Materials unit: Thermoelectricity
Turning Waste Into Energy: the Modern Way
Tony Williams
Efficiency is an integral part of modern-day society. As we bustle about our daily lives, we constantly search for ways to do more while using less energy. Yet 2/3 of the energy that power plants produce is heat energy, not electricity. Only 25% of gas in the tank actually goes toward moving our cars forward. How can we stop wasting such a large percentage of our precious energy? New innovations in the field of thermoelectricity may hold an answer.
The ideas behind thermoelectricity have been around since the 1800s, when German physicist Thomas Johann Seebeck found out that certain metals responded to temperature differences. Different materials work better for this than others because of their properties. Seebeck and others realized the potential for this, but they didn't have the technology or the materials to make it work effectively enough for commercial use.
Only recently have scientists been able to make materials effective enough for thermoelectricity to become useful. This has great implications; according to Science Daily, "More than two-thirds of the energy from primary sources like oil and gas utilized worldwide today is lost through waste heat." Thermoelectric energy has the potential to harness some of this waste heat, but finding a suitable material has proved a daunting task.
Thermoelectricity works by using materials that react electrically when exposed to temperature differences. This means that, when heat is applied, it creates a high voltage across the material. Like a gas expands when it experiences heat, electrons in thermoelectric materials expand toward the cold side, leaving their nuclei behind with holes (absence of electrons) where the electrons once were. This creates an electrical difference between the two sides that can be harnessed as electricity.
Scientists still struggle with creating materials that work efficiently enough to work on a large scale. Tommi Tynell, who creates thermoelectric materials at the Aalto University School of Chemical Technology, says that "Developing more efficient thermoelectric materials is a major challenge, because the physical properties that affect the performance of the materials are not independent of each other. The optimization of a material is very difficult, because as you improve one feature, other properties may deteriorate at the same time,"
The main struggle is the fact that heat and electricity are conducted in the same substances. For thermoelectric purposes, materials work better when they conduct electricity but not heat. Unfortunately, metals are the best electrical conductors, but also conduct heat. Scientists still face the struggle to isolate conduction of heat and electricity.
Recently, scientists have been experimenting with Half-Heusler metal alloys, which are affordable and have high potential for thermoelectricity. They dope these alloys with antimony, a transition metal. Doping is adding small amounts of another material to improve properties. The scientists found that, with small amounts of antimony, they could make electrons more able to move throughout the alloy, tremendously increasing electrical conductivity without increasing heat conductivity. By doing this, they were able to make the alloys efficient and cost-effective enough to be used commercially.
The practical applications of this discovery are already being shown in Germany. ThermoHEUSLER has tested thermoelectric devices in cars and been able to generate up to 600 watts of energy in tested vehicles, using the waste heat in the car's exhaust system. According to Science Daily, several million tons of CO2 could have been saved using these devices, just in Germany.
The need for thermoelectric energy is huge, with so much energy being wasted as heat. Even a 1-2% increase in efficiency could mean harnessing tons of otherwise meaningless heat energy. The primary concern is the affordability of thermoelectric materials, but Half-Heusler alloys are cheaper than a lot of alternatives that scientists have found. With consistent advances in thermoelectricity, we could see massive increases in the productivity of cars and even power plants.
Technology is progressing at a faster rate than ever before, and thermoelectric energy is an example of why we should be optimistic for the future of the world. Environmentally friendly energy is progressing, and the next revolution of efficiency could be thermoelectricity.
Tony Williams
Efficiency is an integral part of modern-day society. As we bustle about our daily lives, we constantly search for ways to do more while using less energy. Yet 2/3 of the energy that power plants produce is heat energy, not electricity. Only 25% of gas in the tank actually goes toward moving our cars forward. How can we stop wasting such a large percentage of our precious energy? New innovations in the field of thermoelectricity may hold an answer.
The ideas behind thermoelectricity have been around since the 1800s, when German physicist Thomas Johann Seebeck found out that certain metals responded to temperature differences. Different materials work better for this than others because of their properties. Seebeck and others realized the potential for this, but they didn't have the technology or the materials to make it work effectively enough for commercial use.
