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Comment by jacquesm | Hacker News Reader

I think HVDC is a game changer for renewables. Any long East-West grid connection is going to improve the total fraction of power that can be generated using renewables because effectively windpower = solar power and having a longer East-West stretch makes the amount of sun hours during a day longer. And any North-South lines will help offset local conditions during the day.

The more the better, especially intercontinental.

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I wanted Russia to invest in a transiberia-HVDC line and solar collectors instead of a war. They could even sell excess capacity to the countries on their southern border. I think Reddit panned this idea last time I proposed it because the longest HVDC line was only 2100 miles long.

Yes, that would have been a lot better than war. But it doesn't make you look strong as a dictator...

It does, if done right.

But russia does not have a solar plant industry, but they had lots of war assets sitting idle around, so they used what they had and learned to do.

Russia is one of the worst countries for solar power, perhaps bottom ten. It's also one the better connected ones with old school AC HV lines.

Wind too then. I'm not picky. Hell maybe they find a coal deposit nearby the HVDC line. It wouldn't be the best but burning the coal near the location and shipping the energy else where is cheaper than shipping the coal elsewhere.

Why in the world would they invest into such HVDC project when they already have a huge synchronous grid (unlike the US and Canada, which have 5 grids in total) shared by other countries, especially on the southern border. I think there are even plans for Iran to join this grid. They have absolutely no trouble sending energy across their territory to smooth consumption peaks. Add to that abundance of coal/gas/oil (FYI during winters they use thermal power stations to generate both electricity and heat for homes), robust atomic and hydroelectric generation, and almost zero (in relative terms) solar generation.

They only need relatively short HVDC links to be able to send energy from their hydroelectric installations in Siberia to China and maybe to South Korea and Japan, though with the current geopolitical climate the latter is quite unlikely.

HVDCs are increasingly being used inside grids too. Any grid needs high capacity links (AC or DC) to connect its far corners.

HVDC line is cheaper to build and has fewer losses. But you need conversion stations which are expensive and also have some loss.

At some distance, HVDC trumps AC even inside synchronized grid. Breakeven point is about 600 km for overhead lines and just 50 km for submarine cables.

And that breakeven point keeps getting shorter as the conversion equipment gets cheaper. It used to be much longer, back when the concept was new.

Solar already generates DC and inverts to the grid, so tying it directly to HVDC could probably be done by just changing the inverters, rather than adding a whole standalone conversion station. So that makes it cheaper still.

The next frontier will be when a customer asks for DC handoff.

> HVDC line is cheaper to build and has fewer losses. But you need conversion stations which are expensive and also have some loss.

I see this argument a lot lately. I fail to see why DC will be better when, at the end, you have to convert it in AC.

In a nutshell: economics. And if two grids are not in sync then you don't have many other options.

AC loses more energy via ground coupling.

Also suspect the losses for high voltage AC/DC conversion is very low. As losses tend to depend on current rather than voltage. Not exactly true because you need to connect switches in series to handle the voltage.

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