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From the article: >The first experiment showed a temperature change of 25 degrees Celsius using less than one volt, a greater temperature lift than demonstrated

From the article: >The first experiment showed a temperature change of 25 degrees Celsius using less than one volt, a greater temperature lift than demonstrated by other caloric technologies. This makes no sense. Voltage is not a measure of energy, it's a measure of electrical potential, or electromotive force. Low voltage with extremely high current is still a lot of energy. The only thing important with refrigeration efficiency is how much (electrical) energy it requires to achieve a certain change in thermal energy; for this, you'd need to measure the voltage and current, or just the wattage, plus measure the actual thermal energy change (usually measured in BTU for air conditioners).

varenc 4y ago
The article is a bit confusing on that point. From looking at the paper it seems like the 1 volt is relevant not because it's supposed to be implying energy efficiency by itself, but for some other reasons I don't understand. From the abstract: > "Our experimental results show a coefficient of performance of 30% relative to Carnot and a temperature lift as high as 25°C using a voltage strength of ~0.22 volts." And from the actual paper: > "To modulate the electrochemical potential in a real system, the ion concentration can be controlled by applying a voltage in an electrolytic cell (e.g., dual-ion battery), where the applied voltage is typically ~1 V. This stimulus is considerably milder than those used in magnetic, electric, and pressure-based caloric systems." I'm not following the paper at all, but it sounds like requiring a low electrical potential is a good thing.
- StrangeDoctor 4y ago
  Electrolysis of water becomes extremely favorable above 1.23 volts, and is not something you want to subject most electrodes to. The closer you get to 1.23 volts the more and more likely it is for electrolysis to happen at a given current used to maintain the field they'd need. I'm not 100% on this given I don't want to buy the paper and am not an expert in this field, but have done a lot electrolysis related work on personal projects. edit: Also electroplating would probably become a concern as well depending on what exactly is in that brew.
l33t233372 4y ago
> Voltage is not a measure of energy, it's a measure of electrical potential, or electromotive force I don’t understand the difference between electromotive force and energy associated with electricity. How can there be low electromotive force with high energy?
- itronitron 4y ago
  I'm not an electrician, but drawing an analogy to water you can think of voltage as water pressure in the sense that you can have a small stream of high pressure water as in a water pik or a large current of low pressure water as a river. The river carries more energy despite having a lower voltage.
  - midoridensha 4y ago
    Exactly: this is the normal analogy used for understanding voltage and current. In a pipe with water, you could have a gargantuan pipe carrying water from a lake or river, at very low pressure (only gravity is moving it), but with a gigantic volume, so the total energy is huge. Or you could have a tiny pipe in your house with water at high pressure (60-90 psi is normal for municipal water supplies), but the total amount of water is low, so the total energy is low compared to that huge pipe with river water.
    - osigurdson 4y ago
      The analogy breaks down once you reach sonic flow in the pipe however.
m463 4y ago
It can be bs. However it's still interesting because a lot of refrigeration uses a compressor which requires a lot of voltage (and current) to start up. It might be like peltier coolers which are solid state, but unfortunately not very efficient and don't cool much in practical terms. (search thermoelectric coolers or peltier) One interesting cooling technology is the free piston stirling cooler. Coleman used to sell one years ago for ~$400, and then discontinued them. They are highly prized now. Basically they took very little energy to start cooling something and could cool to very low temperatures. The coleman model seemed to use CO2 as the cooling medium. They still sell similar coolers now, but for >$2k usually with helium as the medium. They are so pricey now they are mostly used for medical transport. There might be some "you need a license" stuff with these types of coolers since they can go quite far below zero I've also noticed you can buy the FPSC piston part itself (without the box) for random prices. search "free piston stirling cooler" on amazon. It's too bad they didn't take off, I think they would pair very will with solar for solar-powered refrigeration.
- midoridensha 4y ago
  >However it's still interesting because a lot of refrigeration uses a compressor which requires a lot of voltage (and current) to start up. It might be like peltier coolers which are solid state, but unfortunately not very efficient and don't cool much in practical terms. (search thermoelectric coolers or peltier) This is exactly why it's BS: a compressor requires high(er) voltage to start and run, and Peltier coolers can run on 5V USB outlets. However, compressor-based cooling is FAR more efficient than Peltiers, which are infamously inefficient. Voltage really doesn't tell you anything. The problem is that journalists have no idea what a Volt is.
  - skedaddle 4y ago
    They are not comparing to compression cycle efficiencies. They are comparing ionocaloric results to other caloric cooling techniques. Electrocaloric cooling requires an E field of hundreds or thousands of volts per cm to cool a material 15K or so, so it's remarkable that ionocaloric cooling can be driven by a weak field. They never imply that it is more power efficient than every other cooling technique -- that idea was injected upthread. It does take energy to create and sustain such a strong field. But in any case, fields that strong break polymers and other materials (air) and are harder to work with generally. EC/MC cooling devices are expensive and inefficient as a result. > journalists have no idea what a Volt is Institutional science communication doesn't work like that. Bylines aside, these articles are an agglomeration of what the researchers, communication team, grant managers, lab directors, and DOE bureaucrats want to say.
jojobas 4y ago
I don't think I understand either, however, with thermocouples it sort of makes sense - increasing current also increases ohmic heat, so per volt performance is important.
osigurdson 4y ago
It is strange but perhaps this is referring to a ratio. A temperature change similarly does not imply any energy delta (in classical physics at least) as the mass of an object approaches zero. I agree though, just tell us how much more efficient it is than existing technology. >> Low voltage with extremely high current is still a lot of energy To be a bit pedantic, this is strictly a lot of power - it is necessary to multiply by time to get energy. 1 amp * 1 volt = 1 watt = 1 joule / second
Cthulhu_ 4y ago
But you can draw conclusions based on that. Low voltage also means that the amount of electricity is limited - the lower the voltage, the thicker a wire you need for any serious amount of power. In practice, it means that 1 volt will be using power equivalent or below e.g. regular USB chargers. I mean sure, voltage was not the right term to use, but it doesn't necessarily mean they cheated.
stonogo 4y ago
From the paper: "In electrocaloric devices, electric fields of ≈200 MV m^−1 are common (more than 50 times as large as the dielectric strength of air) and can only be generated by applying voltages across micrometer-sized films in the kilovolt range. ... In the ionocaloric device, the applied field is ~0.22 V, which is relatively modest. ... For additional perspective, some high-efficiency aqueous vanadium redox flow batteries operate at 800 mA cm^−2; the ionocaloric device operated at ≈0.5 mA cm^−2 for its highest-efficiency results. If, for example, it operated at 800 mA cm^−2, like in the aqueous system, the cooling power output would be equal to 9.2 kW L^−1." It's fairly common for articles like the one linked to be written by the lab's communications department, who may or may not be familiar with the subject at hand.
- greenbit 4y ago
  It's one of those journalistic, press-release kind of write-ups, the kind that spend some effort explaining basic concepts in a hand wavy kind of way, before proceding to pitch the main point with yet more hand waving interleaved with quotes from those involved. I think the point may be just to make the public at large feel positively about the New Thing.
SnowHill9902 4y ago
You are partially right regarding energy, but not all joules are created equal. Being able to use a small differential such as 1 V is an achievement in itself.

