A new way to turn heat into energy

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An international team of scientists has discovered how to capture the heat and turn it into electricity.

The discovery, published last week in the journal Progress of science, could generate more efficient energy generation from heat, including car exhaust gases, interplanetary space probes and industrial processes.

"With this discovery, we should be able to produce more electrical energy with heat than today," said Joseph Heremans, co-author of the study, professor in mechanical and aerospace engineering and distinguished researcher in nanotechnology from Ohio to Ohio State University. "It's something no one thought possible up to now."

The discovery is based on tiny particles called paramagnons, bits that are not quite magnets, but carry a magnetic flux. This is important because magnets, when heated, lose their magnetic force and become what is called paramagnetic. A flow of magnetism – what scientists call "spins" – creates a type of energy called magnon drag thermoelectricity, which, until this discovery, could not be used to collect water. 39, energy at room temperature.

"Conventional wisdom once was that if you have a paramagnet and you heat it, nothing happens," said Heremans. "And we found that this is not true.What we discovered is a new way of designing thermoelectric semiconductors, materials that convert heat into electricity." The conventional thermoelectric that we have known for twenty or so years are too inefficient and also give us little energy, so they are not really used.This changes this understanding. "

Magnets play a crucial role in the collection of thermal energy: when one side of a magnet is heated, the other, the cold side, becomes more magnetic and produces a rotation that pushes the electrons into the magnet and creates electricity.

The paradox, however, is that when the magnets are heated, they lose most of their magnetic properties, turning them into paramagnets – "magnets almost but not quite" – called them Heremans. This means that, until this discovery, no one thinks of using paramagnetics to harvest heat because scientists thought that paramagnetics were not able to collect energy.

The research team, however, found that paramagnons only grow electrons for one billionth of a millionth of a second, which is enough to make paramagnetics that collect energy viable.

The research team – an international group of scientists from the state of Ohio, North Carolina State University and the Chinese Academy of Sciences (both authors in this review article) – began testing paramagnons to see if, in good circumstances, they would produce the same results. spin needed.

Heremans explained that what they discovered, is that paramagnons actually produce the type of spin that drives electrons.

And that, he said, could help to collect energy.