Clemson (SC) - A researcher at Clemson University is looking at thermoelectric technology in an attempt to save at least 1.5 billion gallons of diesel fuel per year. And this may be the tip of the iceberg.
Thermoelectric devices are solid state pieces of semiconductor technology which cause electrons to flow when there's a temperature differential. Such technology is currently in use in deep space probes like Voyager 1 and 2. Their particular design uses a radioactive element (Plutonium-238) and generates electricity by capturing the resulting heat from alpha particle bombardment. Their capture devices are relatively sophisticated and they were expected to provide sufficient power for about 50 years after release, into the 2020s. Both Voyager 1 and 2 have power plants which are still operating effectively today, just over 30 years of continuous use.
Thermoelectric devices derive their power whenever temperature differentials are applied across special p- and n-type junctions in a type of multi-layer semiconductor comprised of varying materials in a complex manufacturing process. The electrical generation the materials create is called the Seebeck Effect, and was first discovered in the late 1800s. Since then, nanoengineering has greatly improved efficiency. The goal today in applying nano layers of special semiconductor materials is to create a situation where, when heat is applied, phonon pathways are disrupted in some way. This lowers the thermal conductivity of that side of the material while leaving in tact (or even enhancing) the material used on the other side. This provides electrons with an opportunity to begin moving. Basically in such conditions the electrons are "enticed" into flowing and creating electrical current.
Efficiencies seen in even modern thermoelectric devices depend greatly upon the materials used and the temperature differential. According to NASA, with certain materials and a temperature differential approaching a factor of 6 (such as 70F and 420F) the efficiency can be as high as 30%. However, at much lower temperature differentials the efficiency is typically in the single digits. NASA is currently looking into low-scale technology which will operate on the human body, drawing the temperature differential from contact with skin and the ambient outside air. NASA believes bio-suits equipped with such technology would not require external power sources to run in-suit equipment, including communications.
A physicist at Clemson named Dr. Terry M. Tritt hopes to employ devices like this to reclaim the energy lost as heat in automotive exhaust, on the engine block and from the radiator. More than 50% of the power generated from diesel combustion, and more than 60% from gasoline combustion, is lost as heat. The exhaust on diesel truck stacks can reach temperatures above 600F. This common, easily accessible and available portal provide a significant differential potential which could be tapped and then reclaimed as electrical energy. Such energy would be fed back into the truck in some manner (via a large electrical-assist motor?), thereby increasing fuel efficiency. Dr. Tritt believes such technology could save an estimated 1.5 billion dollars annually at only 7% to 8% efficiency. He also believes the technology could be applied to automobiles.
The program Dr. Tritt heads up is called the Department of Energy's Center of Excellence in Thermoelectric Materials Research. They have just been given a three-year, $3 million funding grant to continue this research. No word was given on when practical applications could be created. Theoretically, the materials and technologies exist today which would allow this process to work. Dr. Tritt will continue looking for new materials in an effort to increase efficiency and lower manufacturing complexity and cost.
Thermoelectric devices are solid state pieces of semiconductor technology which cause electrons to flow when there's a temperature differential. Such technology is currently in use in deep space probes like Voyager 1 and 2. Their particular design uses a radioactive element (Plutonium-238) and generates electricity by capturing the resulting heat from alpha particle bombardment. Their capture devices are relatively sophisticated and they were expected to provide sufficient power for about 50 years after release, into the 2020s. Both Voyager 1 and 2 have power plants which are still operating effectively today, just over 30 years of continuous use.
Thermoelectric devices derive their power whenever temperature differentials are applied across special p- and n-type junctions in a type of multi-layer semiconductor comprised of varying materials in a complex manufacturing process. The electrical generation the materials create is called the Seebeck Effect, and was first discovered in the late 1800s. Since then, nanoengineering has greatly improved efficiency. The goal today in applying nano layers of special semiconductor materials is to create a situation where, when heat is applied, phonon pathways are disrupted in some way. This lowers the thermal conductivity of that side of the material while leaving in tact (or even enhancing) the material used on the other side. This provides electrons with an opportunity to begin moving. Basically in such conditions the electrons are "enticed" into flowing and creating electrical current.
Efficiencies seen in even modern thermoelectric devices depend greatly upon the materials used and the temperature differential. According to NASA, with certain materials and a temperature differential approaching a factor of 6 (such as 70F and 420F) the efficiency can be as high as 30%. However, at much lower temperature differentials the efficiency is typically in the single digits. NASA is currently looking into low-scale technology which will operate on the human body, drawing the temperature differential from contact with skin and the ambient outside air. NASA believes bio-suits equipped with such technology would not require external power sources to run in-suit equipment, including communications.
A physicist at Clemson named Dr. Terry M. Tritt hopes to employ devices like this to reclaim the energy lost as heat in automotive exhaust, on the engine block and from the radiator. More than 50% of the power generated from diesel combustion, and more than 60% from gasoline combustion, is lost as heat. The exhaust on diesel truck stacks can reach temperatures above 600F. This common, easily accessible and available portal provide a significant differential potential which could be tapped and then reclaimed as electrical energy. Such energy would be fed back into the truck in some manner (via a large electrical-assist motor?), thereby increasing fuel efficiency. Dr. Tritt believes such technology could save an estimated 1.5 billion dollars annually at only 7% to 8% efficiency. He also believes the technology could be applied to automobiles.
The program Dr. Tritt heads up is called the Department of Energy's Center of Excellence in Thermoelectric Materials Research. They have just been given a three-year, $3 million funding grant to continue this research. No word was given on when practical applications could be created. Theoretically, the materials and technologies exist today which would allow this process to work. Dr. Tritt will continue looking for new materials in an effort to increase efficiency and lower manufacturing complexity and cost.
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