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Renewable here just means electricity powered, rather than oil or gas powered. It is assuming that the electricity is created from renewable sources

stevenjgarner 4y ago
Would that not imply that all energy is renewable, given that you can make endless hydrogen by electrolyzing water with endless electricity? Then convert the hydrogen into your hydrocarbon of choice using the Sabatier process, and again endless electricity? Maybe I am projecting my own bias onto this, but there's something about endless electricity that does not imply renewable.
- fastball 4y ago
  Are you being deliberately obtuse? If not, in common parlance "renewable" implies Solar / Wind / Hydro / Nuclear (this one depending on who you ask), while non-renewable = fossil fuels. If you have a drilling machine powered by diesel it is impossible for that machine to be "fully renewable" in terms of its power source. If you have a drilling machine that is powered entirely by electricity then it can be 100% powered by renewables, but yes as GP pointed out "can be" doesn't mean "is", but still if you care about such things you should obviously prefer the fully electric solution.
  - stevenjgarner 4y ago
    You're right. I was just stunned at the 1.38 gigawatts for a "stage 3" system (including "mother rig" + "father rig") for just a 10-m (33-ft) tunnel.
    - preisschild 4y ago
      1.38GW is insane. The APR-1400 pressurized water reactor outputs 1.4GW, but at this point you would have a huge nuclear power plant to just power a single tunneling operation.
- Andys 4y ago
  You could, but it isn't efficient enough to compete economically with the plain old electricity in more direct forms?
bigiain 4y ago
So at 4-5 acres per MW for solar farms, each one of these will need around 500 acres of land covered in solar panels (almost a square mile), or about 10 of the largest wind turbines you can buy (a Haliade-X @ 13MW) - to be actually "renewable" powered. (Or 1/3rd of those numbers if you "only" want to run it at 40MW instead of the full 120)
- stevenjgarner 4y ago
  That's "for a hole you can barely crawl through". The 10-m "stage 3" tunnel would consume 1.38 gigawatts per day per km, or 57,500 kwh per meter. By contrast, the energy consumption of a traditional Tunnel Boring Machine (TBM) is about 356 kWh per meter [0], or 0.62% of the plasma boring robot. Let's get this in perspective, the Palo Verde nuclear power plant in Arizona is the largest in the US with three reactors and a total capacity of just under 4 GW. Certainly not what I would characterize as "super-cheap tunnel tech". [0] https://core.ac.uk/download/pdf/82422936.pdf https://core.ac.uk/download/pdf/82422936.pdf

stevenjgarner 4y ago

Would that not imply that all energy is renewable, given that you can make endless hydrogen by electrolyzing water with endless electricity? Then convert the hydrogen into your hydrocarbon of choice using the Sabatier process, and again endless electricity? Maybe I am projecting my own bias onto this, but there's something about endless electricity that does not imply renewable.

fastball 4y ago
Are you being deliberately obtuse? If not, in common parlance "renewable" implies Solar / Wind / Hydro / Nuclear (this one depending on who you ask), while non-renewable = fossil fuels. If you have a drilling machine powered by diesel it is impossible for that machine to be "fully renewable" in terms of its power source. If you have a drilling machine that is powered entirely by electricity then it can be 100% powered by renewables, but yes as GP pointed out "can be" doesn't mean "is", but still if you care about such things you should obviously prefer the fully electric solution.
- stevenjgarner 4y ago
  You're right. I was just stunned at the 1.38 gigawatts for a "stage 3" system (including "mother rig" + "father rig") for just a 10-m (33-ft) tunnel.
  - preisschild 4y ago
    1.38GW is insane. The APR-1400 pressurized water reactor outputs 1.4GW, but at this point you would have a huge nuclear power plant to just power a single tunneling operation.
Andys 4y ago
You could, but it isn't efficient enough to compete economically with the plain old electricity in more direct forms?

bigiain 4y ago

So at 4-5 acres per MW for solar farms, each one of these will need around 500 acres of land covered in solar panels (almost a square mile), or about 10 of the largest wind turbines you can buy (a Haliade-X @ 13MW) - to be actually "renewable" powered. (Or 1/3rd of those numbers if you "only" want to run it at 40MW instead of the full 120)

stevenjgarner 4y ago
That's "for a hole you can barely crawl through". The 10-m "stage 3" tunnel would consume 1.38 gigawatts per day per km, or 57,500 kwh per meter. By contrast, the energy consumption of a traditional Tunnel Boring Machine (TBM) is about 356 kWh per meter [0], or 0.62% of the plasma boring robot. Let's get this in perspective, the Palo Verde nuclear power plant in Arizona is the largest in the US with three reactors and a total capacity of just under 4 GW. Certainly not what I would characterize as "super-cheap tunnel tech". [0] https://core.ac.uk/download/pdf/82422936.pdf https://core.ac.uk/download/pdf/82422936.pdf