3 ms·

Turbines cost less to operate part-time than full-time. One operated 4 hours / day, or one day / week, costs a lot less than one run continuously.

by ncmncm 4y ago

DennisP 4y ago
I'm gonna need a source on that. It seems to me that turbine cost is mainly capital cost, and if you're not running it continuously then your cost per kWh is higher. After all, that's the argument you renewables folks make when you say nuclear plants can't load-follow economically. So tell me why a turbine run intermittently is cheaper, and prove it with a source.
- ncmncm 4y ago
  Allow me to invite you to look up steam turbine overhaul cost and frequency. Do mothballed turbines need frequent overhauls? Or will they need overhauls after N hours' use at intensity Y, or after M > N operated at intensity X < Y? Steam turbines are a substantial fraction of nuke operating cost, but far from the only substantial cost.
  - DennisP 4y ago
    An idle turbine also isn't earning revenue. I haven't found specific numbers on steam turbines, but this pdf says a gas turbine's maintenance cost over 30 years is 3 to 4 times the capital cost: https://www.gasturbine.org/papers/GTA%20Comments%20on%20RMRR.pdf https://www.gasturbine.org/papers/GTA%20Comments%20on%20RMRR... So taking the worst case, capital plus maintenance for a continually-running turbine is 5X its capital cost, to get 30 years of power output. For each year of power, the total cost is 5/30 or 1/6 of the capital cost. Now lets take your 4 hours/day example. That's 1/6 as much running time, so only 5 total years of power output. It's also 1/6 as much maintenance cost, so maintenance is 4/6 of the capital cost, for a 30-year total cost of 1.66 times capital cost. Total cost per year of power is 1.66/5 = 1/3 of the capital cost. That puts the cost per kWh for energy storage at double the cost of the continuously-run turbine.
    - Schroedingersat 4y ago
      That's tolerable compared to fission. You could model it roughly as adding the capex cost of half a turbine or so and x% of uptimes to your solar/wind capacity. Lifetime would also be longer but anything after 2060 or so is largely irrelevent for slowing climate change so we'll ignore it. IIRC O&M + Capex for a CCGT is about $20/MWh and fuel is around $30 which would put the capital around $5 and we don't expect to operate it for long as it's a backup. So the generator should cost us <$10 per MWh of solar + wind we use (with the majority being used directly or via batteries/hydro). Green fuel will cost about 2x the renewable energy with capex/O&M on the same order as the turbine or maybe a bit lower (ammonia electrolyzers are estimated about $1000/kw with current tech but you'd only need to put half or less of your peak capacity through it. Additionally they will run most of the time producing fuel if the target is using the fuel as the last resort backup). With projected solar + wind costs around $20/MWh using chemical storage for winter would then have a total cost of $60/MWh for energy that has been stored as ammonia and $40 for energy that has not in a somewhat pessimistic ballpark with price dominated by fuel generation. On par with some current full time gas, but at the upper end. Far less than fission if we use the same 'joules before 2060' constraint, but enough to cause difficulty building out new gas turbines if we don't presently have enough. Fusion isn't really in the running as a steam turbine is much more expensive than a gas one so we're getting close to parity with the renewable + battery + gas turbine just from the steam turbine step.
      - DennisP 4y ago
        From a quick google, steam turbines cost about 50% more than gas turbines.[1][2] Gas is $500-700/kW, steam is $670-1140/kW. That's easily compensated by the higher capacity factor of non-storage applications (since storage turbines, calculated above, cost 100% more per kWh due to idle time). Also, storage has to add the cost of the electrolyzer and ammonia storage tanks. On top of that, round-trip efficiency of energy storage via ammonia is only about 30%.[3] So if your solar farm costs $20/MWh, your cost of stored energy is over $60/MWh before accounting for turbine/electrolyzer costs. This means you can easily be competitive with a steam turbine plus a heat source that costs $60/MWh, at least for baseload. [1] https://www.greentechmedia.com/articles/read/ges-new-gas-turbines-are-state-of-the-art-but-are-we-getting-too-cozy-with https://www.greentechmedia.com/articles/read/ges-new-gas-tur... [2] pdf: https://www.energy.gov/sites/prod/files/2016/09/f33/CHP-Steam%20Turbine.pdf https://www.energy.gov/sites/prod/files/2016/09/f33/CHP-Stea... [3] https://www.ammoniaenergy.org/articles/round-trip-efficiency-of-ammonia-as-a-renewable-energy-transportation-media/ https://www.ammoniaenergy.org/articles/round-trip-efficiency...

