Polar Night Energy

What Polar Night Energy does

Polar Night Energy is a Finnish deep-tech company founded in 2018 that designs and builds industrial-scale, high-temperature thermal energy storage systems — branded as "Sand Batteries" — which use sand or crushed soapstone as the storage medium to capture renewable energy as heat for later use. Its core technology stores heat at high temperatures with 80–90% round-trip efficiency, demonstrated through reference installations including the world's largest sand battery at 2,000 tonnes of thermal storage serving Pornainen, Finland, and a 250 MWh unit under construction for Lahti Energia in Vääksy (completion targeted summer 2027). Quantified customer outcomes include 70% emissions reduction, 60% woodchip combustion reduction, and 100% oil elimination in district heating applications.

The company serves two primary customer segments: (1) district heating providers and municipal energy companies seeking to decarbonize heating networks while reducing exposure to electricity price volatility and fossil fuel dependency, and (2) process industries requiring high-temperature process heat for manufacturing operations. Its go-to-market is direct enterprise sales, with feasibility studies as the lead-generation mechanism and project-based, customized installations as the delivery model. Revenue is generated through three streams: hardware sales of Sand Battery systems, project development and engineering services, and recurring grid balancing services enabled by participation in electricity balancing markets. Named customers are concentrated in Finland — Vatajankoski, Pornainen, Loviisan Lämpö, and Lahti Energia — though the company is positioning internationally via a multilingual corporate website and major global media coverage (BBC, NYT, Washington Post, CNN, Deutsche Welle, Euronews).

Polar Night Energy is privately held, has raised approximately $8.8M in disclosed funding across a 2021 seed and a 2024 round led by Stephen Industries (with Holdix Oy Ab, PC Rettig & CO Impact, and Turret Oy), and operates with 11–50 employees. Strategic credibility has been reinforced by Time Magazine Best Inventions 2025, Popular Science Best of What's New 2025, World Economic Forum recognition, the Net-Zero Industries Award 2025 (Special Prize for Electrification), and finalist status at the European Solar Startup Awards 2026.

Name

Polar Night Energy

Legal name

Polar Night Energy

Website

https://polarnightenergy.fi/

Company type

Private

Founded year

2018

Operating status

Operating

Headcount range

11–50 employees

Short description

Polar Night Energy, founded in 2018 in Finland, designs and builds industrial-scale sand-based thermal energy storage systems ("Sand Batteries") that decarbonize district heating and industrial process heat, serving municipal energy utilities and process industries across Northern Europe.

Ownership category

akta.pro rank

Product category

Thermal Energy Storage

NAICS

Ventilation, Heating, Air-Conditioning, and Commercial Refrigeration Equipment Manufacturing (3334), Air-Conditioning and Warm Air Heating Equipment and Commercial and Industrial Refrigeration Equipment Manufacturing (333415)

SIC

Heating Equipment, Except Electric & Warm Air Furnaces (3433), Industrial Process Furnaces & Ovens (3567), Air-Cond & Warm Air Heatg Equip & Comm & Indl Refrig Equip (3585)

akta.pro primary industry

High-Temperature Solid Media Storage (Bricks, Concrete, Ceramic) (EUAFANAF)

akta.pro secondary industries

Thermal LDES (High-Temperature, Molten Salt, Carnot/Heat-to-Power) (EUAFADAC), District Heating & Cooling Thermal Storage (Network-Integrated TES) (EUAFANAH), Industrial Process Heat TES (Steam, Kilns, Furnaces, Waste-Heat Coupling) (EUAFANAI)

Keywords

• Thermal energy storage
• Sand battery technology
• District heating solutions
• Industrial decarbonization
• Renewable heat storage

Headquarters

HQ city

Pilkanmaa

HQ country

Finland

HQ region

Europe

Offices5 records

Markets served

GTM type

B2B

Offering type

Hardware or Manufacturing

Cost components

Technology or R&D, Supply Chain, Operations, Personnel, Marketing or Sales, Infrastructure

Revenue model

1. Sand Battery System Sales: Sale and installation of industrial-scale sand battery thermal energy storage systems to district heating providers and industrial facilities. Systems are customized per installation with varying capacity specifications.
2. Project Development Services: Feasibility studies, project planning, installation, and commissioning services for thermal energy storage deployments.
3. Grid Balancing Services: Ongoing operational support and grid balancing services for installed systems, with additional revenue from participating in electricity grid balancing markets.

Go-to-market motion1 record

Distribution channels1 record

Marketing channels9 records

Core offering

Polar Night Energy designs, manufactures, and installs industrial-scale sand battery thermal energy storage systems that store renewable energy as high-temperature heat using sand or sand-like materials such as crushed soapstone as the storage medium. Each system is custom-engineered for the customer's site and use case, with capacities ranging from pilot units up to 250 MWh installations serving district heating networks and industrial process heat applications, achieving 80–90% round-trip efficiency and enabling decarbonization of heating and process heat.

Product overview

Polar Night Energy offers a unified product portfolio centered on its Sand Battery technology — a large-scale, high-temperature thermal energy storage system using sand or sand-like materials. The portfolio includes the core Sand Battery product for thermal energy storage, Process Industries Solution for industrial decarbonization, Energy Solution for district heating optimization, and a Feasibility Study Service for pre-project assessment. All offerings share the same underlying thermal energy storage technology but target different market segments: industrial process heat and district energy networks.

