Elstor
Elstor Oy designs and sells modular high-temperature thermal energy storage systems that decarbonize industrial steam and heat production. Founded in 2017 in Finland, the company serves food, chemical, pharma, dairy, laundry, and district heating customers.
- Company typePrivate
- Founded2017
- HeadquartersLappeenranta, Finland
- Headcount1–10
- GTM typeB2B
- OfferingHardware or Manufacturing
What Elstor does
Elstor Oy is a Finnish industrial technology company founded in July 2017 and headquartered in Lappeenranta, Finland, that designs, sells, and commissions modular high-temperature thermal energy storage systems for industrial steam and heat production. The company's core product is a patented power-to-heat storage unit (marketed in Finnish as Lämpöakku) that converts electricity into heat stored in dense graphite-based solid material at temperatures up to 600°C, then discharges as steam at up to 20 bar / 250°C on demand. Modular 5 MWh base units combine into 10 MWh and 20 MWh configurations, and a proprietary AI-based charging algorithm autonomously schedules charging during the lowest-priced electricity hours and is capable of grid flexibility market participation. The 20 MWh quad unit was demonstrated for the first time in 2025 at the Saarioinen Valkeakoski plant, claimed to be the world's first commercial 20 MWh high-temperature thermal storage system for steam production.
The business model is direct enterprise hardware sales supported by full project lifecycle services (profitability calculations, planning, permitting, installation, and commissioning) under multi-year contracts. Pricing is project-specific; a representative 5 MWh installation (Reka Kumi) totaled approximately EUR 1.35 million, while 20 MWh projects carry materially higher ticket values. Customers are large industrial enterprises in Finland, primarily in food and beverage manufacturing, industrial laundries, chemical and rubber processing, pharmaceutical manufacturing, dairy operations, and district heating, replacing fossil fuels such as natural gas, LPG, light fuel oil, and wood chips. Documented payback periods are 4-8 years, and individual units deliver 260-3,250 tonnes of annual CO2 reduction depending on size and fuel displaced.
Elstor was co-founded by LUT University professor Jero Ahola and entrepreneur Ari Piispanen and received a capital loan exceeding EUR 3 million from the Finnish Climate Fund (Ilmastorahasto) at founding. As of late 2025, the company has commissioned six commercial installations, signed multiple 20 MWh delivery contracts for 2026, expanded its first international channel via The Clean Fight New York accelerator, and was ranked 91st on the Deloitte EMEA Technology Fast 500 with 1,554.84% reported revenue growth. The company is privately held, employs approximately 18 people, and reports no public listing.
Elstor firmographics
Firmographics- Name
- Elstor
- Legal name
- Elstor Oy
- Website
- https://elstor.fi
- Company type
- Private
- Founded year
- 2017
- Operating status
- Operating
- Headcount range
- 1–10 employees
- Short description
- Elstor Oy designs and sells modular high-temperature thermal energy storage systems that decarbonize industrial steam and heat production. Founded in 2017 in Finland, the company serves food, chemical, pharma, dairy, laundry, and district heating customers.
- Ownership category
- akta.pro rank
Elstor industry classification
Industry- Product category
- Industrial Thermal Energy Storage
- NAICS
- Power Boiler and Heat Exchanger Manufacturing (33241), Steam and Air-Conditioning Supply (221330), Ventilation, Heating, Air-Conditioning, and Commercial Refrigeration Equipment Manufacturing (33341)
- SIC
- Industrial Process Furnaces & Ovens (3567), Heating Equip, Except Elec & Warm Air; & Plumbing Fixtures (3430), Steam & Air-Conditioning Supply (4961)
- akta.pro primary industry
- Thermal LDES (High-Temperature, Molten Salt, Carnot/Heat-to-Power) (EUAFADAC)
- akta.pro secondary industries
- Industrial Process Heat TES (Steam, Kilns, Furnaces, Waste-Heat Coupling) (EUAFANAI), High-Temperature Process Heat Electrification (E-Boilers, E-Furnaces, Induction, Plasma) (EUABAJAA), Cooling, Water/Steam Cycle & Balance-of-Plant Retrofits (Condensers, Cooling Towers) (EUAEALAK)
Keywords
Where Elstor is headquartered
LocationHeadquarters
- HQ city
- Lappeenranta
- HQ country
- Finland
- HQ region
- Europe
Offices1 record
Markets served
Elstor business model
Business model- GTM type
- B2B
- Offering type
- Hardware or Manufacturing
- Cost components
- Supply Chain, Technology or R&D, Personnel, Operations, Marketing or Sales
Revenue model
- Thermal energy storage equipment sales and installation: Sale and installation of modular thermal energy storage systems (Elstor units) to industrial customers. Equipment includes 5 MWh base units, configurable up to 20 MWh through combining units. Revenue recognized upon delivery and commissioning. Professional services include project planning, profitability calculations, permit assistance, installation, and commissioning support.