Turbines cost less to operate part-time than full-time. One operated 4 hours / day, or one day / week, costs a lot less than one run continuously.

by ncmncm 4y ago

Turbines cost less to operate part-time than full-time. One operated 4 hours / day, or one day / week, costs a lot less than one run continuously.

DennisP 4y ago

I'm gonna need a source on that. It seems to me that turbine cost is mainly capital cost, and if you're not running it continuously then your cost per kWh is higher. After all, that's the argument you renewables folks make when you say nuclear plants can't load-follow economically. So tell me why a turbine run intermittently is cheaper, and prove it with a source.

ncmncm 4y ago
Allow me to invite you to look up steam turbine overhaul cost and frequency. Do mothballed turbines need frequent overhauls? Or will they need overhauls after N hours' use at intensity Y, or after M > N operated at intensity X < Y? Steam turbines are a substantial fraction of nuke operating cost, but far from the only substantial cost.
- DennisP 4y ago
  An idle turbine also isn't earning revenue. I haven't found specific numbers on steam turbines, but this pdf says a gas turbine's maintenance cost over 30 years is 3 to 4 times the capital cost: https://www.gasturbine.org/papers/GTA%20Comments%20on%20RMRR.pdf https://www.gasturbine.org/papers/GTA%20Comments%20on%20RMRR... So taking the worst case, capital plus maintenance for a continually-running turbine is 5X its capital cost, to get 30 years of power output. For each year of power, the total cost is 5/30 or 1/6 of the capital cost. Now lets take your 4 hours/day example. That's 1/6 as much running time, so only 5 total years of power output. It's also 1/6 as much maintenance cost, so maintenance is 4/6 of the capital cost, for a 30-year total cost of 1.66 times capital cost. Total cost per year of power is 1.66/5 = 1/3 of the capital cost. That puts the cost per kWh for energy storage at double the cost of the continuously-run turbine.
  - Schroedingersat 4y ago
    That's tolerable compared to fission. You could model it roughly as adding the capex cost of half a turbine or so and x% of uptimes to your solar/wind capacity. Lifetime would also be longer but anything after 2060 or so is largely irrelevent for slowing climate change so we'll ignore it. IIRC O&M + Capex for a CCGT is about $20/MWh and fuel is around $30 which would put the capital around $5 and we don't expect to operate it for long as it's a backup. So the generator should cost us <$10 per MWh of solar + wind we use (with the majority being used directly or via batteries/hydro). Green fuel will cost about 2x the renewable energy with capex/O&M on the same order as the turbine or maybe a bit lower (ammonia electrolyzers are estimated about $1000/kw with current tech but you'd only need to put half or less of your peak capacity through it. Additionally they will run most of the time producing fuel if the target is using the fuel as the last resort backup). With projected solar + wind costs around $20/MWh using chemical storage for winter would then have a total cost of $60/MWh for energy that has been stored as ammonia and $40 for energy that has not in a somewhat pessimistic ballpark with price dominated by fuel generation. On par with some current full time gas, but at the upper end. Far less than fission if we use the same 'joules before 2060' constraint, but enough to cause difficulty building out new gas turbines if we don't presently have enough. Fusion isn't really in the running as a steam turbine is much more expensive than a gas one so we're getting close to parity with the renewable + battery + gas turbine just from the steam turbine step.
    - DennisP 4y ago
      From a quick google, steam turbines cost about 50% more than gas turbines.[1][2] Gas is $500-700/kW, steam is $670-1140/kW. That's easily compensated by the higher capacity factor of non-storage applications (since storage turbines, calculated above, cost 100% more per kWh due to idle time). Also, storage has to add the cost of the electrolyzer and ammonia storage tanks. On top of that, round-trip efficiency of energy storage via ammonia is only about 30%.[3] So if your solar farm costs $20/MWh, your cost of stored energy is over $60/MWh before accounting for turbine/electrolyzer costs. This means you can easily be competitive with a steam turbine plus a heat source that costs $60/MWh, at least for baseload. [1] https://www.greentechmedia.com/articles/read/ges-new-gas-turbines-are-state-of-the-art-but-are-we-getting-too-cozy-with https://www.greentechmedia.com/articles/read/ges-new-gas-tur... [2] pdf: https://www.energy.gov/sites/prod/files/2016/09/f33/CHP-Steam%20Turbine.pdf https://www.energy.gov/sites/prod/files/2016/09/f33/CHP-Stea... [3] https://www.ammoniaenergy.org/articles/round-trip-efficiency-of-ammonia-as-a-renewable-energy-transportation-media/ https://www.ammoniaenergy.org/articles/round-trip-efficiency...