Sand Battery 

The Sand Battery is a large-scale, high-temperature thermal energy storage system that uses sand or similar materials as its storage medium. It enables our clients to meet their climate goals while significantly reducing energy costs.

Products

Sand Battery 2 MW  

Affordable and sustainable heat production

A compact solution to make your heat production more affordable and sustainable. Ideal for small-to-mid-sized industrial facilities, space heating, or district heating networks.

  • Mid-sized high-temperature thermal energy storage system
  • 2 MW heating power with a capacity of 200 MWh
  • Scalable to meet higher heating demands
  • Approximate round trip efficiency 85%
  • Approximate dimensions: 15 x 12 m
  • Reduces reliance on fossil fuels, cutting emissions and operational costs
  • Easily integrates into existing energy systems

Sand Battery 10 MW  

Make an entire energy system climate-neutral

Designed to decarbonize entire energy systems, perfect for large-scale industrial processes, energy companies, district heating networks, or space heating needs.

  • Large high-temperature thermal energy storage system
  • 10 MW heating power with a capacity of 1000 MWh
  • Scalable to meet even greater heating demands
  • Approximate round trip efficiency 90%
  • Approximate dimensions: 30 x 12 m
  • Dramatically reduces carbon emissions and energy costs
  • Modular and flexible for easy integration with renewable energy sources

Applications

Water

Provide hot water for district heating and other heating systems, reduce energy costs and carbon emissions.

Air

Deliver hot air for space heating, drying, calcination, and other industrial processes, improve efficiency and sustainability.

Steam

Generate hot steam for industrial processes like manufacturing and power generation, offering a clean alternative to fossil fuel-based systems.

Electricity*

A future Power-to-Heat-to-Power (P2H2P) product will convert stored energy back into electricity. *Expected to be ready by 2026.

How Does it Work?

A solution to mitigate climate change  

The world is increasingly turning to renewable energy to combat climate change and reduce pollution. However, intermittent sources like solar and wind only produce energy when the sun shines or the wind blows, creating a mismatch between energy production and consumption.

As the share of renewables grows, energy storage becomes critical for maintaining grid stability and storing energy for later use. The Sand Battery efficiently stores large amounts of intermittent energy for extended periods and returns it as highly valuable heat when needed.

The Sand Battery is a thermal energy storage  

Polar Night Energy’s Sand Battery is a large-scale, high-temperature thermal energy storage system that uses sustainably sourced sand, sand-like materials, or industrial by-products as its storage medium. It stores energy in sand as heat, serving as a high-power and high-capacity reservoir for excess renewable energy.

The Sand Battery has three primary functions: storing excess renewable energy, participating in reserve markets to balance the frequency of the grid, and producing heat and power without combustion.

Storing renewable energy

The system charges by using electricity from the grid or local renewable sources such as solar PV or wind farms, storing energy when clean and low-cost electricity is available. Energy is transferred to the Sand Battery through a closed-loop heat transfer system. When heat is needed, it’s discharged via a heat exchanger.

Hot Water 

Process Steam

Hot Air

The Sand Battery can deliver hot water, steam, or air, with output temperatures of up to 400°C. We are also developing a solution to convert stored heat back into electricity. This heat is suitable for example water-based heating networks or for generating process steam in industrial applications.

Around 36% of all industrial process heat falls within the temperature range of Polar Night Energy’s Sand Battery. These processes, currently dependent on oil and gas, can now be decarbonized through our non-combustion technology.

Flexibility for your heat production and the electric grid

Polar Night Energy’s Sand Battery is highly flexible, capable of adjusting its charging power to take advantage of the fastest ancillary markets and the lowest electricity prices.

Its large storage capacity mitigates risks from electricity price spikes while maintaining a steady heat output for your processes. The system also enables participation in grid balancing markets without compromising heat production.