Only recently have scientists been able to make materials effective enough for thermoelectricity to become useful. This has great implications; according to Science Daily, "More than two-thirds of the energy from primary sources like oil and gas utilized worldwide today is lost through waste heat." Thermoelectric energy has the potential to harness some of this waste heat, but finding a suitable material has proved a daunting task.
Thermoelectricity works by using materials that react electrically when exposed to temperature differences. This means that, when heat is applied, it creates a high voltage across the material. Like a gas expands when it experiences heat, electrons in thermoelectric materials expand toward the cold side, leaving their nuclei behind with holes (absence of electrons) where the electrons once were. This creates an electrical difference between the two sides that can be harnessed as electricity.
Scientists still struggle with creating materials that work efficiently enough to work on a large scale. Tommi Tynell, who creates thermoelectric materials at the Aalto University School of Chemical Technology, says that "Developing more efficient thermoelectric materials is a major challenge, because the physical properties that affect the performance of the materials are not independent of each other. The optimization of a material is very difficult, because as you improve one feature, other properties may deteriorate at the same time,"
The main struggle is the fact that heat and electricity are conducted in the same substances. For thermoelectric purposes, materials work better when they conduct electricity but not heat. Unfortunately, metals are the best electrical conductors, but also conduct heat. Scientists still face the struggle to isolate conduction of heat and electricity.
Recently, scientists have been experimenting with Half-Heusler metal alloys, which are affordable and have high potential for thermoelectricity. They dope these alloys with antimony, a transition metal. Doping is adding small amounts of another material to improve properties. The scientists found that, with small amounts of antimony, they could make electrons more able to move throughout the alloy, tremendously increasing electrical conductivity without increasing heat conductivity. By doing this, they were able to make the alloys efficient and cost-effective enough to be used commercially.
The practical applications of this discovery are already being shown in Germany. ThermoHEUSLER has tested thermoelectric devices in cars and been able to generate up to 600 watts of energy in tested vehicles, using the waste heat in the car's exhaust system. According to Science Daily, several million tons of CO2 could have been saved using these devices, just in Germany.
The need for thermoelectric energy is huge, with so much energy being wasted as heat. Even a 1-2% increase in efficiency could mean harnessing tons of otherwise meaningless heat energy. The primary concern is the affordability of thermoelectric materials, but Half-Heusler alloys are cheaper than a lot of alternatives that scientists have found. With consistent advances in thermoelectricity, we could see massive increases in the productivity of cars and even power plants.
Technology is progressing at a faster rate than ever before, and thermoelectric energy is an example of why we should be optimistic for the future of the world. Environmentally friendly energy is progressing, and the next revolution of efficiency could be thermoelectricity.
Project reflection
Material science has shaped our past and present immensely, and holds many keys to the future. In the past, it led to the selection of gold as a national currency, for example, shaping the way ancient society held things of value. As for the present, silicon and its role in shaping every kind of technology is very evident. For the future, just look at my project about thermoelectricity. In the future, with the powers of technology and thermoelectric materials on our side, we will be able to harness a good portion of the energy we currently waste as heat. As is evident by past, present, and future, the ever-changing study of materials is crucial to the workings of everything we do in the world.
A material's properties ultimately come from how it is built on the subatomic level. Its structure in terms of protons, neutrons, and electrons determine a lot about its properties. Electrons come in rings around the atom. Elements with similar amounts of electrons on the outermost rings, or valence electrons, exhibit similar properties. For example, the Noble Gases have full octets in their rings, so are not very reactive with other elements. This also determines the element's ability to gain electrons or lose electrons and what elements it will react with. Overall, an element's subatomic structure affects a lot of things that we see.
A material's properties ultimately come from how it is built on the subatomic level. Its structure in terms of protons, neutrons, and electrons determine a lot about its properties. Electrons come in rings around the atom. Elements with similar amounts of electrons on the outermost rings, or valence electrons, exhibit similar properties. For example, the Noble Gases have full octets in their rings, so are not very reactive with other elements. This also determines the element's ability to gain electrons or lose electrons and what elements it will react with. Overall, an element's subatomic structure affects a lot of things that we see.