Thermal Energy Storage & Utilization
PIOST develops thermal energy storage (TES) and Carnot Battery systems that store surplus renewable energy as heat and convert it back to electricity when needed—bridging the gap between intermittent renewables and reliable grid power.
PIOST Inc. is a deep-tech startup founded in 2025, dedicated to accelerating carbon neutrality through thermal energy storage and utilization. We develop technologies that store surplus renewable energy as high-temperature heat and convert it back to usable energy when needed.
The global transition to renewable energy faces a critical challenge: solar and wind power are intermittent, but energy demand is constant. PIOST addresses this gap with cost-effective thermal energy storage using abundant materials like rock and sand. Our Carnot Battery technology enables long-duration storage at a fraction of the cost of lithium-ion batteries—paving the way for reliable, 24/7 clean energy.
Thermal Energy Storage (TES) is a technology that stores energy in the form of heat for later use. Unlike batteries that store electricity chemically, TES systems capture and retain thermal energy in materials like rock, sand, or molten salt at high temperatures. When energy is needed, this stored heat can be released for heating applications or converted back to electricity through steam turbines.
The global shift to renewable energy faces a fundamental challenge: the sun doesn't always shine, and the wind doesn't always blow. This intermittency creates a mismatch between when energy is produced and when it is consumed. Without effective storage, excess renewable energy is curtailed, and fossil fuel plants must fill the gaps.
TES offers a compelling solution. Heat can be stored for extended periods with minimal loss, making it ideal for long-duration storage measured in hours or days. The materials—rock and sand—are abundant, inexpensive, and environmentally benign. Unlike lithium-ion batteries, TES systems don't rely on critical minerals or present fire hazards.
TES technology has already been proven at scale in concentrated solar power (CSP) plants worldwide, with over 6.5 GW of installed capacity. The materials—rock, sand, and steel—are abundant, low-cost, and free from supply chain risks associated with lithium and rare earth elements.
With system lifetimes exceeding 30 years and minimal degradation, TES offers a compelling total cost of ownership for long-duration storage applications ranging from residential heating to grid-scale energy management.
A Carnot Battery is an advanced energy storage system that converts electricity to heat for storage, then converts that heat back to electricity when needed. Named after the French physicist Sadi Carnot who established the theoretical limits of heat engine efficiency, this technology represents the cutting edge of thermal energy storage.
The process works in three stages: First, excess electricity (typically from renewable sources) powers electric heaters to raise the temperature of a thermal storage medium to very high temperatures—in our case, exceeding 1,000°C. Second, this thermal energy is retained in insulated storage tanks with minimal loss. Third, when electricity is needed, the stored heat generates steam that drives a turbine to produce power.
Lithium-ion batteries dominate short-duration storage (2–4 hours) but become prohibitively expensive for longer durations. Pumped hydro offers long duration but requires specific geography. Carnot Batteries fill this gap: cost-effective storage for 8–24+ hours using widely available materials and proven industrial components.
The economics are compelling. Thermal storage costs 10–20x less per kWh than batteries at high temperatures. Modern Carnot Battery systems achieve 50–70% round-trip efficiency—competitive with other technologies when considering total system costs and lifespan.
The IEA estimates that achieving net-zero by 2050 requires over 2,000 GW of long-duration storage globally. Carnot Batteries can be manufactured at scale using existing industrial supply chains—steel fabrication, thermal insulation, and steam turbines—without dependence on critical minerals.
With round-trip efficiencies of 50–70% and storage costs 10–20x lower than lithium-ion batteries for durations beyond 8 hours, Carnot Batteries are positioned to capture a significant share of the growing grid storage market.
The thermal energy storage market is experiencing exponential growth as the world transitions to renewable energy.