Pricing tiers
| Model | Billing | Price |
|---|---|---|
| Unit Pricing | Multi-year contract | 5 MWh base unit — suitable for smaller industrial sites |
| Unit Pricing | Multi-year contract | 10 MWh double unit — mid-size industrial facilities |
| Unit Pricing | Multi-year contract | 20 MWh quad unit — large industrial plants |
Go-to-market motion1 record
Distribution channels2 records
Marketing channels9 records
Elstor product offering
Product offeringCore offering
Elstor designs, manufactures, sells, and installs modular high-temperature thermal energy storage systems (5 MWh, 10 MWh, and 20 MWh units) that charge with electricity during low-price hours and discharge as steam or heat on demand for industrial processes. The patented power-to-heat solution, backed by AI-driven charging optimization, replaces fossil fuels such as natural gas, oil, LPG, and wood chips in industrial steam and heat production. The company delivers turnkey projects including profitability calculations, permitting support, installation, and commissioning services to industrial customers primarily in Finland.
Product overview
Elstor offers a modular thermal energy storage system for industrial steam and heat production. The core product is the Elstor Lämpöakku (thermal battery), a patented power-to-heat solution available in three capacity variants: 5 MWh (basic unit), 10 MWh (double unit), and 20 MWh (quad unit). These units store electricity during periods of low prices and convert it to high-temperature heat/steam on demand. The modular architecture allows unlimited scalability by combining multiple 20 MWh units. The AI-optimized system autonomously manages charging schedules based on electricity prices and heat demand forecasts.
Differentiator
Problem solved
Functional benefit
Products and services
- Elstor Thermal Energy Storage (Lämpöakku) Patented high-temperature modular thermal energy storage system that stores electricity during low-price hours, converts it to thermal energy stored at up to 600°C in dense solid material, and discharges as steam or heat on demand. Provides emission-free industrial steam and heat production, with AI-optimized autonomous charging, 95–97% power-to-heat efficiency, sub-1.0 second response, and continuous 0–100% discharge adjustment. Targets industrial enterprises replacing fossil-fuel steam boilers.
- 5 MWh Basic Unit Standard modular Elstor thermal storage unit with 5 MWh capacity. Suitable for smaller industrial sites, producing up to approximately 2,000 MWh of annual heat and enabling ~260–500 tonnes of annual CO2 reduction depending on fuel displaced. Can be combined with additional units for larger installations.
- 10 MWh Double Unit Two 5 MWh modules combined into a 10 MWh Elstor thermal storage unit. Designed for medium-sized industrial operations replacing LPG, light fuel oil, or other fossil fuels, delivering up to approximately 5,000 MWh annual heat and ~1,200 tonnes CO2 reduction per year at pharmaceutical replacement sites.
- 20 MWh Quad Unit Four 5 MWh modules combined into a 20 MWh Elstor thermal storage unit — the world's first high-temperature thermal storage of this scale for industrial steam production. Capable of covering up to 10,000 MWh of annual heat demand (~1,000 detached houses), delivering over 2,300 tonnes of annual CO2 reduction, and producing steam at up to 20 bar / 250°C. Larger systems are built by combining multiple 20 MWh units.
Quantifiable outcome
- Annual CO2 reduction of >2,000 tonnes per unit (varies by fuel type replaced and unit size)
- +9 more outcomes
Companies that use Elstor
Customer profileNamed customers13 records
Segments6 records
Ideal customer profiles4 records
Elstor technology and API
TechnologyTechnology focussed Yes
API detail
- Has API
- No
- API docs
- API detail
Core technology
AI maturity
App detail
AI capability2 records
Feature5 records
Elstor partnerships and signals
Strategic signalPartnerships
Three partnerships are on record, tiered flagship, minor and core.
- The Clean Fight (New York)flagshipSelected as one of 10 participating companies for The Clean Fight's sixth accelerator cohort focused on accelerating deployment of energy storage projects in New York State, USA. Program connects Elstor with US industrial customers, investors, and ecosystem partners. Selected companies offer best-in-class hardware and software solutions designed to be easy to adopt and optimize sustainable energy use.
- Luminus / EDFminorElstor was one of the winners at Luminus startup pitch day in Brussels, Belgium, an event supported and co-hosted by French energy giant EDF. Opportunity to introduce decarbonization solutions to energy industry stakeholders in Belgium and Europe.
- LUT University (Lappeenranta-Lahti University of Technology)coreCo-founding research partner. Professor Jero Ahola, energy efficiency professor at LUT University, collaborated with serial entrepreneur Ari Piispanen in 2016 to research alternative solutions for energy storage. Research results led directly to Elstor's founding in July 2017. Ongoing collaboration includes thesis projects, student employment, and technology development.
