We know that we have now 50/60Hz in our walls due to mainly historical reasons – back 100 years ago there were no ways to up/down scale DC voltage.
These days we just have problems due to that – every single device sold have to have ~1uF cap per 1W of power before it's PSU to have enough power when we go through 0. (this problem does not exist in 3-phase power, but it available mainly in industrial applications only AFAIK) + caps have to have higher rated voltage to survive sine peaks + all this PFC mess.
Is that correct to say that if we were to design modern power grid, we would skip AC, and just have DC everywhere? As far as I see, it would significantly increase reliability & reduce cost of many devices out there.
Best Answer
Guy Allee at Intel Research wrote about this topic last year -- DC - An idea whose time has come and gone? -- in support of a 380VDC grid, with the following bullet points:
He added in the comments:
He also mentions the idea of a mixed distribution of both AC and DC within a building (e.g. data centers). For more on that initiative, see the EMerge Alliance website: http://www.emergealliance.org.