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>now that solar energy is far cheaper than coal ever was I'm sorry, this is simply not true. Usually such claims are the result of ignoring two basic facts: F

>now that solar energy is far cheaper than coal ever was I'm sorry, this is simply not true. Usually such claims are the result of ignoring two basic facts: First, solar is only online 50% of the time, at most (in most regions, considerably less than 50%). That means that you need at a minimum twice the nameplate capacity for a solar plant than for a coal one. Second, being offline half the time means that you also need sufficient (very expensive!) storage capacity to cover the half the time that the solar plant is not working at all. In other words, to replace a 2GW conventional plant you're going to need at least 4GW worth of solar cells, plus 24 megawatt-hours of storage. If you have a source for reliable figures that take these factors into account, and still show solar being "far cheaper", please provide it. Edit: oh, and no woo-woo battery or solar cell technology that's not currently in mass production. Your statement was that it's "far cheaper" right now, not using future fantasy batteries or solar cells that may (or may not) be on the market in the future.

klipklop 2y ago
You nailed it. What do you do when you have cloud cover for two weeks in a row? It’s not unheard of when some areas have 200+ days of at least some cloud coverage. Nuclear is essential to avoid using coal and not having regional rolling blackouts due to weather. Solar alone is not realistic anytime soon in all regions of the US.
- toenail 2y ago
  > You nailed it. What do you do when you have cloud cover for two weeks in a row? Never mind the volcanic winter that seems to happen every few thousand years.
- bryanlarsen 2y ago
  Nuclear is a horrible complement to cheap intermittent renewables. Running it as a peaker multiples your costs and running it as base loads means selling power for negative prices when the sun is shining. Solar/wind plus batteries for short term storage and pumped hydro for long term storage is the cheapest way to get zero carbon energy. Pumped hydro is more expensive than fossil peakera so build out of that hasn't happened yet.
  - kragen 2y ago
    do you have a source on the pumped hydro costs? i thought it was cheaper, just impossible most places
    - bryanlarsen 2y ago
      Costs are high because gas peakers exist and pumped storage generally doesn't. For rarely used long term storage, capital costs dominate, and already built sites don't incur additional capital costs. All you need is a hill and some water for pumped storage. Those sites are very plentiful. https://scholar.google.co.uk/citations?view_op=view_citation&hl=en&user=XlGz2M4AAAAJ&citation_for_view=XlGz2M4AAAAJ:bnK-pcrLprsC https://scholar.google.co.uk/citations?view_op=view_citation...
      - kragen 2y ago
        oh, yeah, i was thinking of places where you already have a reservoir suitable for hydroelectric production, not places where you have to build a dam
  - wait_a_minute 2y ago
    How do you scale up to producing far more energy in that approach? What about the efficiency to produce large amounts of energy on large spacecraft and other planets and in the ocean?
    - kragen 2y ago
      are you asking how you scale up to producing far more energy with solar panels? world marketed energy consumption is about 18 terawatts, total terrestrial insolation is about 128000 terawatts, and current mainstream panels are about 23% efficient, so if you put solar panels on 50% of the earth's surface, you get 15000 terawatts, which is almost 1000 times more than the humans are using now. on the bottom of the ocean you probably need a different approach, maybe nuclear, or egs geothermal, or maybe running a cable up to the surface, or periodically receiving shipments of thermite in a submarine. some other planets will have no trouble with solar panels; others will need nuclear reactors
kragen 2y ago
no place has as high a capacity factor for solar pv as 50%; the world average is 14% (i.e., 14 watts average output per 100 watts nameplate output) and the country with the highest is egypt at 35% (this doesn't mean that you get zero power for 65% or 86% of the day. it means that you get lower than max power at all times except noon. to a great extent you can compensate by that by just installing more panels, but at night you need a better strategy) but the capacity factor is irrelevant to the fact that solar energy on the power grid generally sells for about half the price that coal-generated electricity sells for, on the same grid, when storage capacity is insufficient. in fact, prices used to go negative at night (to avoid shutting down slow-ramping baseload plants) and now they go negative in the day https://pv-magazine-usa.com/2020/05/28/record-low-solar-ppas-in-the-southwest-means-carbon-capture-is-not-going-to-save-coal-plants/ https://pv-magazine-usa.com/2020/05/28/record-low-solar-ppas... is an article from four years ago giving some specific prices: a solar ppa had just been signed for 15 dollars per megawatt hour, while the cost of production with coal at the san juan generating station was 44.90 dollars per megawatt hour, even though it was built right on top of a coal mine to save on shipping costs. that's why the san juan generating station has been decommissioned. if you look, you'll find stories like this all over the place, and solar panels now cost half of what they did when that story was written now, it's true that a ppa that includes battery storage will be more expensive than the 1.5¢ per kilowatt-hour ppa in that article. (https://emp.lbl.gov/pv-ppa-prices https://emp.lbl.gov/pv-ppa-prices has a queryable database of all the ppas signed in the usa, although the usa is less reliable as an indicator of true costs because of how its prices are artificially inflated by protectionist tariffs.) how much more expensive depends on how much utility-scale storage is needed; you suggest 12 hours, but a much more typical number in practice is 3–4 hours, partly because there are still coal plants and partly because electrical demand drops a lot at night also, you are incorrectly assuming that 'conventional' plants have a capacity factor of 100%, when a more typical capacity factor for a coal plant is 60% so let's consider a kind of worst case: replacing your suggested 2 gigawatts (nameplate) of coal plants in the usa, where construction costs are ridiculously inflated. before we swung the wrecking ball, those coal plants were generating 1.2 gigawatts (real) of power (10.5 billion kilowatt hours per year), so we need 1.2 gigawatts (real) of solar panels. in the usa the average capacity factor is 21% (the article i linked above is from an area with more sun than average) so that's 5.7 gigawatts peak. typical costs for utility-scale fixed-tilt solar plants in q1 02024 were 98¢ per peak watt https://www.seia.org/research-resources/solar-market-insight-report-q2-2024 https://www.seia.org/research-resources/solar-market-insight... including costs like permitting, design and engineering, etc. so that's 5.6 billion dollars. utility bond yields in the usa are currently at 4.35%, and often these things are amortized over 25 years. i think the amortization calculation is that you have to pay 372 million dollars a year, which works out to 3.5¢ per kilowatt hour or 35 dollars per megawatt hour. definitely too cheap for coal to compete with, but still a lot more expensive than the price that ppa came in at so, suppose we need 4 hours of storage for our 1.2 gigawatts. that's 4800 megawatt hours. six months ago lithium-ion batteries have fallen precipitously to 139 dollars per kilowatt hour https://about.bnef.com/blog/lithium-ion-battery-pack-prices-hit-record-low-of-139-kwh/ https://about.bnef.com/blog/lithium-ion-battery-pack-prices-... so we need to spend another 670 million dollars on the batteries, which adds about 12% to the cost of the project. except that in real life you need more than just a pile of batteries, you need to pour concrete and run wires and connect inverters and so on. and the batteries won't last 25 years, maybe 8, so you have to amortize this capex over a much shorter period. but it should be clear that this is not a crushing cost that dwarfs the cost of the solar farm (theoretically lead-acid might be cheaper by a factor of 1.5 or 2 or so, but lithium-ion's advantages seem to have driven it out of the utility-scale market) aha, here we go. https://atb.nrel.gov/electricity/2023/utility-scale_battery_storage https://atb.nrel.gov/electricity/2023/utility-scale_battery_... says that a 4-hour 60-megawatt lithium-ion battery system costs 446 dollars per kilowatt hour and has 240 megawatt hours of storage. so our required 4800 megawatt hours cost 2 billion dollars. that's about three times the cost estimate above for just the batteries, but that's an estimate from before the batteries dropped in cost by half, so 1.3 billion dollars is a better estimate. this plus the 5.6 billion dollars for the solar plant gives us a total up-front cost of 6.9 billion dollars since it's getting late, i'll just link you to this four-year-old profile of a ppa for 20 dollars a megawatt hour for generation plus 20 dollars a megawatt hour for storage https://www.energy-storage.news/battery-storage-at-us20-mwh-breaking-down-low-cost-solar-plus-storage-ppas-in-the-usa/ https://www.energy-storage.news/battery-storage-at-us20-mwh-... and this lawrence radiation lab brief https://eta-publications.lbl.gov/sites/default/files/utility-scale_solar_2022_technical_brief.pdf https://eta-publications.lbl.gov/sites/default/files/utility... the main reason for the difference seems to be how sunny the location is; the technical brief explains: > Aided by the ITC, most recent PPAs in our sample are priced around $20/MWh (on a levelized basis, expressed in real 2021 dollars, and including bundled energy, capacity, and RECs) for plants located in the West, and $30-$40/MWh for plants elsewhere in the continental United States. the itc is a subsidy, so the real cost is a bit higher (due to the tariffs)