Global TES market projected to grow more than tenfold by 2035
McKinseyPhotovoltaic capacity projected to reach 670GW by 2028
European Environment AgencyHeat accounts for nearly half of global energy demand
International Energy AgencyGlobal energy storage capacity target to achieve 6x growth by 2030
COP28 Global StocktakeTES market expected to reach $10.9B by 2030
Grand View ResearchTotal installed concentrated solar power capacity in 2022
IRENAAverage winter temperature of -25°C, 8 months of heating required. The most heating-dependent market.
2,200GW solar and 1,100GW wind potential for low-cost renewable-powered thermal storage.
30% renewable energy target by 2030. Strong policy push for clean heating solutions.
How PIOST compares to other thermal energy storage providers.
| Category | Company A | Company B | Company C | PIOST Inc. |
|---|---|---|---|---|
| Max Temperature | 750°C | 450°C | 600-800°C | 1,000°C+ |
| Storage Material | Crushed rocks | Concrete (HEATCRETE) | Volcanic rocks | Composite rock & sand |
| Heat Transfer | Resistive heating | Tube heat exchanger | Hot air circulation | Direct quenching & tube-in-tube |
| System Type | Modular | Modular | Plant-scale | Modular |
Where our technology creates impact
Cold Climate Regions
24/7 clean heating for residential and commercial buildings using stored renewable energyHard-to-Abate Sectors
High-temperature process heat (500–1,000°C) for steel, cement, and chemical manufacturingSolar & Wind Integration
Capture excess generation and dispatch during peak demand to maximize renewable utilizationLong-Duration (8–24h+)
Utility-scale energy storage to balance supply and demand, replacing fossil fuel peaker plantsModular TES systems designed for deployment at multiple scales.
Compact TES units for individual homes. Ideal for off-grid heating in remote areas with rooftop solar or small wind turbines.
TES systems for multi-unit residential buildings and small commercial facilities. Shared infrastructure reduces per-unit costs.
Large-scale TES for district heating networks and Carnot Battery applications. Grid-connected systems for utility-scale energy storage.
Three R&D pillars supported by proprietary technologies.
Designing thermal energy storage systems for deployment across multiple scales—from single households to buildings and district heating networks.
Direct condensation heat exchange technology enabling efficient charging to 1,000°C+ using steam as the heat transfer medium.
Multi-layer insulation engineering with rock & sand composite medium, minimizing heat loss during long-duration storage.
Developing optimal operation strategies for diverse TES configurations, charging methods, and discharge patterns.
Computational modeling for diverse operating scenarios, optimizing charging methods, duration, and discharge patterns.
Physics-based and data-driven models to predict performance boundaries under various operating conditions.
Ensuring consistent, high-quality steam output essential for efficient power generation in Carnot Battery systems.
Once-through and quenching hybrid system for stable steam quality control under varying temperature conditions.
Reinforcement learning-based digital twin for real-time optimal control, ensuring consistent steam quality.
Extensive research experience in steam generation, two-phase flow, and high-temperature thermal systems
Filed patents covering core TES and heat exchange technologies
MOU signed for Mongolia testbed partnership to validate TES under extreme cold-climate conditions
Founded from Inha University's MFTEL (Multiphase Flow & Thermal Engineering Lab), bringing academic research into commercial reality.
Visit MFTEL LabFrom prototype validation to global commercialization.
Combining business expertise with deep technical knowledge in thermal engineering.
CEO & Co-Founder
Market analysis and business strategy
CTO & Co-Founder
R&D planning and technology development
We believe clean energy should be available 24/7—not just when the sun shines or the wind blows. Our team is dedicated to building the infrastructure for a fully renewable grid, making decarbonization practical and affordable for everyone.
Help us build the future of clean energy.
Design and optimize high-temperature thermal storage systems. Experience with heat transfer and CFD preferred.
Develop digital twins and AI-based control systems for TES operation optimization.
Drive partnerships and market expansion in Europe and Asia. Energy sector experience valued.
Interested in investing or exploring partnership opportunities? We'd love to hear from you.
PIOST is currently seeking seed funding to accelerate prototype development and pilot deployments. We welcome conversations with investors, strategic partners, and energy companies interested in thermal storage solutions.