Thermoelectric devices
3-4 years ago I found on the web 25 Watt thermoelectric devices for $25, requiring 50 degrees C difference between cold and hot sides and a 5% efficiency (?). For the moment, let's not examine the specifics of currents and volts and accept that a watt is a watt, is a watt and is always a watt and so 40 of them make a 1kW power battery, that's the power required by a middle of the range home air-conditioning unit. For the 50 degrees C difference, earth's temperature can be used, which all year round is 15 degrees C at about 5 meters depth and the temperature inside a steel box under the sun, which easily can reach 65 degrees C in summer. That's not enough though, because we have to satisfy the energy requirements for the hot side to maintain its temperature in the steel box, and supply 1/0.05=20 kW, that's, rounded up, 20 m2 of sun's energy, that must be concentrated on the steel box through mirrors. Isn't this worth investigation for its application. Isn't it enough that the industry doesn't do anything to harvest waste energy from the myriads of engines out there.
Very grossly speaking, since the efficiency of IC engines is, and will remain for ever, at about 32% and the heating value of gasoline is 124,000 btu/US gal, 84,000 btu per US gal consumed is 'thrown' away. With 25 MPG for an average car, there's potential of harvesting energy from ONE KILOWATT-HOUR source for every mile driven or else, there's potential to draw power from a one kW power setup. Additionally, there are very well known environmental consequences. In US alone, the yearly consumption was about 143 billion gallons for 2016 and the world consumption was about 353 billion gallons for 2012. So about 30 quatrillion btu (84000x353x109l) are wasted. How much useful work can be produced.
Since a year has 8760 hours, a potential source of about 3 trillion Watts of power are neglected. If thermoelectric devices are only 5% efficient then they could account for about 165 bl watts of potential installed power that is 1,300,000 GWh/year, which is about 1/20th of the 24,816,400 GWh that the world's electricity production was in 2016, not bad, not bad at all.
IF THE EFFICIENCY REACHES 15%, AS MENTIONED IN THE SOURCES BELOW, THEN ABOUT 7 m2 MIRRORS WILL BE NEEDED, AND A SOURCE OF 1/6th OF THE WORLD'S ELECTRICITY PRODUCTION WILL BE AVAILABLE TO HARVEST ENERGY.
World’s most efficient thermoelectric material developed
https://newatlas.com/most-efficient-thermoelectric-material/24210/
The new material, which is based on the common semiconductor telluride, is environmentally stable and is expected to convert from 15 to 20 percent of waste heat to electricity. The research team, made up of chemists, material scientists and mechanical engineers from Northwestern University and Michigan State University, say the material exhibits a thermoelectric figure of merit (or “ZT”) of 2.2, which they claim is the highest reported to date.
Can Thermoelectric Generators Compete Against Solar Photovoltaics? | Engineering360
http://insights.globalspec.com/article/98/can-thermoelectric-generators-compete-against-solar-photovoltaics
Thermoelectric generators short circuit some of the drawbacks of traditional power generation technologies. While the best barely reach 8% conversion efficiency, they are well suited for less intense heat sources like concentrated sunlight or vehicle exhaust gases.
Thermoelectrics to replace car alternators and improve MPG
https://newatlas.com/thermoelectric-cars-improve-mpg/10928/
P.S. As mentioned it is a 'speaking grossly' description, that may trigger the interest of some readers on it. One may wonder, first about the cost of the mirrors, which in my opinion is low and second, a detail, if the cold side in the soil must be 'surrounded' by an air envelope or be left in direct conduct with the soil to enject heat.
Very grossly speaking, since the efficiency of IC engines is, and will remain for ever, at about 32% and the heating value of gasoline is 124,000 btu/US gal, 84,000 btu per US gal consumed is 'thrown' away. With 25 MPG for an average car, there's potential of harvesting energy from ONE KILOWATT-HOUR source for every mile driven or else, there's potential to draw power from a one kW power setup. Additionally, there are very well known environmental consequences. In US alone, the yearly consumption was about 143 billion gallons for 2016 and the world consumption was about 353 billion gallons for 2012. So about 30 quatrillion btu (84000x353x109l) are wasted. How much useful work can be produced.
Since a year has 8760 hours, a potential source of about 3 trillion Watts of power are neglected. If thermoelectric devices are only 5% efficient then they could account for about 165 bl watts of potential installed power that is 1,300,000 GWh/year, which is about 1/20th of the 24,816,400 GWh that the world's electricity production was in 2016, not bad, not bad at all.
IF THE EFFICIENCY REACHES 15%, AS MENTIONED IN THE SOURCES BELOW, THEN ABOUT 7 m2 MIRRORS WILL BE NEEDED, AND A SOURCE OF 1/6th OF THE WORLD'S ELECTRICITY PRODUCTION WILL BE AVAILABLE TO HARVEST ENERGY.
World’s most efficient thermoelectric material developed
https://newatlas.com/most-efficient-thermoelectric-material/24210/
The new material, which is based on the common semiconductor telluride, is environmentally stable and is expected to convert from 15 to 20 percent of waste heat to electricity. The research team, made up of chemists, material scientists and mechanical engineers from Northwestern University and Michigan State University, say the material exhibits a thermoelectric figure of merit (or “ZT”) of 2.2, which they claim is the highest reported to date.
Can Thermoelectric Generators Compete Against Solar Photovoltaics? | Engineering360
http://insights.globalspec.com/article/98/can-thermoelectric-generators-compete-against-solar-photovoltaics
Thermoelectric generators short circuit some of the drawbacks of traditional power generation technologies. While the best barely reach 8% conversion efficiency, they are well suited for less intense heat sources like concentrated sunlight or vehicle exhaust gases.
Thermoelectrics to replace car alternators and improve MPG
https://newatlas.com/thermoelectric-cars-improve-mpg/10928/
P.S. As mentioned it is a 'speaking grossly' description, that may trigger the interest of some readers on it. One may wonder, first about the cost of the mirrors, which in my opinion is low and second, a detail, if the cold side in the soil must be 'surrounded' by an air envelope or be left in direct conduct with the soil to enject heat.
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