As spotted by hardwareluxx.de, EKWB could be building a prototype CPU waterblock that uses an electrothermal transducer, assisted with water, to cool a CPU. LinusTechTips gave a sneak peek at this "prototype EKWB" CPU cooler in one of its latest videos. There was no explanation of exactly what it was, but they were able to hit 0 degrees Celcius on a 10900K at idle and 50C under load without the need for LN2, suggesting some sort of electrothermal technology was being used.
Thermoelectric cooling relies on the Peltier effect, which allows electricity to transfer the heat (energy) from one source to another. The discovery was made in 1834 by a physicist named Jean Charles Athanase Peltier. If used effectively, this could be applied to cool CPUs or anything that requires cooling in general. The interesting thing about this technology is the fact it uses current, not air for cooling, meaning sub-ambient temperatures are totally possible (as shown by LinusTechTips with the 0C idle temps).
However, as harewareluxx points out, many manufacturers have already tried this. The problem with this technology stems from a large amount of waste heat the cooler builds up -- as well as condensation. So it'll be interesting to see whether EKWB can solve these problems if they plan to launch this prototype CPU water block to the masses.