varenc 4y ago

The article is a bit confusing on that point. From looking at the paper it seems like the 1 volt is relevant not because it's supposed to be implying energy efficiency by itself, but for some other reasons I don't understand. From the abstract: > "Our experimental results show a coefficient of performance of 30% relative to Carnot and a temperature lift as high as 25°C using a voltage strength of ~0.22 volts." And from the actual paper: > "To modulate the electrochemical potential in a real system, the ion concentration can be controlled by applying a voltage in an electrolytic cell (e.g., dual-ion battery), where the applied voltage is typically ~1 V. This stimulus is considerably milder than those used in magnetic, electric, and pressure-based caloric systems." I'm not following the paper at all, but it sounds like requiring a low electrical potential is a good thing.

StrangeDoctor 4y ago
Electrolysis of water becomes extremely favorable above 1.23 volts, and is not something you want to subject most electrodes to. The closer you get to 1.23 volts the more and more likely it is for electrolysis to happen at a given current used to maintain the field they'd need. I'm not 100% on this given I don't want to buy the paper and am not an expert in this field, but have done a lot electrolysis related work on personal projects. edit: Also electroplating would probably become a concern as well depending on what exactly is in that brew.

l33t233372 4y ago

> Voltage is not a measure of energy, it's a measure of electrical potential, or electromotive force I don’t understand the difference between electromotive force and energy associated with electricity. How can there be low electromotive force with high energy?

itronitron 4y ago
I'm not an electrician, but drawing an analogy to water you can think of voltage as water pressure in the sense that you can have a small stream of high pressure water as in a water pik or a large current of low pressure water as a river. The river carries more energy despite having a lower voltage.
- midoridensha 4y ago
  Exactly: this is the normal analogy used for understanding voltage and current. In a pipe with water, you could have a gargantuan pipe carrying water from a lake or river, at very low pressure (only gravity is moving it), but with a gigantic volume, so the total energy is huge. Or you could have a tiny pipe in your house with water at high pressure (60-90 psi is normal for municipal water supplies), but the total amount of water is low, so the total energy is low compared to that huge pipe with river water.
  - osigurdson 4y ago
    The analogy breaks down once you reach sonic flow in the pipe however.

