A robust thermoelectric device for power generation

  • The first commercially viable high-temperature thermoelectric device
  • Contains proprietary, breakthrough tetrahedrite PowerBlocks™ materials technology
  • 5% efficient at 400° C hot junction temperature
  • Highest power output of any thermoelectric device for power generation
  • Reliable operation in air
  • Thermoelectric material made from abundant, scalable elements

For Use with Exhaust Heat

Alphabet Energy’s tetrahedrite technology has been third-party verifed as the most effcient thermoelectric for exhaust-gas waste-heat recovery. The PowerCard-γ™ is optimized for applications where hot exhaust in the range of 400-600° C passes through heat exchangers that are in contact with the PowerCard™. Alphabet Energy can also supply fully-assembled modules that include both heat exchangers, interface materials, and PowerCards™.

For Use in Primary Power Generation

The PowerCard-γ™ can also be used in primary power applications where source temperatures are higher than 600° C, such as flame-fired consumer products.

Typical Performance in Air

Hot Side Temperature 300° C 350° C 400° C
Cold Side Temperature 100° C 100° C 100° C
Peak Power 4.1 W 6.4 W 9.2 W
Voltage at Peak Power 1.4V 1.8V 2.2V
Current at Peak Power 3.0 A 3.6 A 4.2 A
Open Circuit Voltage 2.7V 3.6V 4.4V
Internal Resistance 0.45 Ω 0.50 Ω 0.52 Ω
Efficiency 3.5% 4.3% 5.0%
Heat Flow 119 W 148 W 183 W
Thermal Resistance 1.7 k/W 1.7 k/W 1.7 k/W

Watts generated at 400° C hot side temperature

(cold side temperature = 100° C)

PowerCard-γ™ Technical Characteristics

Power Curves for various hot side temperatures

I-V Curves for various hot side temperatures


Inches [Millimeters]

PowerCard-γ™ Dimensions


  • The hot side is a hard ceramic with raised metal surfaces
  • The cold side is a polyimide material
  • Exposed copper electrical leads originate at the cold side
  • The PowerCard™ is coated to prevent oxidation and ensure high reliability through extended use in air

PowerCard-γ™ Mechanical Characteristics

Operating the PowerCard-γ

  • The PowerCard™ is a voltage source; peak power occurs where load resistance approximately equals internal resistance
  • Suitable heat exchangers should be selected for both hot- and cold-side heat transfer
  • Suitable interface materials must be used between the PowerCard™ surfaces and the heat exchangers
  • The PowerCard™ must be placed under pressure commensurate with the thermal interface materials used
  • Max hot surface temperature: 350° C for reliable continuous operation (brief excursions to 400° C may not cause damage)
  • Max cold surface temperature: 150° C for reliable continuous operation

A robust thermoelectric device for power generation

The Alphabet Energy PowerCard-γ™ is a robust thermoelectric device for power generation. It is optimized for use in systems where the heat source temperature is in the range 400-600° C, and the junction temperature at the PowerCard™ hot junction is in the range 300-400° C. It utilizes Alphabet Energy’s proprietary PowerBlocks™ technology based on the state-of-the-art thermoelectric materials for this temperature range: tetrahedrite and magnesium silicide stannide.

The PowerCard-γ™ can generate power in any temperature gradient. Like any thermoelectric device, it requires effective heat transfer devices on both the hot and cold sides, suitable interface materials between the PowerCard™ and heat exchangers, and signifcant pressure applied across the assembly. The PowerCard™’s thermoelectric materials are coated to ensure high reliability through extended use in air.

Alphabet Energy PowerCard-γ