3 ms·

Where are you getting 250 milliseconds and needing 15,000 from? Wikipedia claims US yearly electricity consumption is 4,090 TWh, and Bath County stores 24 TWh,

Where are you getting 250 milliseconds and needing 15,000 from? Wikipedia claims US yearly electricity consumption is 4,090 TWh, and Bath County stores 24 TWh, with a generation capacity of 3,003 MW. That comes out as enough storage for a couple of days worth of US electricity use. Obviously you'd need 3 more to cover generation capacity.

xyzzyz 7y ago
Ah, I rechecked, I actually lost 2 orders of magnitude. It's 25 seconds, not 250 milliseconds. However, you lost 3 orders of magnitude: Bath County is 24 GWh, not TWh. My calculation was done under assumption of 101 quads of annual US energy use, but I'll redo this calculation with assumption more charitable to your argument. US uses only 4090 TWh worth of electricity, which is about 13 quads, but it also uses about 70 quads of energy in other forms than electricity. See the breakdown at [1]. Let's assume that moving to all-electric world reduces the transportation energy use by half. In all electric world, the 25 quads we waste to generate electricity also vanish. Thus, the annual US energy needs is 101 - 25 - 14 = 62 quads, assuming we can increase efficiency by replacing majority of heat engines with electric engines. Putting this in Wolfram Alpha[2] gives you about 40 seconds. So, now we need about 100 pumped hydro plants of the same size as largest one energy storage facility in existence, to cover 1 hour of US energy use (I'm ignoring of course the problem of not enough generating capacity to convert that storage to electricity fast enough as needed). Where are you going to build them? Where are you going to take water from? [1] - https://www.eia.gov/energyexplained//us-energy-facts/ https://www.eia.gov/energyexplained//us-energy-facts/ [2] - https://www.wolframalpha.com/input/?i=%2824GWh%2F62+quads%2Fyear%29+to+seconds https://www.wolframalpha.com/input/?i=%2824GWh%2F62+quads%2F...
- flukus 7y ago
  > So, now we need about 100 pumped hydro plants of the same size as largest one energy storage facility in existence There are about 70 > 1MW pumped storage stations around the world already, with 40 more planned (https://en.wikipedia.org/wiki/List_of_pumped-storage_hydroelectric_power_stations https://en.wikipedia.org/wiki/List_of_pumped-storage_hydroel...), mostly in China. These are just glorified dams and as far as dams go they're tiny, so scaling up (and maybe down too) isn't an issue, there are an estimated 84,000 dams already in the United States. At ~$4 bilion dollars to build 100 of them would come in at the cost of about 1/3 the F-35 program and deliver much more national security. So it's entirely feasible to have enough pumped hydro storage to cover this mythical scenario of a continent having no wind for an hour.
  - xyzzyz 7y ago
    Your comment doesn’t answer any of my questions. Where are you going to build 100 dams with enough water to store gigawathours worth of electricity? The problem with massive projects like that is that you simply cannot build them just about anywhere.
    - flukus 7y ago
      You can build them just about anywhere, all you need is a tiny amount of land area for the reservoirs enough of a vertical gradient. There are large mountain ranges running down both coasts with more than enough space to accommodate this. Looking at the surrounding geography of the bath county installation alone looks like it could easily be scaled to 10 times it's current size.
- NeedMoreTea 7y ago
  Oops, seems my split second skim of Wikipedia was a shortcut too far. :) I had to look up a quad (a short-scale quadrillion BTU). Haven't come across British Thermal Units in Britain for decades! Anyway. 100 of that scale might be better or easier as 1,000 smaller capacity, but even then we can reduce further. Some percentage of the grid is nuclear (roughly 20% of US electric) which would not need underwriting nor would 100% of continental wind power ever be becalmed. I would further assume that any concerted national effort to electrify carbon neutrally would come with a matching efficiency drive - insulation, tax inefficient users, take first steps toward a national grid (that TIL the US apparently does not have), etc to allow you to use the power you have rather better. Yet ignoring all that, the US must have thousands or tens of thousands of disused mines and quarries, probably many open ones with an accidental lake in their place that could be repurposed. If there's adequate volume, you don't need much head of water. There's no shortage of hills and mountains with rainfall or snow melt that should give plenty of potential spots, population and environment permitting. The one thing America does not lack is space - of all terrain types.
- cm2187 7y ago
  Plus with a lot of intra day seasonability.

