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Intelligent thermal battery that upgrades your HVAC performance.

Reduce energy costs through smart energy management, improved system performance, and efficient waste-heat recovery.
Explore Technology
Turnkey Thermal Battery Systems for:
  • Industry
  • Commercial Buildings
  • Data Centers
  • Energy Networks
Onyx-Energy thermal battery unit installed outside a modern industrial facility for sustainable heating and cooling.
  • How the Thermal Battery delivers savings

1. HVAC System Optimization

How it works
  • Charging under favorable operating conditions:
    The thermal battery is charged by the existing HVAC system under favorable operating conditions, such as off-peak hours and favorable ambient conditions (e.g. during nighttime), when the system can operate efficiently and stably.
  • Thermal storage and temporal decoupling:
    Cooling or heating energy is generated and stored in the thermal battery, decoupling energy generation from energy demand in time.
  • Controlled energy release for system optimization
    The stored cooling or heating energy is released in a controlled and targeted manner by the thermal battery to improve HVAC system performance through:
  • Load shifting (reducing inefficient peak loads in HVAC systems)
  • Peak shaving (supporting the system during high-load hours)
  • Partial-load optimization (keeping equipment near its ideal efficiency range)
  • Load leveling (reducing fluctuations and start/stop cycling)
  • HVAC equipment operates longer within its optimal high-efficiency range.
  • Charging takes place under favorable load and temperature conditions, resulting in higher COP.
  • High-cost and peak-load periods are reduced.
  • Fewer start/stop cycles reduce start-up losses and operational inefficiencies.
  • Up to 50% lower energy consumption
  • Reduced mechanical wear and fewer breakdowns
  • Extended lifetime of chillers and HVAC equipment
  • Lower maintenance and operational costs
  • More stable and reliable HVAC operation

2. Free Cooling Utilization

How it works
  • Charging under favorable ambient conditions:
    The thermal battery is charged using Free Cooling during colder hours of the day, when active mechanical cooling is not required and only pumps and fans are in operation.
  • Thermal storage and temporal decoupling:
    Cooling energy generated under these conditions is stored in the thermal battery, decoupling cooling generation from cooling demand in time.
  • Cooling support:
    When active cooling is required, the stored cooling energy is released in a controlled manner to support chiller operation. As a result, the HVAC system operates under more favorable thermal conditions, as described in "1. HVAC System Optimization".
  • Free cooling eliminates compressor operation during charging, reducing electrical energy consumption to pumps and fans only.
  • Charging occurs when outdoor temperatures are lowest, maximizing overall system efficiency
  • Stored free-cooling energy reduces daytime peak cooling loads by optimizing HVAC operation.
  • Significant reduction in cooling energy consumption
  • Fewer compressor operating hours and start/stop cycles
  • Extended lifetime of cooling equipment
  • Higher overall system efficiency
  • Lower maintenance and operational costs
  • More stable and reliable cooling system operation

3. Waste-Heat Recovery

How it works
  • Capture under favorable process conditions:
    Surplus heat from industrial processes or other heat sources is captured and stored in the thermal battery instead of being dissipated.
  • Thermal storage and temporal decoupling:
    The thermal battery enables a temporal shift between waste heat availability and heat demand, allowing surplus heat to be stored when available and reused when needed.
  • Controlled heat release for useful applications:
    The stored thermal energy is released in a controlled manner when heat demand arises, for example for the preheating of feedwater, process heating, or heating system support.
  • Recovered waste heat replaces fuel-based or electrically generated heat.
  • Heat generators operate fewer peak-load cycles and closer to their optimal efficiency range.
  • Reduced load fluctuations and steadier operation minimize start-up losses and part-load inefficiencies.
  • Reduced energy consumption for pre-heating and process heating
  • Higher average efficiency of boilers and other heating-generating equipment
  • Lower thermal stress and extended lifetime of heating systems
  • Reduced maintenance and replacement costs
  • Core technology

PCM — Phase Change Materials

Phase Change Materials (PCM) are the core technology enabling compact, highly efficient thermal energy storage for cooling, heating, and waste-heat recovery.


Instead of storing energy solely through temperature increase, PCM stores thermal energy during a controlled solid–liquid phase change.

  • Key properties:
  • Non-toxic, non-corrosive, and environmentally friendly
  • Very high volumetric energy density
  • Application temperature range: −30 °C to +120 °C
  • Tailored phase-change temperature for each application
  • Our PCMs enable large amounts of thermal energy to be stored and released at a precisely defined, constant temperature tailored to each application, from heating to cooling.

Modular & Scalable Thermal Battery System

  • Available thermal battery module capacities:
  • 30 kWh (module)
  • 60 kWh (module)
  • 1.2 MWh (module)
  • System characteristics:
  • All modules can be freely combined and scaled to match the required system capacity
    (e.g. multiple modules combined to reach any target kWh or MWh level)
  • Scalable to multi-MWh system capacities enabled by the modular architecture
  • Single- or dual-circuit configurations for separation of different heat transfer fluids
  • Suitable for indoor or outdoor installation
  • Quick integration into existing HVAC systems (only 3 hydraulic connection points)
  • Minimal installation and commissioning effort