How GREC Works

Simple concept, powerful innovation

The Technology Behind GREC

GREC is an external Carnot motor that uses an electric motor to alternately heat and cool a large enclosed work volume of gas in thin slices—the Work Generating Volume (WGV)—which revolves between hot and cold heat exchanger fins efficiently, rapidly, and repetitively. This cyclic heat transfer results in pressure oscillations that can be converted into mechanical work.

Core Operating Principle

GREC acts as "a closed system with a moving boundary" that transforms an existing temperature difference into pressure pulses, which activate a moving boundary (piston or membrane) to produce kinetic energy.

The "LEGO Pieces" of GREC

GREC has simple components using low-cost, available materials (e.g., aluminum) and is easily scalable:

1. Bottom Plate & Motor

An electric motor controls the revolving shutter (RS), which revolves the sliced gaseous volume between hot and cold blocks.

2. Revolving Shutter (RS)

Contains ¼ opening with the sliced gaseous volume column—the Work Generating Volume (WGV). Thin gaseous slices on large surface areas heat up and cool down faster.

3. Hot & Cold Blocks

Layers of conducting fins and boundary shells represent hot and cold blocks. As WGV passes between these large areas, its sliced volume heats up and cools down quickly.

4. Insulating Blocks

Situated between hot and cold blocks to prevent simultaneous heating and cooling of the WGV.

5. Top Plate & Piston

A connected piston (moving boundary) delivers the power generated by the Work Generation Volume through repeated internal pressure pulses.

6. Work Generating Volume

All thin gaseous slices add up to ONE large sliced Work Generating Volume. The RS opening can contain over 90% of the gaseous volume in the closed system.

Comparison with Existing Technologies

Important Differences from Conventional Heat Engines

  • No requirements on which fuel you use
  • Does not need very high heat (as in combustion) to perform
  • Delivers ready-made alternating pressure pulses (power in both directions)
  • Linearly scalable—larger volume = higher efficiency
  • Can benefit from lower temperature differences than existing heat engines
  • Power range varies from a few kW to several MW (compare with Stirling, often below 100kW)
Feature GREC Stirling Engine ORC System
Temperature Range 80-500°C+ High temp required 80-350°C
Power Range kW to MW <100 kW typically kW to MW
Scalability Linear (proportional) Limited by cylinder volume Good
Complexity Simple, few parts Complex sealing Complex fluid system
Maintenance Minimal Regular Regular
Construction Low-tech, recyclable Precision engineering Specialized components

Heat & Cold Sources

Many temperature gradients are green, and most of them are even free!

🔥 Heat Sources

  • Renewables: geothermal, solar thermal, biofuels, biomass
  • Waste heat recovery: industrial processes, power stations, buildings, data centers
  • Transport infrastructures, electric substations
  • Heat storage
  • Ambient air

❄️ Cold Sources

  • Natural sinks: ponds, canals, rivers, the sea, ambient air, ground-source
  • Amplified sinks: liquefied air, nitrogen, or other cryogenic stores