- 3521 - THERMIONICS - the study of energy flow? This is about thermal to electric energy conversion and how nanotechnology could be used to recover electricity out of waste heat energy. Say you drive a car with a 200 horsepower engine. Only 60 horsepower actually drives the wheels. 140 horsepower is used to generate heat. If that heat could be recovered and turned into electricity it could be used to charge a battery and operate a hybrid car.
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--------------------- 3521 - THERMIONICS - the study of energy flow
- In a typical auto 60% of the energy is lost . The United States uses about 100 quadrillion BTU’s of energy per year. 27% of our energy is consumed in transportation. 80% of that energy is wasted heat energy and not used. Only 20% of transportation energy consumed ends up as Useful Energy.
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- ( These statistics are 2002 when we consumed 97 quadrillion BTU’s. Today it is about 100 Quads so these numbers also act as percentages.)
- Here is how the total U.S. Energy flow breaks out for 2006:
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----------- Residential --------- 21% ------ 75% was useful
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----------- Businesses --------- 18% ------ 80% was useful
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----------- Industrial ----------- 32% ------ 80% was useful
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----------- Transportation ----- 28% ------ 20% was useful
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- So, transportation is the big energy waster here. The second highest energy waster is the electric power plants that generate the electricity for the other three users. 69% of the energy input to power plants is wasted as heat and only 31% gets distributed to the electricity consumers. Mostly, transportation consumes the oil and power plants consume the coal.
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- If you look at all the U.S. energy consumption:
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---------------- 61% is wasted as lost energy
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---------------- 38% is Useful Energy
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- That 61% is a big number and leaves a lot of room for innovation and improvements.
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- Transportation uses 39% of all the energy consumed. 62% of this petroleum is imported from other countries.
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- Power plants consume 38% of all the energy and 60% of that is coal. Power plants operate at only 31% efficiency.
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------------------ Here is where the energy consumed in the U.S comes from:
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------------------------ 3% ------ hydroelectric
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------------------------ 8% ------ nuclear
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------------------------ 23% ----- natural gas
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------------------------ 23% ----- coal
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------------------------ 3% ------ petroleum
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------------------------ 96% ----- Total
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- Solar, wind, waves, biomass, geothermal contribute less than 4% of our energy and really do not even show within the resolution of our diagram.
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- If we want to fix the 61% of the wasted energy problem your students need to become engineers and make transportation more efficient and electric power plants more efficient. At the same time solve the pollution problems with these two energy consumers.
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- Energy consumption in California:
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------------ 25% natural gas -------------- (82% is imported)
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------------ 25% electric power ---------- (16% is nuclear)
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------------ 25% petroleum --------------- (31% Alaskan, 40% Californian, 32% Foreign)
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- The U.S. consume 24% of the world’s oil and 22% of the world’s total energy. We produce 30% of the world’s nuclear energy.
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- An average U.S. household consumes energy in this fashion:
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----------- 32% ----- space heaters
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----------- 13% ------- water heaters
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----------- 12% -------- lighting
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----------- 11% ------- air conditioning
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----------- 8% -------- refrigeration
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----------- 5% ------- electronics
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----------- 5% ------- clothes dryers
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- And 25% of the energy consumption is wasted as unwanted heat and lost energy.
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- The thermocouple is two conductor wires that if heated generate a voltage between them. A voltmeter can be calibrated to measure the temperature of the two conductor junction. It becomes an electronic thermometer. The physics is called the “Seebeck effect” after its discoverer. A voltage is created in the presence of a temperature difference between two different metals or, semiconductors.
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- The reverse of the Seebeck effect is called the “Peltier effect” after its discoverer. A current passed through two dissimilar metals, or semiconductors , that are connected to each other at two junctions will transfer heat from one junction to another. The result is thermoelectric cooling or heating . It is a refrigerator, or a thermoelectric heat pump.
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- These refrigerators and heat pumps and electric generators have no moving parts and are extremely reliable. The problem is they are only about 8% efficient in converting energy. The mechanical, compressor refrigerator in your kitchen is 40% efficient.
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- If the Peltier refrigerator was there instead you electric bill for refrigeration would go up 500%. Not good! The goal for engineering research is to find a design using nanotechnology that is 5 times more efficient so these solutions can become economical.
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- Where efficiency does not matter many Peltier refrigerators are being used today. Fiber optic networks use them to cool their transmission lasers keeping them at a constant temperature.
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- Space probes that venture too far from the Sun to use solar cells use them. In this case, a plutonium cylinder is used as the heat source. The temperature of space is the cool side. The Seebeck Generator created gets 300 watts for continues use for decades with 7% efficiency. But, only NASA can afford one of these generators.
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- What we need is a Seebeck Generator that uses the wasted heat in an automobile engine to charge a battery in the hybrid car. We need a way to use the wasted heat in an electric power plant to generate more electricity. We need to solve the efficiency problems in order to do this.
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- Today wristwatches have been powered by thermocouples using the heat difference between the human body and its surroundings. The Russian army has powered radio transmitters without batteries. They simply stick the probe of a Seebeck Generator into a fire to power the radio.
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- Urbina Design Systems makes Peltier Wine Coolers. Stanza makes hot-cold Peltier serving trays for parties. Some company is making heater-coolers for car seats using Peltier thermionics.
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- The technology is all around us but we need a breakthrough to really begin solving our energy and pollution problems. We need it in a hurry. Tell your kids.
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March 28, 2022 THERMIONICS - energy flow? 852 3520
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--------------------- --- Monday, March 28, 2022 ---------------------------
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