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In every popular discussion advocating "renewable energy". Let's give it a spin. Given a solar operation that can produce 1MW continuous (under normal best co

In every popular discussion advocating "renewable energy". Let's give it a spin. Given a solar operation that can produce 1MW continuous (under normal best conditions, including buffering for night, angles, etc), what happens when it's seriously cloudy for a week? we need to continue that 1MW output for 7 days. That requires 168 MW/h of storage. That would require 800 Tesla PowerPacks, totaling $116,080,000. $116M just to make sure a 1MW provider (which really isn't much) can run a week with insufficient light (hey, sometimes it rains for a while). Then, if the storm continues another day, all the power goes out. To keep electricity on for just one more hour would require another 5 PowerPacks @ $725,500. What people don't seem to grasp about solar/wind + batteries is: when the battery is drained, you're done. No more electricity until the sun pops out again or the wind picks up enough, and no more buffer until those energy "buckets" can be refilled. At this point, optimistic advocates will jump up with "but smart grids!" Yeah, well, show me the numbers. Convince me the national cloud cover I saw a few weeks back (lasting a week) won't promptly shut down the "100% renewables" providers in short order, leaving (say) Chicago completely incapable to achieve the needed 100 degree differential between outdoors and in (that was a very cold week). The value of coal, nuclear, etc is that production keeps going regardless of weather. Renewable energy is absolutely subject to weather, and when the batteries run out, the lights go off.

1123581321 8y ago
I like that you are running these numbers. However, solar and wind will be overprovisioned when costs are low enough, so they will not run at capacity when the weather is sunny and breezy. Also, they do not provide zero output when it is cloudy or calm. Output should not drop from 100% to 0% in this example. The residential battery cost is significant, but should be broken out by home. A home generator would be more appropriate for several days of emergency power, just as now. These cost about $3,000. Anyone willing to buy a Tesla power pack should not find this cost objectionable. Also, I would not look at popular discussions such as the one we’re having as representative of government and private sector ability to plan renewable energy capacity.
- errantspark 8y ago
  If you're interested in some real world napkin math data points. I live off grid in the bay area and on the worst case rainy day around the solstice I made about 2/3 of the wattage of my solar array in watt hours. That day was in the worst week and I made about 7x the wattage of my solar array in watt hours over the course of the week. LiFePo4 storage cost me about $3/Wh including BMS, solar cost me about $0.7/W including charge controller.
imtringued 8y ago
You can also just turn on your gas plants (which produce less CO than coal plants) instead of using obsolete technologies like coal or nuclear that are not capable of load following. After this step you can start investing in infrastructure to create your own carbon neutral gas because you now have an oversupply of renewable energy.

1123581321 8y ago

I like that you are running these numbers. However, solar and wind will be overprovisioned when costs are low enough, so they will not run at capacity when the weather is sunny and breezy. Also, they do not provide zero output when it is cloudy or calm. Output should not drop from 100% to 0% in this example. The residential battery cost is significant, but should be broken out by home. A home generator would be more appropriate for several days of emergency power, just as now. These cost about $3,000. Anyone willing to buy a Tesla power pack should not find this cost objectionable. Also, I would not look at popular discussions such as the one we’re having as representative of government and private sector ability to plan renewable energy capacity.

errantspark 8y ago
If you're interested in some real world napkin math data points. I live off grid in the bay area and on the worst case rainy day around the solstice I made about 2/3 of the wattage of my solar array in watt hours. That day was in the worst week and I made about 7x the wattage of my solar array in watt hours over the course of the week. LiFePo4 storage cost me about $3/Wh including BMS, solar cost me about $0.7/W including charge controller.

imtringued 8y ago

You can also just turn on your gas plants (which produce less CO than coal plants) instead of using obsolete technologies like coal or nuclear that are not capable of load following. After this step you can start investing in infrastructure to create your own carbon neutral gas because you now have an oversupply of renewable energy.