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Germany made a similar announcement recently, and I have the same questions here as for there. Although there has been progress to use coal plants as variable

Germany made a similar announcement recently, and I have the same questions here as for there. Although there has been progress to use coal plants as variable output plants, they tend to be used base load plants that run all or most of the time. The same thing is true for Nuclear plants, and to the extent that power prices occasionally go _negative_. (This essentially means that the utility is willing to pay people to take their power for a brief time at low system loading, so that they can avoid turning a plant down or off.) Renewables are used differently, in that there's a lot less ability to rely on them to generate power. So they're not really a replacement. This makes me think the ability to shutter these coal plants is a lot more dependent on the decision to extend the life of the nuclear plant and buy the NG plant than it is to do with the renewables they're adding.

_bxg1 7y ago
There have also been great gains made in energy storage lately, which is what's needed to make renewables a true replacement.
- mschaef 7y ago
  Absolutely. This has to be viewed holistically, as a combination of greener generation, better efficiency, storage, lifestyle changes.... The problem's too big to solve otherwise.
pm24601 7y ago
> Renewables are used differently, in that there's a lot less ability to rely on them to generate power. I am confused on your reasoning here. Solar energy covers the daylight hours. Wind power covers the evening / night time hours. Storage technologies smooth out the bumps. Nuclear plants tend to experience long down times for maintenance - which hardly makes them 'reliable'. Xcel is based in a part of the country with easy access to wind energy. I suspect that that calculation is playing a much larger role than you are considering. Specifically, if Xcel can site wind farms close to the customer, there can be a significant savings in power loss due to transmission. Windfarms can be built in smaller units of generation power and built in the airspace over farms. (This is why conservative Kansas really like renewables - farmers see them as a backup source of revenue.)
- mschaef 7y ago
  > Solar energy covers the daylight hours. The number of daylight hours varies considerably over the course of the year, as well as over varying weather conditions. > Wind power covers the evening / night time hours. Wind power presents several logistical problems. One is that it tends to fall off in the heat of a summer day. This has the net effect of increasing the ramp rate required from other generation assets at the time of peak network load. There are also issues around the fact that wind power tends to be located away from areas of the highest demand. (Generation being in more rural areas, with demand largely being centered in urban areas.) This creates a need to move power in bulk over long distances, which creates issues around the need for reactive support to maintain voltage and therefore grid stability. > Storage technologies smooth out the bumps. Energy storage represents around 4% of US generation capacity, so I'm hoping they're small bumps, at least for the time being. (To put that 4% in perspective, the area I'm in is projecting a 50% increase in system load from this morning's low to this afternoon's high.) http://css.umich.edu/factsheets/us-grid-energy-storage-factsheet http://css.umich.edu/factsheets/us-grid-energy-storage-facts... > Nuclear plants tend to experience long down times for maintenance - which hardly makes them 'reliable'. Capacity factors for nuclear plants hover around 90%, with Solar around 25% and Wind around 30%. https://www.eia.gov/electricity/monthly/epm_table_grapher.php?t=epmt_6_07_b https://www.eia.gov/electricity/monthly/epm_table_grapher.ph...
war1025 7y ago
Our municipal power plant where I live converted from coal to natural gas recently. My understanding was the decision was based solely on the (now cancelled?) Clean Power Plan, and the inability to make the existing plant meet those regulations. Given the instability of US politics, I'd guess most utility companies are operating under the assumption that those laws could quickly be put back in place after any given election cycle.
- jsight 7y ago
  According to a utility in South Carolina (Santee Cooper): "Related to cost — in 2008, natural gas generation was as low as $55/MWh and coal was about $22/MWh in our most efficient units. In 2018, the comparable prices were $26/MWh for natural gas and $34/MWh for coal."
  - hef19898 7y ago
    Thong in Germany is that CO2 certificates are so dirt cheap that the incremental cost of power generation puts coal plants second behind wind and solar with basically zero variable cost (I'd have to look up where hydro power stands). So gas effectively gets squeezed out of the market. The easy fix would be cutting the available CO2 certificates or making them more expensive. But for some reason that ain't happening.
    - war1025 7y ago
      Doesn't Germany get most of its natural gas from Russia, which is a bit contentious for political reasons?
      - hef19898 7y ago
        Well, yes. Still supply was stable. Not for Ukraine, so. Also a lot of the has is used for heating.
      - village-idiot 7y ago
        Yes. Fun fact, all of the natural gas that Germany bought from Russia used to flow through former Warsaw Pact nations like Poland. Now the gas goes at least partially through the undersea Nord Stream pipeline and the under construction Nord Stream 2. It's generally believed that this transition has made Russia much more bellicose in the region, as they can now threaten to turn off Poland's gas supply without also harming Western Europe at the same time.