klipklop 2y ago

You nailed it. What do you do when you have cloud cover for two weeks in a row? It’s not unheard of when some areas have 200+ days of at least some cloud coverage. Nuclear is essential to avoid using coal and not having regional rolling blackouts due to weather. Solar alone is not realistic anytime soon in all regions of the US.

toenail 2y ago
> You nailed it. What do you do when you have cloud cover for two weeks in a row? Never mind the volcanic winter that seems to happen every few thousand years.
bryanlarsen 2y ago
Nuclear is a horrible complement to cheap intermittent renewables. Running it as a peaker multiples your costs and running it as base loads means selling power for negative prices when the sun is shining. Solar/wind plus batteries for short term storage and pumped hydro for long term storage is the cheapest way to get zero carbon energy. Pumped hydro is more expensive than fossil peakera so build out of that hasn't happened yet.
- kragen 2y ago
  do you have a source on the pumped hydro costs? i thought it was cheaper, just impossible most places
  - bryanlarsen 2y ago
    Costs are high because gas peakers exist and pumped storage generally doesn't. For rarely used long term storage, capital costs dominate, and already built sites don't incur additional capital costs. All you need is a hill and some water for pumped storage. Those sites are very plentiful. https://scholar.google.co.uk/citations?view_op=view_citation&hl=en&user=XlGz2M4AAAAJ&citation_for_view=XlGz2M4AAAAJ:bnK-pcrLprsC https://scholar.google.co.uk/citations?view_op=view_citation...
    - kragen 2y ago
      oh, yeah, i was thinking of places where you already have a reservoir suitable for hydroelectric production, not places where you have to build a dam
- wait_a_minute 2y ago
  How do you scale up to producing far more energy in that approach? What about the efficiency to produce large amounts of energy on large spacecraft and other planets and in the ocean?
  - kragen 2y ago
    are you asking how you scale up to producing far more energy with solar panels? world marketed energy consumption is about 18 terawatts, total terrestrial insolation is about 128000 terawatts, and current mainstream panels are about 23% efficient, so if you put solar panels on 50% of the earth's surface, you get 15000 terawatts, which is almost 1000 times more than the humans are using now. on the bottom of the ocean you probably need a different approach, maybe nuclear, or egs geothermal, or maybe running a cable up to the surface, or periodically receiving shipments of thermite in a submarine. some other planets will have no trouble with solar panels; others will need nuclear reactors