xyzzyz 7y ago

Ah, I rechecked, I actually lost 2 orders of magnitude. It's 25 seconds, not 250 milliseconds. However, you lost 3 orders of magnitude: Bath County is 24 GWh, not TWh. My calculation was done under assumption of 101 quads of annual US energy use, but I'll redo this calculation with assumption more charitable to your argument. US uses only 4090 TWh worth of electricity, which is about 13 quads, but it also uses about 70 quads of energy in other forms than electricity. See the breakdown at [1]. Let's assume that moving to all-electric world reduces the transportation energy use by half. In all electric world, the 25 quads we waste to generate electricity also vanish. Thus, the annual US energy needs is 101 - 25 - 14 = 62 quads, assuming we can increase efficiency by replacing majority of heat engines with electric engines. Putting this in Wolfram Alpha[2] gives you about 40 seconds. So, now we need about 100 pumped hydro plants of the same size as largest one energy storage facility in existence, to cover 1 hour of US energy use (I'm ignoring of course the problem of not enough generating capacity to convert that storage to electricity fast enough as needed). Where are you going to build them? Where are you going to take water from? [1] - https://www.eia.gov/energyexplained//us-energy-facts/ https://www.eia.gov/energyexplained//us-energy-facts/ [2] - https://www.wolframalpha.com/input/?i=%2824GWh%2F62+quads%2Fyear%29+to+seconds https://www.wolframalpha.com/input/?i=%2824GWh%2F62+quads%2F...

flukus 7y ago
> So, now we need about 100 pumped hydro plants of the same size as largest one energy storage facility in existence There are about 70 > 1MW pumped storage stations around the world already, with 40 more planned (https://en.wikipedia.org/wiki/List_of_pumped-storage_hydroelectric_power_stations https://en.wikipedia.org/wiki/List_of_pumped-storage_hydroel...), mostly in China. These are just glorified dams and as far as dams go they're tiny, so scaling up (and maybe down too) isn't an issue, there are an estimated 84,000 dams already in the United States. At ~$4 bilion dollars to build 100 of them would come in at the cost of about 1/3 the F-35 program and deliver much more national security. So it's entirely feasible to have enough pumped hydro storage to cover this mythical scenario of a continent having no wind for an hour.
- xyzzyz 7y ago
  Your comment doesn’t answer any of my questions. Where are you going to build 100 dams with enough water to store gigawathours worth of electricity? The problem with massive projects like that is that you simply cannot build them just about anywhere.
  - flukus 7y ago
    You can build them just about anywhere, all you need is a tiny amount of land area for the reservoirs enough of a vertical gradient. There are large mountain ranges running down both coasts with more than enough space to accommodate this. Looking at the surrounding geography of the bath county installation alone looks like it could easily be scaled to 10 times it's current size.
NeedMoreTea 7y ago
Oops, seems my split second skim of Wikipedia was a shortcut too far. :) I had to look up a quad (a short-scale quadrillion BTU). Haven't come across British Thermal Units in Britain for decades! Anyway. 100 of that scale might be better or easier as 1,000 smaller capacity, but even then we can reduce further. Some percentage of the grid is nuclear (roughly 20% of US electric) which would not need underwriting nor would 100% of continental wind power ever be becalmed. I would further assume that any concerted national effort to electrify carbon neutrally would come with a matching efficiency drive - insulation, tax inefficient users, take first steps toward a national grid (that TIL the US apparently does not have), etc to allow you to use the power you have rather better. Yet ignoring all that, the US must have thousands or tens of thousands of disused mines and quarries, probably many open ones with an accidental lake in their place that could be repurposed. If there's adequate volume, you don't need much head of water. There's no shortage of hills and mountains with rainfall or snow melt that should give plenty of potential spots, population and environment permitting. The one thing America does not lack is space - of all terrain types.
cm2187 7y ago
Plus with a lot of intra day seasonability.