Fact Check - Underground Lines would be not be 10x the cost of overhead AC lines
We all know where the claim comes from. So let's look at what the data says:
Please download and read the excellent study called “NextGen Highways Feasibility Study for the Minnesota Department of Transportation” - it specifically addresses the expected costs and benefits of buried High Voltage Direct Current (HVDC) lines.
I am highlighting some of the really perfect pull quotes from the study in the following screenshots:
Page 72 “It is worth noting that a 2GW, 300 miles-long, buried HVDC transmission line would cost roughly $2.5 billion. As such, $1 billion of societal value would equate to 40 percent of the transmission line’s cost.” [WHY is this 1200MW, 150ish mile line projected to cost $2.9 billion? Isn’t that twice as expensive as the going rate???]
Page 13 “Buried HVDC transmission is comparable in cost to overhead AC transmission while providing additional reliability and resilience benefits.”
page 36 “Modern HVDC transmission lines require minimal maintenance (namely, annual visual inspections).” [Note: minimal maintenance means less cost]
page 42 “The transmission cable has a strong and thick layer of insulation. As such, simply touching the line while operational would not be problematic.”
Page 55 “Modern buried HVDC transmission cables require minimal maintenance over their forty-year design life.” [What is the design life of the AC corridor???]
Page 66-67 “The figure shows that buried HVDC projects are cost-competitive with overhead AC transmission projects.” [Note that the comparison includes several projects that are over 100 miles long.]
Other notes, kindly sourced by Andrew Ballentyne:
There are probably more than 100 transmission lines underground that are longer than this proposed line, including: Wind Energy in Germany and New York State
It would take about a week to fix lines: Underground vs. Overhead
And of course, underground lines are unlikely to go down in snow storms, get covered in ice, or start forest fires…..
Hey I appreciate you writing this. I'm a PhD student researching transmission lines. It's not easy to find cost estimates for those nice buried HVDC lines. have a great one :)