kragen 2y ago

no place has as high a capacity factor for solar pv as 50%; the world average is 14% (i.e., 14 watts average output per 100 watts nameplate output) and the country with the highest is egypt at 35% (this doesn't mean that you get zero power for 65% or 86% of the day. it means that you get lower than max power at all times except noon. to a great extent you can compensate by that by just installing more panels, but at night you need a better strategy) but the capacity factor is irrelevant to the fact that solar energy on the power grid generally sells for about half the price that coal-generated electricity sells for, on the same grid, when storage capacity is insufficient. in fact, prices used to go negative at night (to avoid shutting down slow-ramping baseload plants) and now they go negative in the day https://pv-magazine-usa.com/2020/05/28/record-low-solar-ppas-in-the-southwest-means-carbon-capture-is-not-going-to-save-coal-plants/ https://pv-magazine-usa.com/2020/05/28/record-low-solar-ppas... is an article from four years ago giving some specific prices: a solar ppa had just been signed for 15 dollars per megawatt hour, while the cost of production with coal at the san juan generating station was 44.90 dollars per megawatt hour, even though it was built right on top of a coal mine to save on shipping costs. that's why the san juan generating station has been decommissioned. if you look, you'll find stories like this all over the place, and solar panels now cost half of what they did when that story was written now, it's true that a ppa that includes battery storage will be more expensive than the 1.5¢ per kilowatt-hour ppa in that article. (https://emp.lbl.gov/pv-ppa-prices https://emp.lbl.gov/pv-ppa-prices has a queryable database of all the ppas signed in the usa, although the usa is less reliable as an indicator of true costs because of how its prices are artificially inflated by protectionist tariffs.) how much more expensive depends on how much utility-scale storage is needed; you suggest 12 hours, but a much more typical number in practice is 3–4 hours, partly because there are still coal plants and partly because electrical demand drops a lot at night also, you are incorrectly assuming that 'conventional' plants have a capacity factor of 100%, when a more typical capacity factor for a coal plant is 60% so let's consider a kind of worst case: replacing your suggested 2 gigawatts (nameplate) of coal plants in the usa, where construction costs are ridiculously inflated. before we swung the wrecking ball, those coal plants were generating 1.2 gigawatts (real) of power (10.5 billion kilowatt hours per year), so we need 1.2 gigawatts (real) of solar panels. in the usa the average capacity factor is 21% (the article i linked above is from an area with more sun than average) so that's 5.7 gigawatts peak. typical costs for utility-scale fixed-tilt solar plants in q1 02024 were 98¢ per peak watt https://www.seia.org/research-resources/solar-market-insight-report-q2-2024 https://www.seia.org/research-resources/solar-market-insight... including costs like permitting, design and engineering, etc. so that's 5.6 billion dollars. utility bond yields in the usa are currently at 4.35%, and often these things are amortized over 25 years. i think the amortization calculation is that you have to pay 372 million dollars a year, which works out to 3.5¢ per kilowatt hour or 35 dollars per megawatt hour. definitely too cheap for coal to compete with, but still a lot more expensive than the price that ppa came in at so, suppose we need 4 hours of storage for our 1.2 gigawatts. that's 4800 megawatt hours. six months ago lithium-ion batteries have fallen precipitously to 139 dollars per kilowatt hour https://about.bnef.com/blog/lithium-ion-battery-pack-prices-hit-record-low-of-139-kwh/ https://about.bnef.com/blog/lithium-ion-battery-pack-prices-... so we need to spend another 670 million dollars on the batteries, which adds about 12% to the cost of the project. except that in real life you need more than just a pile of batteries, you need to pour concrete and run wires and connect inverters and so on. and the batteries won't last 25 years, maybe 8, so you have to amortize this capex over a much shorter period. but it should be clear that this is not a crushing cost that dwarfs the cost of the solar farm (theoretically lead-acid might be cheaper by a factor of 1.5 or 2 or so, but lithium-ion's advantages seem to have driven it out of the utility-scale market) aha, here we go. https://atb.nrel.gov/electricity/2023/utility-scale_battery_storage https://atb.nrel.gov/electricity/2023/utility-scale_battery_... says that a 4-hour 60-megawatt lithium-ion battery system costs 446 dollars per kilowatt hour and has 240 megawatt hours of storage. so our required 4800 megawatt hours cost 2 billion dollars. that's about three times the cost estimate above for just the batteries, but that's an estimate from before the batteries dropped in cost by half, so 1.3 billion dollars is a better estimate. this plus the 5.6 billion dollars for the solar plant gives us a total up-front cost of 6.9 billion dollars since it's getting late, i'll just link you to this four-year-old profile of a ppa for 20 dollars a megawatt hour for generation plus 20 dollars a megawatt hour for storage https://www.energy-storage.news/battery-storage-at-us20-mwh-breaking-down-low-cost-solar-plus-storage-ppas-in-the-usa/ https://www.energy-storage.news/battery-storage-at-us20-mwh-... and this lawrence radiation lab brief https://eta-publications.lbl.gov/sites/default/files/utility-scale_solar_2022_technical_brief.pdf https://eta-publications.lbl.gov/sites/default/files/utility... the main reason for the difference seems to be how sunny the location is; the technical brief explains: > Aided by the ITC, most recent PPAs in our sample are priced around $20/MWh (on a levelized basis, expressed in real 2021 dollars, and including bundled energy, capacity, and RECs) for plants located in the West, and $30-$40/MWh for plants elsewhere in the continental United States. the itc is a subsidy, so the real cost is a bit higher (due to the tariffs)