The Sand Battery reduces emissions

100 Mt of CO2e

According to a 2020 assessment by Mission Innovation, Polar Night Energy’s Sand Battery could save over 100 Mt of CO2e annually by 2030—roughly 3% of current EU emissions or double the emissions of present-day New York City.

Services

Monitoring & Reporting

Ensure peak performance with our cloud-based monitoring and reporting solution which tracks the Sand Battery’s operational status and availability in real-time.

Reserve market operation

Maximize your participation in grid balancing markets. Optimize energy storage and dispatch during peak times. Enhance grid stability and generate additional revenue.

Technical support

Our support service includes ticketing, maintenance, and spare part management. Regular reporting and proactive care ensure that the Sand Battery operates smoothly.

FAQ

What is the structure of your thermal energy storage?

Our thermal energy storage consists of an insulated steel silo filled with sand or a similar material, along with heat transfer pipes. Additional external equipment includes automation components, valves, a fan, and either a heat exchanger or a steam generator.

How do you heat the sand?

We use electricity from the grid or local renewable sources like wind and solar. The system charges when clean, low-cost electricity is available. Electrical energy is transferred to the storage via a closed-loop air-pipe system where air is heated by electrical resistors and circulated through heat transfer pipes.

How hot does the sand get?

In our current design, the storage material reaches temperatures of up to 600 °C. Higher temperatures are possible, depending on customer needs. The maximum temperature is determined not by the sand, but by the heat resistance of the construction materials.

How is heat extracted from the storage?

Cool air is blown through the pipes, absorbing heat as it passes through the storage. This heated air can then be used to convert water into steam for industrial processes or to heat water for district heating via an air-to-water heat exchanger.

Why use sand?

Sand and similar materials can be heated to temperatures far beyond the boiling point of water, allowing them to store much more energy than water in a similar volume. This makes sand a space-efficient and versatile solution for various industrial applications.

What type of sand is used?

Our system isn’t very sensitive to sand grain size. We prefer using high-density, low-cost materials that are not in demand for construction, often utilizing industrial by-products. This ensures sustainability and cost-effectiveness.

Does grain size matter?

Not significantly. We prioritize using grain sizes that are unsuitable for the construction industry to reduce resource competition.

How is the storage insulated?

The storage is constructed with steel and insulated with standard heat-resistant materials. The insulation surrounds the storage, placed between the outer and inner steel layers to keep the heat contained. Additionally, sand itself has natural self-insulating properties, enhancing the overall insulation.

How long does the sand stay hot in winter?

The sand itself can retain heat for months. Depending on the application, the system is designed to be charged and discharged between 20 and 200 times per year.

Is the outer surface of the energy storage hot?

No. The storage is well-insulated, so the exterior surface remains cool while the heat stays inside where it’s needed.

What is the output temperature?

Our current output temperature range spans 60–400 °C, covering 36% of all industrial process heat needs.

Can it store electricity?

Not directly. The Sand Battery stores energy as heat, which can be converted back to electricity using turbines, such as ORC or steam turbines. However, this requires additional investment and has inherent efficiency losses. We are developing a solution to convert stored heat back into electricity.

Is this a new technology?

Yes and no. The concept of using heated sand for energy storage isn’t new, but our approach to commercializing it on a large scale and improving efficiency is innovative.

Can I buy a Sand Battery for my home?

Not yet. We currently focus on larger industrial and commercial applications and do not have products designed for individual homes. Subscribe to out newsletter and stay updated with our latest developments and news.

Who are your clients?

We serve a wide range of industries, including energy utilities, residential and commercial building operators, and sectors like food & beverage, textiles, chemistry, pharmaceuticals, metal production, and pulp & paper.

Process Industries

Decarbonize your industrial processes with our innovative Sand Battery technology.

Energy

Optimize your energy production, storage and distribution with our climate-neutral Sand Battery solution.

How can our company start a heat storage project with Polar Night Energy?

To start a project, fill out our contact form or reach out to our sales team. We receive many inquiries, so response times may vary. We appreciate your patience!

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