TLDR connecting far-flung regions into one huge grid can mitigate the intermittency of renewables. High-voltage direct current is a good way to do this.

  • zifnab25 [he/him, any]
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    edit-2
    1 year ago

    Is this really more efficient than, say, building a big plant that does electrolysers or a bunch of giant flywheels to store excess energy? Or simply optimizing time-of-use to correspond when productivity is highest?

    • iie [they/them, he/him]
      hexagon
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      edit-2
      1 year ago

      I haven't seen a comparison, but wikipedia claims HVDC loses only 3% per 1000 km.

      https://en.wikipedia.org/wiki/Grid_energy_storage#Economics

      The Atlantic Ocean is like 3–5000 kilometers wide. Over 5000 km you'd lose around 14%.

      • zifnab25 [he/him, any]
        ·
        1 year ago

        I mean, that's great. But what are the capital costs relative to a local power repository?

        • iie [they/them, he/him]
          hexagon
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          edit-2
          1 year ago

          The 1,208 km euro-asia subsea power cable will carry 2000 MW of power and cost $745,000 per km, $900 million total

          For comparison, this 2013 80% efficient scalable flywheel design costs around $1333 per kW. Handling 2000 MW would cost $1333 x 1000 x 2000 = $2.7 billion

          The costs are comparable, but the 1,208 km euro-asia HVDC cable wins unless I fucked up my math or misunderstood how flywheel cost works

          The length where flywheels overtake cables is $2.7 billion / $745,000 per km ≈ 3600 km, so flywheels might beat a trans-Atlantic cable, depending on the route

    • zoe [none/use name]
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      edit-2
      1 year ago

      electrolyzers consume about 44kwh per kg H2 generated, and solar ain't efficient either:200w capacity per m²..