What ElleThermo does

ElleThermo is a Tokyo-based energy technology company founded in 2023 as a spin-out from Tokyo Institute of Technology. It develops and commercializes a proprietary Semiconductor-Sensitized Thermal Cell (STC) technology that converts low-temperature waste heat — typically in the 30-40°C range — into electricity. The technology addresses an energy-recovery gap left by conventional thermoelectric and steam turbine solutions, which struggle to efficiently capture heat below 100°C. As of April 2026, the company operated with 1-10 employees from a Tokyo headquarters and was in early commercial/pilot deployment.

ElleThermo's primary target verticals are enterprise data centers and industrial/geothermal sites where low-temperature waste heat is abundant but currently unutilized. The company's lead commercial validation is a completed demonstration project with At Tokyo, a Japanese data center operator, in which STC systems were tested at two Tokyo data center sites including hot-aisle zones and mechanical rooms. The company markets to enterprise customers through direct sales and pilot engagements, with awareness-building through academic partnerships and industry webinars. It is legalized as a Japanese kabushiki kaisha (株式会社elleThermo) with the trade name エレサーモ.

The business model centers on hardware sales of STC technology systems, pilot deployment services, and potentially long-term service agreements, with pricing not publicly disclosed. The company has raised 360 million yen (~$2.5M) in a pre-Series A round in August 2024 led by Keio Innovation Initiative, with participation from multiple strategic and financial investors including Mirai Creation Fund, Mizuho Capital, Mitsubishi UFJ Capital, KDDI Green Partners Fund, Hulic, and Energy & Environment Investment. Capital is earmarked for manufacturing scale-up, STC product development, and personnel hiring.

Name

ElleThermo

Legal name

株式会社elleThermo

Website

https://ellethermo.studio.site

Company type

Private

Founded year

2023

Operating status

Operating

Headcount range

1–10 employees

Short description

ElleThermo is a Tokyo-based energy technology company that develops proprietary Semiconductor-Sensitized Thermal Cell (STC) technology to convert low-temperature waste heat (30-40°C) into electricity, primarily serving enterprise data center operators and industrial/geothermal sites.

Ownership category

akta.pro rank

Product category

Waste Heat Recovery Systems

NAICS

Ventilation, Heating, Air-Conditioning, and Commercial Refrigeration Equipment Manufacturing (33341), Heating Equipment (except Warm Air Furnaces) Manufacturing (333414)

SIC

Cogeneration Services & Small Power Producers (4991), Air-Cond & Warm Air Heatg Equip & Comm & Indl Refrig Equip (3585)

akta.pro primary industry

Thermal Management Components (Heat sinks, TIMs, fans/blowers, thermal pads) (IMAGAJAL)

akta.pro secondary industries

Industrial Process Heat TES (Steam, Kilns, Furnaces, Waste-Heat Coupling) (EUAFANAI), Heat Exchangers & Thermal Transfer Equipment (IMAHAKAC)

Keywords

• Waste heat recovery
• Thermoelectric generators
• Low-temperature heat conversion
• Renewable energy devices
• Semiconductor thermal cells

Headquarters

HQ city

Minato

HQ country

Japan

HQ region

Asia

Offices1 record

Markets served

GTM type

B2B

Offering type

Hardware or Manufacturing

Cost components

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

Revenue model

1. STC Technology Solutions: The company appears to generate revenue through the sale and deployment of its Semiconductor-Sensitized Thermal Cell technology systems for converting waste heat to electricity. Given the B2B enterprise focus and pilot project stage, revenue likely comes from equipment sales, installation services, and potentially long-term service agreements.

Go-to-market motion1 record

Distribution channels1 record

Marketing channels3 records

Core offering

ElleThermo manufactures and deploys Semiconductor-Sensitized Thermal Cell (STC) systems that convert low-temperature waste heat (30-40°C) into electricity. The technology, originating from Tokyo Institute of Technology research, is sold to enterprise customers—primarily data center operators and industrial facilities with geothermal or low-grade process heat—through custom pilot and demonstration deployments.

Product overview

ElleThermo offers its Semiconductor-Sensitized Thermal Cell (STC) technology as a single core product for converting unused low-temperature heat into electricity. The company, originating from Tokyo Institute of Technology and based in Tokyo, is developing this technology primarily for applications in data centers, geothermal sites, and other environments with low-temperature heat sources. The STC technology has been validated through pilot testing and a completed demonstration project at two data centers in Tokyo with partner At Tokyo.

