Alphabet Energy raised $12 million from three clean technology investors to speed up the development of a thermoelectric generator that can recover waste heat for electricity with the use of silicon.
The two-year-old San Francisco startup plans to use the round’s proceeds to employ more people, relocate to a new facility in the San Francisco Bay Area, and finally complete a prototype of a silicon-based thermoelectric device.
The round was led by new investor TPG Biotech and existing investors Claremont Creek Ventures and CalCEF Clean Energy Angel Fund.
Alphabet, a Lawrence Berkeley National Laboratory spin-off, previously raised a $1 million seed round in May last year from Claremont and CalCEF.
The company did not disclose the details of its product but said they will be the first company to use silicon as a thermoelectric material to produce power.
Thermoelectrics
When heated on one side, electrons in thermoelectric materials move from the hot to the cold side, producing electricity in the process. Despite its promise in deriving power from waste heat, thermoelectric devices have not been popular because most of them use materials like bismuth telluride and lead telluride that are expensive to make.
Silicon, Alphabet Energy explained, will help bring thermoelectric products to greater commercial use because it is cheaper and more abundant than materials used in current devices.
Commonly used in solar energy production, silicon is the second most abundant element on the earth’s crust.
Research has shown that silicon nanowires make good thermoelectric materials. Last year, a team of scientists from the California Institute of Technology designed a new nanomesh material that does the job.
The team found a way to lower the thermal conductivity of silicon in order to increase its efficiency in producing power. Lowering thermal conductivity makes it easier for the silicon to keep one side of the device cold to create that temperature difference for generating electricity.
«Alphabet’s approach is currently the only [company] in the field of thermoelectrics that has the potential to generate electricity at or below grid parity,» said Mark Gudiksen of TPG Biotech. «We believe that waste heat is an enormous and important resource.»
The company said it is banking on a $100 billion global market for products that convert medium- to high-grade waste heat into electricity.
High-grade waste heat is mainly limited to industries that use intense heat to make products like iron steel, glass and ceramics. In the near term, the company said it will initially market their thermoelectric generators to heavy industrial applications and engines that produce hot exhaust gas.
The industrial sector alone accounted for approximately one-third of all energy used in the United States in 2008, consuming approximately 32 quadrillion British thermal units of energy annually. One quad is equal to around 293 billion kilowatt hour. As much as 50 percent of the energy consumed is lost as waste heat, according to the Department of Energy.