m463 4y ago

It can be bs. However it's still interesting because a lot of refrigeration uses a compressor which requires a lot of voltage (and current) to start up. It might be like peltier coolers which are solid state, but unfortunately not very efficient and don't cool much in practical terms. (search thermoelectric coolers or peltier) One interesting cooling technology is the free piston stirling cooler. Coleman used to sell one years ago for ~$400, and then discontinued them. They are highly prized now. Basically they took very little energy to start cooling something and could cool to very low temperatures. The coleman model seemed to use CO2 as the cooling medium. They still sell similar coolers now, but for >$2k usually with helium as the medium. They are so pricey now they are mostly used for medical transport. There might be some "you need a license" stuff with these types of coolers since they can go quite far below zero I've also noticed you can buy the FPSC piston part itself (without the box) for random prices. search "free piston stirling cooler" on amazon. It's too bad they didn't take off, I think they would pair very will with solar for solar-powered refrigeration.

midoridensha 4y ago
>However it's still interesting because a lot of refrigeration uses a compressor which requires a lot of voltage (and current) to start up. It might be like peltier coolers which are solid state, but unfortunately not very efficient and don't cool much in practical terms. (search thermoelectric coolers or peltier) This is exactly why it's BS: a compressor requires high(er) voltage to start and run, and Peltier coolers can run on 5V USB outlets. However, compressor-based cooling is FAR more efficient than Peltiers, which are infamously inefficient. Voltage really doesn't tell you anything. The problem is that journalists have no idea what a Volt is.
- skedaddle 4y ago
  They are not comparing to compression cycle efficiencies. They are comparing ionocaloric results to other caloric cooling techniques. Electrocaloric cooling requires an E field of hundreds or thousands of volts per cm to cool a material 15K or so, so it's remarkable that ionocaloric cooling can be driven by a weak field. They never imply that it is more power efficient than every other cooling technique -- that idea was injected upthread. It does take energy to create and sustain such a strong field. But in any case, fields that strong break polymers and other materials (air) and are harder to work with generally. EC/MC cooling devices are expensive and inefficient as a result. > journalists have no idea what a Volt is Institutional science communication doesn't work like that. Bylines aside, these articles are an agglomeration of what the researchers, communication team, grant managers, lab directors, and DOE bureaucrats want to say.

jojobas 4y ago

I don't think I understand either, however, with thermocouples it sort of makes sense - increasing current also increases ohmic heat, so per volt performance is important.

osigurdson 4y ago

It is strange but perhaps this is referring to a ratio. A temperature change similarly does not imply any energy delta (in classical physics at least) as the mass of an object approaches zero. I agree though, just tell us how much more efficient it is than existing technology. >> Low voltage with extremely high current is still a lot of energy To be a bit pedantic, this is strictly a lot of power - it is necessary to multiply by time to get energy. 1 amp * 1 volt = 1 watt = 1 joule / second

Cthulhu_ 4y ago

But you can draw conclusions based on that. Low voltage also means that the amount of electricity is limited - the lower the voltage, the thicker a wire you need for any serious amount of power. In practice, it means that 1 volt will be using power equivalent or below e.g. regular USB chargers. I mean sure, voltage was not the right term to use, but it doesn't necessarily mean they cheated.

stonogo 4y ago

From the paper: "In electrocaloric devices, electric fields of ≈200 MV m^−1 are common (more than 50 times as large as the dielectric strength of air) and can only be generated by applying voltages across micrometer-sized films in the kilovolt range. ... In the ionocaloric device, the applied field is ~0.22 V, which is relatively modest. ... For additional perspective, some high-efficiency aqueous vanadium redox flow batteries operate at 800 mA cm^−2; the ionocaloric device operated at ≈0.5 mA cm^−2 for its highest-efficiency results. If, for example, it operated at 800 mA cm^−2, like in the aqueous system, the cooling power output would be equal to 9.2 kW L^−1." It's fairly common for articles like the one linked to be written by the lab's communications department, who may or may not be familiar with the subject at hand.

greenbit 4y ago
It's one of those journalistic, press-release kind of write-ups, the kind that spend some effort explaining basic concepts in a hand wavy kind of way, before proceding to pitch the main point with yet more hand waving interleaved with quotes from those involved. I think the point may be just to make the public at large feel positively about the New Thing.

SnowHill9902 4y ago

You are partially right regarding energy, but not all joules are created equal. Being able to use a small differential such as 1 V is an achievement in itself.