Finnish City Launches 1 MW/100 MWh Sand Battery for Innovative Energy Storage Solutions

technology. Discover how this groundbreaking approach is transforming district heating and reducing carbon emissions.">

September 3, 2024

Pornainen, Finland – A groundbreaking energy storage solution is gaining momentum in Finland, demonstrating a pathway towards reduced carbon emissions and increased energy independence. Engineers have successfully implemented a large-scale ‘sand battery’ system, which is expected to decrease carbon emissions from district heating by an remarkable 70 percent.

Beyond Batteries: The Rise of Thermal Energy Storage

While conventional battery technology dominates the energy storage landscape, innovators are exploring alternative methods. These include utilizing materials like fire bricks for industrial process heat and even arrangements of massive concrete blocks to convert kinetic energy. Finland, however, has emerged as a frontrunner with its pioneering sand battery technology.

How Sand Batteries Work: A Simple Yet Effective Concept

The concept behind a sand battery is remarkably straightforward.Excess renewable electricity is used to heat a large pile of sand to approximately 500°C (932°F). This heated sand then serves as a thermal reservoir, releasing heat when needed for various applications, including heating homes, factories, and swimming pools. Remarkably, the sand can retain heat for months.

From Prototype to Practical Implementation

The journey began several years ago with Finnish engineers Markku Ylönen and Tommi Eronen, who founded Polar Night Energy. Their initial prototype, consisting of 100 tons of sand housed in a silo-like structure in Kankaanpää, proved the viability of the concept.Now, a significantly larger battery, filled with 2,000 tons of crushed stone, is operational in Pornainen, southern Finland.

District Heating Transformed: Eliminating Oil Reliance

Loviisan Lämpö, a Finnish district heating company serving multiple municipalities, collaborated with Polar Night Energy on the pornainen project.Previously,the majority of heat for the system came from burning oil. The new sand battery has completely eliminated the need for oil, supplemented only by wood chips, a carbon-neutral but less ideal source.

“A couple of years ago, we started considering how to take district heating in pornainen to the next level,” stated Mikko Paajanen, CEO of Loviisan Lämpö. “The Sand Battery proved to be the best option, aligning with our sustainability goals.”

Technical Specifications and Efficiency

The operational sand battery is a towering steel cylinder, measuring 42 feet in height and 50 feet in width. A heat exchanger and closed-loop system circulate heat through a network of pipes filled with hot water,delivering warmth to buildings via radiators and floor heating systems. The system boasts a round-trip efficiency of 90 percent.

Feature	Specification
battery material	Crushed Soapstone Chips
Storage Capacity	2,000 tons
Operating Temperature	500°C (932°F)
Heat retention	Weeks to months
round-Trip Efficiency	90%

investment and Future Prospects

Polar Night Energy anticipates a strong financial future for sand batteries, driven by their potential to participate in electricity reserve markets, reduce reliance on single energy sources, and integrate electricity and heat sectors. Investment firm CapMan Infra, the owner of Loviisan Lämpö, has lauded the technology as a cost-efficient and sustainable investment.

“If it works here, it will work anywhere,” said Sauli Antila, investment director at CapMan Infra.

The company is actively pursuing new projects, including an electricity production pilot in valkeakoski and large-scale thermal storage ventures for district heating and industrial process heat. “Industrial applications are notably promising, especially where heat above 100°C is required,” added Liisa Naskali, COO of Polar Night Energy.

Did You Know? Finland’s move toward sand battery technology was partially spurred by its need to secure energy independence following russia’s cessation of energy supplies after Finland’s decision to join NATO.

Pro Tip: Thermal energy storage, like sand batteries, is most efficient when paired with intermittent renewable energy sources like solar and wind, smoothing out supply fluctuations.

The Broader Context of Thermal Energy Storage

thermal energy storage (TES) isn’t a new concept. However, advancements in materials and system design are making it increasingly viable. TES systems encompass a range of technologies beyond sand batteries,including molten salt storage,ice storage,and even utilizing water as a storage medium. According to a recent report by the International Renewable Energy Agency (IRENA), TES could play a vital role in decarbonizing heating and cooling sectors globally, offering a significant reduction in greenhouse gas emissions.

The increasing focus on energy efficiency and renewable energy integration is driving innovation in the TES market. Global investment in TES projects is projected to grow significantly in the coming years, as countries and industries seek sustainable alternatives to traditional heating and cooling solutions.

Frequently Asked Questions about Sand Batteries

• What is a sand battery? A sand battery is an energy storage system that uses heated sand to store thermal energy for later use.
• How long can a sand battery store heat? Sand batteries can retain heat for weeks or even months, depending on insulation and environmental factors.
• What are the benefits of sand batteries? They offer a sustainable, cost-effective, and long-lasting alternative to traditional battery storage, with high efficiency and no chemical degradation.
• Are sand batteries safe? Yes, sand batteries do not rely on chemicals and won’t catch fire, making them a very safe storage solution.
• Can sand batteries be used for electricity storage? While primarily designed for thermal energy,sand batteries can indirectly contribute to electricity grid stability by storing energy for heating purposes,reducing peak demand.
• What materials besides sand can be used? Crushed soapstone chips, or any material crushed to a sand-size particle, can be utilized.
• How efficient are sand batteries at converting energy? Current systems demonstrate a round-trip efficiency of approximately 90 percent.

