a significant advantage over lithium-ion batteries, which typically retain energy for only a few hours.

Polar Night Energy opts to use sand or similar materials that are not suitable for the construction industry. This allows them to utilize locally available materials or even waste products.

Why Natural Batteries Are Surging in Popularity

Unlike fossil fuels that can be easily transported and stored, renewable energy sources such as solar and wind power are dependent on weather conditions and vary in availability. Consequently, innovative storage techniques are required.

While lithium-ion batteries are widely used in various devices, including electric vehicles, they have their limitations. These batteries have a limited capacity, degrade with each recharge, and present a significant fire hazard. Additionally, the extraction of cobalt, a crucial raw material for lithium-ion batteries, often involves child labor and poses environmental and human rights concerns.

These challenges present a significant obstacle for the electric vehicle industry, which relies heavily on a stable supply of critical minerals.

Investors are increasingly directing their funds towards larger battery projects, with over $900 million invested in clean storage technologies since 2021. The Long Duration Energy Storage Council predicts that by 2040, investments in large-scale renewable energy storage could reach $3 trillion.

Among these ventures are initiatives focused on transforming natural materials into batteries. Start-ups that were once obscure are now receiving substantial government and private funding as they experiment with unconventional materials.

Examples include a carbon dioxide-based battery in Sardinia, a rock-based storage system in Tuscany, and a Swiss company using massive bricks to store renewable energy in a 230-foot tall building.

Additionally, a Danish battery start-up that stores energy from molten salt plans to establish power plants in decommissioned coal mines across three continents.

In an interview with The Washington Post, Kurt Engelbrecht, an associate professor specializing in energy storage at the Danish Tech University, highlighted that these technologies have been around for a long time. He and his colleagues have been advocating for simple, natural-based storage solutions for years.

However, the energy crisis resulting from the Russo-Ukrainian war has finally catapulted clean batteries to a place of prominence in the energy industry.

The Future of Natural Batteries

The success of natural batteries hinges on their ability to provide consistent power at scale, comparable to fossil fuels. Energy experts are uncertain if this can be accomplished.

Like the broader renewable energy sector, the natural battery industry may face hurdles. Projects must be built from scratch and may only be embraced by developed countries with the financial means to experiment with such technology.

In a recent interview, Lovschall-Jensen, CEO of molten salt-based storage start-up Hyme, highlighted the challenge of maintaining the current standards of modern society. People want reliable, on-demand power at the flip of a switch. Jensen believes that while natural batteries are in early stages of development, they can meet this objective.

Although it’s far from guaranteed, sand batteries could soon replace lithium-ion batteries due to their low cost and long storage periods. 

Image Source: JAKsbak,