Power converters are the little-known systems that make electricity so magical. They are what allow us to plug in our computers, lamps and televisions and turn them on in a snap. Converters transform the alternating current (AC) that comes out of wall sockets into the exact level of direct current (DC) that our electronics need. But they also tend to lose, on average, up to 20% of their energy in the process.
source https://techxplore.com/news/2021-03-nanotransistors-cool-high-voltages.html