Alphabet Energy (Alphabet) is a Hayward, California, company that develops thermoelectric materials and products that convert waste heat to electric power.
Alphabet’s web site provides this overview of the concept of thermoelectrics:
Thermoelectrics are solid-state semiconductors that turn heat into electricity. They generate power cleanly and with few or no moving parts from a difference in temperature. They are like solar panels that use heat–instead of light–as an energy source. Alphabet is revolutionizing the way we think about both thermoelectrics and the prototypical functional material, silicon. We have developed and licensed the key technologies to use silicon as a thermoelectric generator.
Alphabet owns at least five U.S. patent applications relating to its thermoelectric materials. U.S. Application Publication No. 2011/0114146 (’146 Application) is entitled “Uniwafer thermoelectric modules” and directed to a single wafer device (100) including functionalized n-type regions (113) and p-type regions (115) with shunts (123) formed overlying those regions from the front side (102) of the wafer substrate (101).
A partial portion of wafer material (101A) is removed from the back side (103) of the substrate. One or more conductor shunts (125) are formed overlying the exposed n-type regions (113) and p-type regions (115) from the back side (103).
According to the ’146 Application, this device can be used to output power from thermoelectrics:
As an implementation of the present invention, the two external electric leads 131 and 132 can [be]used as two electrodes for outputting electric power induced by thermoelectric effect when the single-wafer device 100 is subjecting the conductor shunts 123 at the front side 102 and conductors 125 at the back side 103 to a temperature gradient.
Alphabet’s other patent applications relate to nanostructures and fabrication processes for nanostructure thermoelectric devices. They are U.S. Application Publication Nos. 2012/0152295, 2012/0247527 (’527 Application), 2012/0295074, and 2012/0319082.
The ’527 Application is entitled “Electrode structures for arrays of nanostructures and methods thereof” and directed to a thermoelectric device comprising an array (110) of nanowires (120) with spacings (150) between them. The spacings (150) may contain fill materials (160) having a low thermal conductivity.
An electrode structure (195) is formed on the array (110) of nanowires (120) by covering protruding segments (135) with semiconductor contact materials (170). A contact layer (174) provides electrical connection between each of the protruding segments (135), and a shunt (180) may be formed to provide an electrical connection between the contact layer (174) and other devices in the thermoelectric device.
According to this Greentech Media piece, thermoelectrics is a “brilliant pursuit” which no one has brought to market economically at scale yet. Perhaps Alphabet Energy will be the first.
Eric Lane is a patent attorney at McKenna Long & Aldridge LLP in San Diego and the author of Green Patent Blog. Mr. Lane can be reached at email@example.com