What other innovative energy storage solutions do you think could revolutionize the power industry? Share your thoughts in the comments below!

Do you believe sand battery tech will be adopted globally, or is it largely suited for colder climates?

What are the primary advantages of using sand as an energy storage medium compared to traditional battery technologies like lithium-ion?

What is a Sand Battery?

A sand battery, a relatively new concept in energy storage, utilizes readily available and inexpensive sand as its primary storage medium. Unlike traditional batteries relying on lithium or other rare earth minerals, sand batteries store energy as heat. This heat is generated by excess electricity – often from renewable energy sources like wind and solar – and is retained within a large mass of sand. The process involves heating the sand to extremely high temperatures (around 800°C / 1472°F) using excess electricity and then insulating it to retain that heat for extended periods. When energy is needed, the heat is extracted to produce steam, which drives a turbine to generate electricity.

The Kaukasuo Sand Battery: A Pioneering Project

The city of Kaukasuo, Finland, has recently commissioned a groundbreaking 1 MW / 100 MWh sand battery storage system. Developed by Polar Night Energy, this facility represents a significant leap forward in thermal energy storage technology. This isn’t a theoretical concept; it’s a fully operational system designed to address the intermittency challenges inherent in renewable energy generation.

Here’s a breakdown of the Kaukasuo project:

Capacity: 1 megawatt (MW) power output and 100 Megawatt-hours (MWh) of energy storage capacity. This means it can continuously deliver 1 MW of power for 100 hours.

Storage Medium: Approximately 200 tonnes of sand, sourced locally.

Heat retention: The system boasts an notable heat retention capability,allowing stored energy to be discharged even months after initial charging.

Integration: Directly connected to the local district heating network, providing heat to homes and businesses.

Efficiency: While the round-trip efficiency (electricity-to-heat-to-electricity) is lower than lithium-ion batteries, the low cost and long lifespan of sand make it a compelling alternative for specific applications.

How Does the Kaukasuo Sand Battery Work?

The process is surprisingly straightforward:

1. Excess Electricity Input: When wind turbines or solar panels generate more electricity than the grid demands, the excess power is diverted to the sand battery.
2. Heating element Activation: An electric resistance heater embedded within the sand mass converts the electricity into heat.
3. Sand Heating: The sand is heated to extremely high temperatures (around 800°C).
4. Insulation & Storage: A highly insulated steel container prevents heat loss, allowing the sand to retain the heat for days, weeks, or even months.
5. Heat Extraction: When electricity is needed,heat is extracted from the sand using heat exchangers.
6. Steam Generation: The extracted heat boils water, creating high-pressure steam.
7. Electricity Generation: The steam drives a turbine, generating electricity that is fed back into the grid or used for district heating.

Benefits of Sand Battery Technology

Sand batteries offer a unique set of advantages, notably in the context of a growing renewable energy sector:

Low Cost: Sand is abundant and inexpensive, considerably reducing material costs compared to lithium-ion batteries. This makes large-scale energy storage more economically viable.

Long Lifespan: Sand has an essentially unlimited lifespan, unlike lithium-ion batteries which degrade over time.

Sustainability: Utilizing a readily available natural resource minimizes environmental impact and reduces reliance on critical mineral supply chains.This addresses concerns highlighted in reports about sand shortages and the environmental impact of sand extraction.

Safety: Sand is non-flammable and non-toxic, making sand batteries inherently safer than many other energy storage technologies.

Scalability: Sand batteries can be scaled to various sizes, making them suitable for a range of applications, from individual buildings to entire cities.

District Heating Integration: Ideal for integration with district heating networks, providing a sustainable and efficient heat source.

Applications Beyond Kaukasuo: Potential use Cases

The Kaukasuo project is just the beginning.Sand battery technology has the potential to revolutionize grid-scale energy storage in several ways:

Renewable Energy smoothing: Stabilizing the grid by storing excess energy from intermittent sources like wind and solar.

Peak Shaving: Reducing peak demand charges by discharging stored energy during periods of high electricity consumption.

Industrial Heat Supply: Providing a sustainable heat source for industrial processes.

Off-Grid Power: Enabling reliable power supply in remote areas with limited grid access.

Combined Heat and Power (CHP) Systems: Integrating with CHP plants to improve efficiency and reduce emissions.

Sand Battery vs. Lithium-Ion: A Comparison

| Feature | Sand Battery | Lithium-Ion Battery |

|—|—|—|

| Cost | Low | High |

| Lifespan | Virtually Unlimited | Limited (Degradation) |

| Sustainability | High | Moderate (mineral Sourcing) |

| Safety | Very High | Moderate (Thermal Runaway Risk) |

| Energy Density | Low | High |

| Round-Trip efficiency | Lower (30-40%) | Higher (8