Scale indicators9 records
Recent moves6 records
Expansion highlights6 records
Elstor competitors and assessment
Company assessmentDirect peers
- EnergyNest: Norway-based thermal battery company using concrete-based storage modules (HEATCRETE) for industrial waste-heat recovery and heat supply. Targets similar industrial steam/heat decarbonization use cases across oil & gas and process industries.
- Rondo Energy: US-based industrial heat battery company supplying zero-carbon industrial process heat to manufacturers, replacing fossil fuels. Directly comparable in technology positioning and target industrial steam/heat customers.
- Antora Energy: US-based thermal energy storage and carbon heat-to-power company using solid-state storage to deliver zero-carbon industrial heat and electricity. Directly comparable in high-temperature solid-material thermal storage architecture.
- Polar Night Energy: Finnish developer of sand-based high-temperature thermal energy storage for industrial heat and district heating. Direct competitor to Elstor in the Finnish and Nordic industrial steam/heat decarbonization market with overlapping customer verticals.
- Kraftblock: Sweden-based developer of high-temperature thermal storage using recycled steel slag, serving industrial heat decarbonization. Overlapping industrial heat/steam customer base with Elstor across Europe.
- Brenmiller Energy: Israel-based provider of thermal energy storage (bGen) systems for industrial steam and heat customers, displacing natural gas and oil. Comparable in industrial heat decarbonization focus with global commercial deployments.
Broad incumbents
- ABB: Global industrial automation and electrification incumbent with electric boiler and process heat electrification offerings serving industrial customers. Broad incumbent operating across many industrial verticals with overlapping decarbonization solutions.
- Siemens Energy: Global incumbent in power generation equipment and industrial heat solutions, including electric boilers and process heat electrification. Provides overlapping industrial steam/heat technology as part of a much broader portfolio.
Emerging players
- Caldera: UK-based developer of industrial-scale thermal batteries using low-cost materials to provide zero-carbon process heat for manufacturers. Emerging player with similar Power-to-Heat industrial storage positioning.
- Electrified Thermal Solutions (ETS): US-based developer of electrified thermal storage (Joule Hive) for industrial process heat decarbonization. Comparable emerging player with similar high-temperature TES positioning targeting hard-to-abate industrial customers.
Market position
Strengths5 records
Weaknesses5 records
Competitive moat5 records
Key risks6 records
Key highlights7 records
Customer concentration
Elstor social profiles
Digital presenceElstor compliance and trust
Trust signalCompliance1 record
Elstor financial estimates
Financial estimateRevenue estimate
Valuation estimate
Elstor leadership team
Management profileNumber of profiles
Profiles10 records
Elstor funding detail
Funding detailFunding overview
Funding rounds2 records
Investors1 record
Funding detail is available on the Subscription and Enterprise plan.Contact sales →
Elstor M&A and investment
M&A and investmentM&A
Investments
M&A and investment is available on the Subscription and Enterprise plan.Contact sales →
Frequently asked questions about Elstor
What does Elstor do?
Elstor designs, manufactures, sells, and installs modular high-temperature thermal energy storage systems (5 MWh, 10 MWh, and 20 MWh units) that charge with electricity during low-price hours and discharge as steam or heat on demand for industrial processes. The patented power-to-heat solution, backed by AI-driven charging optimization, replaces fossil fuels such as natural gas, oil, LPG, and wood chips in industrial steam and heat production. The company delivers turnkey projects including profitability calculations, permitting support, installation, and commissioning services to industrial customers primarily in Finland.
Is Elstor a public or private company?
Elstor is a private company. It is classified as venture growth investor backed and is currently operating.
When was Elstor founded?
Elstor was founded in 2017. It employs 1 to 10 people.
Where is Elstor based?
Elstor is headquartered in Lappeenranta, Finland, in the Europe region.
How does Elstor make money?
One revenue line is on record: thermal energy storage equipment sales and installation.
Who are Elstor's main competitors?
Direct peers on record are EnergyNest, Rondo Energy, Antora Energy, Polar Night Energy, Kraftblock and Brenmiller Energy. Broad incumbents are ABB and Siemens Energy. Emerging players are Caldera and Electrified Thermal Solutions (ETS).
Does Elstor have an API?
No public API is recorded for Elstor.
What industry is Elstor in?
Elstor's product category is Industrial Thermal Energy Storage. Its primary akta.pro industry code is EUAFADAC, Thermal LDES (High-Temperature, Molten Salt, Carnot/Heat-to-Power), with a secondary code of EUAFANAI, Industrial Process Heat TES (Steam, Kilns, Furnaces, Waste-Heat Coupling). Its NAICS code is 33241 and its SIC code is 3567.