Differentiator

Problem solved

Functional benefit

Products and services

• Sand Battery Large-scale, high-temperature thermal energy storage system that uses sand or sand-like materials (including crushed soapstone) as the storage medium. Stores renewable energy as heat and serves as a high-capacity reservoir for district heating utilities and industrial process heat users.
• Process Industries Solution Application of Polar Night Energy's sand battery thermal energy storage technology tailored for decarbonizing industrial process heat in manufacturing operations. Designed for industrial facilities that require high-temperature heat for production processes.
• Energy Solution Climate-neutral thermal energy storage solution for optimizing energy storage, production and distribution in district heating networks. Built on the sand battery platform and targeted at energy utilities and municipalities.
• Feasibility Study Service Pre-project assessment service that evaluates the potential of a sand battery installation for a prospective customer's site and use case, used as a lead generation and project scoping tool for enterprise customers.
• Pornainen Sand Battery (World's Largest Sand Battery) Industrial-scale 2,000-tonne sand battery installation in Pornainen, Finland, serving the municipality's district heating network. Achieved 70% emissions reduction, 60% reduction in woodchip combustion, 100% elimination of oil use, and 80–90% round-trip efficiency through Finland's harshest winter.
• Lahti Energia 250 MWh Sand Battery 250 MWh sand battery installation under construction in Vääksy, Finland for Lahti Energia, delivering 2 MW of thermal output to substitute natural gas and wood chips in district heating and provide grid balancing services. Completion targeted for summer 2027.
• Loviisan Lämpö Sand Battery Industrial-scale sand battery installation for Loviisan Lämpö's district heating network in Loviisa, Finland, decarbonizing heating supply in the region.

Quantifiable outcome

• 70% reduction in carbon emissions
• +5 more outcomes

Named customers4 records

Segments2 records

Ideal customer profiles2 records

Technology focussed Yes

API detail

Has API

No

API docs

API detail

Core technology

AI maturity

App detail

Feature3 records

Partnerships

Two partnerships are on record, tiered flagship and core.

• Lahti EnergiaflagshipStrategic or Co-development Partner · 25 November 2025Polar Night Energy and Lahti Energia are partnering on construction of a 250 MWh sand-based thermal energy storage project in Vääksy, Finland. The project aims to significantly reduce fossil fuel emissions in Lahti Energia's district heating network by substituting natural gas and wood chips, with completion targeted for summer 2027. The partnership provides 2 MW of thermal output and additional grid balancing benefits.
• Loviisan LämpöcoreStrategic or Co-development Partner · 14 June 2025Polar Night Energy developed an industrial-scale sand battery to decarbonize the district heating network of Loviisan Lämpö in Finland. The project represents a significant step towards sustainable energy solutions in the Loviisa region.

Scale indicators9 records

Recent moves6 records

Expansion highlights6 records

Direct peers

• Rondo Energy: Rondo Energy builds industrial heat batteries using solid media (bricks) to deliver high-temperature, zero-carbon heat for industrial processes. It is a directly comparable competitor to Polar Night Energy in industrial thermal energy storage, with similar target customers, technology category, and decarbonization value proposition.
• Antora Energy: Antora Energy uses carbon block thermal storage to deliver industrial heat and electricity around the clock. Like Polar Night Energy, it targets industrial decarbonization via high-temperature solid-media storage, making it a closely comparable direct competitor in the LDES-for-heat space.
• EnergyNest: EnergyNest (Norway) develops Thermal Battery technology for industrial heat decarbonization using a modular solid-media approach. It is a direct peer to Polar Night Energy in Nordic industrial thermal storage, targeting similar process-industry customers with comparable technology positioning.
• Kraftblock: Kraftblock (Germany) builds modular high-temperature thermal storage systems using recycled steel slag as the storage medium for industrial heat decarbonization. Comparable to Polar Night Energy as a direct peer in solid-media, high-temperature industrial thermal storage.
• Brenmiller Energy: Brenmiller Energy (Israel) provides bGen — a thermal energy storage system using crushed rock for industrial process heat and steam generation. Directly comparable to Polar Night Energy in technology category (high-temperature solid-media storage) and customer segment (industrial decarbonization).
• Electrified Thermal Solutions: Electrified Thermal Solutions (Joule Hive) builds thermal batteries using firebrick resistive heating for industrial process decarbonization. It is a direct peer to Polar Night Energy in solid-media, high-temperature industrial heat storage with similar decarbonization use cases.
• Malta Inc. Malta Inc. develops pumped heat thermal energy storage systems for long-duration grid storage and industrial applications. Comparable to Polar Night Energy as a long-duration thermal storage peer with overlapping LDES positioning and utility/industrial customer overlap.

Emerging players

• Highview Power: Highview Power develops liquid air energy storage (LAES) for long-duration grid-scale storage. While its technology differs (cryogenic rather than thermal solid media), it is a comparable peer in the broader long-duration energy storage category pursuing utility and industrial customers.

Broad incumbents

• Siemens Energy: Siemens Energy is a major incumbent supplying industrial power, heat, and electrification solutions to utilities and process industries. It is a broad incumbent that overlaps with Polar Night Energy's industrial decarbonization customer base and could compete or partner across the same opportunity set.
• MAN Energy Solutions: MAN Energy Solutions supplies large-scale engines, turbines, and thermal process equipment for industrial and district energy applications. It is a broad incumbent serving the same industrial heat and district heating customer segments that Polar Night Energy targets.

Market position

Strengths5 records

Weaknesses5 records

Competitive moat5 records

Key risks6 records

Key highlights7 records

Customer concentration

• YouTubeyoutube.com/@polarnightenergy
• LinkedInfi.linkedin.com/company/polar-night-energy-oy
• Instagraminstagram.com/polarnightenergy
• Xx.com/pne_energy

Revenue estimate

Valuation estimate

Number of profiles

Profiles3 records

Funding overview

Funding rounds2 records

Investors5 records

Funding detail is available on the Subscription and Enterprise plan.Contact sales →

M&A

Investments

M&A and investment is available on the Subscription and Enterprise plan.Contact sales →

Frequently asked questions about Polar Night Energy