_bxg1 7y ago

There have also been great gains made in energy storage lately, which is what's needed to make renewables a true replacement.

mschaef 7y ago
Absolutely. This has to be viewed holistically, as a combination of greener generation, better efficiency, storage, lifestyle changes.... The problem's too big to solve otherwise.

pm24601 7y ago

> Renewables are used differently, in that there's a lot less ability to rely on them to generate power. I am confused on your reasoning here. Solar energy covers the daylight hours. Wind power covers the evening / night time hours. Storage technologies smooth out the bumps. Nuclear plants tend to experience long down times for maintenance - which hardly makes them 'reliable'. Xcel is based in a part of the country with easy access to wind energy. I suspect that that calculation is playing a much larger role than you are considering. Specifically, if Xcel can site wind farms close to the customer, there can be a significant savings in power loss due to transmission. Windfarms can be built in smaller units of generation power and built in the airspace over farms. (This is why conservative Kansas really like renewables - farmers see them as a backup source of revenue.)

mschaef 7y ago
> Solar energy covers the daylight hours. The number of daylight hours varies considerably over the course of the year, as well as over varying weather conditions. > Wind power covers the evening / night time hours. Wind power presents several logistical problems. One is that it tends to fall off in the heat of a summer day. This has the net effect of increasing the ramp rate required from other generation assets at the time of peak network load. There are also issues around the fact that wind power tends to be located away from areas of the highest demand. (Generation being in more rural areas, with demand largely being centered in urban areas.) This creates a need to move power in bulk over long distances, which creates issues around the need for reactive support to maintain voltage and therefore grid stability. > Storage technologies smooth out the bumps. Energy storage represents around 4% of US generation capacity, so I'm hoping they're small bumps, at least for the time being. (To put that 4% in perspective, the area I'm in is projecting a 50% increase in system load from this morning's low to this afternoon's high.) http://css.umich.edu/factsheets/us-grid-energy-storage-factsheet http://css.umich.edu/factsheets/us-grid-energy-storage-facts... > Nuclear plants tend to experience long down times for maintenance - which hardly makes them 'reliable'. Capacity factors for nuclear plants hover around 90%, with Solar around 25% and Wind around 30%. https://www.eia.gov/electricity/monthly/epm_table_grapher.php?t=epmt_6_07_b https://www.eia.gov/electricity/monthly/epm_table_grapher.ph...

war1025 7y ago

Our municipal power plant where I live converted from coal to natural gas recently. My understanding was the decision was based solely on the (now cancelled?) Clean Power Plan, and the inability to make the existing plant meet those regulations. Given the instability of US politics, I'd guess most utility companies are operating under the assumption that those laws could quickly be put back in place after any given election cycle.

jsight 7y ago
According to a utility in South Carolina (Santee Cooper): "Related to cost — in 2008, natural gas generation was as low as $55/MWh and coal was about $22/MWh in our most efficient units. In 2018, the comparable prices were $26/MWh for natural gas and $34/MWh for coal."
- hef19898 7y ago
  Thong in Germany is that CO2 certificates are so dirt cheap that the incremental cost of power generation puts coal plants second behind wind and solar with basically zero variable cost (I'd have to look up where hydro power stands). So gas effectively gets squeezed out of the market. The easy fix would be cutting the available CO2 certificates or making them more expensive. But for some reason that ain't happening.
  - war1025 7y ago
    Doesn't Germany get most of its natural gas from Russia, which is a bit contentious for political reasons?
    - hef19898 7y ago
      Well, yes. Still supply was stable. Not for Ukraine, so. Also a lot of the has is used for heating.
    - village-idiot 7y ago
      Yes. Fun fact, all of the natural gas that Germany bought from Russia used to flow through former Warsaw Pact nations like Poland. Now the gas goes at least partially through the undersea Nord Stream pipeline and the under construction Nord Stream 2. It's generally believed that this transition has made Russia much more bellicose in the region, as they can now threaten to turn off Poland's gas supply without also harming Western Europe at the same time.