Differentiator

Problem solved

Functional benefit

Products and services

• Semiconductor-Sensitized Thermal Cell (STC) A semiconductor-sensitized thermal cell system that converts low-temperature waste heat (30-40°C) into electricity. Designed for enterprise customers such as data center operators and industrial facilities with low-grade process or geothermal heat. Validated through demonstration projects at two data centers in Tokyo with At Tokyo.

Quantifiable outcome

• Successfully converted low-temperature waste heat (30-40°C) into electricity in active data center environments

Named customers1 record

Segments2 records

Ideal customer profiles2 records

Technology focussed Yes

API detail

Has API

No

API docs

API detail

Core technology

AI maturity

App detail

Feature1 record

Partnerships

One partnership is on record.

• At TokyocoreStrategic or Co-development Partner · 29 April 2026Completed successful demonstration project testing STC technology at two data centers in Tokyo. At Tokyo is a Japanese data center operator that collaborated with elleThermo to validate the technology in real-world conditions. The project tested heat-to-power conversion in hot-aisle zones and mechanical rooms. Both companies have signaled intention to further develop the technology for improved energy efficiency and broader sustainability applications.

Scale indicators3 records

Recent moves4 records

Expansion highlights4 records

Direct peers

• Phononic: Phononic develops solid-state thermoelectric devices for both cooling and power generation, targeting waste-heat recovery and energy efficiency. Like ElleThermo, it leverages semiconductor-based thermal technology to convert heat differentials into usable electricity and competes for similar industrial and clean-energy customers.
• Ferrotec Corporation: Ferrotec manufactures thermoelectric modules and a broad portfolio of thermal management and semiconductor products. As a Japan-headquartered company with established thermal-component manufacturing, it is a directly comparable peer in semiconductor-based thermal-to-electric conversion and represents potential competitive overlap in the Japanese market.

Broad incumbents

• Gentherm: Gentherm is a large incumbent specializing in thermoelectric and climate-control technologies, primarily for automotive and medical applications. It operates broadly in semiconductor thermal technology with overlapping capabilities to ElleThermo's heat-to-power approach, though it does not focus specifically on low-temperature waste-heat recovery in data centers.
• Coherent Corp (formerly II-VI Incorporated): Coherent is a major semiconductor and photonics company with broad thermal-management and power-electronics capabilities. While not a direct competitor in low-temp heat-to-power cells, it represents the kind of large incumbent with semiconductor manufacturing scale that could enter or acquire in ElleThermo's niche.
• Ormat Technologies: Ormat designs, develops, and operates geothermal and recovered-energy power plants worldwide. It overlaps with ElleThermo's industrial and geothermal heat-to-power use cases, serving similar customer needs for converting underutilized heat into electricity, though Ormat focuses on larger-scale Organic Rankine Cycle systems.
• Vertiv: Vertiv is a global provider of critical digital infrastructure and continuity solutions, including thermal management and power systems for data centers. It is a broad incumbent whose data-center customer base overlaps with ElleThermo's target market, even though it focuses on cooling and power delivery rather than low-temperature heat harvesting.

Emerging players

• ZutaCore: ZutaCore develops direct-liquid-on-chip cooling for data centers, addressing energy efficiency and thermal management in high-density compute environments. It is an emerging player with a partial overlap to ElleThermo's data-center energy-efficiency mission, even though it targets active cooling rather than waste-heat-to-power conversion.
• Asperitas: Asperitas provides immersion-cooling solutions for data centers to improve energy efficiency and enable heat reuse. Its focus on capturing and repurposing server heat intersects thematically with ElleThermo's waste-heat valorization thesis, positioning it as an emerging player competing for the same sustainability-driven data-center customers.
• Iceotope: Iceotope delivers precision liquid cooling for data centers and edge computing, with an emphasis on energy efficiency and reduced carbon footprint. It overlaps with ElleThermo in serving data-center operators seeking to manage low-grade heat and lower PUE, though its mechanism is cooling rather than electricity generation.
• Green Revolution Cooling: Green Revolution Cooling (GRC) offers single-phase immersion cooling for data centers, with messaging around waste-heat reuse and sustainability. It is an emerging player addressing similar data-center energy-efficiency and heat-capture pain points as ElleThermo, providing alternative technology approaches to the same customer base.

Market position

Strengths4 records

Weaknesses5 records

Competitive moat4 records

Key risks6 records

Key highlights5 records

Customer concentration

Revenue estimate

Valuation estimate

Number of profiles

Funding overview

Funding rounds2 records

Investors11 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 ElleThermo