Summarizer

> So how did we get to a point where one component can hold trillion-dollar industries hostage? Turns out, a quirk of history made the entire world’s electricity systems reliant on transformers. > At the end of the 19th century, when electricity was just starting to become a commercial source of energy, two businessmen fought to control its future in what came to be known as “the war of the currents.” Thomas Edison promoted the use of direct current (DC) and George Westinghouse, inventor and industrialist, was convinced that alternating current (AC) would prove more practical. > In a clash of personality, finance and some genuine technical advantages, Westinghouse won out and the world has been mostly stuck with using AC as a means of generating and transmitting electricity. Transformers are necessary to make the AC system work. This entire section is a glaring load of nonsense and needs to be removed. We had to start with AC for a variety of technical reasons, the main one being that boosting DC voltage pre-switching technology was impossible. DC cant pass through a transformer unless it is converted to some form of AC, usually in the form of PWM square waves these days. Before the invention of the mercury arc rectifier (And later valve) in 1902 you had boost DC using mechanical methods: generators. The problem there is physical, they did not have the ability to insulate the generator windings at high voltage potentials. They also had problems with DC voltages over 2000 volts on commutators [1] citing excessive arcing. Commutators are also a limiting factor in machine size as beyond several MW they dissipate too much power. So with all this the highest practical voltage for a DC grid using early electrical machinery is around 2 kV. Now imagine all that mechanical complexity on the distribution end. Meanwhile, early AC transmission was already in the tens of kilovolts: 11/22/33 kV (multiples of the early Edison 110 volt standard.) As for the whole war of currents, I feel it is vastly overstated and was more a public spectacle than serious scientific dispute. It was already known from early on that AC was the future thanks to its ability to easily be transformed to higher voltages for transmission and back again with no moving parts. The "war" was likely Edison marketing to sell off the remaining inventory less desirable DC machinery. 1. https://en.wikipedia.org/wiki/Commutator_(electric)

> practical voltage for a DC grid using early electrical machinery is around 2 kV. What is a current (pun!) practical limit? If a 100MW PV farm and a data center are separated by 1km (20 Olympic pools) - is there a way to avoid AC? I know there are future solutions [1] [1] https://techcrunch.com/2025/04/07/former-tesla-exec-drew-bag...

>>> However, DC does not make sense for a radial power distribution network. Why not? Pure geeky curiosity.

Not an expert but every node in an UHVDC network would need expensive equipment Point to point is just two nodes, but scaling that outward would be very expensive AC transmission is relatively cheap in comparison

Yup. The only thing missing from the writeup is a eulogy for the death of the rotary converter.

"Transformers are necessary to make the AC system work." This isn't quite wrong but the motivation is backwards: AC is necessary to make transformers work. 1. All grids need to move energy at high voltage and low current to minimize losses. 2. This requires a mechanism to step voltages up and down for transmission. 3. In 1890 the only such mechanism was the transformer. 4. Transformers only work on AC, not DC. Hence our legacy grid is AC. Nowadays we have an additional mechanism: Power electronics. Power electronics work on both AC and DC, so transformers with their huge requirements for copper and steel are no longer necessary. We need to accelerate the transition of our grid to DC because DC grids are simpler and cheaper than AC grids.